Biomass-derived functional porous carbons for adsorption and catalytic degradation of binary micropollutants in water

Modulation of radical and nonradical pathways via modified carbon nanotubes toward efficient oxidation of binary pollutants in water

In order to minimize the knowledge gap between single and binary pollutants degradation by persulfate-based advanced oxidation processes (PS-AOPs), iron-loaded N-doped carbon nanotubes (Fe-NCNT) and its acid-washing sample (Fe-NCNT-W) were synthesized as peroxymonosulfate (PMS) activator for simultaneous oxidation of acid orange 7 (AO7) and electron-rich (phenol/ibuprofen) or electron-deficient pollutants (nitrobenzene/benzoic acid). Mechanistic studies revealed that both radical (HO•, SO4•-) and nonradical (electron-transfer, high-valent iron) pathways involved for organic oxidation in Fe-NCNT/PMS system, while electron-transfer pathway (ETP) and high-valent iron-oxo species accounted for pollutant degradation at the surface and inner space of Fe-NCNT-W, respectively. The oxidation performances in single or binary systems were systematically investigated. In comparison to benchmark radical-based (Fe2+/PMS), nonradical ETP (NCNT/PMS) and mixed (Fe-NCNT/PMS) systems, Fe-NCNT-W/PMS outperformed superior performance toward oxidation of binary pollutants with little inference from solution pH or background substances, which could also be fabricated into membrane reactor for actual dyeing sewage treatment. Such superiorities should be mainly ascribed to the particular selectivity and intensive treatment of nonradical pathways in Fe-NCNT-W/PMS system with nanoconfinement effect. This work affords novel insights into the treatment of combined pollution via PMS activation by engineered nanomaterials.

Functional Carbon from Nature: Biomass-Derived Carbon Materials and the Recent Progress of Their Applications

Biomass is considered as a promising source to fabricate functional carbon materials for its sustainability, low cost, and high carbon content. Biomass-derived-carbon materials (BCMs) have been a thriving research field. Novel structures, diverse synthesis methods, and versatile applications of BCMs have been reported. However, there has been no recent review of the numerous studies of different aspects of BCMs-related research. Therefore, this paper presents a comprehensive review that summarizes the progress of BCMs related research. Herein, typical types of biomass used to prepare BCMs are introduced. Variable structures of BCMs are summarized as the performance and properties of BCMs are closely related to their structures. Representative synthesis strategies, including both their merits and drawbacks are reviewed comprehensively. Moreover, the influence of synthetic conditions on the structure of as-prepared carbon products is discussed, providing important information for the rational design of the fabrication process of BCMs. Recent progress in versatile applications of BCMs based on their morphologies and physicochemical properties is reported. Finally, the remaining challenges of BCMs, are highlighted. Overall, this review provides a valuable overview of current knowledge and recent progress of BCMs, and it outlines directions for future research development of BCMs.

Enhancing catalytic activity through the construction of praseodymium tungstate decorated on hierarchical three-dimensional porous biocarbon for determination of furazolidone in aquatic samples

Boosting catalytic performance as a vital role for an electrochemical sensor for monitoring various hazardous nitro drugs. Herein, an inexpensive, facile, and eco-friendly construction of praseodymium tungstate decorated on three dimensional porous biocarbon (PrW/3D-PBC) for electrochemical determination of carcinogenic residue furazolidone (FZ). The nanostructured PrW nanoparticles were prepared by solvent evaporation from peroxo-tungstic acid and 3D-PBC was prepared from biomass precursor under the carbonization method. Furthermore, the composite of PrW decorated on 3D-PBC was prepared by an ultrasonic-assisted wet chemical approach. Besides, the composite characterization of crystalline, functional group, degree of carbonization, chemical states, and morphology were utilized by theXRD, FTIR, RAMAN, XPS, and FESEM analysis. These 3D porous carbon decorated PrW nanoparticles facilitate the electrochemical anchoring sites, surface area, and ease of diffusion layers towards the detection of hazardous nitro pollutant FZ by using CV analysis. The low LOD and high sensitivity were achieved by FZ determination through using LSV and DPV techniques. The practical capability of the PrW/3D-PBC/GCE sensor was determined by using aquatic samples to achieve a good recovery result. These results instigate that the PrW/3D-PBC will be an efficient electrocatalytic material for FZ sensor in environmental aquatic samples.

Biomass-Derived Carbon Materials in Heterogeneous Catalysis: A Step towards Sustainable Future

Biomass-derived carbons are emerging materials with a wide range of catalytic properties, such as large surface area and porosity, which make them ideal candidates to be used as heterogeneous catalysts and catalytic supports. Their unique physical and chemical properties, such as their tunable surface, chemical inertness, and hydrophobicity, along with being environmentally friendly and cost effective, give them an edge over other catalysts. The biomass-derived carbon materials are compatible with a wide range of reactions including organic transformations, electrocatalytic reactions, and photocatalytic reactions. This review discusses the uses of materials produced from biomass in the realm of heterogeneous catalysis, highlighting the different types of carbon materials derived from biomass that are potential catalysts, and the importance and unique properties of heterogeneous catalysts with different preparation methods are summarized. Furthermore, this review article presents the relevant work carried out in recent years where unique biomass-derived materials are used as heterogeneous catalysts and their contribution to the field of catalysis. The challenges and potential prospects of heterogeneous catalysis are also discussed.

Removal of micropollutants through bio-based materials as a transition to circular bioeconomy: Treatment processes involved, perspectives and bottlenecks

The recent increase in micropollutant levels in water bodies is a growing concern globally. The generation of new materials and techniques for wastewater treatment often involves the release of hazardous wastes and the utilization of energy related to it. This can be resolved by the synthesis of bio-based materials through the use of already released wastes and naturally occurring components, adding their value as reusable resources. These bio-based materials find wide applications for micropollutant elimination and energy tapping due to the presence of various functional groups, large surface area, high stability, and reusability. The processes involved in micropollutant elimination through biomaterials generally include adsorption and degradation. These treatment processes are suggested to depend on various operational parameters like pH, temperature, dose, reaction time, presence of other contaminants, ions, etc. in the system, which may influence the process efficiency. Understanding the potential of bio-based materials many steps can be taken towards its large-scale application to upgrade wastewater treatment plants for micropollutant elimination. Furthermore, the recent advances of bio-based materials in energy storage and conversion have widened its scope for implementation in a circular bioeconomy. The bottlenecks towards such a transition and future recommendations are also presented and discussed.

Ultrathin porous carbon nanosheet as an efficient adsorbent for the removal of bisphenol A: The overlooked role of topological defects

Carbon-based materials are emerging as a type of inexpensive and efficient adsorbent, although their genuine adsorption site is still debatable. Herein, we present a novel approach for designing and constructing an ultra-thin defect-rich hierarchically porous carbon nanosheet (ZG-C). The ZG-C sample demonstrated a high adsorption capacity for bisphenol A (BPA) (602.2 mg/g) along with a fast adsorption process (20 min), and stable reusability (the decline efficiency was 9.14% after five consecutive cycles). Based on comprehensive experiments and a number of characterizations, the high adsorption capacity of ZG-C for BPA was connected with the hierarchical porous structure of ZG-C and multiple intrinsic defects of ZG-C. The results of density functional theory (DFT) further demonstrated that topological defects played an indispensable role in promoting adsorption, and its adsorption energy (-0.595 eV) for BPA was much higher than that of other intrinsic defects. This study not only provides an innovative and simple strategy for preparing hierarchically porous carbon-based adsorbent with abundant intrinsic defects for the efficient removal of BPA, but also significantly contributes to the understanding of the application of carbon-based materials to remove bisphenols.

Ring defects-rich and pyridinic N-doped graphene aerogel as floating adsorbent for efficient removal of tetracycline: Evidence from NEXAFS measurements and theoretical calculations

The rational design of carbon-based adsorbents with a high uptake efficiency for polar organic molecules is a key challenge in water purification research. Herein, we report a graphene aerogel that is doped with pyridinic-N and has abundant ring defects (denoted by DNGA). The aerogel sample exhibits a high adsorption capacity of 607.1 mg/g toward tetracycline (TC), a fast adsorption process (20 min), and good reusability (with a declining efficiency < 10.0% after five cycles), while being easy to recycle. C/N K-edge X-ray absorption near-edge structure (XANES) measurements demonstrate that the efficient adsorption capacity of the DNGA sample is related to the presence of ring defects and the pyridinic-N species. Density functional theory (DFT) calculations demonstrate that ring defects of type 5-8-5 and the pyridinic-N species at the edge location are primarily responsible for TC removal. In this study, we resolve a controversial issue regarding the origin of the adsorption performance origin of N-doped carbon-based adsorbents. The findings of this study can guide the development of novel and improved N-doped carbon-based adsorbents for the removal of target contaminants.

Carbon nitride-based Z-scheme heterojunctions for solar-driven advanced oxidation processes

Solar-driven advanced oxidation processes (AOPs) via direct photodegradation or indirect photocatalytic activation of typical oxidants, such as hydrogen peroxide (H₂O₂), peroxymonosulfate (PMS), and peroxydisulfate (PDS), have been deemed to be an efficient technology for wastewater remediation. Artificial Z-scheme structured materials represent a promising class of photocatalysts due to their spatially separated charge carriers and strong redox abilities. Herein, we summarize the development of metal-free graphitic carbon nitride (g-C₃N₄, CN)-based direct and indirect Z-scheme photocatalysts for solar-driven AOPs in removing organic pollutants from water. In the work, the classification of AOPs, definition and validation of Z-schemes are summarized firstly. The innovative engineering strategies (e.g., morphology and dimensionality control, element doping, defect engineering, cocatalyst loading, and tandem Z-scheme construction) over CN-based direct Z-scheme structure are then examined. Rational design of indirect CN-based Z-scheme systems using different charge mediators, such as solid conductive materials and soluble ion pairs, is further discussed. Through examining the relationship between the Z-scheme structure and activity (charge transfer and separation, light absorption, and reaction kinetics), we aim to provide more insights into the construction strategies and structure modification on CN-based Z-schemes towards improving their catalytic performances in AOPs. Lastly, limitations, challenges, and perspectives on future development in this emerging field are proposed.

Rational Regulation of Co-N-C Coordination for High-Efficiency Generation of 1O2 toward Nearly 100% Selective Degradation of Organic Pollutants

Single oxygen-based advanced oxidation processes (¹O₂-AOPs) exhibit great prospects in selective degradation of organic pollutants. However, efficient production of ¹O₂ via tailored design of catalysts to achieve selective oxidation of contaminants remains challenging. Herein, we develop a simple strategy to regulate the components and coordination of Co-N-C catalysts at the atomic level by adjusting the Zn/Co ratio of bimetallic zeolitic imidazolate frameworks (Zn_xCo₁-ZIFs). Zn₄Co₁-C demonstrates 98% selective removal of phenol in the mixed phenol/benzoic acid (phenol/BA) solutions. Density functional theory calculations and experiments reveal that more active CoN₄ sites are generated in Zn₄Co₁-C, which are beneficial to peroxymonosulfate activation to generate ¹O₂. Furthermore, the correlation between the origin of selectivity and well-defined catalysts is systematically investigated by the electron paramagnetic resonance test and quenching experiments. This work may provide novel insights into selective removal of target pollutants in a complicated water matrix.

Microwave-assisted preparation of Ag/Fe magnetic biochar from clivia leaves for adsorbing daptomycin antibiotics

Novel clivia biochar adsorbing daptomycin (DAP) was prepared by microwave digestion–anaerobic carbonization in this work. Fe/Ag submicron particles were introduced to the biochar surface based on the reducibility of biochar to enhance its adsorption capacity. Characterization confirmed that modified biochar (AF-biochar) had a higher particle size (126 μm), larger specific surface area (521.692 m2 g−1), richer pore structure, and higher thermal stability. The effects of the main variables (e.g., the solution pH, contact time, initial DAP concentration, and temperature) were investigated during adsorption. The results showed that AF-biochar could reach the adsorption equilibrium at pH 4.8 for 85 min. Besides, the adsorption capacity was 48.25 mg g−1, and the adsorption efficiency was 96.50% when the concentration of DAP was 25 mg L−1. The pseudo-second-order kinetics (R 2 = 0.9997), Langmuir equation (R 2 = 0.9999), and thermodynamics (R 2 = 0.9631) of AF-biochar fit well, indicating that the main adsorption process of AF-biochar was spontaneous, exothermic, and monolayer. Their adsorption was analyzed by physical and chemical adsorption. The main adsorption mechanisms included the electron donor–acceptor interaction, electrostatic force interaction, Lewis acid–base interaction, and H-bond interaction.

Metal-organic framework-derived magnetic carbon for efficient decontamination of organic pollutants via periodate activation: Surface atomic structure and mechanistic considerations

Practical implementation of periodate-based advanced oxidation processes for environmental remediation largely relies on the development of cost-effective and high-performance activators. Surface atomic engineering toward these activators is desirable but it remains challenging to realize improved activation properties. Here, a surface atomic engineering strategy used to obtain a novel hybrid activator, namely cobalt-coordinated nitrogen-doped graphitic carbon nanosheet-enwrapped cobalt nanoparticles (denoted as Co@NC-rGO), from a sandwich-architectured metal-organic framework/graphene oxide composite is reported. This activator exhibits prominent periodate activation properties toward pollutant degradation, surpassing previously reported transition-metal-based activators. Importantly, the activator shows good stability, magnetic reusability, and the potential for application in a complex water matrix. Density functional theory modeling implies that the strong activation capability of Co@NC-rGO is related to its surface atomic structure for which the embedded cobalt nanoparticles with abundant interfacial Co-N coordinations display modified electronic configurations on the active centers and benefit periodate adsorption. Quenching experiments and electrochemical measurements showed that the system could oxidize organics through a dominant nonradical pathway. Additionally, a lower concentration of cobalt leaching was observed for the Co@NC-rGO/periodate system than for its Co@NC-rGO/persulfate counterpart. Our work provides a pathway toward engineering surface atomic structures in hybrid activators for efficient periodate activation.

Kinetics and mechanism of synergistic adsorption and persulfate activation by N-doped porous carbon for antibiotics removals in single and binary solutions

Porous carbon serves as a green material for efficient wastewater purification by adsorption and advanced oxidation processes. However, a clear understanding of the simultaneous removal of multiple pollutants in water is still ambiguous. Herein, the synergistic effect of adsorption and peroxydisulfate (PS) activation on kinetics and mechanism of removing single and binary antibiotic pollutants, sulfamethoxazole (SMX) and ibuprofen (IBP), from water by biomass-derived N-doped porous carbon was investigated. Our findings suggest that adsorption contributed to efficient removals of SMX/IBP. Comparative quenching experiments and electrochemical analysis demonstrated that hydroxyl (•OH) and sulfate (SO₄^•-) radicals, as well as singlet oxygen (¹O₂) led to the catalytic degradation of SMX, while only ¹O₂ reacted for IBP oxidation. Superoxide ion (O₂^•-) radicals were not related to SMX/IBP degradation. Electron transfer pathway accounted for PS activation but was not involved in direct SMX/IBP oxidation. Only slight differences were found between the degradation kinetics of SMX and IBP in the binary and single SMX or IBP solutions. This arose from the non-selective effect of adsorption and ¹O₂ attack for SMX/IBP removal, and the weak selective oxidation process of SMX by •OH and SO₄^•-. This study provides a new viewpoint on the role of adsorption in catalysis and enriches the mechanistic study of multi-component antibiotic degradation.

Catalytic degradation of sulfamethoxazole by peroxymonosulfate activation system composed of nitrogen-doped biochar from pomelo peel: Important roles of defects and nitrogen, and detoxification of intermediates

Nitrogen doping could improve the catalytic performance of carbon materials, in which the nitrogen configuration could be used as active sites for peroxymonosulfate (PMS) activation. Herein, this paper studied how to turn waste to "treasure" by agriculture waste pomelo peel to prepare nitrogen-doped biochar and successfully applied it to advanced oxidation field. The effects of the sodium bicarbonate (NaHCO₃), melamine, and pyrolysis temperature on the catalytic activity of biochar for the removal of sulfamethoxazole (SMX) were investigated. The optimized nitrogen-doped biochar (C-N-M 1:3:4) possessed high specific surface area (SSA, 738 m²/g) and high level of nitrogen doping (nitrogen content 13.54 at%). Accordingly, it exhibited great catalytic performance for PMS activation to remove SMX antibiotic, and 95% of SMX was removed within 30 min. High catalytic activity of C-N-M 1:3:4 was attributed to rich defects, carbonyl group, high content of graphitic N and pyrrolic N, and large SSA, in which non-radical oxidation process based on singlet oxygen (¹O₂) and electron transfer contributed to the SMX degradation. The prepared nitrogen-doped biochar possessed high stability and reusability and the removal efficiency of SMX still reached 80% after four cycles. Additionally, the phytotoxicity assay indicated that the toxicity of degradation intermediates was obviously decreased in the PMS/ C-N-M 1:3:4 system.

Constructing highly porous carbon materials from porous organic polymers for superior CO2 adsorption and separation

The increase in atmospheric carbon dioxide (CO₂) concentration has led to numerous problems related to our living environment, seeking an efficient carbon capture and storage (CCS) strategy associated with low energy consumption and expenditures is highly desirable. Here, we demonstrate a facile approach to synthesize a series of highly porous carbon materials derived from porous organic polymers synthesized from three low-cost isomers of triphenyl using chemical activation with KOH at different temperatures. Compared with the precursor porous organic polymers, the porosity of the prepared porous carbon materials is significantly enhanced with surface areas as high as 3367 m² g^-1 and pore volumes up to 1.224 cm³ g^-1. Notably, such porous carbon materials deliver an exceptionally high CO₂ adsorption capacity of 7.78 mmol g^-1 at 273 K and 1 bar, a value that is superior to most of the previously reported adsorbents. In addition, these porous organic polymers and derived porous carbon materials exhibit high CO₂/N₂ selectivity at ambient conditions. Therefore, the facile construction of highly porous carbon materials from porous organic polymers may offer an efficient strategy for CO₂ adsorption and separation and further mitigates greenhouse effect.

Graphitic carbon nitride nanosheets via acid pretreatments for promoted photocatalysis toward degradation of organic pollutants

Acid treatment serves as an effective engineering strategy to modify the structure of graphitic carbon nitride (g-C₃N₄) for enhanced metal-free photocatalysis, while their lacks a comprehensive understanding about the impacts of different acid species and acid treatment approaches on the intrinsic structure and properties of g-C₃N₄ and structure-activity relationships are ambiguous. Employing inorganic/organic acids including hydrochloric acid (HCl), nitric acid (HNO₃), acetic acid (HAc), sulphuric acid (H₂SO₄), or oxalic acid (H₂C₂O₄) as treatment acids, herein, we compare the impacts of different acid pretreatment approaches on the structure and properties of g-C₃N₄. Due to different acid-melamine interaction modes and the activation roles of various acids, the obtained g-C₃N₄ samples exhibit varied structures, physiochemical properties and photocatalytic activities. Compared with bulk graphitic carbon nitride (BCN), g-C₃N₄ prepared by acid pretreatment show enhanced photocatalytic performance on bisphenol A (BPA) degradation. The photocatalytic degradation rates of BPA by g-C₃N₄ prepared by HNO₃, HAc, H₂SO₄, H₂C₂O₄, or HCl pretreatment are about 2.2, 2.7, 2.8, 3.2 and 3.8 folds faster than that by BCN. HCl pretreatment proves to be the optimal approach, with the derived g-C₃N₄ (HTCN) showing more intact heptazine structural units, and increased specific surface area, which promote the exposure of more active sites, accelerate charge transfer, and give rise to a notable improvement in photocatalysis, eventually. Mechanistic investigations through quenching experiments and electron paramagnetic resonance (EPR) characterization unveil that superoxide ion radical (O₂^-) and photo-induced holes (h⁺) worked principally in the photodegradation reaction. This work provides new insights for the rational selection of acid types and treatment methods to synthesize metal-free carbon nitrides with improved activity for photocatalytic applications.

Biomass-derived N/S dual-doped hierarchically porous carbon material as effective adsorbent for the removal of bisphenol F and bisphenol S

Biomass-derived heteroatom-doped porous carbon-based materials are emerging as low-cost adsorbents for removing common pollutants, although the adsorption performance is still unsatisfactory and the main adsorption mechanisms are still controversial. Herein, we report a facile and general method for fabricating biomass-derived N/S dual-doped hierarchically porous carbon adsorbent (MZ-NSPC). The MZ-NSPC material exhibits excellent adsorption capacity (295.8 mg/g for bisphenol F (BPF), 308.7 mg/g for bisphenol S (BPS)), short equilibrium time (30 min), and good reusability (the decline efficiency < 6.15% after five times). The remarkable adsorption performance originates from a large BET surface area, hierarchically porous structure, and N/S heteroatoms dual-doping. Combined with comparative experiments and density functional theory (DFT) calculations, we revealed that the doped N, S heteroatoms played a synergistic effect which promoted the adsorption performance and adsorption sites are mainly the oxidized-S and pyridinic-N. Importantly, for BPF, the proportion contribution of different mechanisms followed the order of hydrophobic interaction > π-π interaction > hydrogen bonding interaction. However, adsorption mechanism of BPS was mainly controlled by π-π interaction. This work not only promotes the development of low-cost and sustainable heteroatom-doped carbon-based materials, but also systematically studies adsorption mechanism of heteroatom-doped carbon-based materials for bisphenols.

Selective oxidation of alcohols by graphene-like carbon with electrophilic oxygen and integrated pyridinic nitrogen active sites

The selective oxidations of alcohols into corresponding aldehydes or ketones are essential reactions for organic synthesis. The development of facile, green and cost-effective protocols to accomplish selective oxidation is highly attractive. Here, we present the selective oxidation of alcohols using peroxymonosulfate (PMS) oxidants with N-doped graphene-like carbon (NG) synthesized via a metal-free approach without producing a large amount of hazardous wastes. In the tested selective oxidation reaction, over 96% of benzyl alcohol (BzOH) was converted into benzaldehyde (BzH) with high selectivity under mild conditions. The synthesized NG catalyst contains abundant electrophilic oxygen species, serving as the major active sites for the generation of reactive radicals from PMS to enable the selective oxidation of BzOH in the radical pathway. Besides, non-radical oxidation of BzOH occurs via the electron transfer through the surface coordinated complex, dominantly upon the N species. Particularly, the configuration of integrated pyridinic N is possible to create active domains for BzOH oxidation with activated PMS. This work opens a new avenue to convert metal-free raw materials into effectively functionalized carbon materials, coupled with their potential applications in the selective oxidation of alcohols.

Carbon aerogel from forestry biomass as a peroxymonosulfate activator for organic contaminants degradation

The carbon catalyst has been widely used as a peroxymonosulfate (PMS) activator to degrade organic contaminants. The biomass carbon aerogel (CA) derived from poplar powder was synthesized in this study. CA with three-dimensional structure exhibited an excellent degradation performance of PMS activation for different types of organic contaminants including bisphenol A (BPA), rhodamine 6 G, phenol, and p-chlorophenol with the removal efficiencies up to 91%, 100%, 100%, and 60% within 60 min, respectively. It was found that singlet oxygen (¹O₂) dominated the non-radical pathway worked for BPA removal in CA/PMS system. The possible mechanism for PMS activation was discussed. A portion of ¹O₂ was produced through the transformation of superoxide radical (O₂^•-) in CA/PMS system. Electronic impedance spectroscopy (EIS) proved that the hierarchical structure of CA contributed to the electron transfer process for PMS activation. The ketonic/carbonyl groups (C˭O) on the surface of CA could serve as a possible active site to facilitate the generation of ¹O₂. In addition, CA showed superior degradation performance in actual water bodies and reusability with high-temperature regeneration treatment. This study developed an efficient and environmentally benign catalyst for water remediation of organic pollutants.

Different activation methods in sulfate radical-based oxidation for organic pollutants degradation: Catalytic mechanism and toxicity assessment of degradation intermediates

With the continuous development of industrialization, a growing number of refractory organic pollutants are released into the environment. These contaminants could cause serious risks to the human health and wildlife, therefore their degradation and mineralization is very critical and urgent. Recently sulfate radical-based advanced oxidation technology has been widely applied to organic pollutants treatment due to its high efficiency and eco-friendly nature. This review comprehensively summarizes different methods for persulfate (PS) and peroxymonosulfate (PMS) activation including ultraviolet light, ultrasonic, electrochemical, heat, radiation and alkali. The reactive oxygen species identification and mechanisms of PS/PMS activation by different approaches are discussed. In addition, this paper summarized the toxicity of degradation intermediates through bioassays and Ecological Structure Activity Relationships (ECOSAR) program prediction and the formation of toxic bromated disinfection byproducts (Br-DBPs) and carcinogenic bromate (BrO₃^-) in the presence of Br^-. The detoxification and mineralization of target pollutants induced by different reactive oxygen species are also analyzed. Finally, perspectives of potential future research and applications on sulfate radical-based advanced oxidation technology in the treatment of organic pollutants are proposed.

Sustainable Carbon Materials toward Emerging Applications

It is desirable for a sustainable society that the production and utilization of renewable materials are net-zero in terms of carbon emissions. Carbon materials with emerging applications in CO₂ utilization, renewable energy storage and conversion, and biomedicine have attracted much attention both academically and industrially. However, the preparation process of some new carbon materials suffers from energy consumption and environmental pollution issues. Therefore, the development of low-cost, scalable, industrially and economically attractive, sustainable carbon material preparation methods are required. In this regard, the use of biomass and its derivatives as a precursor of carbon materials is a major feature of sustainability. Recent advances in the synthetic strategy of sustainable carbon materials and their emerging applications are summarized in this short review. Emphasis is made on the discussion of the original intentions and various sustainable strategies for producing sustainable carbon materials. This review provides basic insights and significant guidelines for the further design of sustainable carbon materials and their emerging applications in catalysis and the biomedical field.

Disassembly of lignocellulose into cellulose, hemicellulose, and lignin for preparation of porous carbon materials with enhanced performances

Lignocellulose is the primary component of many biomasses, including corn straw. Herein, lignocellulose in corn straw was disassembled into the individual polymers, cellulose, hemicellulose, and lignin via a mild and facile method. Subsequently, three porous carbon materials were prepared by carbonization and chemical activation of cellulose (PCCC), hemicellulose (PCHC), and lignin (PCLC). The three materials showed higher specific surface areas (2565.7, 2996.1, and 2590.3 m² g^-1) and higher porosities (1.4261, 1.5876, and 1.2406 cm³ g^-1) than that of PCCS, a porous carbon material derived from raw corn straw (1993 m² g^-1 and 1.19 cm³ g^-1). Of note, PCCC and PCHC exhibited higher adsorption (1025.5 and 950.1 mg g^-1) of brilliant green (BG), than PCCS (876.7 mg g^-1). Besides, the BG adsorption capacities of the designed materials were higher than that of most adsorbents, and 2-2.5 times higher than that of graphite oxide (416.7 mg g^-1). These study results indicate that the disassembly of lignocellulosic biomass into cellulose, hemicellulose, and lignin is an effective strategy for preparing various porous carbon materials with enhanced performances.

Enhanced removals of micropollutants in binary organic systems by biomass derived porous carbon/peroxymonosulfate

Water pollution usually involves multiple pollutants, and their degradation mechanisms are complicated. In this study, we investigated the degradation of single and binary pollutants (phenol and p-hydroxybenzoic acid (HBA)) in water, using biomass-derived N-doped porous carbon (Y-PC) for peroxymonosulfate (PMS) activation and we found better kinetics and efficiencies of degradation in binary pollutants than single pollutant systems. Electron paramagnetic resonance (EPR), quenching experiments, and electrochemical tests indicated that •OH, SO₄^•-, O₂^•-, and ¹O₂ accounted for the catalytic oxidation of phenol/HBA, while the electron-transfer pathway had an additional contribution to phenol degradation. We unveiled that the HBA degradation rate was similar in the binary and single systems due to the non-selective attack of the micropollutants by •OH, SO₄^•-, O₂^•- and ¹O₂. However, phenol degradation rate was significantly accelerated in the binary phenol/HBA system as compared to that in the single phenol solution, due to the exclusive and selective role of electron transfer pathway. In the binary micropollutant system, a fortified electron-transfer pathway over phenol directly expedited its decomposition and contributed indirectly to this process. This study provides new insights into porous carbon-based advanced oxidation processes for the simultaneous removal of multicomponent contaminants in practical applications.

Mechanistic understanding of highly selective adsorption of bisphenols on microporous-dominated nitrogen-doped framework carbon

Producing a desirable adsorbent for removing endocrine disrupting compounds (EDCs) from aqueous solutions remains a major challenge. In this work, microporous-dominated nitrogen-doped framework carbons (MNFCs, s means the calcination temperature) with high specific surface area, ultra-microporous structure, and high nitrogen-doping can be obtained by a direct calcination of ethylene diamine tetraacetic acid tetrasodium (EDTA-4Na) without aid of any catalyst and nitrogen source. MNFCs were applied adsorbents to remove bisphenols from aqueous solution. Batch experiments showed MNFC-750 had a large adsorption capacity for bisphenols from aqueous solutions (409 mg/g for bisphenol A, 364 mg/g for bisphenol F, and 521 mg/g for bisphenol S) along with short equilibrium time (30 min), and good stability and reusability. Using multiple characterizations and comparative experiments along with theoretical calculations, we discovered that: (1) nitrogen-doping can significantly boost the adsorption capacity; (2) adsorption sites are mainly the pyridinic-N instead of pyrrolic-N and graphitic-N; and (3) the adsorption mechanisms were mainly driven by Lewis acid-base interaction, hydrophobic interaction, π-π interaction and hydrogen bond interaction. These findings indicate that MNFCs present a promising potential for practical applications and shed light on the rational design of nitrogen doped carbon-based adsorbents for efficient pollutant removal.

Promoting adsorption of organic pollutants via tailoring surface physicochemical properties of biomass-derived carbon-attapulgite

Biomass-derived carbon-attapulgite adsorbent was developed for organic pollutants removal. All the batch assays were performed to evaluate the effects of organic components, contact time, and initial concentration of organic pollutants on the adsorption performance of the as-prepared adsorbent. The samples were characterized via Brunauer-Emmett-Teller (BET), Fourier transform infrared (FTIR), X-ray diffractometer (XRD), and scanning electron microscopy (SEM). The results demonstrated that the acid-treated carbon-attapulgite adsorbent (H-ATP/BC) showed a large specific surface area (237 m² g^-1) and possessed abundant oxygen-containing functional groups and silicon-oxygen bonds (i.e., O-Si-O and O-Si), which provided more active sites and conduced to the adhesive of organic pollutants. Both physical adsorption and chemical adsorption were involved in the adsorption process, and competitive adsorption occurred when two or more target pollutants coexist. Especially, phenol and/or aniline with an aromatic ring were much more likely to adhere to the H-ATP/BC surface than pyridine, and the selectivity order of H-ATP/BC for these pollutants was phenol > aniline > pyridine. From the model fitting, it was observed that the adsorption data could be described well by a pseudo-second-order model and Freundlich isotherms. The theoretical maximum phenol, aniline, and pyridine adsorption capacities of the H-ATP/BC were 14.31 mg g^-1, 15.21 mg g^-1, and 20.74 mg g^-1, respectively. Comparison among the commercial adsorbents price also illustrated that H-ATP/BC could be a promising material for efficient treatment of organic pollutants.Graphical abstract.

Magnetically steerable iron oxides-manganese dioxide core-shell micromotors for organic and microplastic removals

Because of micro/nanoscale manipulation and task-performing capability, micro/nanomotors (MNMs) have attracted lots of research interests for potential applications in biomedical and environmental applications. Owing to the low-cost, good motion behavior, and environmental friendliness, various low-cost metal oxides based MNMs become promising alternatives to the precious metal based MNMs, in particular for environmental remediation applications. Hereby, we demonstrate the facile and scalable fabrication of two types of bubble-propelled iron oxides-MnO₂ core-shell micromotors (Fe₃O₄-MnO₂ and Fe₂O₃-MnO₂) for pollutant removal. The Fe₂O₃-MnO₂ micromotor exhibits efficient removals of both aqueous organics and suspended microplastics via the synergy of catalytic degradation, surface adsorption, and adsorptive bubbles separations mechanisms. The adsorptive bubbles separation achieved more than 10% removal of the suspended microplastics from the polluted water in 2 h. We clarified the major contributions of different remediation mechanisms in pollutants removals, and the findings may be beneficial to a wide range of environmental applications of MNMs.