Single-step pyrolysis of phosphoric acid-activated chitin for efficient adsorption of cephalexin antibiotic

A water-stable Zn(II)-based metal-organic framework as a multifunctional fluorescent sensor for vitamin B6, Fe3+ ion and cephalexin

A water-stable metal-organic framework Zn-MOF, [Zn3(tzta)2(NMP)2(H2O)2]·2H2O, was successfully synthesized under solvothermal condition using a carboxylate-tetrazolyl ligand H2tzta (H2tzta = 2-(2-H-tetrazol-5-yl)-terephthalic acid). Zn-MOF exhibits a three-dimensional (3D) framework structure with rtl rutile topological type. The TGA and PXRD measurements demonstrate the high thermostability and water stability. The solid-state fluorescence emission spectra present that Zn-MOF and H2tzta exhibit the similar emission peaks. Furthermore, Zn-MOF can be used as a "turn-on" fluorescent sensor to detect vitamin B6 (VB6) and cephalexin (CEP) in phosphate buffer solution, and it can also sense Fe3+ as a "turn-off" fluorescent sensor in phosphate buffer solution. The limit of detection for VB6, Fe3+ and CEP are 0.080 μM, 0.29 μM and 0.021 μM, respectively. In addition, the fluorescence detection mechanism of Zn-MOF for VB6, Fe3+ and CEP was discussed based on fluorescence resonance energy transfer (FRET), internal filtration effect (IFE) and photon-induced electron transfer (PET). Significantly, a visual film utilizing Zn-MOF@SA was constructed for the detection of VB6, Fe3+ and CEP with high reusability and visuality.

Pilot-scale adsorption of pharmaceuticals from municipal wastewater effluent using low-cost magnetite-pine bark: Regeneration/enumeration of viable bacteria with a study on their biotoxicity

A low-cost and renewable magnetite-pine bark (MPB) sorbent was evaluated in continuous-flow systems for the removal of various pharmaceuticals from municipal wastewater effluent following membrane bioreactor (MBR) treatment. A 33-day small-scale column test (bed volume: 791 cm3) was conducted using duplicate columns of biochar (BC, Novocarbo) and activated carbon (AC, ColorSorb) as reference for two columns of BC and MPB in order to compare the efficiency of AC and MPB. After the small-scale column test, the pharmaceutical concentrations were generally below the detection limit. In the next stage, a four-month pilot-scale adsorption test was performed using a large column (bed volume: 21 L) filled with BC and MPB. A variety of compounds were removed after the pilot-scale column, including trimethoprim (99.7%), hydrochlorothiazide (81.8%), candesartan (26.0%), carbamazepine (86.1%), ketoprofen (89.4%), clindamycin (86.6%), oxazepam (91.3%), sulfadiazine (38.6%), sulfamethoxazole (58.3%), tramadol (88.9%), zopiclone (73.5%), venlafaxine (93.7%), furosemide (93.5%), fexofenadine (91.6%) and losartan (81.2%). The enumeration of viable bacteria in the pilot-scale column samples revealed that regenerating the BC-MPB bed with NaOH increased bacterial counts in the treated water due to the desorption of adsorbed bacteria from the bed. A biotoxicity study using the Nitrosomonas europaea bioreporter strain indicated that the wastewater was generally non-toxic to this nitrifying bacterium and regeneration of pilot-scale column samples caused short-time toxicity immediately after regeneration. The study confirms that MPB is efficient for the adsorption of pharmaceuticals and can be applied in column mode with a support material such as BC. Therefore, MPB is a viable alternative for AC for the remediation of pharmaceutical-contaminated wastewaters.

Biochar for mitigating pharmaceutical pollution in wastewater: A sustainable solution

Pharmaceutical contaminants (PCs), including antibiotics, analgesics, and other medications, pose a growing threat to aquatic ecosystems and human health due to their persistence and bioaccumulation potential. Biochar, a carbonaceous material derived from biomass pyrolysis, has emerged as a sustainable adsorbent for removing PCs from wastewater. Biochar is reported to remove PCs from water with an average range of 58 to 91 %, depending on the nature of feedstock, pyrolysis conditions, and characteristics of the pharmaceuticals. Biochar's effectiveness is attributed to its unique properties, including high porosity, large surface area and diverse functional groups, which enable the adsorption of various pharmaceutical compounds through physical and chemical interactions. Common PCs such as tetracycline, ciprofloxacin, ibuprofen, paracetamol, sulfamethoxazole, and cephalexin can be effectively removed using biochar. The adsorption process involves different mechanisms such as Van der Waals forces, electrostatic interactions, hydrogen bonding, and surface complexation. This review summarizes the current state of knowledge on biochar-based adsorption mechanisms, highlights successful applications in wastewater treatment, and identifies areas for future research. While promising, a deeper understanding of adsorption mechanisms, optimization of biochar production, and the development of effective regeneration methods are crucial for maximizing biochar's efficacy and ensuring its sustainable implementation in wastewater treatment systems.

Advanced biopolymer-based Ti/Si-terephthalate hybrid materials for sustainable and efficient adsorption of the tetracycline antibiotic

This study involves the synthesis of an organic-inorganic hybrid material consisting of Ti/Si-terephthalate (Ti-TPA-Si) in a 1:1:1 ratio using sol-gel method and its reaction with cellulose and chitosan (Ti-TPA-Si-C and Ti-TPA-Si-CS). Characterization techniques such as XRD, FTIR, SEM, EDS, XPS, BET, TGA, and DTA were used. The incorporation of biopolymers (cellulose and chitosan) into the Ti/Si-terephthalate structure improved the morphology and textural properties of the hybrid materials, leading to increased adsorption capacity and sustainability. Adsorption experiments reveal that Ti-TPA-Si, Ti-TPA-Si-C, and Ti-TPA-Si-CS hybrid materials exhibit a high affinity towards tetracycline, achieving remarkable adsorption efficiencies of 88.27, 89.60, and 88.98 %, respectively. Isotherm studies indicate that the adsorption process follows both Langmuir (R2 = 0.971, 0.990, and 0.994) and Dubinin-Radushkevich (R2 = 0.922, 0.965, and 0.949) isotherm models. According to the Langmuir model, the maximum adsorption capacity (qm) of Ti-TPA-Si, Ti-TPA-Si-C, and Ti-TPA-Si-CS adsorbents was found to be 24.10, 33.56, and 26.59 mg/g, respectively. Kinetic studies indicate that the adsorption process follows both pseudo-second-order (R2 = 0.998, 0.984, and 0.989) and intra-particle diffusion (R2 = 0.995, 0.994, and 0.988) models. Thermodynamic studies reveal that adsorption processes are spontaneous and endothermic in nature. Reusability studies demonstrate their potential for repeated use without significant loss in performance.

Mechanisms and extended kinetic model of thermal desorption in organic-contaminated soil

Thermal desorption is a preferred technology for site remediation due to its various advantages. To ensure the effective removal of different pollutants in practical applications, it is necessary to understand the kinetic behaviors and removal mechanisms of pollutants in thermal desorption process. This paper explored the thermal desorption processes of five organic pollutants (nitrobenzene, naphthalene, n-dodecane, 1-nitronaphthalene, and phenanthrene) at 50-350 °C in two different subsoils with 6-18% moisture content. The results suggested that the thermal desorption process was well-fitted by the exponential decay model (R2 = 0.972-0.999) and could be divided into two distinct stages. The first stage was relatively fast and highly influenced by soil moisture, while the second stage showed a slower desorption rate due to the constraints imposed by the soil texture and structure. The influence of soil moisture on thermal desorption depended on the octanol/water partition coefficient (KOW) of pollutants. Pollutants with log KOW values lower than the critical value exhibited enhanced thermal desorption, while those with log KOW values higher than the critical value were inhibited. The critical value of log KOW might be between 3.33 and 4.46. Changes in soil texture and structure caused by heating promoted thermal desorption, especially for naphthalene, 1-nitronaphthalene and phenanthrene. The differences in texture and structure between the two soils diminished as the temperature increased. Finally, an extended kinetic model under changing temperature conditions was derived, and the simulation results for the two subsoils were very close to the actual thermogravimetric results, with the differences ranging from -1.28% to 0.94% and from -0.67% to 1.35%, respectively. These findings propose new insights into the influencing mechanisms of soil moisture and structure on the thermal desorption of organic pollutants. The extended kinetic model can provide reference for future kinetic research and guide practical site remediation.

Critical review on organophosphate esters in water environment: Occurrence, health hazards and removal technologies

Organophosphate esters (OPEs), which are phosphoric acid ester derivatives, are anthropogenic substances that are widely used in commerce. Nevertheless, there is growing public concern about these ubiquitous contaminants, which are frequently detected in contaminated water sources. OPEs are mostly emitted by industrial operations, and the primary routes of human exposure to OPEs include food intake and dermal absorption. Because of their negative effects on both human health and the environment, it is clear that innovative methods are needed to facilitate their eradication. In this study, we present a comprehensive overview of the existing characteristics and origins of OPEs, their possible impacts on human health, and the merits, drawbacks, and future possibilities of contemporary sophisticated remediation methods. Current advanced remediation approaches for OPEs include adsorption, degradation (advanced oxidation, advanced reduction, and redox technology), membrane filtration, and municipal wastewater treatment plants, degradation and adsorption are the most promising removal technologies. Meanwhile, we proposed potential areas for future research (appropriate management approaches, exploring the combination treatment process, economic factors, and potential for secondary pollution). Collectively, this work gives a comprehensive understanding of OPEs, providing useful insights for future research on OPEs pollution.

Optimization and mechanistic approach for removal of crystal violet and methylene blue dyes via activated carbon from pyrolyzed-ZnCl2 bamboo waste

In this study, bamboo waste (BW) was subjected to pyrolysis-assisted ZnCl2 activation to produce mesoporous activated carbon (BW-AC), which was then evaluated for its ability to remove cationic dyes, specifically methylene blue (MB) and crystal violet (CV), from aqueous environments. The properties of BW-AC were characterized using various techniques, including potentiometric-based point of zero charge (pHpzc), scanning electron microscopy with energy dispersive X-rays (SEM-EDX), X-ray diffraction (XRD), gas adsorption with Brunauer-Emmett-Teller (BET) analysis, infrared (IR) spectroscopy. To optimize the adsorption characteristics (BW-AC dosage, pH, and contact time) of PBW, a Box-Behnken design (BBD) was employed. The BW-AC dose of 0.05 g, solution pH of 10, and time of 8 min are identified as optimal operational conditions for achieving maximum CV (89.8%) and MB (96.3%) adsorption according to the BBD model. The dye removal kinetics for CV and MB are described by the pseudo-second-order model. The dye adsorption isotherms revealed that adsorption of CV and MB onto BW-AC follow the Freundlich model. The maximum dye adsorption capacities (qmax) of BW-AC for CV (530 mg/g) and MB (520 mg/g) are favorable, along with the thermodynamics of the adsorption process, which is characterized as endothermic and spontaneous. The adsorption mechanism of CV and MB dyes by BW-AC was attributed to multiple contributions: hydrogen bonding, electrostatic forces, π-π attraction, and pore filling. The findings of this study highlight the potential of BW-AC as an effective adsorbent in wastewater treatment applications, contributing to the overall goal of mitigating the environmental impact of cationic dyes and ensuring the quality of water resources.

Preparation of a highly functionalized activated carbon from waste third-monomer pressure filter liquid for removal of methylene blue in aqueous solution

Third monomer dimethyl isophthalate-5-sodium sulfonate (SIPM) is an additive widely used to modify polyester chips. During the manufacture of SIPM, large amounts of waste third-monomer pressure filter liquid are produced. As the liquid contains lots of toxic organics and highly concentrated Na₂SO₄, it will cause serious environmental pollution if discharged directly. In this study, highly functionalized activated carbon (AC) was prepared by directly carbonizing the dried waste liquid under ambient pressure. Structural and adsorption properties of the prepared AC were analyzed and evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), N₂ adsorption-desorption analysis and methylene blue (MB) as the adsorbate, respectively. Results showed that the adsorption capacity of the prepared AC to MB reached the highest when carbonization was conducted at 400 °C. XRD analysis showed that the AC has a disordered graphite-like crystal structure. FT-IR and XPS analyses showed that there were plenty of carboxyl and sulfonic functional groups in the AC. The adsorption follows the pseudo-second-order kinetic model and the isotherm process is consistent with the Langmuir model. The adsorption capacity increased with increasing solution pH and dropped when the solution pH exceeded 12. Increasing solution temperature favors the adsorption, where the maximum value can reach as high as 2816.4 mg g^-1 at 45 °C, more than double the values reported to date. The adsorption of MB on the AC is mainly controlled by the electrostatic interaction between MB and the anionic form of carboxyl and sulfonic groups.

Removal of Fluoride from Aqueous Solution Using Shrimp Shell Residue as a Biosorbent after Astaxanthin Recovery

Natural astaxanthin has been widely used in the food, cosmetic, and medicine industries due to its exceptional biological activity. Shrimp shell is one of the primary natural biological sources of astaxanthin. However, after astaxanthin recovery, there is still a lot of chitin contained in the residues. In this study, the residue from shrimp (Penaeus vannamei) shells after astaxanthin extraction using ionic liquid (IL) 1-ethyl-3-methyl-imidazolium acetate ([Emim]Ac) was used as a bioadsorbent to remove fluoride from the aqueous solution. The results show the IL extraction conditions, including the solid/liquid ratio, temperature, time, and particle size, all played important roles in the removal of fluoride by the shrimp shell residue. The shrimp shells treated using [Emim]Ac at 100 °C for 2 h exhibited an obvious porous structure, and the porosity showed a positive linear correlation with defluorination (DF, %). Moreover, the adsorption process of fluoride was nonspontaneous and endothermic, which fits well with both the pseudo-second-order and Langmuir models. The maximum adsorption capacity calculated according to the Langmuir model is 3.29 mg/g, which is better than most bioadsorbents. This study provides a low-cost and efficient method for the preparation of adsorbents from shrimp processing waste to remove fluoride from wastewater.

Mesoporous Activated Carbon from Leaf Sheath Date Palm Fibers by Microwave-Assisted Phosphoric Acid Activation for Efficient Dye Adsorption

Remazol Brilliant Blue R (RBBR) is a common dye used in the industry, and its presence in wastewater and discharge into the environment can create a serious concern for the ecosystem and human health. Activated carbon produced from crop residues has emerged as a promising technique for removing contaminants from wastewater. In this study, leaf sheath date palm fiber-based activated carbon (LSDAC) was synthesized via phosphoric acid, H₃PO₄, treatment, followed by a microwave-induced carbonization process. The produced LSDAC was found to have a BET surface area of 604.61 m²/g, a Langmuir surface area of 922.05 m²/g, a total pore volume of 0.35 cm³/g, and an average pore size of 2.75 nm. The highest removal of RBBR was achieved at a solution pH of 3 (92.56 mg/g) and a solution temperature of 50 °C (90.37 mg/g). Adsorption of RBBR onto LSDAC followed the Langmuir isotherm model with a maximum monolayer capacity, Q _m, of 243.43 mg/g, whereas in terms of kinetics, this adsorption system was best described by the pseudo-first-order (PFO) model. The calculated thermodynamic parameters ΔH°, ΔS°, ΔG°, and Arrhenius activation energy, E _a, were 4.71 kJ/mol, 0.10 kJ/mol·K, -26.25 kJ/mol, and 5.88 kJ/mol, respectively, indicating that the adsorption of RBBR onto LSDAC was endothermic in nature, exhibited increased randomness at the solid-liquid interface, and was spontaneous and controlled by physisorption.

Physicochemical Characteristics of Biochar from Waste Cricket Chitin (Acheta domesticus)

The properties of biochar (BC) from crustacean chitin are relatively well understood, while there are few studies on BC from insect chitin. This study presents the characterization and phytotoxic assessment of BC produced from crickets and cricket chitin. Cricket powder (BCCR) and cricket chitin (BCCH) were pyrolyzed at 500 °C and 700 °C. Physicochemical characteristics, N ad-/desorption, FTIR, were examined. SEM images were also performed. Regardless of the pyrolysis temperature, biochars were characterized by a densely "packed" solid surface/monolithic type with a non-porous structure (0.05-0.22 m²/g) and high content of N (9.4-11.8%). BCCHs showed a higher pH (12.2-12.4) compared to BCCR (8.7-10.8). Based on the XRD analysis, BCs were characterized by an amorphous carbon turbostratic structure and a randomly oriented graphitic-like micro-crystallite structure. FTIR spectra of BCs confirmed the presence of various O₂ and N-functional groups on the BC surface. BCCHs added to soil at rates from 0.5 to 1.5% significantly reduced the germination of Lepidium sativum. Stimulation of root elongation was also observed in the case of BCCR500 1.0% and BCCR700 1.5%. Thermal degradation of cricket powder and cricket chitin promotes the formation of organic N-containing heterocyclic rings, which lead to the production of N-doped carbons with potential uses in energy storage and the contaminations sorption.

Highly efficient adsorption of Bisphenol A using NaHCO3/CO2 activated carbon composite derived from shrimp shell@cellulose

In this study, the efficiency of activated carbon (AC) synthesized from the shrimp shell plus cellulose (SS@C) was optimized toward Bisphenol A (BPA) adsorption. Low-cost, renewable, and non-toxic shrimp shells mixed with cellulose were carbonized, followed by activation via CO₂ and NaHCO₃ to produce SS@C-AC. The results revealed that SS@C-AC samples were a porous composite with mesoporous structures comprising a relatively high specific surface area (935.20 m²/g) with a mean pore size of around 3.8 nm and mesoporous volume of 1.83E-02 cm³/g. The influences of initial concentrations, pH values, and adsorption on BPA were investigated systematically. Isotherm model and kinetics study of the adsorption of BPA on SS@C-AC exhibited that the obtained data were in agreement with the Langmuir adsorption isotherm model while there is no difference between PFO and PSO kinetic results for BPA concentrations in the range 25-100 mg/L. The impregnation ratio of 1.5 NaHCO₃ and an activation time of 90 min at 800°C were the optimum conditions under which BPA removal of 81.78% was obtained.

Adsorption Properties of Modified ATP-RGO Composite Aerogel for Removal of Malachite Green and Methyl Orange from Unitary and Binary Aqueous Solutions

In this paper, the modified attapulgite-reduced graphene oxide composite aerogel (ATP-RGO CA) was prepared by sol-gel method using modified attapulgite as silica source. The removal of the cationic dye malachite green (MG) and azo dye methyl orange (MO) onto ATP-RGO CA from unitary and binary systems was investigated. Morphology and microstructure studies of ATP-RGO CA were investigated by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and specific surface area and porosity analysis. Experiments were carried out as a function of pH, contact time, initial dye concentration, and temperature in unitary and binary systems. The adsorption kinetics, isotherms, thermodynamics, and dye desorption were studied in unitary and binary dye systems. The adsorption kinetics was modeled using the pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetics equations. The equilibrium adsorption data of MG and MO dyes on ATP-RGO CA were analyzed. Thermodynamic parameters of dye adsorption were obtained. In addition, the regeneration of ATP-RGO CA was studied using dye desorption in unitary and binary dye systems. The adsorption kinetics of the dyes followed pseudo-second-order kinetics. The results indicate that the Langmuir model provides the best correlation of the experimental data. The thermodynamic studies showed that the dye adsorption onto ATP-RGO CA was a spontaneous and endothermic reaction. High desorption of MG and MO showed the regeneration of ATP-RGO CA. It can be concluded that ATP-RGO CA is suitable as an adsorbent material to remove MG and MO dyes from unitary and binary systems.

Cephalexin Adsorption by Acidic Pretreated Jackfruit Adsorbent: A Deep Learning Prediction Model Study

Cephalexin (CFX) residues in the environment represent a major threat to human health worldwide. Herein we investigate the use of novel approaches in deep learning in order to understand the mechanisms and optimal conditions for the sorption of cephalexin in water onto an acidic pretreated jackfruit peel adsorbent (APJPA). The interaction between the initial concentration of CFX (10–50 mg/100 mL), APJAP dosage (3–10 mg/100 mL), time (10–60 min), and the pH (4–9), was simulated using the one-factor-at-a-time method. APJPA was characterized by FESEM images showing that APJPA exhibits a smooth surface devoid of pores. FTIR spectra confirmed the presence of -C-O, C–H, C=C, and -COOH bonds within the APJPA. Maximum removal was recorded with 6.5 mg/100 mL of APJAP dosage, pH 6.5, after 35 min and with 25 mg/100 mL of CFX, at which the predicted and actual adsorption were 96.08 and 98.25%, respectively. The simulation results show that the dosage of APJAP exhibits a high degree of influence on the maximum adsorption of CFX removal (100%) between 2 and 8 mg dose/100 mL. The highest adsorption capacity of APJAP was 384.62 mg CFX/g. The simulation for the effect of pH determined that the best pH for the CFX adsorption lies between pH 5 and 8.

Preparation and evaluation of a chitosan modified biochar as an efficient adsorbent for pipette tip-solid phase extraction of triazine herbicides from rice

The low allowable limit of triazine herbicides (THs) in rice makes it imperative to develop novel sample pretreatment methods for extraction and preconcentration of THs. Herein, a phosphoric acid activated biochar (PBC) was prepared and modified by chitosan (CS). For THs with different polarities, CS-PBC with multiple interaction sites exhibited satisfactory chemisorption. On this basis, a CS-PBC-based pipette tip-solid phase extraction (PT-SPE) was developed combined with HPLC to extract THs from rice. Low limits of detection (1.41-3.35 ng g^-1), satisfactory linearity (0.01-2.00 μg g^-1, R² > 0.9974) and recoveries (96.13-116.25 %) were obtained with acceptable inter-day and intra-day precision (RSD ≤ 13.60 %). CS-PBC showed superior performance to three commercial single-mode adsorbents and comparable results to a hydrophilic-lipophilic balance adsorbent. The study explored the feasibility of PT-SPE for extracting THs from rice and broadened the application of plant biochar as an environmentally-friendly matrix in food sample pretreatment.

A high-performance microreactor integrated with chitosan/ Bi2WO6/CNT/TiO2 nanofibers for adsorptive/photocatalytic removal of cephalexin from aqueous solution

A Z-scheme Bi₂WO₆/CNT/TiO₂ photocatalyst was synthesized hydrothermally and loaded on chitosan nanofibers with different mass percentages using the electrospinning process. The batch adsorption experiments for chitosan nanofibrous samples containing Bi₂WO₆/CNT/TiO₂ revealed that the adsorption process and its kinetic followed the Langmuir isotherm and pseudo-second-order model, respectively. A planar microreactor with a reusable plate-type configuration was fabricated employing an inexpensive micromachining technique and integrated with chitosan/Bi₂WO₆/CNT/TiO₂ nanofibers. The synergistic effect of the adsorption and photocatalysis was assessed for removing cephalexin under simulated sunlight irradiation in a continuous flow microreactor. The nanofibers containing 15 wt% of Bi₂WO₆/CNT/TiO₂ exhibited the most removal efficiency. The effects of operational variables were investigated in the microreactor and optimized using response surface methodology as light intensity = 17.45 W/m², retention time = 256 s, pH = 4.8, and initial cephalexin concentration = 29 mg/L. At this condition, cephalexin and TOC removal efficiencies reached 99.2% and 92.4%, respectively. The kinetic of disappearance of cephalexin under optimal conditions followed the Langmuir-Hinshelwood model. The adsorption equilibrium constant deduced from this model was similar to that one calculated from the Langmuir isotherm model. At the optimum condition, cephalexin removal efficiency reduced to 80% after 1500 min of microreactor operation and the nanofibers revealed appropriate stability and reusability.

Anionic Dye Removal by Polypyrrole-Modified Red Mud and Its Application to a Lab-Scale Column: Adsorption Performance and Phytotoxicity Assessment

In this study, polypyrrole-modified red mud (PRM) was prepared for the efficient removal of anionic dyes (methyl orange and Congo red) from aqueous solutions. The phytotoxicity (bean sprouts) of the dye solution before and after dye removal was investigated. Adsorption kinetics confirmed that the adsorption of methyl orange (MO) and Congo red (CR) on PRM was controlled by chemical reactions between the functional groups of polypyrrole and dyes. From Langmuir isotherm fitting, we found the theoretical adsorption capacities of MO and CR on PRM were 194.1 and 314.9 mg/g, respectively. The adsorption progress of MO and CR on PRM was found to be spontaneous and endothermic. The column studies demonstrated that, under dynamic flow, the PRM can efficiently remove MO and CR from aqueous solution, with adsorption capacities of 31.08 and 55.04 mg/g, respectively. In the toxicity test, the phytotoxicity of the column effluents (after dye removal) was significantly lowered compared to the initial dye influents. After the removal of MO and CR, the average root length of bean sprouts was increased from 3.30 cm to 5.18 cm and from 3.01 cm to 7.00 cm, respectively. These findings highlighted the efficient removal of dyes by PRM from aqueous solution, demonstrating the possible application of PRM for the removal of dye from dye-contaminated wastewaters.

Cephalexin removal by a novel Cu-Zn bionanocomposite biosynthesized in secondary metabolic products of Aspergillus arenarioides EAN603 with pumpkin peels medium: Optimization, kinetic and artificial neural network models

The present study aimed to investigate the removal efficiency of cephalexin (CFX) by a novel Cu-Zn bionanocomposite biosynthesized in the secondary metabolic products of Aspergillus arenarioides EAN603 with pumpkin peels medium (CZ-BNC-APP). The optimization study was performed based on CFX concentrations (1, 10.5 and 20 ppm); CZ-BNC-APP dosage (10, 55 and 100 mg/L); time (10, 55 and 100 min), temperature (20, 32.5 and 45 °C). The artificial neural network (ANN) model was used to understand the CFX behavior for the factors affecting removal process. The CZ-BNC-APP showed an irregular shape with porous structure and size between 20 and 80 nm. The FTIR detected CC, C-O and OH groups. ANN model revealed that CZ-BNC-APP dosage exhibited the vital role in the removal process, while the removal process having a thermodynamic nature. The CFX removal was optimized with 12.41 ppm CFX, 60.60 mg/L of CZ-BNC-APP, after 97.55 min and at 35 °C, the real maximum removal was 95.53% with 100.52 mg g^-1 of the maximum adsorption capacity and 99.5% of the coefficient. The adsorption of CFX on CZ-BNC-APP was fitted with pseudo-second-order model and both Langmuir and Freundlich isotherms models. These findings revealed that CZ-BNC-APP exhibited high potential to remove CFX.

Sustainable approaches for removal of cephalexin antibiotic from non-clinical environments: A critical review

In this article, the removal of cephalexin (CFX) antibiotic from non-clinical environment is reviewed. Adsorption and photocatalytic degradation techniques are widely used to remove CFX from waters and wastewaters, the combination of these methods is becoming more common for CFX removal. The treatment methods of CFX has not been reviewed before, the present article aim is to organize the scattered available information regarding sustainable approaches for CFX removal from non-clinical environment. These include adsorption by nanoparticles, bacterial biomass, biodegradation by bacterial enzymes and the photocatalysis using different catalysts and Photo-Fenton photocatalysis. The metal-organic frameworks (MOFs) appeared to have high potential for CFX degradation. It is evident from the recently papers reviewed that the effective methods could be used in place of commercial activated carbon. The widespread uses of photocatalytic degradation for CFX remediation are strongly recommended due to their engineering applicability, technical feasibility, and high effectiveness. The adsorption capacity of the CFX is ranging from 7 mg CFX g^-1 of activated carbon nanoparticles to 1667 mg CFX g^-1 of Nano-zero-valent iron from Nettle. In contrast, the photo-degradation was 45% using Photo-Fenton while has increased to 100% using heterogeneous photoelectro-Fenton (HPEF) with UVA light using chalcopyrite catalyst.

Application of Saccharomyces cerevisiae/Calcium Alginate Composite Beads for Cephalexin Antibiotic Biosorption from Aqueous Solutions

Cephalexin (CPX) is recognized as a water pollutant, and it has been listed in a number of countries with a risk factor greater than one. Herein, the present work focused on the synthesis, characterization and biosorption capacity evaluation of Saccharomyces cerevisiae immobilized in calcium alginate as a biosorbent to remove CPX from aqueous solutions. Biosorbent was characterized by SEM and FTIR techniques. Batch biosorption experiments were conducted in order to evaluate the effect of the initial pH, biosorbent dose and CPX initial concentration. The removal efficiency, in considered optimal conditions (pH = 4, CPX initial concentration = 30 mg/L, biosorbent dose = 1 g/L) was 86.23%. CPX biosorption was found to follow the pseudo–second-order kinetics. The equilibrium biosorption data were a good fit for the Langmuir model with correlation coefficient of 0.9814 and maximum biosorption capacity was 94.34 mg/g. This study showed that the synthesized biosorbent by immobilization technique is a low-cost one, easy to obtain and handle, eco-friendly, with high feasibility to remove CPX antibiotic from aqueous solution. The findings of this study indicate that the biosorbents based on microorganisms immobilized on natural polymers have the potential to be applied in the treatment of wastewater.

Pyrolyzed carbon derived from red soil as an efficient catalyst for cephalexin removal

Red soil, a typical soil type in southern China, has been deemed infertile or nutrient-deficient. In this study, red soil was firstly utilized as a substrate for preparing catalysts, which were then successfully applied to the catalytic wet peroxide oxidation (CWPO) of cephalexin. The highest cephalexin removal was 95.23% and TOC removal was 60.58%, with the catalyst pyrolyzed at 500 °C (RC500). The high iron content and proportion of Fe(II) on the surface of RC500 was responsible for the decomposition of H₂O₂ into· OH. Moreover, the porous structure and existence of other minerals (such as SiO₂ and Al₂O₃) in the catalyst were also significant for enhancing the catalytic activity of RC500. Afterwards, the influencing parameters, including temperature, pH, the dose of H₂O₂, and catalyst, were examined for cephalexin degradation. It was noteworthy that RC500 was efficient in treating hospital wastewater when using a self-design pilot device. A density functional theory analysis of cephalexin was conducted to establish the possible position attacked by ·OH, and the possibly ruptured one. Meanwhile, the intermediates generated during CWPO were identified. Finally, a reliable degradation pathway of cephalexin was proposed on the basis of the results.

Evaluating the Removal of the Antibiotic Cephalexin from Aqueous Solutions Using an Adsorbent Obtained from Palm Oil Fiber

This study aimed to understand the adsorption process of cephalexin (CPX) from aqueous solution by a biochar produced from the fiber residue of palm oil. Scanning electron microscopy, Fourier transform infrared spectroscopy, Boehm titration, and the point of zero charge were used to characterize the morphology and surface functional groups of the adsorbent. Batch tests were carried out to evaluate the effects of the solution pH, temperature, and antibiotic structure. The adsorption behavior followed the Langmuir model and pseudo-second-order model with a maximum CPX adsorption capacity of 57.47 mg g^-1. Tests on the thermodynamic behavior suggested that chemisorption occurs with an activation energy of 91.6 kJ mol^-1 through a spontaneous endothermic process. Electrostatic interactions and hydrogen bonding represent the most likely adsorption mechanisms, although π-π interactions also appear to contribute. Finally, the CPX removal efficiency of the adsorbent was evaluated for synthetic matrices of municipal wastewater and urine. Promising results were obtained, indicating that this adsorbent can potentially be applied to purifying wastewater that contains trace antibiotics.

Kinetics, isotherms, effect of structure, and computational analysis during the removal of three representative pharmaceuticals from water by adsorption using a biochar obtained from oil palm fiber

Acetaminophen (ACE), cephalexin (CPX), and valsartan (VAL) are recognized water pollutants, which can be removed by adsorption. Herein, the removal of these pharmaceuticals using a biochar (BP), prepared from oil palm fiber, was tested. It was studied the structural effects of the pharmaceuticals and biochar on the adsorption process supported by experimental and computational results, plus characterizations of the material. The biochar has 76.05 m² g^-1 of surficial area, and carboxylic groups (1.343 mmol g^-1) predominantly. The maximum adsorption uptakes were 7.3, 7.9, and 23.85 mg g^-1 for ACE, CPX, and VAL, respectively; following pseudo-second-order kinetics. The best pollutants removal was obtained at acidic pH (3.0). Computational analyses indicated that oxygenated groups of BP (able to generate H-bond interactions) influenced the adsorption of pharmaceuticals. It can be remarked that BP is a low-cost adsorbent synthesized easily from wastes, with high feasibility to remove pharmaceutical structures from water.

Enhanced adsorption of Congo red using chitin suspension after sonoenzymolysis

In the present work, chitin suspensions after enzymolysis and sonoenzymolysis were taken as adsorbents to evaluate the adsorption properties of Congo red (CR) dyes. Compared with untreated chitin suspension, the CR adsorption performance was significantly improved after enzymolysis and even more after sonoenzymolysis. According to different adsorption kinetic and isotherm models, Langmuir isotherm and the pseudo-second order model were more reliable to describe the adsorption process of CR onto different chitin samples and demonstrated a monolayer and favorable physisorption process. What's more, negative values of ΔG (Gibbs free energy change) and the shifts to higher negative values with the temperature increasing from adsorption thermodynamic study proved a spontaneous CR adsorption process. The structural characterization before and after adsorption further verified the physical adsorption between chitin and CR, and a larger specific area and higher porosity of chitin suspension was obtained after sonoenzymolysis with more available active sites.

Properties evaluation of biochar/high-density polyethylene composites: Emphasizing the porous structure of biochar by activation

Activated biochars (AB-0.5, AB-1, AB-1.5, AB-2) prepared under different concentrations of an activating agent were used to manufacturing composites (ABHC-0.5, ABHC-1, ABHC-1.5, ABHC-2) based on high-density polyethylene (HDPE) by compounding and injection molding. Thermal and mechanical properties of the composites were characterized and analyzed. The addition of activated biochars improved the thermal properties of HDPE shown by Differential scanning calorimetry and Thermogravimetric analysis. Additionally, ABHC-0.5 exhibited the best flexural strength (38.66 MPa), flexural modulus (2.46 GPa), tensile strength (32.17 MPa), tensile modulus (1.95 GPa), rigidity, elasticity, creep resistance, and anti-stress relaxation ability due to the best porous structure of AB-0.5. A decrease of mechanical properties was observed in ABHC-1, ABHC-1.5, ABHC-2 compared to ABHC-0.5, which was due to the fact that the porous structure was damaged by an excessive activating agent. The results of this study provided a predictive insight in view of optimizing process parameters and establishing the meaningful relationship between biochar porous structure and its resulting composites.

Insights into the isotherm and kinetic models for the coadsorption of pharmaceuticals in the absence and presence of metal ions: A review

Pharmaceuticals are a wide class of emerging pollutants due to their continuous and the increasing consumption of users. These pollutants are usually found in the real environment as mixtures alone or with metal ions. Thus, the migration risk increases, which complicates the removal of pharmaceuticals because of the combined and synergistic effects. The focus of treatment of pharmaceutical mixtures and their coexistence with metals is of considerable importance. For this purpose, adsorption has been efficiently applied to several studies for the treatment of such complex systems. In this article, the coadsorption behavior of pharmaceuticals in the absence and existence of metals on several adsorbents has been reviewed. The adsorption isotherms and kinetics of these two systems have been analyzed using different models and discussed. Important challenges and promising routes are suggested for the future development of the coadsorption of the studied systems. This article provides an overview on the most utilized and effective adsorbents, widely studied adsorbates, best applied isotherm and kinetic models, and competitive effect in coadsorption of pharmaceuticals, both with and without metals.

The roles of phosphorus species formed in activated biochar from rice husk in the treatment of landfill leachate

Untreated landfill leachate is a threat to the environment. Here, the phosphoric acid activated biochars prepared from rice husk were successfully used for leachate treatment to achieve a high removal of color (100%), pollutants (>90%), chemical oxygen demand (∼80%) and NH₄⁺-N (100%). The leachate treatment process on phosphoric acid activated biochar could be well described by the pseudo-second order and Langmuir isotherm model, and it was controlled by external mass transfer followed by intra-particle diffusion. The phosphorus species formed in activated biochar could adjust and control the textural properties and structures of biochar, while the phosphorus species of activated biochar could attract humic acid-like organics in the leachate via hydrogen bond and π-π interactions, which were found to significantly enhance the treatment of leachate. The findings provided important insights for efficient treatment of wastewater using agricultural waste residues on an industrial scale.

Preparation of porous biomass-derived hydrothermal carbon modified with terminal amino hyperbranched polymer for prominent Cr(VI) removal from water

Herein, a series of functionalized hydrochars with high density of nitrogen-containing functional groups were engineered by co-processing of terminal amino hyperbranched polymer and walnut shell biomass in the hydrothermal carbonization media. Hydrothermal Carbonization with optimized key parameters was implemented to determine the impact of added polymer to the biomass on the properties of the obtained hydrochars. Consequently, the optimum hydrochar which was achieved with the values of 250 °C, 60 min, and 50% (w/w) for temperature, time, and polymer/biomass weight ratio, demonstrated a highly improved surface area of 544 m².g^-1 and the highest adsorption capacity for Cr(VI) removal which was obtained from Freundlich isotherm model and described by the pseudo-second-order kinetic model to be 363.22 mg.g^-1 (at pH = 2.0). This work suggests that the co-hydrothermal carbonization promotes the uniform incorporation of polymers into the hydrochar matrix and provides adsorbents for the effective removal of Cr(VI) from water.