Removal of Ciprofloxacin from Water by a Potassium Carbonate-Activated Sycamore Floc-Based Carbonaceous Adsorbent: Adsorption Behavior and Mechanism.

In this study, a porous carbonaceous adsorbent was prepared from sycamore flocs by pyrolysis method and K2CO3 activation. The effects of preparative conditions of the material on its adsorptive property were explored. The optimal material (SFB2-900) was obtained with a K2CO3/biochar mass ratio of 2:1 at an activation temperature of 900 °C, possessing a huge surface specific area (1651.27 m2/g). The largest adsorption capacity for ciprofloxacin on SFB2-900 was up to 430.25 mg/g. The adsorption behavior was well described by the pseudo-second-order kinetic model and the Langmuir isothermal model. Meanwhile, this process was spontaneous and exothermic. The obtained material showed excellent adsorption performance in the conditions of diverse pH range, ionic strength, and water quality of the solution. The optimum adsorption conditions (pH = 7.01, dosage = 0.6 g/L, and C0 = 52.94 mg/L) determined based on the response surface methodology were in accordance with the practical validation consequences. The good regeneration effect of SFB2-900 manifested that this material had great practical application potential. Combining the experimental results and density functional theory calculation results, the adsorption mechanisms mainly included pore filling, π-π EDA interactions, electrostatic interactions, and H-bonds. The material could be regarded as a novel and high-efficiency adsorbent for antibiotics. Additionally, these findings also provide reference for the reuse of waste biomass in water treatment.

Using a sulfur autotrophic fluidized bed reactor for simultaneous perchlorate and nitrate removal from water: S disproportionation prediction and system optimization.

The sulfur autotrophic reduction (SAR) process is promising in co-reduction of perchlorate and nitrate from aqueous solution. To further understand the reaction process, we developed a sulfur autotrophic fluidized bed reactor where the proceeding extent of sulfur (S) disproportionation was predicted by Response surface methodology (RSM) for the first time. Three fundamental reaction parameters including the hydraulic retention time (HRT), co-existing nitrate concentration ([Formula: see text]) and recirculation ratio (R) were considered for reactor optimization. The results demonstrated that S disproportionation was promoted by long HRT and high R, whereas was inhibited by high [Formula: see text]. Also, the optimal HRT, [Formula: see text] and R were 0.50 h, 10.00 mg/L and 14, respectively, the bioreactor can achieve high reduction efficiency of perchlorate and nitrate (> 98.45%), and generate less sulfate (236.07 mg/L). High-throughput sequencing showed that Chlorobaculum was related to S disproportionation, and Sulfurovum was associated with nitrate/perchlorate reducing. All results indicate that the sulfur autotrophic fluidized bed reactor is a promising candidate for the treatment of perchlorate and nitrate wastewater in future practical applications.

Enhanced Adsorption of Aqueous Tetracycline Hydrochloride on Renewable Porous Clay-Carbon Adsorbent Derived from Spent Bleaching Earth via Pyrolysis.

In this study, spent bleaching earth (SBE) and pyrolyzed SBE (SBE@C) were tested for their capacity to remove tetracycline hydrochloride (TCH) from aqueous solution. The maximum adsorption capacity obtained by the Langmuir model is 0.114 mmol/g for SBE@C and 0.087 mmol/g for SBE. The deleterious effects of coexisting cations were ranked in a decline: Al3+ > Mg2+ > Na+. The results of various characterization methods show that the adsorption mechanisms mainly included π-π interactions, hydrogen bonding, electrostatic interactions, and changes in physical and chemical properties. After 3 repeated cycles of pyrolysis, the adsorption capacity of SBE@C remained at 85.4%, with SBE@C potentially recycled 21 times before complete loss of adsorption capacity. Furthermore, the problem of secondary pollution caused by SBE and residual oil is resolved by the use of SBE@C. All results indicate that SBE@C is a likely candidate for the treatment of TCH wastewater in the coming practical applications.

Biodegradation of tetracycline antibiotics in A/O moving-bed biofilm reactor systems.

An anaerobic/aerobic moving-bed biofilm (A/O-MBBR) reactor system was constructed, and the treatment efficiency of aqueous antibiotics in wastewater was investigated. The effects of antibiotics on the microbial communities in the A/O-MBBR were also investigated. Under the optimized reaction conditions, removal of tetracycline antibiotics (TCs) was studied in a series of experiments. When a low concentration of tetracycline (TC) was added to the reactor system, high removal efficiency of conventional pollutants (TC concentration decreased from 10 turn to 2.8 µg L-1) was achieved. When mixed TCs (50 µg L-1) were added to the system, the removal efficiencies of chlortetracycline (CTC), TC and oxytetracycline (OTC) reached 52.03, 41.79, and 38.42%, respectively. TC degradation was decreased to 21.16% when the antibiotic concentration was 500 µg L-1; exposure to this TC concentration destroyed the community structure of the activated sludge bacteria in the reactor. The products of the biodegradation analysis revealed the possible degradation pathways functioning in the experimental A/O-MBBRs.

Perchlorate reduction by hydrogen autotrophic bacteria and microbial community analysis using high-throughput sequencing.

Hydrogen autotrophic reduction of perchlorate have advantages of high removal efficiency and harmless to drinking water. But so far the reported information about the microbial community structure was comparatively limited, changes in the biodiversity and the dominant bacteria during acclimation process required detailed study. In this study, perchlorate-reducing hydrogen autotrophic bacteria were acclimated by hydrogen aeration from activated sludge. For the first time, high-throughput sequencing was applied to analyze changes in biodiversity and the dominant bacteria during acclimation process. The Michaelis-Menten model described the perchlorate reduction kinetics well. Model parameters q(max) and K(s) were 2.521-3.245 (mg ClO4(-)/gVSS h) and 5.44-8.23 (mg/l), respectively. Microbial perchlorate reduction occurred across at pH range 5.0-11.0; removal was highest at pH 9.0. The enriched mixed bacteria could use perchlorate, nitrate and sulfate as electron accepter, and the sequence of preference was: NO3(-) > ClO4(-) > SO4(2-). Compared to the feed culture, biodiversity decreased greatly during acclimation process, the microbial community structure gradually stabilized after 9 acclimation cycles. The Thauera genus related to Rhodocyclales was the dominated perchlorate reducing bacteria (PRB) in the mixed culture.

Functional versatility of Zur in metal homeostasis, motility, biofilm formation, and stress resistance in Yersinia pseudotuberculosis.

Zur (zinc uptake regulator) is a significant member of the Fur (ferric uptake regulator) superfamily, which is widely distributed in bacteria. Zur plays crucial roles in zinc homeostasis and influences cell development and environmental adaptation in various species. Yersinia pseudotuberculosis is a Gram-negative enteric that pathogen usually serves as a model organism in pathogenicity studies. The regulatory effects of Zur on the zinc transporter ZnuABC and the protein secretion system T6SS have been documented in Y. pseudotuberculosis. In this study, a comparative transcriptomics analysis between a ∆zur mutant and the wild-type (WT) strain of Y. pseudotuberculosis was conducted using RNA-seq. This analysis revealed global regulation by Zur across multiple functional categories, including membrane transport, cell motility, and molecular and energy metabolism. Additionally, Zur mediates the homeostasis not only of zinc but also ferric and magnesium in vivo. There was a notable decrease in 35 flagellar biosynthesis and assembly-related genes, leading to reduced swimming motility in the ∆zur mutant strain. Furthermore, Zur upregulated multiple simple sugar and oligopeptide transport system genes by directly binding to their promoters. The absence of Zur inhibited biofilm formation as well as reduced resistance to chloramphenicol and acidic stress. This study illustrates the comprehensive regulatory functions of Zur, emphasizing its importance in stress resistance and pathogenicity in Y. pseudotuberculosis. IMPORTANCE: Bacteria encounter diverse stresses in the environment and possess essential regulators to modulate the expression of genes in responding to the stresses for better fitness and survival. Zur (zinc uptake regulator) plays a vital role in zinc homeostasis. Studies of Zur from multiple species reviewed that it influences cell development, stress resistance, and virulence of bacteria. Y. pseudotuberculosis is an enteric pathogen that serves a model organism in the study of pathogenicity, virulence factors, and mechanism of environmental adaptation. In this study, transcriptomics analysis of Zur's regulons was conducted in Y. pseudotuberculosis. The functions of Zur as a global regulator in metal homeostasis, motility, nutrient acquisition, glycan metabolism, and nucleotide metabolism, in turn, increasing the biofilm formation, stress resistance, and virulence were reviewed. The importance of Zur in environmental adaptation and pathogenicity of Y. pseudotuberculosis was emphasized.

Evaluation of biological removal efficiency in a UCT process treating municipal wastewater during start-up stage.

This study reports the performance of University of Cape Town (UCT) municipal wastewater treatment plant, during the startup stage with the focus on the relationship between hydraulic retention time (HRT) and biological nutrient removal (BNR) efficiency. The entire experimental period was 144 days, divided into four periods. Results showed that the removal efficiency of TN, NH4+-N, and Kjeldahl nitrogen (KN) was closely related to the HRT. Furthermore, the biodegradation kinetics analysis was used to calculate the specific degradation rates of pollutants. The GPS-X modeling was also used to examine the effect of the UCT pilot plant on BNR. The UCT pilot plant used in this study achieved high BNR efficiency even during the startup stage. With HRT of 24 hr (Period 1, day 1-40, data set 1-10), the highest levels of TN, NH(4+)-N and KN removal efficiency were approximately 72, 76 and 78%, respectively. The COD showed consistent high removal efficiency, with the highest level of approximately 96% at HRT of 15 hr (Period 3, day 81-120, data set 21-30). The TP removal efficiency rose at first and subsequently decreased abruptly. The maximum removal efficiency was 85% with HRT of 19 hr (Period 2, day 41-80, data set 11-20). With the optimal HRT 19 hr, the average removal efficiency values of COD, TP, TN, NH(4+)-N and KN were 89, 80, 65, 67 and 68%, respectively. The GPS-X modeling results indicated that the UCT process was effective in COD, TP and TN removal.

Synergistic adsorption and advanced oxidation activated by persulfate for degradation of tetracycline hydrochloride using iron-modified spent bleaching earth carbon.

At present, tetracycline hydrochloride (TCH) is a widely used antibiotic, and is often detected in water, posing a serious harm to human and ecological health. In this study, spent bleaching earth (SBE) was pyrolyzed to obtain spent bleaching earth carbon (SBE@C) and the nano Fe0/SBE@C prepared after zero-valent iron loading was adopted to remove TCH in water for the first time. The combination of nano Fe0/SBE@C and PS, the strong adsorption of SBE@C coupled with the oxidation of free radicals could achieve TCH efficient removal. The effects of nano Fe0 load, nano Fe0/SBE@C dosage, solution initial pH, and PS/TCH molar ratio on TCH removal efficiency in nano Fe0/SBE@C + PS system were studied. The results indicate that the optimal reaction conditions are 5% nano Fe0 load, 0.2 g/L nano Fe0/SBE@C dosage, initial pH of 3, PS/TCH molar ratio of 100:1. Under these conditions, TCH removal efficiency could reach 91%. Meanwhile, response surface methodology (RSM) was applied to predict optimal value of reaction conditions. The removal efficiency corresponding to the predicted optimal conditions was consistent with the actual removal efficiency obtained from the experiment. Moreover, six reaction systems were tested, and TCH removal efficiency in the SBE@C + PS system was 22.6%. When nano Fe0 was loaded on SBE@C, TCH removal efficiency in Fe0/SBE@C + PS system increased to 78.2%, in which TCH was first adsorbed on the surface of nano Fe0/SBE@C, and then was degraded by the oxidation of SO4•- and •OH. Totally, the nano Fe0/SBE@C + PS system displayed excellent TCH removal efficiency, good stability and reusability, exhibiting a promise toward TCH removal.

Enhanced biological antimony removal from water by combining elemental sulfur autotrophic reduction and disproportionation.

Antimony (Sb), a toxic metalloid, has serious negative effects on human health and its pollution has become a global environmental problem. Bio-reduction of Sb(V) is an effective Sb-removal approach. This work, for the first time, demonstrates the feasibility of autotrophic Sb(V) bio-reduction and removal coupled to anaerobic oxidation of elemental sulfur (S0). In the S0-based biological system, Sb(V) was reduced to Sb(III) via autotrophic bacteria by using S0 as electron donor. Meanwhile, S0 disproportionation reaction occurred under anaerobic condition, generating sulfide and SO42- in the bio-systems. Subsequently, Sb(III) reacted with sulfide and formed Sb(III)-S precipitate, achieving an effective total Sb removal. The precipitate was identified as Sb2S3 by SEM-EDS, XPS, XRD and Raman spectrum analyses. In addition, it was found that co-existing nitrate inhibited the Sb removal, as nitrate is the favored electron acceptor over Sb(V). In contrast, the bio-reduction of co-existing SO42- enhanced sulfide generation, followed by promoting Sb(V) reduction and precipitation. Illumina high-throughput sequencing analysis revealed that Metallibacterium, Citrobacter and Thiobacillus might be responsible for Sb(V) reduction and S0 disproportionation. This study provides a promising approach for the remediation of Sb(V)-contaminated water.

Synergistic adsorption and degradation of diclofenac by zero-valent iron modified spent bleaching earth carbon: Mechanism and toxicity assessment.

Diclofenac (DCF) is a drug compound that exists widely in water bodies, which may pose a threat to the ecological environment. In this study, spent bleaching earth (SBE) was pyrolyzed, modified with cetyltrimethylammonium bromide (CTAB) and loaded with zero-valent iron (nZVI) to obtain CTAB-SBE@C-nZVI. The effects of CTAB concentration, Fe0 loading, CTAB-SBE@C-nZVI dosage, and initial pH value on the removal efficiency of DCF were studied. The results showed that the DCF removal efficiency could reach a maximum of 87.0% with 2.0 g/L dosage of the optimal material, which was prepared under the conditions of 30 mmol/L CTAB concentration, 25% Fe0 loading, and initial pH 5. It indicated that the strong adsorption of the material and the reduction effect of nZVI can achieve high-efficiency removal of DCF. Based on the detected reaction intermediate products, four possible degradation paths were inferred. The toxicity assessment of DCF and its intermediates manifested that the degradation of DCF by CTAB-SBE@C-nZVI was a process of gradual dechlorination and toxicity reduction. CTAB-SBE@C-nZVI displayed excellent DCF removal efficiency, good stability and environmental friendliness, achieving wastes treat wastes and exhibiting good prospects.

Performance and mechanism of sycamore flock based biochar in removing oxytetracycline hydrochloride.

In this study, sycamore flocs (SF), which caused environmental and health problems, were utilized to prepare biochar. SFB2-900 obtained under the conditions of activation agent K2CO3, pyrolysis temperature 900℃ and m(K2CO3):m(BC) 2 had the strongest adsorption capacity (730 mg/g) for oxytetracycline hydrochloride (OTC-HCl). The pseudo-second-order kinetic model and Langmuir model described the adsorption kinetics and isotherms best. SFB2-900 exhibited high OTC-HCl adsorption capacity in both higher ionic strength and wide pH range. The theoretical simulation indicated that the closest interaction distance between OTC-HCl and SFB2-900 was 2.44 Å via π-π stacking configuration. Pore filling, π-π electron donor acceptor (EDA) interaction, H-bonding and electrostatic interactions were also involved in the process of OTC-HCl removal. SFB2-900 showed great removal efficiency for OTC-HCl in different water matrices and good regeneration ability. This study solved the problems caused by SF, realized waste biomass recycling, and achieved preparing high-efficient adsorbent for antibiotic.

Effect of nitrate and sulfate coexistence on hydrogen autotrophic reduction of antimonate (Sb(V)) and microbial community structures.

Hydrogen autotrophic bioreduction of antimonate (Sb(V)) to antimonite (Sb(III)) is an alternative approach for removing antimony (Sb) from water. This study investigated Sb(V) reduction kinetics and the effects of various parameters on the Sb(V) removal performance in a hydrogen autotrophic reaction system (HARS). Sb(V) reduction in the HARS was well fitted to the Michaelis-Menten model, showing a positive correlation between the reaction rate and biomass. The maximum specific substrate removal rates were 0.29-4.86 and 6.82-15.87 mg Sb(V)/(g·VSS·h) at initial Sb(V) concentrations of 500 µg/L and 10 mg/L, respectively. Coexisting nitrate significantly inhibited Sb(V) reduction, and the inhibition intensified with increasing nitrate concentration. However, coexisting sulfate had a positive effect on Sb(V) reduction, and the sulfate effectively enhanced total antimony (TSb) removal performance by generating sulfide from sulfate reduction. Illumina high-throughput sequencing technology was used to determine the changes in microbial community structure during different periods in the HARS, revealing the effects of co-existing ions on the dominant Sb(V) reducing bacteria. In the HARS, Longilinea and Terrimonas were the dominant genera in the presence of nitrate, and Longilinea was the dominant genus in the presence of sulfate, at initial Sb(V) concentration of 500 µg/L. When the concentration of Sb(V) was 10 mg/L, Longilinea and Thauera were the dominant genus in the HARS for treating water co-polluted with nitrate and sulfate, respectively. These results provide a theoretical basis of the application of HARS for the bio-remediation of Sb(V) contaminated water.

Effective adsorption of bisphenol A from aqueous solution over a novel mesoporous carbonized material based on spent bleaching earth.

In this study, the novel mesoporous carbonized material (HSBE/C) was prepared from clay/carbon composite (SBE/C) treated with hydrofluoric acid (HF) for the first time, and was employed to efficiently adsorb bisphenol A (BPA) in water. Specifically, SBE/C was derived from the pyrolysis of spent bleaching earth (SBE), an industrial waste. HF removed SiO2 from SBE/C and increased the specific surface area of HSBE/C (from 100.21 to 183.56 m2/g), greatly providing more adsorption sites for enhanced BPA adsorption capacity. The Langmuir monolayer maximum adsorption capacity of HSBE/C (103.32 mg/g) was much higher than the commercial activated carbon (AC) (42.53 mg/g). The adsorption process by HSBE/C followed well with the Freundlich isotherm model and the pseudo-second-order kinetic model and also was endothermic (ΔH0 > 0) and spontaneous (ΔG0 < 0). Based on the systematic characterization and factor experiment (temperature, dosage, initial pH, co-existing ions), BPA adsorption mechanism by HSBE/C likely included the hydrogen bonding, electrostatic interaction, and hydrophobic interaction. Moreover, there was no secondary pollution during the total adsorption process. Extraordinary, HSBE/C manifested stability by NaOH desorption regeneration. This study provides a new sight for application of waste-based materials as the promising adsorbents in the treatment of endocrine disruptors.

Adsorption of toxic dye Eosin Y from aqueous solution by clay/carbon composite derived from spent bleaching earth.

The environmentally friendly clay/carbon composite (SBE/C) was prepared by one-step pyrolysis under N2 atmosphere at 700°C of spent bleaching earth (SBE) from the industrial waste of the refined oil industry. SBE/C was tested to remove anionic dye Eosin Y from aqueous water. The results revealed that SBE/C had larger specific surface area than SBE, and the equilibrium adsorption capacity of SBE/C (11.15 mg/g) was about 3 times than that of SBE (4.04 mg/g). The adsorption process was found to be exothermic and spontaneous. The adsorption capacity of SBE/C was independent on pH (5-12), and exhibits satisfactorily recyclable performance. Combined with characterization analysis, the adsorption mechanism likely includes electrostatic interaction, hydrogen bonding, hydrophobic interaction, halogen bonding, and π-π interaction. Overall, this exploration of SBE/C might open a window to the design of an efficient and low-cost adsorbent for Eosin Y dye elimination from wastewater. PRACTITIONER POINTS: The resource utilization of industrial waste SBE was achieved. SBE/C was synthesized and tested to adsorb Eosin Y for the first time. SBE/C had characteristics with porous structure and large surface area. pH had little effect on adsorption capacity of SBE/C for Eosin Y. SBE/C exhibited potential for dye elimination from wastewater.

Synergetic adsorption and Fenton-like degradation of tetracycline hydrochloride by magnetic spent bleaching earth carbon: Insights into performance and reaction mechanism.

In this study, the synergetic adsorption and Fenton-like degradation of tetracycline hydrochloride (TCH) by magnetic spent bleaching earth carbon (Mag-SBE@C) with H2O2 were developed and performed, with 91.5% of TCH degradation efficiency and 42.1% of TOC removal efficiency. The effects of the reaction parameters (temperature, initial pH, catalyst dosage, molar ratio of TCH to H2O2) on TCH degradation in Mag-SBE@C/H2O2 system were studied. Under the optimal conditions (temperature 41.1 °C, initial pH 4.89 and molar ratio of H2O2 to TCH 114.435) forecasted by response surface methodology (RSM), high TCH degradation efficiency (99%) was achieved. Also, four cycling tests were performed to confirm the excellent stability and regeneration ability of Mag-SBE@C in presence of H2O2. In addition, the characteristics of Mag-SBE@C after reaction are analyzed in details via scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Brunner-Emmet-Teller (BET), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrum (FTIR) and X-ray diffraction (XRD), and it was found that Fe3O4 nanoparticles on Mag-SBE@C surface acted as co-catalyst and participated in degradation and improved reaction efficiency, while its properties were not greatly changed. The quenching experiments showed that hydroxyl radicals on Mag-SBE@C surface (OHadsorption) were dominant in Mag-SBE@C/H2O2 system. Meanwhile, three possible TCH degradation pathways were given based on the possible intermediates determined by liquid chromatography quadrupole-time-of-flight mass spectrometry (LC-Q-TOF-MS/MS). Mag-SBE@C is an excellent heterogeneous Fenton-like catalyst, exhibiting greatly potential to antibiotics elimination.

Using the modified pine wood as a novel recyclable bulking agent for sewage sludge composting: Effect on nitrogen conversion and microbial community structures.

This study investigated the effect of a recoverable sulphuric acid and sodium hydroxide-modified pinewood (MOP) as a bulking agent during sewage sludge and sawdust composting (MOPC), with a control experiment using unpretreated pinewood (UNP; UNPC) as the bulking agent. Results show that addition of MOP effectively promoted the degradation of organic matter during composting. The maximum temperature increased by 1.50 °C and the high temperature period (T > 50 °C) of composting was extended 4 days longer than the control experiment. Furthermore, MOP addition reduced the loss of nitrogen by 9.40%. High-throughput sequencing analysis showed that the bacterial communities in the UNPC and MOPC treatments were significantly different. Pseudoxanthomonas was the dominant bacteria during the thermophilic and cooling phases of the MOPC treatment. In addition, the recycling efficiency of the UNP and MOP was 99.18% and 99.37%, respectively.

Peroxymonosulfate-enhanced photocatalysis by carbonyl-modified g-C3N4 for effective degradation of the tetracycline hydrochloride.

In this work, carbonyl-modified g-C3N4 (CO-C3N4) is prepared through one-step calcination of the melamine-oxalic acid aggregates. The visible light-assisted photocatalytic degradation efficiency of the tetracycline hydrochloride (TCH) for CO-C3N4 is significantly enhanced by introducing the peroxymonosulfate (PMS), and the apparent rate constant is greatly increased from 0.01966 min-1 in CO-C3N4/vis system to 0.07688 min-1 in CO-C3N4/PMS/vis system. It is found that carbonyl for CO-C3N4 might offer possible reactive sites for PMS activation and collection sites of photo-generated electrons, greatly accelerating carrier's separation for PMS activation. The favorable conditions, such as the higher catalyst dosage, higher PMS amount and alkaline pH, contribute to TCH degradation. The deleterious effects of co-existing anions on the TCH degradation efficiency are ranked in a decline: H2PO4- > SO42- > HCO3- > NO3- > Cl-, and it may be affected by the type and amounts of anions and active radicals generated. The radical trapping tests and electron spin resonance (ESR) detection display that the O2-, h+, 1O2, OH and SO4- all contribute to TCH degradation. Meanwhile, possible degradation mechanism, intermediates and degradation pathway of TCH are revealed in CO-C3N4/PMS/vis system. This study will offer a new insight for constructing PMS activation with carbonyl modified g-C3N4 photocatalysis system to achieve effective treatment of organic wastewater.

Stable LBL self-assembly coating porous membrane with 3D heterostructure for enhanced water treatment under visible light irradiation.

The development of visible light-responsive photocatalytic membranes (vis-PMs) has opened a promising direction in water purification field. Herein, supramolecular aggregates from cyanuric acid (C), melamine (M), and urea (U) in dimethyl sulfoxide (DMSO) were used to prepare the porous carbon nitride nanosheet (MCU-C3N4) with excellent photocatalytic performance. A sort of 3D heterostructure PMs consisting of MCU-C3N4 and carbon nanotube (CNTs) interposed into graphene oxide (GO) on the PVDF membrane was firstly fabricated by the layer-by-layer (LbL) assembly method, in which CNTs/MCU-C3N4/GO material was immobilized on the polyelectrolytes (PE) modified PVDF based on their electrostatic attractions. Such PMs with abundant nano-channels had excellent mechanical strength, satisfactory water permeability (14.35 L m-2 h-1 bar-1) and synergetic removal efficiency of rhodamine B (RhB, 98.31%) in long -term operation, relative to the pristine GO membrane and MCU-C3N4/GO membrane fabricated by the same method. In addition, such PMs also exhibited the satisfactory tetracycline hydrochloride (TC) removal rate (84.81%) under visible light irradiation. Construction and performance of such carbon-based PMs might provide guidance for development of vis-PMs in terms of bonding strength, multidimensional morphology and water purification application.

Magnetic spent bleaching earth carbon (Mag-SBE@C) for efficient adsorption of tetracycline hydrochloride: Response surface methodology for optimization and mechanism of action.

The utilization of spent bleaching earth (SBE)-based materials for adsorption of pollutants from water and wastewater has received growing attention. In this work, a comparative study of magnetic spent bleaching earth carbon (Mag-SBE@C) and spent bleaching earth carbon (SBE@C) was performed to remove tetracycline hydrochloride (TCH) from aqueous solutions. Mag-SBE@C exhibits the larger adsorption capacity (0.238 mmol/g) obtained by the Langmuir model than the original SBE@C (0.150 mmol/g). The adsorption process fits well with the pseudo second-order model and is found to be exothermic (ΔH0 < 0) and spontaneous (ΔG0 < 0). The optimal adsorption conditions (Mag-SBE@C dose 2.217 g/L, initial TCH concentration 0.113 mmol/L, initial solution pH 6.533) predicted by the response surface methodology (RSM) are consistent with the actual verification results. The inhibition extents of coexisting cations are ranked in a decline: Al3+ > Cu2+ > Fe3+ > Mg2+ > K+ > Na+. Various characterization results indicate that the adsorption mechanism of TCH by Mag-SBE@C likely includes the π-π interactions, hydrogen bonding, electrostatic interactions, π-cations interactions, FeN covalent bonding, and changes in physical and chemical properties. Mag-SBE@C is easily solid-liquid separated using magnetic field, and can be potentially reused for 13 times before completely losing its activity, exhibiting great potential to antibiotics elimination.

Simultaneous reduction of perchlorate and nitrate in a combined heterotrophic-sulfur-autotrophic system: Secondary pollution control, pH balance and microbial community analysis.

A combined heterotrophic-sulfur-autotrophic system (CHSAS) was established to simultaneously reduce perchlorate and nitrate in water. In this system, the OH- produced by the acetate heterotrophic part (H-part) could be neutralized with the H+ produced by the sulfur autotrophic part (S-part); thus, the pH of the final effluent could keep neutral. In addition, the S-part could further reduce the pollutants and residual carbon from the H-part to achieve a high performance. For 19.62 ±â€¯0.30 mg/L ClO4- and 21.56 ±â€¯0.83 mg/L NO3--N in the influent, the operating parameters were optimal at a hydraulic retention time (HRT) of 1.0 h and an acetate concentration of 70 mg/L. The removal efficiency of ClO4- and NO3- reached 95.43% and 99.23%, without secondary pollution caused by residual organic carbon. It was also revealed that sulfur (S0) disproportionation can be inhibited by shortening the HRT and reducing the acetate dosage. The dominant heterotrophic and autotrophic bacteria were Thauera and Ferritrophicum, respectively, while Chlorobaculum was related to S0 disproportionation.