Decolorization of RhB on three-dimensional porous CeO2/LaFeO3/SrTiO3 catalyst via photo-fenton-like catalysis.

The catalysts with three-dimensional porous (3DP) CeO2, LaFeO3 and SrTiO3 are synthesized by sol-gel method and chemical precipitation method. The resulting multi-component 3DP CeO2/LaFeO3/SrTiO3 composite material featured a high specific surface area (26.08 m2/g), which can provide more surface active sites to improve adsorption capacity and catalytic performance. The photocatalytic, Fenton-like, photo-Fenton-like performance of the catalyst are studied on decolorization of RhB under UV irradiation, respectively. 3DP CeO2/LaFeO3/SrTiO3 exhibits high catalytic performance. Compared with photocatalytic or Fenton-like performance, 3DP CeO2/LaFeO3/SrTiO3 catalyst exhibits higher photo-Fenton-like performance, facilitating efficient decolorization of the rhodamine B. Moreover, the initial reaction rate on decolorization of RhB with 3DP CeO2/LaFeO3/SrTiO3 is 10.55, 5.52, 3.67 and 1.51 times higher than that with SrTiO3, LaFeO3, 3DP CeO2 and 3DP CeO2/LaFeO3, respectively. Meanwhile, 3DP LaFeO3/CeO2/SrTiO3 has a wider pH usage range in the synergistic reaction. Finally, a catalytic mechanism for the decolorization of rhodamine B is proposed. The continuous cycling of Fe3+/Fe2+ and Ce4+/Ce3+ and the production of active substances are achieved under the photo-Fenton-like effect of the catalyst.

Evaluation of antibiotic resistant lactose fermentative opportunistic pathogenic Enterobacteriaceae bacteria and blaTEM-2 gene in cephalosporin wastewater and its discharge receiving river.

This study investigated the concentration of cephalosporin, the resistant levels of lactose fermentative opportunistic pathogenic Enterobacteriaceae bacteria (LFOPEB) against seven antibiotics and one cephalosporin-resistant gene in cephalosporin wastewater (CPWW) treatment plant and its discharge receiving river. Although large numbers of bacteria have been removed during the CPWW treatment process, the antibiotic resistant rates of the isolates to ß-lactam antibiotics significantly increased (p = 0.032) after treatment, while the percentage of resistant LFOPEB to non-ß-lactam antibiotics did not change dramatically. Furthermore, the discharge of the effluent of CPWW treatment plant (CPWWeff) led to an obvious increase in the percentages of ß-lactam antibiotic-resistant LFOPEB and relative abundance of the blaTEM-2 gene in the downstream receiving river (RWdown) in comparison with those in the upstream receiving river (RWup). The antibiotic resistant phenotypes of isolates in the influent of CPWW treatment plant (CPWWin), CPWWeff and RWdown appeared to be seriously affected by the cephalosporin residues, which suggested that main antibiotic resistance phenotypes in antibiotic contaminated water were closely associated with its antibiotic composition. Therefore, CPWW treatment process has been proved to result in selective growth of ARB and proliferation of ARG. Besides, CPWWeff was also proved to be an important supplier of ARB and ARG to the receiving river.

Adsorbing low concentrations of Cr(VI) onto CeO2@ZSM-5 and the adsorption kinetics, isotherms and thermodynamics.

The CeO2@ZSM-5 was prepared by the dipping method. We used ZSM-5 and CeO2 as the carrier and load components, respectively. The aim was to reduce the low concentration of Cr(VI) in simulated wastewater (the concentration of Cr(VI) ranged from 0.2 to 1 mg/L). The characteristics of ZSM-5 and CeO2@ZSM-5 samples were determined by X-ray powder diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET). Characterization results showed that the particle size, BET surface area and pore volume for CeO2@ZSM-5 was around 0.783 nm, 421.307 m2/g and 0.313 m3/g, respectively. In addition, the optimum conditions were obtained by the orthogonal test, and the details were as follows: optimal pH, adsorbent dose, initial concentration of Cr(VI) and equilibrium time were 3, 5 g/L, 0.6 mg/L and 70 min respectively. The removal of Cr(VI) was 99.56% in these conditions. The pseudo-second-order model best described the adsorption kinetics of Cr(VI) onto CeO2@ZSM-5. Isotherm data were treated according to Langmuir, Freundlich and Temkin isotherm models. The results showed that the Freundlich adsorption isotherm model fitted best in the temperature range studied. Adsorption capacity increased with temperature, showing the endothermic nature of Cr(VI) adsorption. The desorption results showed the best recovery of Cr(VI) using 0.1 M HCl.

Quantification of multi-antibiotic resistant opportunistic pathogenic bacteria in bioaerosols in and around a pharmaceutical wastewater treatment plant.

Pharmaceutical wastewater treatment plants (WWTPs) are thought to be a "seedbed" and reservoirs for multi-antibiotic resistant pathogenic bacteria which can be transmitted to the air environment through aeration. We quantified airborne multi-antibiotic resistance in a full-scale plant to treat antibiotics-producing wastewater by collecting bioaerosol samples from December 2014 to July 2015. Gram-negative opportunistic pathogenic bacteria (GNOPB) were isolated, and antibiotic susceptibility tests against 18 commonly used antibiotics, including 11 ß-lactam antibiotics, 3 aminoglycosides, 2 fluoroquinolones, 1 furan and 1 sulfonamide, were conducted. More than 45% of airborne bacteria isolated from the pharmaceutical WWTP were resistant to three or more antibiotics, and some opportunistic pathogenic strains were resistant to 16 antibiotics, whereas 45.3% and 50.3% of the strains isolated from residential community and municipal WWTP showed resistance to three or more antibiotics. The calculation of the multiple antibiotic resistance (MAR) index demonstrated that the air environment in the pharmaceutical WWTP was highly impacted by antibiotic resistance, while the residential community and municipal WWTP was less impacted by antibiotic resistance. In addition, we determined that the dominant genera of opportunistic pathogenic bacteria isolated from all bioaerosol samples were Acinetobacter, Alcaligenes, Citrobacter, Enterobacter, Escherichia, Klebsiella, Pantoea, Pseudomonas and Sphingomonas. Collectively, these results indicate the proliferations and spread of antibiotic resistance through bioaerosols in WWTP treating cephalosporin-producing wastewater, which imposed a potential health risk for the staff and residents in the neighborhood, calling for administrative measures to minimize the air-transmission hazard.

Catalytic ozonation of bisphenol A in aqueous solution using Mn-Ce/HZSM-5 as catalyst.

Mixed manganese and cerium oxide supported on HZSM-5 were synthesized and used as heterogeneous catalysts for ozonation of bisphenol A (BPA) in aqueous solution. The prepared catalysts of Mn-Ce/HZSM-5 were characterized by X-ray diffraction, scanning electron microscopy and Fourier transform-infrared spectroscopy. The results indicated that Mn-Ce/HZSM-5 exhibits extraordinary catalytic activity for the degradation of BPA. Removal of 89.3% of BPA and 90.4% of total organic carbon (TOC) was achieved in 30 min, compared to non-catalytic ozonation, where only 50.5% BPA and 28.1% TOC removal were reached under the same conditions. Adsorption of BPA on HZSM-5 support and Mn-Ce/HZSM-5 catalysts was negligible. The strong inhibition of BPA removal by tert-butyl alcohol indicated that the attack of hydroxyl radicals was responsible for the improvement of catalytic ozonation. It was observed that at neutral pH, which is near the point of zero charge of the catalyst, the catalytic activity reached its maximum. Increasing the amount of Mn-Ce/HZSM-5 catalyst until it exceeded 3 g/L did not show a strong effect on BPA removal. The catalysts showed high stability and reusability.

A combined evaluation of the characteristics and acute toxicity of antibiotic wastewater.

The conventional parameters and acute toxicities of antibiotic wastewater collected from each treatment unit of an antibiotic wastewater treatment plant have been investigated. The investigation of the conventional parameters indicated that the antibiotic wastewater treatment plant performed well under the significant fluctuation in influent water quality. The results of acute toxicity indicated that the toxicity of antibiotic wastewater could be reduced by 94.3 percent on average after treatment. However, treated antibiotic effluents were still toxic to Vibrio fischeri. The toxicity of antibiotic production wastewater could be attributed to the joint effects of toxic compound mixtures in wastewater. Moreover, aerobic biological treatment processes, including sequencing batch reactor (SBR) and aerobic biofilm reactor, played the most important role in reducing toxicity by 92.4 percent. Pearson׳s correlation coefficients revealed that toxicity had a strong and positive linear correlation with organic substances, nitrogenous compounds, S(2-), volatile phenol, cyanide, As, Zn, Cd, Ni and Fe. Ammonia nitrogen (NH4(+)) was the greatest contributor to toxicity according to the stepwise regression method. The multiple regression model was a good fit for [TU50-15 min] as a function of [NH4(+)] with the determination coefficient of 0.981.

Phosphate removal from aqueous solutions with a zirconium-loaded magnetic biochar composite: performance, recyclability, and mechanism.

Phosphate (P) removal is significant for water pollution control. In this paper, a novel penicillin biochar modified with zirconium (ZMBC) was synthesized and used to adsorb P in water. The results showed that ZMBC had a porous structure and magnetic properties, and the zirconium (Zr) was mainly present in the form of an amorphous oxide. P adsorption displayed strong pH dependence. The Freundlich model described the adsorption process well, and the saturated adsorption capacity was 27.97 mg/g (25 ℃, pH = 7). The adsorption kinetics were consistent with the pseudo-second-order model, and the adsorption rates were jointly controlled by the surface adsorption stage and intraparticle diffusion stage. Coexisting anion experiments showed that CO32- inhibited P adsorption, reducing the adsorption capacity by 62.63%. The adsorbed P was easily desorbed by washing with a 1 M NaOH solution, and after 5 cycles, the adsorbent had almost the same capacity. The mechanism for P adsorption was inner-sphere complexation and electrostatic adsorption.

Effect of homemade compound microbial inoculum on the reduction of terramycin and antibiotic resistance genes in terramycin mycelial dreg aerobic composting and its mechanism.

In order to tackle the issue of terramycin mycelial dreg (TMD) diagnosis and removal of terramycin and antibiotic resistance genes (ARGs), this study adopted aerobic composting (AC) technology and added homemade compound microbial inoculum (HCMI) to promote the AC of TMD and enhance the removal of terramycin and ARGs. The findings demonstrated that terramycin residue could be basically harmless after AC. Moreover, HCMI not only reduced QacB and tetH but also increased the degradation rates of VanRA, VanT, and dfrA24 by 40.81%, 5.65%, and 54.18%, respectively. The HCMI improved the removal rate of ARG subtypes to a certain extent. According to redundancy analysis, during AC, the succession of the microbial community had a stronger influence on the variance of ARG subtype than the environmental conditions. Differences in the abundance of various bacteria due to changes in temperature may be an intrinsic mechanism for the variation of ARG subtypes.

Characteristic analysis of bio-oil from penicillin fermentation residue by catalytic pyrolysis.

The hazardous waste penicillin fermentation residue (PR) is a huge hazard to the environment. The bio-oil produced by the pyrolysis of the penicillin fermentation residue has the potential to become a biofuel in the future. This paper studied the pyrolysis characteristics of PR at 400°C ∼700°C. According to the weight loss and weight loss rate of PR, the whole process of pyrolysis can be divided into three stages for analysis: dehydration and volatilization, initial pyrolysis, and pyrolytic char formation. The experimental results showed that the yield of the liquid phase is the highest (33.11%) at 600°C. GC-MS analysis results showed that high temperature is beneficial to reduce the generation of oxygenated hydrocarbons (73%∼31%) and the yield of nitrogenous compounds gradually increased (19%∼43%); the yield of hydrocarbons was low in 400°C∼600°C pyrolysis (2%∼5%) but significantly increased around 700°C (22%). In the temperature range of 400°C to 700°C, the proportion of C5-C13 in bio-oil gradually increased (26%-64%), and the proportion of C14-C22 gradually decreased (47%-16%). The catalyst can increase the proportion of hydrocarbons in the bio-oil component. And the Fe2O3/HZSM-5 mixed catalyst has a significant reduction effect on oxygen-containing hydrocarbons and nitrogen-containing compounds.

[The structure and function analysis of bacterial community during aerobic composting of chicken manure].

In order to determine the changes of bacterial community structure and function in the early, middle and late stage of aerobic composting of chicken manure, high-throughput sequencing and bioinformatics methods were used to determine and analyze the 16S rRNA sequence of samples at different stages of composting. Wayne analysis showed that most of the bacterial OTUs in the three composting stages were the same, and only about 10% of the operational taxonomic units (OTUs) showed stage specificity. The diversity indexes including Ace, Chao1 and Simpson showed a trend of increasing at first, followed by decreasing. However, there was no significant difference among different composting stages (P < 0.05). The dominant bacteria groups in three composting stages were analyzed at the phylum and genus levels. The dominant bacteria phyla at three composting stages were the same, but the abundances were different. LEfSe (line discriminant analysis (LDA) effect size) method was used to analyze the bacterial biological markers with statistical differences among three stages of composting. From the phylum to genus level, there were 49 markers with significant differences among different groups. The markers included 12 species, 13 genera, 12 families, 8 orders, 1 boundary, and 1 phylum. The most biomarkers were detected at early stage while the least biomarkers were detected at late stage. The microbial diversity was analyzed at the functional pathway level. The function diversity was the highest in the early stage of composting. Following the composting, the microbial function was enriched relatively while the diversity decreased. This study provides theoretical support and technical guidance for the regulation of livestock manure aerobic composting process.

Effects of adding biochar on the preservation of nitrogen and passivation of heavy metal during hyperthermophilic composting of sewage sludge.

Hyperthermophilic composting (HTC) is regarded as an effective method for processing sewage sludge. The aim of the study was to investigate effects of using biochar as an amendment on the preservation of nitrogen and passivation of heavy metal during the HTC process of sewage sludge. Results showed that HTC improved the fermentation efficiency and the compost maturity by increases in the temperature and germination index (GI) value, and decreases in the moisture and C/N ratio compared to conventional thermophilic composting. HTC process and the biochar addition resulted in a decrease of the nitrogen loss compared with the control pile during composting by promoting transforming ammonium into nitrite nitrogen. Adding biochar to composting inhibited the transformation of Cu, Zn and Pb into more mobile speciation compared to the control pile although their contents increased during composting, which lead to reduction in availability of heavy metals. Thus, HTC process with the addition of biochar is viable for the reduction of the nitrogen losses and mobility of heavy metal in compost.Implications: The treatment of sewage sludge is imminent due to its threat to general health and ecosystems. This work represents the effects of adding biochar on the preservation of nitrogen and passivation of heavy metal during hyperthermophilic composting of sewage sludge. Our results indicate that the additions of biochar and hyperthermophilic composting engendered the several of positive effects on the preservation of nitrogen and passivation of heavy metal. Thus, HTC process with the addition of biochar is viable for the reduction of the nitrogen losses and mobility of heavy metal in compost.

[Adsorption Characteristics of Fluoride in Low-Concentration Water by Aluminum and Zirconium-Modified Biochar].

To deal with problems such as the difficult treatment of low-concentration fluoride-containing water and water pollution caused by excessive fluoride (F-) discharge, aluminum and zirconium-modified biochar (AZBC) was prepared and its adsorption characteristics and adsorption mechanism for low-concentration fluoride in water were studied. The results showed that AZBC was a mesoporous biochar with uniform pore structure. It could rapidly adsorb F- from water and reach adsorption equilibrium within 20 min. When the initial ρ(F-) was 10 mg·L-1and the AZBC dosage was 30 g·L-1, the removal rate was 90.7%, and the effluent concentration was lower than 1 mg·L-1. The pHpzc of AZBC was 8.9, and the recommended pH in practical application was 3.2-8.9. The adsorption kinetics accorded with pseudo-second order kinetics, and the adsorption process accorded with the Langmuir model. The maximum adsorption capacities at 25, 35, and 45℃ were 8.91, 11.40, and 13.76 mg·g-1, respectively. Fluoride could be desorbed by 1 mol·L-1 NaOH. The adsorption capacity of AZBC decreased by approximately 15.9% after 5 cycles. The adsorption mechanisms of AZBC were the combination of electrostatic adsorption and ion exchange.Taking actual sewage as theexperimental object, when the AZBC dosage was 10 g·L-1, the ρ(F-) was reduced to below 1 mg·L-1.

Struvite precipitation for ammonia nitrogen removal in 7-aminocephalosporanic acid wastewater.

7-Aminocephalosporanic acid wastewater usually contains high concentrations of ammonium (NH4⁺-N), which is known to inhibit nitrification during biological treatment processes. Chemical precipitation is a useful technology to remove ammonium from wastewater. In this paper, the removal of ammonium from 7-aminocephalosporanic acid wastewater was studied. The optimum pH, molar ratio, and various chemical compositions of magnesium ammonium phosphate (MAP) precipitation were investigated. The results indicated that ammonium in 7-aminocephalosporanic acid wastewater could be removed at an optimum pH of 9. The Mg²âº:NH4⁺-N:PO4 ³â»-P molar ratio was readily controlled at a ratio of 1:1:1.1 to both effectively remove ammonium and avoid creating a higher concentration of PO4 ³â»-P in the effluent. MgCl2·6H2O + 85% H3PO4 was the most efficient combination for NH4⁺-N removal. Furthermore, the lowest concentration of the residual PO4 ³â»-P was obtained with the same combination. Struvite precipitation could be considered an effective technology for the NH4⁺-N removal from the 7-aminocephalosporanic acid wastewater.

Efficient removal of tetracycline from aqueous solution by K2CO3 activated penicillin fermentation residue biochar.

In this study, biochar was prepared using penicillin fermentation residue (PR) as the raw material by different methods. The adsorption behavior and adsorption mechanism of biochar on tetracycline (TC) in an aqueous environment were investigated. The results showed that K2CO3 as an activator could effectively make porous structures, and that biochar with mesoporous or microporous could be prepared in a controlled manner with two kinds of different activation methods, the dry mixing method and the impregnation method. The dry mixing method could create more mesopores, while the impregnation method could prepare more micropores. Microporous biochar (IKBCH) with a high specific surface area could be prepared by the impregnation method combined with HCl soaking, which has an excellent adsorption effect on tetracycline. When the concentration of tetracycline was 200 mg/L, the removal rate of 99.91% could be achieved with the dosage of microporous biochar at 1 g/L. The adsorption process was in accordance with the Langmuir model and the pseudo-second-order model, respectively. The maximum adsorption capacity of IKBCH was 268.55 mg/g (25°C). The adsorption mechanisms were pore filling, π-π interaction, electrostatic adsorption, and hydrogen bond. Its stable and wide applicability adsorption process does not cause ecological pollution in the aqueous environment, and it is a promising biochar adsorbent.

Preparation of three-dimensional ordered macroporous Ag/LaFeO3 and heterogeneous photo-Fenton degradation of penicillin G potassium.

3DOMLaFeO3 was prepared by template method combined with sol-gel method using monodisperse polystyrene (PS) microspheres as template, and Ag/3DOMLaFeO3 perovskite catalyst was prepared by impregnation method combined with sodium borohydride reduction method. The catalysts were characterised by means of TG, XRD, SEM, BET, XPS, UV-vis DRS, etc. The photo-Fenton catalytic performance, stability and catalytic reaction mechanism of Ag/3DOMLaFeO3 were studied with penicillin G potassium (PEN G) as the model pollutant. The results indicated that the as-prepared Ag/3DOMLaFeO3 exhibited a three-dimensional ordered macroporous (3DOM) structure, and the light capture and mass transfer were enhanced through abundant pores and large specific surface area. Based on the surface plasmon resonance effect (SPR), Ag loading enhanced the absorption of the material in the visible light region, and inhibited the recombination of photogenerated carriers, which improved the photocatalytic performance of 3DOMLaFeO3 under visible light. Under the conditions of hydrogen peroxide dosage of 1.5 mL·L-1, initial pH of 5, PEN G initial concentration of 100 mg·L-1, catalyst dosage of 300 mg·L-1, xenon lamp irradiation, the degration ratio of PEN G and the removal rate of TOC reached 99.99% and 85.45% within 120 min, respectively. In addition, it had a wide range of pH application, excellent stability and practical application value. The quenching experiment and ESR test showed that ·OH and ·O2- were the reasons for high catalytic degradation. The least square method was used to fit the experimental data, and the results displayed that the degradation of PEN G was approximately in line with the first-order kinetic reaction.

Effectively compound the heterojunction formed by flower-like Bi2S3 and g-C3N4 to enhance photocatalytic activity.

In this study, the flower-shaped Bi2S3/g-C3N4-2.6 heterojunction obtained by solvothermal method and its photocatalytic degradation efficiency of rhodamine B (RhB) and tetracycline (TC) in aqueous solution within 40 min is as high as 98.8% and 94.6%. For RhB degradation, the photocatalytic reaction rate constant (k) of Bi2S3/g-C3N4-2.6 is approximately 1.8 and 45.5 times that of Bi2S3 and g-C3N4. For TC, k is 3.1 and 2.4 times that of Bi2S3 and g-C3N4, respectively. The key to determining the high catalytic activity of Bi2S3/g-C3N4 lies in the formation of a good heterojunction between Bi2S3 and g-C3N4, which accelerates the electron transfer rate between the heterojunction interface and effectively avoids electron-hole recombination. The effects of catalyst dosage, different pH values, inorganic anions, and capture agents on the photodegradation performance of RhB were investigated. The results show that the catalyst dosage is 1.33 g/L, and the solution pH is in the range of 5-9, which has the best removal effect on pollutants, and the isolation of holes (h+) with strong oxidizing ability promotes the collapse of pollutant molecules. Combined with electrochemical tests, a possible degradation mechanism was advised.

Effect of biochar on antibiotic resistance genes in the anaerobic digestion system of antibiotic mycelial dreg.

To address the problem of antibiotic mycelial dreg (AMD) treatment and removal of antibiotic resistance genes (ARGs), this study adopted anaerobic digestion (AD) technology, and added biochar (BC) and biochar loaded with nanosized zero-valent iron (nZVI-BC) to promote the AD of AMD and enhance the removal of ARGs. Results showed that nZVI-BC was better than BC in promoting AD due to the hydrogen evolution corrosion and the synergistic effect of nZVI and BC. In addition, BC and nZVI-BC can enhance the oxidative stress response and reduce ammonia stress phenomenon, which significantly reduces the abundance of aadA, ant(2″)-Ⅰ, qacEdelta1 and sul1. In conclusion, the enhance effect of nZVI-BC is greater than BC. The removal efficiency rates of nZVI-BC on the above-mentioned four ARGs were improved by 33%, 9%, 24% and 11%.

Molecular characterization of the composition and transformation of dissolved organic matter during the semi-permeable membrane covered hyperthermophilic composting.

Current knowledge of dissolved organic matter (DOM) in semi-permeable membrane-covered thermophilic compost (smHTC) is limited. Therefore, this study provided a comprehensive characterization of composition and transformation of DOM in smHTC using multiple spectroscopic methods and ultrahigh resolution mass spectrometry. The results showed that the values of SUVA280, SUVA254, A240-400 (0.042, 0.048, 34.193) in smHTC were higher than those of conventional thermophilic composting (cTC) (0.030, 0.037, 18.348), and the increment of PV,n in smHTC were 2.4 times higher than that of cTC. These results suggested that smHTC accelerated the humification process by promoting the degradation of labile DOM and the production of humus-like substances. Mass spectrometry further confirmed that the DOM of smHTC possessed higher degree of aromatization and humification, based on the lower H/C (1.14), higher aromaticity index (0.34) and double bond equivalence (10.36). Additionally, smHTC increased the proportion of carboxyl-rich, unsaturated and aromatic compounds, and simultaneously improved the degradation of aliphatic/proteins, lipids, carbohydrates, along with even some refractory substances such as CHO subcategory (24.1%), especially lignin-like structures (14.8%). This investigation provided molecular insights into the composition and transformations of DOM in smHTC, and extended the current molecular mechanisms of humification in composting.

Amorphous cobalt oxide decorated halloysite nanotubes for efficient sulfamethoxazole degradation activated by peroxymonosulfate.

In this study, a new hollow nanotube material, 30% Co-CHNTs was prepared by the impregnation-chemical reduction-calcination method. This material can be used as a peroxymonosulfate (PMS) activator to catalyse the degradation of sulfamethoxazole (SMX). The best reaction conditions that correspond to the degradation rate of SMX, up to 97.5%, are as follows: the concentration of SMX is 10 mg L-1, the amount of catalyst is 0.20 g L-1, the dosage is 1.625 mM, and the solution pH is 6.00. X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectrometry (ICP-OES) show that the calcined composites mainly stimulate an increase in the content of bivalent cobalt in PMS and reduce the leaching of cobalt ions after the reaction. Additionally, the 30% Co-CHNTs + PMS reaction system exhibits a reasonable SMX degradation rate in a natural organic matter solution and excellent stability after three repeated experiments. Furthermore, the possible degradation mechanism in the 30% Co-CHNTs + PMS reaction system was analysed through electron paramagnetic resonance (EPR) and free-radical capture experiments, and it was observed that the non-radical degradation of 1O2 plays a leading role in SMX degradation. Finally, according to the nine degradation intermediates detected by liquid chromatography-mass spectrometry (LC-MS), four possible SMX degradation routes were proposed. This study proved that a 30% Co-CHNTs heterogeneous catalyst is easily prepared, inexpensive, and environmentally friendly and has potential application in antibiotic wastewater treatment.

Removal of phosphorus using biochar derived from Fenton sludge: Mechanism and performance insights.

A phosphorus removal biochar adsorbent was prepared from Fenton sludge. The adsorption process was optimized, and its phosphorus adsorption mechanism was discussed. It was found that the phosphorus adsorption performance of biochar prepared from single Fenton sludge (FBC-400) was better than that of co-pyrolysis of Fenton sludge and bamboo powder. The optimum condition was that Fenton sludge pyrolyzed at 400°C (FBC-400). FBC-400 had a larger specific surface area than that prepared by co-pyrolysis with bamboo powder. And the high content of iron element could provide a higher surface charge of the biochar, thereby increasing the electrostatic adsorption of phosphorus onto FBC-400. The phosphorus adsorption was highly pH dependent by FBC-400, which can enhance electrostatic adsorption and increase adsorption capacity in acidic conditions. The effect of coexisting anion on adsorption performance was mainly affected by CO3 2- , reducing the adsorption capacity by at least 49%, whereas other anions had no obvious interference. The adsorption process of FBC-400 accorded with the pseudo-second-order kinetic model and the Langmuir model, which indicated that the adsorption process was monolayer adsorption and mainly chemical adsorption, and the maximum saturated phosphorus adsorption capacity was 8.77 mg g-1 . The mechanisms for phosphorus adsorption were electrostatic adsorption and inner-sphere complexing. 1 M NaOH was used for desorption, and the adsorption capacity remained at 81% in the fifth cycle. PRACTITIONER POINTS: The Fenton sludge biochar usage as an adsorbent could be a win-win strategy to convert waste biomass to valuable - product. The adsorption process accorded with the Langmuir model, the maximum phosphorus adsorption capacity was 8.77 mg/g at 25°C. The adsorption mechanisms were electrostatic adsorption and inner-sphere complexing. 1M NaOH was used for desorption, and the adsorption capacity remained at 81% in the fifth cycle.