S0-dependent bio-reduction for antimonate detoxification from wastewater by an autotrophic bioreactor with internal recirculation.

Elemental sulfur (S0) autotrophic reduction is a promising approach for antimonate [Sb(V)] removal from water; however, it is hard to achieve effective removal of total antimony (TSb). This study established internal recirculation in an S0 autotrophic bioreactor (SABIR) to enhance TSb removal from Sb(V)-contaminated water. Complete Sb(V) reduction (10 mg/L) with bare residual Sb(III) (< 0.26 mg/L) was achieved at hydraulic retention time (HRT) = 8 h. Shortening HRT adversely affected the removal efficiencies of Sb(V) and TSb; meanwhile, an increased reflux ratio was conducive to Sb(V) and TSb removal at the same HRT. Sulfur disproportionation occurred in the SABIR and was the primary source for SO42- generation and alkalinity consumption. The alkalinity consumption decreased with the shortening HRT and increased with an increased reflux ratio at the same HRT. The generated SO42- was significantly higher (50-100 times) than the theoretical value for Sb(V) reduction. Coefficient of variation (CV), first-order kinetic models, and osmolality analyses showed that internal recirculation did not significantly affect the stability of SABIR but contributed to enhancing TSb removal by increasing mass transfer and reflowing generated sulfide back to the SABIR. SEM-EDS, Raman spectroscopy, XRD and XPS analyses identified that the precipitates in the SABIR were Sb2S3 and Sb-S compounds. In addition, high-throughput sequencing analysis revealed the microbial community structure's temporal and spatial distribution in the SABIR. Dominant genera, including unclassified-Proteobacteria (18.72-38.99%), Thiomonas (0.94-4.87%) and Desulfitobacterium (1.18-2.75%) might be responsible for Sb(V) bio-reduction and removal. This study provides a strategy to remove Sb from water effectively and supports the theoretical basis for the practical application of the SABIR in Sb(V)-contaminated wastewater.

Molecular dynamics investigation of IEPOX chemical behavior at the interface and in the bulk phase of acidic aerosols.

Isoprene epoxydiol (IEPOX) is an important reactive gas-phase intermediate produced by the photooxidation of isoprene under low NOx conditions, playing a key role in the formation of secondary organic aerosols (SOA). Previous studies have mostly focused on the liquid-phase reactions of IEPOX within aerosols; however, interfacial heterogeneous chemical reactions are equally important in SOA formation. This study systematically explores the reaction mechanisms of IEPOX at the acidic aerosol interface and in the bulk phase using classical molecular dynamics (MD) and ab initio molecular dynamics simulations (AIMD). The study found that the free energy of IEPOX at the aerosol interface significantly decreases, indicating that interfacial heterogeneous chemical reactions are indispensable for the formation of IEPOX-derived SOA. The research reveals the formation pathways of 2-methyltetrols (2-MTO) and 1,3,4-trihydroxy-3-methylbutan-2-yl sulfates (2-MTOOS), finding that the protonation of the epoxy O atom and the cleavage of the C-O bond are the rate-controlling steps, while the nucleophilic addition is a spontaneous process. Through multiple sets of simulations, it was observed that the formation frequency of 2-MTO at the acidic aerosol interface and in the bulk phase reached 53.8%, significantly higher than the 30.8% of 2-MTOOS, which is consistent with field observation data. Additionally, through metadynamics (MTD) simulations, it was suggested that IEPOX could undergoes acid-catalyzed ring-opening reactions at the interface, potentially followed by the transfer of H atoms from primary alcohols into the aerosol, leading to the possible formation of the intermediate product 3-methylbut-3-ene-1,2,4-triol (one of the proposed structures of C5-alkene triols). These findings provide new insights into the formation mechanism of IEPOX-derived SOA and offer a scientific basis for future studies on their physicochemical properties and atmospheric fate.

Discovery of astragaloside IV against high glucose-induced apoptosis in retinal ganglion cells: Bioinformatics and in vitro studies.

OBJECTIVE: To examine the therapeutic mechanism of astragaloside IV (AS-IV) in the management of retinal ganglion cell (RGC) injury induced by high glucose (HG), a comprehensive approach involving the integration of network pharmacology and conducting in vitro and in vivo experiments was utilized. METHODS: A rat model of diabetic retinopathy (DR) injury was created by administering streptozotocin through intraperitoneal injection. Additionally, a model of RGC injury induced by HG was established using a glucose concentration of 0.3 mmol/mL. Optical coherence tomography (OCT) images were captured 8 weeks after the injection of AS-IV. AS-IV and FBS were added to the culture medium and incubated for 48 h. The viability of cells was assessed using a CCK-8 assay, while the content of reactive oxygen species (ROS) was measured using DCFH-DA. Apoptosis was evaluated using Annexin V-PI. To identify the targets of AS-IV, hyperglycemia, and RGC, publicly available databases were utilized. The Metascape platform was employed for conducting GO and KEGG enrichment analyses. The STRING database in conjunction with Cytoscape 3.7.2 was used to determine common targets of protein-protein interactions (PPIs) and to identify the top 10 core target proteins in the RGC based on the MCC algorithm. qRT-PCR was used to measure the mRNA expression levels of the top10 core target proteins in RGCs. RESULTS: OCT detection indicated that the thickness of the outer nucleus, and inner and outer accessory layers of the retina increased in the AS-IV treated retina compared to that in the DM group but decreased compared to that in the CON group. Coculturing RGC cells with AS-IV after HG induction resulted in a significant increase in cell viability and a decrease in ROS and apoptosis, suggesting that AS-IV can reduce damage to RGC cells caused by high glucose levels by inhibiting oxidative stress. There were 14 potential targets of AS-IV in the treatment of RGC damage induced by high glucose levels. The top 10 core target proteins identified by the MCC algorithm were HIF1α, AKT1, CTNNB1, SMAD2, IL6, SMAD3, IL1ß, PPARG, TGFß1, and NOTCH3. qRT-PCR analysis showed that AS-IV could upregulate the mRNA expression levels of SMAD3, TGF-ß1, and NOTCH3, and downregulate the mRNA expression levels of HIF1α, AKT1, CTNNB1, SMAD2, SMAD3, and IL-1ß in high glucose-induced RGC cells. CONCLUSION: The findings of this study validate the efficacy of astragaloside IV in the treatment of DR and shed light on the molecular network involved. Specifically, HIF1α, AKT1, CTNNB1, SMAD2, SMAD3, and IL-1ß were identified as the crucial candidate molecules responsible for the protective effects of astragaloside IV on RGCs.

Bioinformatics-based Study on the Effects of Umbilical Cord Mesenchymal Stem Cells on the Aging Retina.

BACKGROUND: Retinal aging is one of the common public health problems caused by population aging and has become an important cause of acquired vision loss in adults. The aim of this study was to determine the role of human umbilical cord mesenchymal stem cells (hUCMSCs) in delaying retinal ganglion cell (RGC) aging and part of the network of molecular mechanisms involved. METHODS: A retinal ganglion cell senescence model was established in vitro and treated with UCMSC. Successful establishment of the senescence system was demonstrated using ß- galactosidase staining. The ameliorative effect of MSC on senescence was demonstrated using CCK8 cell viability and Annexin V-PI apoptosis staining. The relevant targets of RGC, MSC, and senescence were mainly obtained by searching the GeneCards database. The protein interaction network among the relevant targets was constructed using the String database and Cytoscape, and 10 key target genes were calculated based on the MCC algorithm, based on which Gene ontologies (GO) enrichment and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment were performed. Changes in relevant target genes were detected using real-time fluorescence quantitative PCR and the mechanism of action of UCMSC was determined by RNA interference. RESULTS: ß-galactosidase staining showed that UCMSC significantly reduced the positive results of RGC. The retinal aging process was alleviated. The bioinformatics screen yielded 201 shared genes. 10 key genes were selected by the MCC algorithm, including vascular endothelial growth factor A (VEGFA), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), albumin (ALB), interleukin- 6 (IL6), tumor necrosis factor (TNF), tumor protein P53 (TP53), insulin (INS), matrix metalloproteinase 9 (MMP9), epidermal growth factor (EGF), interleukin-1ß (IL1B), and enrichment to related transferase activity and kinase activity regulated biological processes involved in oxidative stress and inflammation related pathways. In addition, PCR results showed that all the above molecules were altered in expression after UCMSC involvement. CONCLUSION: This experiment demonstrated the role of UCMSC in delaying retinal ganglion cell senescence and further elucidated that UCMSC may be associated with the activation of VEGFA, TP53, ALB, GAPDH, IL6, IL1B, MMP9 genes and the inhibition of INS, EGF, and TNF in delaying retinal senescence.

Effective removal of nitrate in water by continuous-flow electro-dialysis ion exchange membrane bioreactor (CF-EDIMB): Performance optimization and microbial analysis.

The use of nitrogen fertilizer has been causing nitrate pollution in groundwater, and there is an urgent need for efficient approach to remove nitrate from groundwater. In our job, a novel continuous-flow electrodialysis ion exchange membrane bioreactor system (CF-EDIMB) was set up to remove nitrate (NO3-) from water for the first time. Nitrate removal was positively dependent on water chamber HRT and voltage; voltage had significant effect on the water chamber effluent pH; acetate utilization efficiency was closely correlated with acetate dosage. The optimal conditions forecasted through response surface method (RSM) were given as follows: water chamber HRT was 20 h, biological chamber HRT was 24 h, voltage was 6.65 V and acetate dosage was 454.99 mg/L, dedicating to nitrate removal of 81.90% (83.70% in prediction), water chamber effluent pH of 7.10 (7.00 in prediction) and acetate utilization efficiency of 92.87% (96.51% in prediction). Meanwhile, microorganisms are crucial for nitrate removal, and the microbial community was not sensitive to the variation of acetate dosage. The microbial analysis results indicated that when CF-EDIMB system was operated for 20 d, the sulfate-reducing bacteria Sediminibacterium appeared in the biological chamber, and the effluent sulfate concentration of biological chamber was decreased. During the whole operation, Thauera was the dominant genus. Denitrifying functional genes nirS presented a better expression than the gene narG, and there was no accumulation of nitrite.

Activation of persulfate by heterogeneous nano zero-valent iron/halloysite nanotubes: reaction behavior, mechanism, and implication for tetracycline hydrochloride degradation.

A novel composite (nZVI/HNTs) was prepared via incorporating nano zero-valent iron (nZVI) on halloysite nanotubes (HNTs) for degrading tetracycline hydrochloride (TCH) with existence of persulfate (PS). The adsorption process of nZVI/HNTs to TCH conformed to the Freundlich isotherm model and pseudo-second-order kinetic model, and its maximum adsorption capacity was 76.62 mg·g-1. Furthermore, the nZVI/HNTs + PS system exhibited satisfactory degradation efficiency (84.21%) for TCH, and stable nZVI/HNTs (Fe leaching < 0.001 mg·L-1) could be reused. When nZVI/HNTs dosage, PS dosage and temperature increased, TCH degradation could be enhanced. After four cycling, nZVI/HNTs + PS system had still 65.8% degradation for TCH. The quenching tests and EPR analysis evidenced that SO4•- was predominant instead of •OH in such system. Three possible pathways of TCH degradation were provided through the liquid chromatograph-mass spectrometer (LC-MS) determination. Meanwhile, the biological toxicity prediction analysis indicated that the nZVI/HNTs + PS system would be an environment friendly treatment method toward TCH pollution.

An integrated method for studying the biodegradation of benzo[a]pyrene by Citrobacter sp. HJS-1 and interaction mechanism based on the structural model of the initial dioxygenase.

A bacterial strain Citrobacter sp. HJS-1 was discovered from the sludge in a drainage canal of a coal mine. Firstly, its biodegradation capacity for benzo[a]pyrene (BaP) was detected under different concentrations. The results proved that the strain possessed excellent biodegradation capacity for BaP with high-efficiency degradation rates ranging from 78.9 to 86.8%. The highest degradation rate was observed in the low-concentration sample, and the high-concentration BaP had a slight influence on the biodegradation capacity due to the potential toxicity of BaP and its oxygen-containing derivatives. Meanwhile, the degradation test for the other five aromatic hydrocarbons (2- to 4-ring) proved that the strain had a comprehensive degradation potential. To clarify the biodegradation mechanism of BaP, a dioxygenase structure was constructed by homology modeling. Then, the interactions between dioxygenase and BaP were researched by molecular simulation. Combined with the identification of the vital BaP-cis-7,8-dihydrodiol intermediate and the interaction analysis, the initial oxidation mode and the binding site of BaP were revealed in the dioxygenase. Taken together, this study has offered a way to understand the biodegradation process of BaP and its interaction mechanism based on experimental and theoretical analysis.

Biotransformation of benzo[a]pyrene by Pannonibacter sp. JPA3 and the degradation mechanism through the initially oxidized benzo[a]pyrene-4,5-dihydrodiol to downstream metabolites.

Owing to its adverse effects on the environment and human health, benzo[a]pyrene (BaP) has attracted considerable attention and has been used as a model compound in ecotoxicology. In this study, Pannonibacter sp. JPA3 as a BaP-degrading strain was isolated from the production water of an oil well. The strain could remove 80% of BaP at an initial concentration of 100 mg L-1 after 35 d culture. The BaP-4,5-dihydrodiol, BaP-4,5-epoxide, 5-hydroxychrysene, and 2-hydroxy-1-naphthoic acid metabolites were identified in the biodegradation process. Simultaneously, the gene sequence coding for dioxygenase in the strain was amplified and a dioxygenase model was built by homology modeling. Combined with the identification of the metabolites, the interaction mechanism of BaP with dioxygenase was investigated using molecular docking. It was assumed that BaP was initially oxidized at the C4-C5 positions in the active cavity of dioxygenase. Moreover, a hypothesis for the progressive degradation mechanism of BaP by this strain was proposed via the identification of the downstream metabolites. In conclusion, our study provided an efficient BaP degrader and a comprehensive reference for the study of the degradation mechanism in terms of the degrading metabolites and theoretical research at the molecular level.

Excessive dietary L-tryptophan regulated amino acids metabolism and serotonin signaling in the colon of weaning piglets with acetate-induced gut inflammation.

L-Tryptophan (Trp) was shown to improve the gut barrier and growth of weaning piglets. However, whether excessive dietary Trp regulates amino acids (AAs) metabolism and gut serotonin (5-HT) homeostasis in piglets with gut inflammation is not clear yet. We hypothesize that excessive dietary Trp alleviates acetate-induced colonic inflammation and gut barrier damage in weaning piglets partially through the regulation of colonic AAs metabolism and 5-HT signaling. Fifty-four 21-day-old weaned piglets were divided into six groups: control, acetate, 0.2%Trp, 0.2%Trp + acetate, 0.4% Trp, and 0.4%Trp + acetate. Piglets were fed a basal diet supplemented with 0%, 0.2%, or 0.4% of Trp throughout the 12-day experiment. During days 0-7, all piglets had free access to diet and drinking water. On day 8, piglets were intrarectal administered with 10 mL of 10% acetate saline solution or 0.9% saline. During days 8-12, all piglets were pair-fed the same amount of feed per kg bodyweight. Results showed that excessive dietary Trp alleviated acetate-induced reductions in daily weight gain and increase in feed/gain ratio. Trp restored (P < 0.05) acetate-induced increase in concentrations of free aspartate, glutamate/glutamine, glycine, 5-HT, and 3-methylindole in the colon, downregulation of zonula occludens-1 and 5-HT reuptake transporter (SERT) expression and upregulation of IL-1ß, IL-8, TLR4, and 5-HT receptor 2A (HTR2A) expression, and the increase in ratios of p-STAT3/ STAT3 and p-p65/p65 in the colon. The above findings suggested that excessive dietary Trp in the proper amount regulated colonic AAs metabolism, 5-HT homeostasis, and signaling that may contribute as important regulators of gut inflammation during the weaning transition.

Construction of heterotrophic-sulfur autotrophic integrated fluidized bed reactor for simultaneous and efficient removal of compound pollution of perchlorate and nitrate in water.

A heterotrophic sulfur autotrophic integrated fluidized bed reactor was established for simultaneous and efficient removal of ClO4- and NO3- from water. The optimum operating conditions forecasted through the response surface method (RSM) were the hydraulic retention time (HRT) of 0.50 h, the influent acetate (CH3COO-) concentration of 55 mg/L and the reflux ratio of 14, contributing to ClO4- and NO3- removal of 98.99% and 99.96%, respectively, without secondary pollution caused by residual carbon (NPOC <3.89 mg/L). Meanwhile, the effluent pH fluctuated in a range of 6.70-8.02 and sulfur-containing by-products (i.e., SO42- and S2-) could be controlled by adjusting operation conditions throughout the experimental stage. The increase of the influent CH3COO- concentration reduced the load borne by autotrophic reduction process and further reduced SO42- production. Shortening HRT, increasing the influent CH3COO- concentration and decreasing the reflux ratio could all reduce alkalinity consumption. Shortening HRT and decreasing the reflux ratio could shorten contact time between sulfur and water and thus inhibit S0 disproportionation. High-throughput sequencing result showed that Proteobacteria and Chlorobi were the dominant bacteria. Sulfurovum, Sulfuricurvum and Ignavibacterium were the major heterotrophic denitrifying bacteria (DB)/perchlorate reducing bacteria (PRB), Ferritrophicum and Geothrix were DB, and Chlorobaculum was S0 disproportionation bacteria.

Electrodialysis ion-exchange membrane bioreactor (EDIMB) to remove nitrate from water: Optimization of operating conditions and kinetics analysis.

Nitrate pollution has become a worldwide problem. In this study, we remove nitrate from water by electrodialysis ion-exchange membrane bioreactor (EDIMB) and enabling simultaneous nitrate enrichment and denitrification. In this reactor, nitrate migrated from the water chamber to the biological chamber via electrodialysis and was degraded by microorganisms. The effects of voltage and biomass concentration on the reactor performance were examined, and the kinetics data of the water chamber and biological chamber were fitted. The experimental results showed that the migration of nitrate in the water chamber conformed to the first-order model, and the constructed zero-Michaelis-Menten model described changes in nitrate concentration in the biological chamber. Furthermore, when the inflow nitrate concentration was 40 mg N/L, 5 V was the best voltage, and 3.00 g VSS/L was the best biomass concentration. The nitrate removal rate in the water chamber was 98.94%, and there was no accumulation of nitrate or nitrite in the biological chamber. Compared with traditional ED processes, the nitrate removal efficiency was 8.86% higher, and the current efficiency was 22.14% higher. The total organic carbon (TOC) of the water chamber was only 1.43 mg C/L, which proves that the structure of the EDIMB confined the denitrifying bacteria and organic carbon donors in the biological chamber and avoided secondary pollution in the water chamber. Microbial community analysis showed that Thauera (66.06%) was the dominant bacterium in the EDIMB system, and Azoarcus (9.81%) was a minor denitrifying genus.

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 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.

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.

Fabrication of self-assembled 0D-2D Bi2MoO6-g-C3N4 photocatalytic composite membrane based on PDA intermediate coating with visible light self-cleaning performance.

A Self-cleaning surface can efficaciously solve the problem of irreversible contamination buildup on filtration membranes. Photocatalytic membranes were fabricated via vacuum assisted layer-by-layer (LBL) self-assembly of 0D-2D Bi2MoO6-g-C3N4 on a PDA coated thin-film composite PVDF substrate by Schiff base reaction. The rejection rate of the simulated polysaccharide was more than 90%, and that of the simulated protein was more than 80%. The combination of the membrane and the photocatalyst promoted the degradation of tetracycline hydrochloride by the composite membrane to 67.85% when original membranes had minor effect. Under visible light, reversible radiation pollutants (Rr) gradually replaced irreversible pollutants (Rir) as the main pollutants. The flux recovery ratio (FRR) of 0D-2D Bi2MoO6-g-C3N4/PVDF membrane was 85% after being irradiated with visible light for 30 min. The flux recovery rate of contaminated photocatalytic membrane remained 75%, and the rejection was maintained in a stable range after four cycles of the cleaning operation under visible light. The results indicated that the excellent photocatalytic performance of 0D-2D Bi2MoO6-g-C3N4 photocatalysis material and the increase of multi-dimensional functional layer morphology on pollutant contact area improved the mechanical stability, interception performance and self-cleaning performance of the composite membrane. This work not only builds a new type of composite coating membranes, but also help us to further understand the relationship between the dimensions of photocatalytic materials and the improvement of photocatalytic membrane performance.

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.

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.