Waste-wood-derived biochar cathode and its application in electro-Fenton for sulfathiazole treatment at alkaline pH with pyrophosphate electrolyte

Preparation of functionalized porous chitin carbon to enhance the H2O2 production and Fe3+ reduction properties of Electro-Fenton cathodes for efficient degradation of RhB

The performance of Electro-Fenton (EF) cathode materials is primarily assessed by H2O2 yield and Fe3+ reduction efficiency. This study explores the impact of pore structure in chitin-based porous carbon on EF cathode effectiveness. We fabricated mesoporous carbon (CPC-700-2) and microporous carbon (ZPC-700-3) using template and activation methods, retaining nitrogen from the precursors. CPC-700-2, with mesopores (3-5 nm), enhanced O2 diffusion and oxygen reduction, producing up to 778 mg/L of H2O2 in 90 min. ZPC-700-3, with a specific surface area of 1059.83 m2/g, facilitated electron transport and ion diffusion, achieving a Fe2+/Fe3+ conversion rate of 79.9%. EF systems employing CPC-700-2 or ZPC-700-3 as the cathode exhibited superior degradation performance, achieving 99% degradation of Rhodamine B, efficient degradation, and noticeable decolorization. This study provides a reference for the preparation of functionalized carbon cathode materials for efficient H2O2 production and effective Fe3+ reduction in EF systems.

Removal of tetracycline in the water by a kind of S/N co-doped tea residue biochar

Tetracycline (TC) is widely present in the environment, and adsorption technology is a potential remediation method. S/N co-doped tea residue biochar (SNBC) was successfully prepared by hydrothermal carbonization method using tea residue as raw material. S was doped by Na2S2O3·5H2O, and N was doped by N in tea residue. The adsorption efficiency of SNBC could reach 94.16% when the concentration of TC was 100 mg L-1. The adsorption effect of SNBC on TC was 9.38 times more than that of unmodified biochar. Tea biochar had good adsorption effect at pH 4-9. The maximum adsorption capacity of 271 mg g-1 was calculated by the Langmuir isotherm model. The adsorption mechanism involved many mechanisms such as pore filling, π-π interaction and hydrogen bonding. The adsorbent prepared in this study could be used as an effective adsorbent in the treatment of TC wastewater.

Antibiotic Degradation via Fenton Process Assisted by a 3-Electron Oxygen Reduction Reaction Pathway Catalyzed by Bio-Carbon-Manganese Composites

Bio-carbon-manganese composites obtained from olive mill wastewater were successfully prepared using manganese acetate as the manganese source and olive wastewater as the carbon precursor. The samples were characterized chemically and texturally by N2 and CO2 adsorption at 77 K and 273 K, respectively, by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. Electrochemical characterization was carried out by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The samples were evaluated in the electro-Fenton degradation of tetracycline in a typical three-electrode system under natural conditions of pH and temperature (6.5 and 25 °C). The results show that the catalysts have a high catalytic power capable of degrading tetracycline (about 70%) by a three-electron oxygen reduction pathway in which hydroxyl radicals are generated in situ, thus eliminating the need for two catalysts (ORR and Fenton).

Unlocking the potential of magnetic biochar in wastewater purification: a review on the removal of bisphenol A from aqueous solution

Bisphenol A (BPA) is an essential and extensively utilized chemical compound with significant environmental and public health risks. This review critically assesses the current water purification techniques for BPA removal, emphasizing the efficacy of adsorption technology. Within this context, we probe into the synthesis of magnetic biochar (MBC) using co-precipitation, hydrothermal carbonization, mechanical ball milling, and impregnation pyrolysis as widely applied techniques. Our analysis scrutinizes the strengths and drawbacks of these techniques, with pyrolytic temperature emerging as a critical variable influencing the physicochemical properties and performance of MBC. We explored various modification techniques including oxidation, acid and alkaline modifications, element doping, surface functional modification, nanomaterial loading, and biological alteration, to overcome the drawbacks of pristine MBC, which typically exhibits reduced adsorption performance due to its magnetic medium. These modifications enhance the physicochemical properties of MBC, enabling it to efficiently adsorb contaminants from water. MBC is efficient in the removal of BPA from water. Magnetite and maghemite iron oxides are commonly used in MBC production, with MBC demonstrating effective BPA removal fitting well with Freundlich and Langmuir models. Notably, the pseudo-second-order model accurately describes BPA removal kinetics. Key adsorption mechanisms include pore filling, electrostatic attraction, hydrophobic interactions, hydrogen bonding, π-π interactions, and electron transfer surface interactions. This review provides valuable insights into BPA removal from water using MBC and suggests future research directions for real-world water purification applications.

A sustainable activated carbon fiber/TiO2 cathode for the photoelectro-Fenton treatment of pharmaceutical pollutant enalapril

In this work, a TiO2-decorated electrode was fabricated by dip coating activated carbon fibers (ACF) with TiO2, which were then used as a cathode for the photoelectro-Fenton (PEF) treatment of the pharmaceutical enalapril, an angiotensin-converting enzyme inhibitor that has been detected in several waterways. The TiO2 coating was found to principally improve the electrocatalytic properties of ACF for H2O2 production via the 2-e- O2 reduction, in turn increasing enalapril degradation by PEF. The effect of the current density on the mineralization of enalapril was evaluated and the highest TOC removal yield (80.5% in 3 h) was obtained at 8.33 mA cm-2, in the presence of 0.5 mmol L-1 of Fe2+ catalyst. Under those conditions, enalapril was totally removed within the first 10 min of treatment with a rate constant k = 0.472 min-1. In contrast, uncoated ACF only achieved 60% of TOC removal in 3 h at 8.33 mA cm-2. A degradation pathway for enalapril mineralization is proposed, based on the degradation by-products identified during treatment. Overall, the results demonstrate the promises of TiO2 cathodes for PEF, a strategy that has often been overlooked in favor of photoelectrocatalysis (PEC) based on TiO2-modified photoanodes.

One-step self-assembly of Fe-biochar composite for enhanced persulfate activation to phenol degradation: Different active sites-induced radical/non-radical mechanism

Persulfate (PS) activation by nanoscale zerovalent iron (nZVI) is promising for water purification, while is limited due to its easy agglomeration and oxidation. Herein, nZVI encapsuled in carbon matrix shell was synthesized via one-step carbothermal reduction. The core-shell structure effectively inhibited oxidation and agglomeration of nZVI core, and graphitized porous structures facilitated phenol binding with maximal adsorption capacity of 117.10 mg/g achieved by nZVI_0.6-BC₈₀₀. Both reactive oxygen species (SO₄^•-, O•H, O₂^•- and ¹O₂) and electron transfer process resulted in phenol decomposition. Owing to diversified active sites, the nZVI_0.6-BC₈₀₀/PS system could completely degrade phenol degradation within short time, and exhibited great adaptation to extensive pH range (3.0-9.0) and coexisting substances. Additionally, the nZVI_0.6-BC₈₀₀/PS system could maintain over 85% removal of phenol after three recycles or 50 days of storage, and was highly-efficient to different water environments, thus proposing rational design of iron-carbon catalyst with potential in water treatment.

Highly selective electrosynthesis of H2O2 by N, O co-doped graphite nanosheets for efficient electro-Fenton degradation of p-nitrophenol

The activity and selectivity of the cathode towards electrosynthesis of H₂O₂ are critical for electro-Fenton process. Herein, nickel-foam modified with N, O co-doped graphite nanosheets (NO-GNSs/Ni-F) was developed as a cathode for highly efficient and selective electrosynthesis of H₂O₂. Expectedly, the accumulation of H₂O₂ at pH= 3 reached 494.2 mg L^-1 h^-1, with the selectivity toward H₂O₂ generation reaching 93.0%. The synergistic effect of different oxygen-containing functional groups and N species on the performance and selectivity of H₂O₂ electrosynthesis was investigated by density functional theory calculations, and the combination of epoxy and graphitic N (EP + N) was identified as the most favorable configuration with the lowest theoretical overpotential for H₂O₂ generation. Moreover, NO-GNSs/Ni-F was applied in the electro-Fenton process for p-nitrophenol degradation, resulting in 100% removal within 15 min with the kinetic rate constant of 0.446 min^-1 and 97.6% mineralization within 6 h. The efficient removal was mainly attributed to the generation of bulk ·OH. Furthermore, NO-GNSs/Ni-F exhibited excellent stability. This work provides a workable option for the enhancement of H₂O₂ accumulation and the efficient degradation of pollutants in electro-Fenton system.

Three-dimensional structured electrode for electrocatalytic organic wastewater purification: Design, mechanism and role

Considering the growing need in decentralized water treatment, the application of electrocatalytic processes (EP) to achieve organic wastewater purification will be dominant in the near future due to high efficiency, small reactor assembly as well as the flexibility of operation and management. The catalytic performance of electrode materials determines the development of this technology. Among them, the unique three-dimensional (3D) structure electrode shows better performance than two-dimensional (2D) electrode in increasing mass transfer, enhancing adsorption and exposing more active sites. Hence, this review starts with the introduction of definition, classification, advantages and disadvantages of 3D electrode materials. Then a critical discussion on the design and construction of 3D electrode materials for organic wastewater purification application is provided. Next, the removal mechanism of organic pollutants on the surface of 3D electrode, the role of 3D structure, the design of reactor with 3D electrode, the conversion and toxicity of degradation products, electrode energy efficiency, stability and cost, are comprehensively reviewed. At last, current challenges and future perspectives for the development of 3D electrode materials are addressed. We deem that this review will provide a valuable insight into the design and application of 3D electrodes in environmental water purification.

Novel magnetic graphoxide/biochar composite derived from tea for multiple SAs and QNs antibiotics removal in water

Antibiotics pollution is an urgent public health issue. Biochar is a kind of promising composite for removal antibiotic in aqueous environment. In this study, a novel magnetic graphoxide/biochar composite (mGO/TBC) was synthesized by simple impregnation method and used as an efficient and recyclable persulfate (PS) activator for degradation and removal of sulfonamides (SAs) and quinolones (QNs) antibiotics. Based on the synergism pre-adsorption and degradation between graphoxide and biochar, the removal rates of mGO/TBC on sarafloxacin hydrochloride, sulfadimethoxine, sulfapyridine, sulfadoxine, sulfamonomethoxine, sulfachloropyridazine, enrofloxacin, and ciprofloxacin were increased above 95%. Moreover, the mGO/TBC could be reused at least seven times after degradation-recovery cycles. Quenching experiment and ESR analysis proved that ¹O₂, ^•OH, and SO₄^•- from mGO/TBC/PS system were the primary oxidation active species to degrade SAs and QNs. It is a promising substrate for antibiotic bioremediation with good application prospects.

State-of-the-art review and bibliometric analysis on electro-Fenton process

The electro-Fenton (EF) process was first proposed in 1996 and, since then, considerable development has been achieved for its application in wastewater treatment, especially at lab and pilot scale. After more than 25 years, the high efficiency, versatility and environmental compatibility of EF process has been demonstrated. In this review, bibliometrics has been adopted as a tool that allows quantifying the development of EF as well as introducing some useful correlations. As a result, information is summarized in a more visual manner that can be easily analyzed and interpreted as compared to conventional reviewing. During the recent decades under review, 83 countries have contributed to the dramatic growth of EF publications, with China, Spain and France leading the publication output. The top 12 most cited articles, along with the top 32 most productive authors in the EF field, have been screened. Four stages have been identified as main descriptors of the development of EF throughout these years, being each stage characterized by relevant breakthroughs. To conclude, a general cognitive model for the EF process is proposed, including atomic, microscopic and macroscopic views, and future perspectives are discussed.

Hydrothermal carbonization of alfalfa: role of processing variables on hydrochar properties

Hydrothermal carbonization of alfalfa is a potential way to reuse agricultural waste. However, the effects of hydrothermal conditions on the properties of alfalfa-derived hydrochar are not clear. Herein, this study investigated the impact of different synthesis conditions (e.g., heating temperature, heating time, and solid to liquid ratio) on the formation and properties of hydrochar. Characterization and thermogravimetric analysis results revealed that with the increase of hydrothermal temperature and the extension of time, cellulose in alfalfa broken down more completely, and the number of carbon spheres and the aromatization degree increased, while the functional groups decreased. Furthermore, there was a surge in the carbon content, fixed carbon yield, high heating value, reduced oxygen, and volatile content. Additionally, the enhancement solid-liquid ratio could effectively improve the energy and mass yields. In all, by adjusting the process parameters of hydrochar, cleaner and higher productivity products could be obtained. This study provides theory basis for the production of target hydrochar that is used to soil amendments, adsorbents, and energy sources in the future.

One-pot synthesis of porous N-doped hydrochar for atrazine removal from aqueous phase: Co-activation and adsorption mechanisms

KOH-activated N-doped hydrochar (KHCN) was synthesized via co-activation method to eliminate atrazine (AT) in water efficiently. Compared to primitive HC, KHCN had advantages of splendid specific surface area (1205.82 m2/g) and developed microsphere structures on the surface. Specially for KHCN, the extra melamine added strengthened and preserved partial structure of polar oxygen-containing groups that were decomposed in the process of pore making. Besides, the estimated uptake amount of AT onto KHCN (216.50 mg/g) was remarkably superior to KHC (114.25 mg/g). KHCN exhibited the pH-dependence for AT removal, and presented excellent uptake capacity at a relatively neutral environment. Notably, the proposed mechanisms for AT removal by KHCN included electrostatic attraction, pore filling, π-π EDA, H-bond as well as hydrophilic effect. Hence, the porous N-doped hydrochar was a kind of adsorbent which was easy to prepare and had the application prospect for AT removal in natural water.

One-step preparation of Fe/N co-doped porous biochar for chromium(VI) and bisphenol a decontamination in water: Insights to co-activation and adsorption mechanisms

Herein, magnetic nitrogen doped porous biochar (Fe/N-PBC) was prepared by mixing KHCO₃, K₂FeO₄ and CO(NH₂)₂ through one-step pyrolysis, and was employed for adsorbing Cr(VI) and BPA in water. The whole co-activated process was accompanied with pore-forming, carbon thermal reduction and element doping. Specifically, the developed microporous structures and high surface area of Fe/N-PBC (1093.68 m²/g) were achieved under synergistic activation of KHCO₃ and K₂FeO₄. Meanwhile, carbon thermal reduction process successfully converted K₂FeO₄ to Fe⁰ with introduction of heterocyclic-N (pyrrolic N and pyridinic N) structures by CO(NH₂)₂ doping. Fe/N-PBC exhibited outstanding uptake for Cr(VI) (340.96 mg/g) and BPA (355.14 mg/g), and possessed favorable regeneration properties after three cycles. Notably, the high-performance Cr(VI) removal was associated to reduction, electrostatic interaction, complexation, pore filling and ion exchange, while pore filling, hydrogen-bonding interaction and π-π stacking were responsible for BPA binding. This work presents reasonable design of Fe/N-carbon materials for Cr(VI)/BPA polluted water remediation.

Supramolecular Self-Assembly Strategy towards Fabricating Mesoporous Nitrogen-Rich Carbon for Efficient Electro-Fenton Degradation of Persistent Organic Pollutants

The electro-Fenton (EF) process is regarded as an efficient and promising sewage disposal technique for sustainable water environment protection. However, current developments in EF are largely restricted by cathode electrocatalysts. Herein, a supramolecular self-assembly strategy is adopted for synthetization, based on melamine-cyanuric acid (MCA) supramolecular aggregates integrated with carbon fixation using 5-aminosalicylic acid and zinc acetylacetonate hydrate. The prepared carbon materials characterize an ordered lamellar microstructure, high specific surface area (595 m2 g-1), broad mesoporous distribution (4~33 nm) and high N doping (19.62%). Such features result from the intrinsic superiority of hydrogen-bonded MCA supramolecular aggregates via the specific molecular assembly process. Accordingly, noteworthy activity and selectivity of H2O2 production (~190.0 mg L-1 with 2 h) are achieved. Excellent mineralization is declared for optimized carbon material in several organic pollutants, namely, basic fuchsin, chloramphenicol, phenol and several mixed triphenylmethane-type dyestuffs, with total organic carbon removal of 87.5%, 74.8%, 55.7% and 54.2% within 8 h, respectively. This work offers a valuable insight into facilitating the application of supramolecular-derived carbon materials for extensive EF degradation.

Pinecone-derived magnetic porous hydrochar co-activated by KHCO3 and K2FeO4 for Cr(VI) and anthracene removal from water

Herein, magnetic porous pinecone-derived hydrochar (MPHC_MW) co-activated by KHCO₃ and K₂FeO₄ through one-step microwave-assisted pyrolysis was innovatively synthesized for hexavalent chromium (Cr(VI)) and anthracene (ANT) removal from water. The analyses of characterization consequences and co-activation mechanisms not merely proved the high specific surface area (703.97 m²/g) and remarkable microporous structures of MPHC_MW caused by the synergistic chemical activation of KHCO₃ and K₂FeO₄, but also testified successful loading of Fe⁰ and Fe₃O₄ on MPHC_MW by the process of carbothermal reduction between K₂FeO₄ and carbon matrix of hydrochar. The resultant MPHC_MW possessed pH-dependence for Cr(VI), while adsorption for ANT was hardly impacted by the pH of solution. Moreover, the adsorption processes of MPHC_MW could attain equilibrium within 60 min for Cr(VI) and 30 min for ANT with multiple kinetics, and the corresponding adsorption capacity for Cr(VI) and ANT was 128.15 and 60.70 mg/g, respectively. Additionally, the adsorption percentages of MPBC_MW for Cr(VI)/ANT was maintained at 87.87/82.64% after three times of adsorption-desorption cycles. Furthermore, pore filling, complexation, electrostatic interaction, reduction and ion exchange were testified to enhance the removal of Cr(VI), while the ANT removal was achieved via π-π stacking, complexation, pore filling and hydrogen bonding force.

Sulfidised nanoscale zerovalent iron-modified pitaya peel-derived carbon for enrofloxacin degradation and swine wastewater treatment: Combination of electro-Fenton and bio-electro-Fenton process

In this study, a new Fenton system combining electro-Fenton and bio-electro-Fenton (EF-BEF) processes was proposed for ENR degradation and swine wastewater treatment, and pitaya peel-derived carbon modified with sulfidised nanoscale zerovalent iron (SnZVI) was developed as a catalyst for the system. The as-prepared PPC-800 carbon displayed a hierarchical porous structure (693.5 m²/g), abundant oxygen-containing groups, and carbon defects, which endowed it with a good adsorption capacity, high H₂O₂ generation capacity (151.9 ± 10.5 mg/L) during the EF period, and good power production performance (194.3 ± 12.50 mW/m²) during the BEF period. When modified with SnZVI, despite the decrease in the adsorption capacity and power output (102.05 ± 4.05 mW/m²), the SnZVI@PPC-2 exhibited the best ENR removal performance with that of 98.9 ± 0.2% in the EF period and 86.2 ± 5.6% during the BEF period. An increase in the current intensity and air flow rate promoted ENR degradation. Finally, swine wastewater was treated using the SnZVI@PPC-2 EF-BEF system, and 97.9 ± 1.3% of the TOC was removed using the combined system.

Applications of functionalized magnetic biochar in environmental remediation: A review

Magnetic biochar (MBC) is extensively applied on contaminants removal from environmental medium for achieving environmental-friendly remediation with reduction of secondary pollution owing to its easy recovery and separation. However, the summary of MBC synthesis methods is still lack of relevant information. Moreover, the adsorption performance for pollutants by MBC is limited, and thus it is imperative to adopt modification techniques to enhance the removal ability of MBC. Unfortunately, there are few reviews to present modification methods of MBC with applications for removing hazardous contaminants. Herein, we critically reviewed (i) MBC synthetic methods with corresponding advantages and limitations; (ii) adsorption mechanisms of MBC for heavy metals and organic pollutants; (iii) various modification methods for MBC such as functional groups grafting, nanoparticles loading and element doping; (iv) applications of modified MBC for hazardous contaminants adsorption with deep insight to relevant removal mechanisms; and (v) key influencing conditions like solution pH, temperature and interfering ions toward contaminants removal. Finally, some constructive suggestions were put forward for the practical applications of MBC in the near future. This review provided a comprehensive understanding of using functionalized MBC as effective adsorbent with low-cost and high-performance characteristics for contaminated environment remediation.

Concurrent elimination and stepwise recovery of Pb(II) and bisphenol A from water using β-cyclodextrin modified magnetic cellulose: adsorption performance and mechanism investigation

Coexistence of heavy metals and endocrine disrupting compounds in polluted water with competitive adsorption behavior necessitates design of tailored adsorbents. In this work, β-cyclodextrin modified magnetic rice husk-derived cellulose (β-CD@MRHC) which can provide independent functional sites for effectively binding the above two types of contaminants was synthesized and used for Pb(II) and BPA elimination in both unit and multivariate systems. Characterizations results confirmed successful β-CD grafting and Fe₃O₄ loading, and the β-CD@MRHC had excellent magnetic property for its effectively recovery from water, which was not affected by the adsorption of pollutants. The β-CD@MRHC possessed superior adsorption performance with maximal Pb(II)/BPA uptake of 266.2 or 412.8 mg/g, severally, and the adsorption equilibrium was fleetly reached in 30 and 7.5 min. Moreover, the β-CD@MRHC could accomplish synergetic Pb(II) and BPA elimination through averting their competitive behaviors owing to diverse capture mechanisms for Pb(II) (ion exchange, complexation and electrostatic attraction) and BPA (hydrogen bonding and host-guest inclusion). Furthermore, after three cycles of step-wise desorption, the binding of Pb(II) as well as BPA byβ-CD@MRHC dropped slightly in dualistic condition. In summary, β-CD@MRHC was a promising tailored adsorbent to practical application for simultaneously removing heavy metals and organic matters from wastewater with high-performance magnetic recovery.

Recent advances in waste-derived functional materials for wastewater remediation

Water pollution is a major concern for public health and a sustainable future. It is urgent to purify wastewater with effective methods to ensure a clean water supply. Most wastewater remediation techniques rely heavily on functional materials, and cost-effective materials are thus highly favorable. Of great environmental and economic significance, developing waste-derived materials for wastewater remediation has undergone explosive growth recently. Herein, the applications of waste (e.g., biowastes, electronic wastes, and industrial wastes)-derived materials for wastewater purification are comprehensively reviewed. Sophisticated strategies for turning wastes into functional materials are firstly summarized, including pyrolysis and combustion, hydrothermal synthesis, sol-gel method, co-precipitation, and ball milling. Moreover, critical experimental parameters within different design strategies are discussed. Afterward, recent applications of waste-derived functional materials in adsorption, photocatalytic degradation, electrochemical treatment, and advanced oxidation processes (AOPs) are analyzed. We mainly focus on the development of efficient functional materials via regulating the internal and external characteristics of waste-derived materials, and the material's property-performance correlation is also emphasized. Finally, the key future perspectives in the field of waste-derived materials-driven water remediation are highlighted.

New insights into iron/nickel-carbon ternary micro-electrolysis toward 4-nitrochlorobenzene removal: Enhancing reduction and unveiling removal mechanisms

The ternary micro-electrolysis material iron/nickel-carbon (Fe/Ni-AC) with enhanced reducibility was constructed by introducing the trace transition metal Ni based on the iron/carbon (Fe/AC) system and used for the removal of 4-nitrochlorobenzene (4-NCB) in solution. The composition and structures of the Fe/Ni-AC were analyzed by various characterizations to estimate its feasibility as reductants for pollutants. The removal efficiency of 4-NCB by Fe/Ni-AC was considerably greater than that of Fe/AC and iron/nickel (Fe/Ni) binary systems. This was mainly due to the enhanced reducibility of 4-NCB by the synergism between anode and double-cathode in the ternary micro-electrolysis system (MES). In the Fe/Ni-AC ternary MES, zero-iron (Fe⁰) served as anode involved in the formation of galvanic couples with activated carbon (AC) and zero-nickel (Ni⁰), respectively, where AC and Ni⁰ functioned as double-cathode, thereby promoting the electron transfer and the corrosion of Fe⁰. The cathodic and catalytic effects of Ni⁰ that existed simultaneously could not only facilitate the corrosion of Fe⁰ but also catalyze H₂ to form active hydrogen (H*), which was responsible for 4-NCB transformation. Besides, AC acted as a supporter which could offer the reaction interface for in-situ reduction, and at the same time provide interconnection space for electrons and H₂ to transfer from Fe⁰ to the surface of Ni⁰. The results suggest that a double-cathode of Ni⁰ and AC could drive much more electrons, Fe²⁺ and H*, thus serving as effective reductants for 4-NCB reduction.

Enhanced electrochemical removal of sulfadiazine using stainless steel electrode coated with activated algal biochar

With the increasingly discharging and inappropriately disposing of antibiotics from human disease treatment and breeding industry, extensive development of antibiotic resistance in bacteria raised serious public health concern. In this work, algal biochar was coated onto the stainless steel mesh, and was employed as cathodic electrode for the degradation of sulfadiazine (SDZ) in an electro-Fenton (EF) system. It was found that algal biochar pyrolyzed at 600 °C with 1:1 KOH achieved best catalytic performance to generate H₂O₂ via oxygen reduction. Moreover, removal efficiency of SDZ reached 96.11% in 4 h with an initial concentration of 25 μg/mL, under the optimized condition as: initial pH at 3, 50 mM of Na₂SO₄ as electrolyte and an applied current of 20 mA/cm². In addition, it was found that the SDZ removal kept at about 96.99% even after four repeated degradation process. Moreover, four possible SDZ degradative pathways during the EF process were proposed according to determined intermediates, model optimization and density functional theory calculation. Finally, acute and chronic biotoxicity of the degradative products against fish and green algae was evaluated, to further elaborate the environmental impact of SDZ after electrochemical degradation.

Stabilization of lead and cadmium in soil by sulfur-iron functionalized biochar: Performance, mechanisms and microbial community evolution

Sulfur-iron functionalized biochar (BC-Fe-S) was designed by simultaneously supporting Fe₂O₃ nanoparticles and grafting sulfur-containing functional groups onto biochar to stabilize Pb and Cd in soil. The BC-Fe-S exhibited excellent stabilization performance for Pb and Cd with fast kinetic equilibrium within 5 days associating with pseudo-second-order model. The bioavailable-Pb and -Cd contents decreased by 59.22% and 70.28% with 3% BC-Fe-S treatment after 20 days of remediation. Speciation transformation analysis revealed that the increase of stabilization time and BC-Fe-S dosage with appropriate soil moisture and pH promoted toxicities decrease of Pb and Cd with transformation of labile fractions to more steady fractions. The labile fractions of Pb and Cd decreased by 12.22% and 16.21% with 3% BC-Fe-S treatment, and transformed to the residual speciation. Meanwhile, wetting-drying and freezing-thawing aging did not markedly alter the bioavailability of Pb and Cd, proving that the BC-Fe-S holds promise for stabilization of Pb and Cd in varying environmental conditions. 16S rRNA sequencing analysis demonstrated that the BC-Fe-S significantly improved diversity and composition of microbial community, especially increasing the relative abundance of heavy metal-resistant bacteria. Overall, these results suggested BC-Fe-S as a high-performance and environmental-friendly amendment with stability to remediate heavy metals polluted soil.

A microbubble-assisted rotary tubular titanium cathode for boosting Fenton's reagents in the electro-Fenton process

To improve cathodic H₂O₂ accumulation and Fe³⁺ reduction synchronously in the electro-Fenton (EF) process, a microbubble-assisted rotary tubular titanium cathode (MRTTC) was designed for the first time. By utilizing this MRTTC, H₂O₂ accumulation improved by 4.05-fold, along with a 200% enhancement in iron reduction compared to the conventional EF process. This promotion is mainly attributed to a considerably higher oxygen mass transfer, which reduces the thickness of the adhered diffusion layer. The oxygen mass transfer coefficient (K_La) also improved from 0.0073 s^-1 to 0.012 s^-1 at a rotational speed of 300 rpm. In addition, the microbubble-assisted cathode further improved the K_La to 0.047 s^-1. The synergistic effect between the rotating and microbubble-assisted cathodes further intensified H₂O₂ accumulation in MRTTC. Apart from H₂O₂ promotion, the iron reduction rate was elevated because the newly formed O₂^-• provided an additional reduction pathway for Fe³⁺ reduction in addition to the cathodic path. The effectiveness of MRTTC was confirmed by treating a benchmark organic pollutant, sulfamerazine (SMR), where approximately 100% SMR decay was obtained in 3 h. The results show that MRTTC is a novel and promising design in EF for antibiotic wastewater treatment.

Highly efficient and precise two-step cell selection method for tetramethylenedisulfotetramine-specific monoclonal antibody production

Monoclonal antibodies (mAbs) are useful biological tools for research, diagnostics, and pharmaceuticals. Here, we proposed a new mAb discovery platform named the two-step cell selection method (TCSM) for mAbs production of some small molecule haptens as antibiotic, toxins, and pesticides. The first step was performed by a fluorescence-activated cell sorter to enrich the hapten-specific B cells, the second step was an image-based precise pick of single hapten-specific hybridoma cells by confocal laser scanning microscopy. In this study, we used tetramethylenedisulfotetramine (TETS) as a model analyte, which is a highly lethal neurotoxic rodenticide. The TETS-specific hybridoma cells selection was completed within 10 days by the TCSM, compared with at least 40 days in the traditional hybridoma method (THM). The half maximal inhibitory concentration (IC₅₀) of the best mAb 1G6 for TETS in the TCSM was 1.98 ng mL^-1, and that of mAb 2B6 in the THM was 11.49 ng mL^-1. Antibody-TETS recognition also showed more interactions in mAb 1G6 than in mAb 2B6. Then, the mAb 1G6 was then successfully applied to develop an icELISA for TETS in biological samples with satisfactory sensitivity, accuracy and precision. The results demonstrated that the TCSM was a feasible and efficient method for mAb discovering of poisonous hapten molecules.

Effective lead passivation in soil by bone char/CMC-stabilized FeS composite loading with phosphate-solubilizing bacteria

Bioremediation by phosphate-solubilizing bacteria (PSB) has attracted extensive attentions due to its economical and eco-friendly properties for lead (Pb) passivation in soil. Herein, bone char (BC) supported biochemical composite (CFB₁-P) carrying advantages of BC, PSB, iron sulfide (FeS) and carboxymethyl cellulose (CMC) was designed and applied to Pb passivation. The composite at a mass ratio of BC:CMC:FeS = 1:1:1 possessed high passivation efficiency (65.47%), and has been demonstrated to offer appropriate habitat environment for PSB to defend against Pb(II) toxicity, thus enhancing the phosphate-solubilizing amount of PSB to 140.72 mg/L for passivating Pb(II). Batch experiments showed that the CFB₁-P possessed excellent adsorption properties with maximal monolayer Pb(II) uptake of 452.99 mg/g during an extensive pH range of 2.0-6.0. Furthermore, by applying CFB₁-P dosage of 3% into Pb-contaminated soil, the labile Pb fractions were reduced from 29.05% to 6.47% after simulated remediation of 10 days, and converted into steady fractions. The CFB₁-P was demonstrated to achieve high Pb(II) passivation through combined functions of chemical precipitation, complexation, electrostatic attraction and biomineralization, accompanied by the formation of more stable crystal structures, for instance, Pb₅(PO₄)₃OH, Pb₃(PO₄)₂ and PbS. These results suggested CFB₁-P as a potential alternative for efficient remediation of Pb-contaminated soil.

Removal of chlortetracycline from water using spent tea leaves-based biochar as adsorption-enhanced persulfate activator

Antibiotic compounds have caused serious environmental concerns. In this study, we developed an effective technology for treatment of chlortetracycline (CTC), a widely used antibiotic compound. A natural heteroatom-doped spent tea leaves-based biochar (STLB) with excellent adsorption and catalytic property was prepared by simple thermal treatment. An adsorption-promoted persulfate-based advanced oxidation process (PS-AOP) using STLB was studied for CTC removal. The results showed that the as-prepared STLB presented favorable adsorption affinity towards CTC with the maximum adsorption capacity of 627 mg g^-1. Meanwhile, CTC enriched on the surface of STLB was good for in-situ decomposition of CTC and nearly 97.4 % of CTC was removed within 30 min of pre-adsorption and 60 min of subsequent degradation. The STLB had excellent recyclability and wide pH tolerance range of 3.0-9.0 in combined pre-adsorption and PS-AOP. Reactive oxygen species analysis confirmed that CTC degradation was mainly due to non-radical (singlet oxygen, ¹O₂) and radicals (SO₄^- and OH). This study suggests that STLB is a promising adsorption-enhanced PS activator for the treatment of refractory wastewater and also provides a strategy of waste control by spent tea leaves.

One-pot synthesis of Ca-based magnetic hydrochar derived from consecutive hydrothermal and pyrolysis processing of bamboo for high-performance scavenging of Pb(Ⅱ) and tetracycline from water

Ca-based magnetic bamboo-derived hydrochar described as Ca-MBHC was synthesized by one-pot pyrolysis, and was applied to remediation of lead (Pb) and tetracycline (TC) polluted water. Characterizations not only attested the loading of CaCO₃ and Fe⁰ onto the hydrochar, but also demonstrated the magnetism of Ca-MBHC. Adsorption kinetic experiments showed that the Ca-MBHC could eliminate Pb(II) and TC during a wide range of pH, and appeared rapid uptake equilibrium within 240 and 60 min for Pb(II) and TC, severally. Adsorption isotherm experiments showed that the Ca-MBHC possessed highest adsorption of 475.58 mg/g concerning Pb(II), and heterogeneous uptake of 142.44 mg/g for TC. Furthermore, the Ca-MBHC could achieve Pb(II) binding owing to complexation, reduction, ion exchange and electrostatic attraction, whereas the TC uptake might be related to π-π stacking reciprocities, pore filling and hydrogen bonding. Overall, the Ca-MBHC could be viewed as an excellent adsorbent for scavenging Pb(II) and tetracycline from water.

Magnetic porous biochar with high specific surface area derived from microwave-assisted hydrothermal and pyrolysis treatments of water hyacinth for Cr(Ⅵ) and tetracycline adsorption from water

Magnetic porous water hyacinth-derived biochar (MPBC_MW3) was synthesized via two-step Microwave (MW)-assisted processes. Characterization results not only testified high specific surface area (2097.50 m²/g) of the MPBC_MW3 assisted by MW-assisted pyrolysis, but also revealed its favorable magnetism derived from MW-assisted hydrothermal process. The MPBC_MW3 possessed pH-dependent monolayer adsorption capacities of 202.61 and 202.62 mg/g for Cr(VI) and TC with quick attainments of uptake equilibrium within 150 and 200 min. Moreover, the Cr(VI) and TC uptake were substantially steady under the interference from multifarious co-existing ions with slight decline after three adsorption-desorption cycles. Furthermore, the MPBC_MW3 was demonstrated to achieve excellent Cr(VI) binding primarily through complexation, electrostatic interaction, reduction and ion exchange, while presenting outstanding TC removal via pore filling, π-π stacking, hydrogen bonding force, electrostatic interaction and complexation. All these findings suggested the MPBC_MW3 synthesized by MW-assisted processes as an excellent adsorbent for purification of Cr(VI) and TC-contaminated water.

Rhodanine-based fluorometric sequential monitoring of silver (I) and iodide ions: Experiment, DFT calculation and multifarious applications

A simple rhodanine derived fluorophoric unit has been designed for selective detection of Ag⁺ and I^- ions in DMSO-H₂O medium. The sensor R1 showed an obvious "turn-on" fluorescence response toward Ag⁺ due to the inhibition of both C-N single bond free rotation, internal charge transfer (ICT) and the formation of chelation enhanced fluorescence (CHEF) effects. The fluorescence quantum yield (Φ) was increased from 0.0013 to 0.032 for receptor R1 upon the Ag⁺-complexation. In addition, the 1:1 complexing stoichiometry was employed based on Job's plot analysis with detection limit of 24.23 × 10^-7 M. Conversely, receptor R1+Ag⁺ particularly detects I^- ion over other co-existing anions by the "turn-off" fluorescence response due to the formation of AgI, displacing the receptor R1 with the quantum yield of 0.0014. The detection limit was calculated to be 22.83 × 10^-7 M. The sensing behaviour of receptor R1 toward Ag⁺ was also supported by density functional theory (DFT) calculations. Moreover, the sensing ability of reported receptor R1 could be exercised in multifarious applications like paper strip, silica-supported analysis, staining test for latent finger print, logical behaviour, smartphone-assisted quantitative detection and real water samples studies.

Removal of Cd(Ⅱ) and anthracene from water by β-cyclodextrin functionalized magnetic hydrochar: Performance, mechanism and recovery

Magnetic hydrochar modified by β-cyclodextrin (β-CD) described as β-CD@MHC was successfully synthesized and applied to simultaneous removal of cadmium (Cd) and anthracene (ANT). Characterizations attested the grafting of β-CD groups onto β-CD@MHC with excellent magnetism. Moreover, the β-CD@MHC could eliminate Cd(II) and ANT during an extensive pH scope, and presented fast adsorption equilibrium in 60 min and 80 min for Cd(II) and ANT, respectively. And the β-CD@MHC possessed prominent adsorption properties with maximum monolayer binding of 47.28 mg/g for Cd(II), and corresponding heterogeneous uptake of 60.27 mg/g concerning ANT. Furthermore, the β-CD@MHC could effectively avoid the competitive behavior between Cd(II) and ANT mainly due to complexation and electrostatic attraction effects for capturing Cd(II), and host-guest interaction in the removal of ANT. Additionally, the binding of Cd(II) and ANT onto β-CD@MHC dropped slightly after stepwise desorption, suggesting the β-CD@MHC as a high-performance adsorbent for heavy metals and PAHs elimination from wastewater.

Photo-assisted electrochemical advanced oxidation processes for the disinfection of aqueous solutions: A review

Disinfection is usually the final step in water treatment and its effectiveness is of paramount importance in ensuring public health. Chlorination, ultraviolet (UV) irradiation and ozone (O3) are currently the most common methods for water disinfection; however, the generation of toxic by-products and the non-remnant effect of UV and O3 still constitute major drawbacks. Photo-assisted electrochemical advanced oxidation processes (EAOPs) on the other hand, appear as a potentially effective option for water disinfection. In these processes, the synergism between electrochemically produced active species and photo-generated radicals, improve their performance when compared with the corresponding separate processes and with other physical or chemical approaches. In photo-assisted EAOPs the inactivation of pathogens takes place by means of mechanisms that occur at different distances from the anode, that is: (i) directly at the electrode's surface (direct oxidation), (ii) at the anode's vicinity by means of electrochemically generated hydroxyl radical species (quasi-direct), (iii) or at the bulk solution (away from the electrode surface) by photo-electrogenerated active species (indirect oxidation). This review addresses state of the art reports concerning the inactivation of pathogens in water by means of photo-assisted EAOPs such as photo-electrocatalytic process, photo-assisted electrochemical oxidation, photo-electrocoagulation and cathodic processes. By focusing on the oxidation mechanism, it was found that while quasi-direct oxidation is the preponderant inactivation mechanism, the photo-electrocatalytic process using semiconductor materials is the most studied method as revealed by numerous reports in the literature. Advantages, disadvantages, trends and perspectives for water disinfection in photo-assisted EAOPs are also analyzed in this work.

Enhanced electro-Fenton catalytic performance with in-situ grown Ce/Fe@NPC-GF as self-standing cathode: Fabrication, influence factors and mechanism

Heterogeneous electro-Fenton (E-F) is considered as an attractive technique for efficient removal of refractory organic pollutants in wastewater. The regeneration of Fe^II and catalyst reusability are key issues for effective and sustainable degradation. Developing binder-free iron phase/carbon composite cathode is a feasible strategy. In this work, the stable Ce/Fe-nanoporous carbon modified graphite felt electrode (Ce/Fe@NPC-GF) was fabricated using in situ solvothermal method and subsequent carbonization treatment, which worked as the cathode in a heterogeneous electro-Fenton system to degrade sulfamethoxazole. The electrocatalytic activity was significantly improved with doping of Ce. It was found that mesoporous Ce/Fe@NPC-GF cathode demonstrated high oxygen reduction activity and low resistance. The co-existence of Fe^Ⅱ/Fe^Ⅲ and Ce^Ⅲ/Ce^Ⅳ redox couples enhanced remarkably interfacial electron transfer, promoting in-situ H₂O₂ generation and decomposition, sequentially boosting the production of reactive radicals (·OH and ·O₂^-). Under 20 mA and pH 3, Sulfamethoxazole (SMX) was basically degraded in 120 min, and the removal rate was satisfactory in wide pH (2-6). After 8 cycles, the electrode could still maintain high stability and outstanding catalytic capacity. This work displayed a novel in-situ preparation method of composite cathode with excellent catalytic performance in E-F system, which offered inspiration for developing efficient heterogeneous electro-Fenton cathode material.

Cost-effective method of benzene-containing wastewater treatment using floating electro-Fenton system

Traditional electro-Fenton systems must continuously supply oxygen to the cathode, which leads to extensive volatilisation of benzene in solutions. In this study, we adopted a floating cathode electro-Fenton system without bubbling oxygen into the solution to treat benzene-containing wastewater. The effects of the floating cathode position and main reaction parameters on benzene degradation were analysed, and the degradation cost was estimated. The results indicated that the electro-Fenton system with floating cathode could effectively degrade benzene in solutions. For the cathode, the complete utilisation of air and oxygen released from the anode was crucial. The benzene degradation rate increased with an increase in benzene concentrations. Additionally, pH mainly affected the existing ionic state of iron and production ratio of active substances. The current intensity significantly influenced the reaction activity. Using the floating cathode electro-Fenton method, the benzene removal ratio in the solution could reach 74.80% after 60 min under the optimum reaction conditions. For the floating cathode electro-Fenton system, the cost of treating benzene-containing sewage per cubic metre was $1.2187, which is significantly lower than that for traditional electro-Fenton technology ($1.4000). Hence, the floating cathode electro-Fenton system is an economical and efficient method for benzene degradation in solutions.

Carbonaceous cathode materials for electro-Fenton technology: Mechanism, kinetics, recent advances, opportunities and challenges

Electro-Fenton (EF) technique has gained significant attention in recent years owing to its high efficiency and environmental compatibility for the degradation of organic pollutants and contaminants of emerging concern (CECs). The efficiency of an EF reaction relies primarily on the formation of hydrogen peroxide (H₂O₂) via 2e^─ oxygen reduction reaction (ORR) and the generation of hydroxyl radicals (^●OH). This could be achieved through an efficient cathode material which operates over a wide pH range (pH 3-9). Herein, the current progresses on the advancements of carbonaceous cathode materials for EF reactions are comprehensively reviewed. The insights of various materials such as, activated carbon fibres (ACFs), carbon/graphite felt (CF/GF), carbon nanotubes (CNTs), graphene, carbon aerogels (CAs), ordered mesoporous carbon (OMCs), etc. are discussed inclusively. Transition metals and hetero atoms were used as dopants to enhance the efficiency of homogeneous and heterogeneous EF reactions. Iron-functionalized cathodes widened the working pH window (pH 1-9) and limited the energy consumption. The mechanism, reactor configuration, and kinetic models, are explained. Techno economic analysis of the EF reaction revealed that the anode and the raw materials contributed significantly to the overall cost. It is concluded that most reactions follow pseudo-first order kinetics and rotating cathodes provide the best H₂O₂ production efficiency in lab scale. The challenges, future prospects and commercialization of EF reaction for wastewater treatment are also discussed.

A novel fluorescent probe based on N, B, F co-doped carbon dots for highly selective and sensitive determination of sulfathiazole

The widespread occurrence of sulfathiazole (STZ) in the environment has raised concerns regarding the potential risks to ecosystem and human health. Thus, there is a need to develop facile and efficient methods for monitoring STZ. In this study, a novel fluorescent probe, based on N, B, F co-doped carbon dots (N, B, F-CDs), was developed for the highly sensitive and selective determination of STZ. The fluorescent N, B, F-CDs were prepared via a one-step hydrothermal method using malonate and 1-allyl-3-vinylimidazolium tetrafluoroborate ionic liquid as precursors. The obtained N, B, F-CDs exhibited excellent fluorescence response toward STZ due to the inner filter effect (IFE), which caused the fluorescence to be quenched. The fluorescent probe allowed the STZ concentration to be accurately determined with a low detection limit of 5.5 ng mL^-1 in two wide linear ranges of 0.008-10 μg mL^-1 and 10-45 μg mL^-1. The practicability of the fluorescent probe was further validated in river water, soil, milk, and egg samples, and the satisfactory spiked recoveries of STZ ranged from 96.1 to 101.6%. The proposed fluorescent probe based on N, B, F-CDs can be easily prepared and possess high selectivity and sensitivity, thereby displaying its tremendous potential for the identification and determination of STZ in the environment.

Enhancing the degradation of carbamazepine by UVA-LED/WO3 process with peroxydisulfate: Effects of light wavelength and water matrix

In this study, peroxydisulfate (PDS) was used as electron acceptor to improve the photocatalytic activity of WO₃. The results indicated that the degradation of carbamazepine by UVA-LED/WO₃/PDS process followed pseudo-first order and PDS addition significantly enhanced the degradation rate by inhibiting the recombination of electrons and holes. The observed pseudo-first order rate constant (k_obs) was in linear relationship with the dosage of WO₃, while inversely proportional to the initial concentration of CBZ. PDS decreased the k_obs slightly when its concentration exceeded 0.5 mM. The 365 nm UVA-LED performed much better than 385 nm or 405 nm even though its energy efficiency was the lowest. Based on the steady-state kinetic model, sulfate radical was the dominant radical. The effects of water matrix were complex: bicarbonate ion and humic acid showed strong inhibitory effect; increasing the pH above 7 led to significant drop in CBZ removal; sulfate ion slightly decreased the k_obs while 5 mM chloride ion more than doubled the k_obs. The interactions between anions and WO₃ surface were theoretically analysed to explain the effects of anions. The electrical energy per order values suggest that UVA-LED/WO₃/PDS process is suitable for water with low organic carbon.

Enhanced phosphate scavenging with effective recovery by magnetic porous biochar supported La(OH)3: Kinetics, isotherms, mechanisms and applications for water and real wastewater

Herein, La(OH)₃ decorated magnetic porous biochar (MPBC) was synthesized via KHCO₃ activation and hydrothermal processes. The La-to-MPBC mass ratio of 3:1 described as La₃-MPBC possessed a monolayer phosphate adsorption capacity of 116.08 mg/g across a pH range of 3.0-6.0 with fast attainment of adsorption equilibrium in 150 min. Moreover, the phosphate adsorption was substantially stable during the interference of various co-existing ions with over 92% of phosphate removal and 77% of desorption efficiency maintained after four recycles. And La₃-MPBC was easily separated by magnet force with negligible La and Fe leakages within the pH range of 3.0-10.0. Furthermore, La₃-MPBC was supported to achieve phosphate binding through the synergistic actions of electrostatic attraction, ligand exchange, inner-sphere complexation and weak precipitation. Significantly, La₃-MPBC exhibited a high performance for decontaminating low-concentration phosphate to meet regulatory requirements. All these results suggested La₃-MPBC to be an ideal candidate for phosphate removal in real applications.

High-efficiency electro-catalytic performance of green dill biochar cathode and its application in electro-Fenton process for the degradation of pollutants

Biochar (BC) is a kind of carbon-rich, renewable and low-cost material, which can be prepared from various organic materials.

A review of recent advancements in utilization of biomass and industrial wastes into engineered biochar

For past few years, biochar has gained a great deal of attention for its versatile utility in agricultural and environmental applications. The diverse functionality and environmental-friendly nature of biochar have motivated many researchers to delve into biochar researches and spurred rapid expansion of literature in recent years. Biochar can be produced from virtually all the biomass, but the properties of biochar are highly dependent upon the types of feedstock biomass and preparation methods. The overall performances of as-prepared biochar in treating soil and water contaminants is generally inferior to activated carbon due to its lower surface area and limited functionalities. This limitation has led to many follow-up studies that focused on improving material characteristics by imparting desired functionality. Such efforts have greatly advanced knowledge to produce better-performing engineered biochar with enhanced capability and versatility. To this end, this review was prepared to compile recent advancements in fabrication and application of engineered biochar, especially with respect to the influences of biomass feedstock on the properties of biochar and the utilization of industrial wastes in fabrication of engineered biochar.

Simultaneously enhanced removal and stepwise recovery of atrazine and Pb(II) from water using β-cyclodextrin functionalized cellulose: Characterization, adsorptive performance and mechanism exploration

Heavy metals and pesticides often coexist in contaminated water, while their potential competition behaviors make the adsorptive removal more challenging. Thus, decorating an adsorbent with independent functional sites could be a promising alternative to radically prevent the competitive process for improving the adsorption performance. Herein, β-cyclodextrin functionalized rice husk-based cellulose (β-CD@RH-C) was designed and applied for synchronous removal of atrazine and Pb(II). The characterization results supported the successful grafting of β-cyclodextrin onto the cellulose. The β-CD@RH-C presented a pH-dependent adsorption performance for Pb(II) with a theoretical monolayer adsorption capacity of 283.00 mg/g, while was mostly unrelated to pH for atrazine adsorption with a heterogeneous uptake of 162.21 mg/g in the mono-component system. Most importantly, the β-CD@RH-C could efficiently achieve simultaneous removal of atrazine and Pb(II) via avoiding their competitive behaviors, which was due to the different adsorption mechanisms for atrazine (i.e. host-guest interaction) and Pb(II) (i.e. complexation and electrostatic interaction). Moreover, the adsorbed atrazine and Pb(II) could be sequentially desorbed with slight decrease in the adsorption performance of β-CD@RH-C even after four cycles in the atrazine-Pb(II) multi-component system. All these results suggested β-CD@RH-C to be a tailored adsorbent with high-performance elimination of co-existing heavy metals and organic pollutants in water.

Long-term continuous and real-time in situ monitoring of Pb(II) toxic contaminants in wastewater using solid-state ion selective membrane (S-ISM) Pb and pH auto-correction assembly

Lead (Pb) contaminants in wastewater have inhibited microbial activities and thus exerted high energy consumption in wastewater treatment plants (WWTPs). Current Pb monitoring has been conducted ex situ and off line, unable to affect real-time proactive control and operation. This study targets the crucial challenge of better and faster Pb monitoring by developing novel mm-sized screen-printed solid-state ion-selective membrane (S-ISM) Pb sensors with low-cost, high accuracy and long-term durability and that enable real-time in situ monitoring of Pb(II) ion contamination down to low concentrations (15 ppb-960 ppb) in wastewater. An innovative pH auto-correction data-driven model was built to overcome the inextricable pH inferences on Pb(II) ISM sensors in wastewater. Electrochemical impedance spectroscopy (EIS) and cyclic voltammograms (CV) analysis showed (3,4-ethylenedioxythiophene, EDOT) deposited onto the mm-sized screen-printed carbon electrodes using electropolymerization effectively alleviated the interferences from dissolved oxygen and improved long-term stability in wastewater. Monte Carlo simulation of the nitrification process predicted that real-time, and high accurate in situ monitoring of Pb(II) in wastewater and swift feedback control could save ∼53 % of energy consumption by alleviating the errors from pH and DO impacts in WWTPs.

Hazardous wastes treatment technologies

A review of the literature published in 2019 on topics related to hazardous waste management in water, soils, sediments, and air. The review covered treatment technologies applying physical, chemical, and biological principles for the remediation of contaminated water, soils, sediments, and air. PRACTICAL POINTS: This report provides a review of technologies for the management of waters, wastewaters, air, sediments, and soils contaminated by various hazardous chemicals including inorganic (e.g., oxyanions, salts, and heavy metals), organic (e.g., halogenated, pharmaceuticals and personal care products, pesticides, and persistent organic chemicals) in three scientific areas of physical, chemical, and biological methods. Physical methods for the management of hazardous wastes including general adsorption, sand filtration, coagulation/flocculation, electrodialysis, electrokinetics, electro-sorption ( capacitive deionization, CDI), membrane (RO, NF, MF), photocatalysis, photoelectrochemical oxidation, sonochemical, non-thermal plasma, supercritical fluid, electrochemical oxidation, and electrochemical reduction processes were reviewed. Chemical methods including ozone-based, hydrogen peroxide-based, potassium permanganate processes, and Fenton and Fenton-like process were reviewed. Biological methods such as aerobic, anoxic, anaerobic, bioreactors, constructed wetlands, soil bioremediation and biofilter processes for the management of hazardous wastes, in mode of consortium and pure culture were reviewed. Case histories were reviewed in four areas including contaminated sediments, contaminated soils, mixed industrial solid wastes and radioactive wastes.

Study of polarized activated carbon filters as simultaneous adsorbent and 3D-type electrode materials for electro-Fenton reactors

Electro-Fenton (EF) based water treatment processes using activated carbon (AC) packed beds constitute an attractive approach for the development of competitive degradation technology of persistent pollutants in aqueous effluents. In this work, the results of a study aimed to assess the effect on the EF performance of different parameters of the reactor's operation are presented. By means of a factorial experimental design, the influence of the AC source (lignitic or vegetal), AC acid pre-treatment, particle size distribution and the amount of Fe loaded resin in the reactor were analyzed. From the resulting data it was found that the most influential parameter in the EF performance of the reactor is the AC source. Modest effects were observed for AC acid pre-treatment, which limits Fe ion adsorption on the AC substrate. The use of a wide particle distribution of AC particles was also found to improve inter-particle electrical contact, thus favoring the electrochemical processes that take place inside the reactor. An investigation on the effect of the amount of Fe in the reactor as well as its distribution dynamics, also revealed that an excess of Fe ions in the reactor decreases the EF performance of the system since Fe ions efficiently adsorb on the AC substrate, particularly in non- acid treated samples. The best operation conditions consisted on using un-meshed vegetable AC, without acid pretreatment in an EF reactor loaded with 0.25 g of Fe, which allowed to reach full color removal of bright blue FCP model dye in 70 min.

Unconventional electro-Fenton process operating at a wide pH range with Ni foam cathode and tripolyphosphate electrolyte

We propose an unconventional electro-Fenton (EF) system with a nickel-foam (Ni-F) cathode and tripolyphosphate (3-PP) electrolyte at near-neutral pH (EF/Ni-F-3-PP) to overcome pH restrictions in EF while preventing Ni-F corrosion. Response surface modelling was used to optimize the main operating parameters with a model prediction analysis (R² = 0.99): pH = 5.8, Fe²⁺ = 3.0 mM and applied current = 349.6 mA. Among the three variables, the pH exerted the highest influence on the process. Under optimal conditions, 100 % of phenol removal was achieved in 25 min with a pseudo-first-order apparent rate constant (k_app) of 0.2 min^-1, 3.2-fold higher than the k_app of EF/Ni-F with SO₄^2- electrolyte at pH 3. A mineralization yield of 81.5 % was attained after 2 h; furthermore, it was found that 3-PP enhanced H₂O₂ accumulation by preventing bulk H₂O₂ decomposition. Finally, toxicity evaluation revealed the formation of toxic by-products at the early stages of treatment, which were totally depleted after 2 h, demonstrating the detoxifying capacity of the system. In conclusion, this study shows for the first time the potential of Ni-F as a cathode for EF under near-neutral conditions, rendered possible by the 3PP electrolyte. Under these conditions, the Ni-F corrosion issue could be alleviated.

Technical Overview of Orbitrap High Resolution Mass Spectrometry and Its Application to the Detection of Small Molecules in Food (Update Since 2012)

Food safety and quality issues are becoming increasingly important and attract much attention, requiring the development of better analytical platforms. For example, high-resolution (especially Orbitrap) mass spectrometry simultaneously offers versatile functions such as targeted/non-targeted screening while providing qualitative and quantitative information on an almost unlimited number of analytes to facilitate routine analysis and even allows for official surveillance in the food field. This review covers the current state of Orbitrap mass spectrometry (OMS) usage in food analysis based on research reported in 2012-2019, particularly highlighting the technical aspects of OMS application and the achievement of OMS-based screening and quantitative analysis in the food field. The gained insights enhance our understanding of state-of-the-art high-resolution mass spectrometry and highlight the challenges and directions of future research.