Optimal Degradation Conditions Research Articles

Facile design and fabrication of RP/ZnIn2S4 composite photocatalysts with efficient removal of antibiotics under visible-light irradiation

Efficient photocatalysts with visible light irradiation have a bright future in practical environmental remediation. ZnIn2S4 is a promising environmentally friendly visible-light photocatalyst, due to its appropriate narrow band gap and excellent chemical stability. In this research, the RP/ZnIn2S4 composites with flower spheroidal morphology were synthesized by loading RP onto the surface of ZnIn2S4 via a one-pot hydrothermal process. The experimental results show that the tetracycline (TC) degradation efficiency of RP(1 wt%)/ZnIn2S4 was up to 85.1 %, compared with pure RP, ZnIn2S4, and other series of RP/ZnIn2S4 composites. The optimal degradation conditions were as following: 1 wt% RP modification amount, 30 mg catalyst amount, 30 mg/L initial TC solution concentration, and the initial reaction pH of 7. At the same time, good repeatability and stability of RP(1 wt%)/ZnIn2S4 toward TC removal confirm its potential value for practical applications. In addition, the degradation efficiency of RP(1 wt%)/ZnIn2S4 for rifamycin and ofloxacin under the similar conditions was 80.2 % and 65.3 %, respectively, indicating the universal application of RP/ZnIn2S4 for degradation of different antibiotic pollutants. The possible photocatalytic mechanism was proposed based on the trapping experiment and ESR test. The RP(1 wt%)/ZnIn2S4 composite photocatalytic materials with high efficiency and stability are expected to contribute to the exploration of the environmental protection field.

Isolation and Optimization of Aflatoxin B1 Degradation by Uniform Design and Complete Genome Sequencing of Novel Deep-Sea Kocuria rosea Strain 13.

Aflatoxin B1 is a natural carcinogenic mycotoxin. The biological detoxification of aflatoxin could result in less environmental pollution, more moderate conditions, and less impact on food and feed, and be more convenient than physical and chemical methods. In this study, strain 13 with aflatoxin B1 degradation activity (67.47 ± 1.44%) was isolated and identified as Kocuria rosea. A uniform design was applied to optimize the degradation activity using a software Data Processing System, and a quadratic polynomial stepwise regression model was selected to investigate the relationships between the degradation rate and five independent variables. Furthermore, the optimal degradation conditions (culture temperature of 30 °C, culture time of 4.2 days, seawater ratio of 100%, pH of 7.11, and inoculation dosage of 0.09%) were verified with a degradation rate of 88 ± 0.03%, which was well matched with the predicted value (92.97%) of the model. Complete genome sequencing of Kocuria rosea, conducted with a combination of Illumina and single-molecule real-time sequencing, was used to analyze the genomic features and functions of the strain, which were predicted by the annotation based on seven databases, and may provide insights into the potential of Kocuria rosea, as well as providing a reference for degradation gene and protein mining. These results indicate that Kocuria rosea strain 13 has the ability to degrade aflatoxin B1 efficiently, and it also has the potential to provide aflatoxin-degrading enzymes.

Pesticide Residues and Berry Microbiome after Ozonated Water Washing in Table Grape Storage.

Nowadays, different systems for reducing pesticides in table grapes are being tested at different production stages either in the field or in postharvest. The present study tested ozonated water treatments at the beginning of the cold storage of the Princess® seedless table grape variety to reduce the residue contents of some pesticides and to evaluate their effect on gray mold and the berry microbiome. An ozone generator capable of producing an ozone concentration ranging from 18 to 65 Nm3 was utilized for obtaining three ozone concentration levels in water: 3, 5 and 10 mg/L. Ozonated water was placed in a 70 L plastic box where 500 g grape samples closed in perforated plastic clamshell containers were immersed utilizing two washing times (5 and 10 min). Overall, six ozonated water treatments were tested. After the ozonated water treatments, all samples were stored for 30 days at 2 °C and 95% relative humidity to simulate commercial practices. The pesticide residue contents were determined before the ozonated water treatments (T0) and 30 days after the cold storage (T1). The treatments with ozonated water washing reduced the pesticide residues up to 100%, while the SO2 control treatment reduced the pesticide residues ranging from 20.7 to 60.7%. Using 3 mg/L ozonated water to wash grapes for 5 min represented the optimal degradation conditions for all of the analyzed pesticides, except for fludioxonil, which degraded better with a washing time of 10 min. The ozone treatments did not significantly reduce the gray mold and the fungal and bacterial microbiome, while a relevant reduction was observed in the yeast population.

The Optimization, Kinetics Model, and Lab-Scale Assessments of Phenol Biodegradation Using Batch and Continuous Culture Systems

Phenol was considered a severe hazard to all ecosystems even at low concentrations. The bioremediation process is an eco-friendly process for complete phenol degradation and bioelectricity generation. In the present study, a consortium of native isolates was used for phenol biodegradation and bioenergy generation using nano-graphite electrodes. The optimization of nutritional and environmental parameters using batch culture revealed that the optimum conditions for maximum phenol degradation and energy generation were inoculum concentration, 1%; incubation period, 48 h; phenol, 6 ppm; MgSO4, 70 mg/L; K2HPO4, 175 mg/L; and CaCl2, 1 mg/L. Phenol biodegradation reached 93.34% with a power density of 109.419 mW/cm3. A lab-scale bioreactor was used as a continuous culture with aeration rate, agitation speed, and dissolved oxygen of 0.5 v/v/m, 750 rpm, and 30%, respectively. On using the continuous culture, phenol biodegradation and bioenergy production reached 97.8% and 0.382 W/cm3, respectively. A kinetics study using Haldane’s kinetics model reported the best fit to achieve a significant correlation coefficient (R2) value (0.9865) reaching maximum specific growth rate with initial phenol concentration of approximately 9 mg L−1 where the specific growth rates (μ, h−1) varied with different initial phenol concentrations. In conclusion, the native isolated consortium could be considered as an economical and sustainable approach to phenol biodegradation in industrial wastewater as well as bioelectricity generation.

Efficient degradation of thiamethoxam pesticide in water by iron and manganese oxide composite biochar activated persulfate

Neonicotinoid pesticides in aquatic environments pose a risk to the sustainability of ecosystems and human health. However, there is limited research on the removal of these pesticides from aquatic systems. In this study, biochar doped with different Fe/Mn ratios (FeMn­BC) were prepared at various pyrolysis temperatures and used for the degradation of a typical neonicotinoid pesticide, thiamethoxam (TMX), by activated persulfate (PS). From the experimental results, it is known that the biochar with a Fe/Mn ratio of 3/1 prepared at 600 °C has the most excellent removal efficiency. Optimal degradation conditions were investigated, and under these conditions, TMX removal rates of up to 99.0 % in 90 min were achieved. The applicability of this system in natural surroundings were tested by investigating the effects of inorganic anions and humic acid and in real water samples on TMX removal. In addition, the TMX removal remainly reach to 90.0 % by FeMn-BC activated PS and basically no change after five reuse cycles. Free radical quenching experiments and electron paramagnetic resonance analysis revealed that SO4− and OH radicals on the catalyst surface were the main radicals promoting TMX degradation. Combining the catalyst characterization and experimental results, the possible mechanisms were proposed: the interaction of iron and manganese ions and the oxygen-containing functional groups on the catalyst surface together promote the generation of reactive radicals. This study provides a novel approach for removing neonicotinoid pesticides using modified biochar.

Flower-like nanocomposite of carbon quantum dots, MoS2, and dendritic Ag-based Z-scheme type photocatalysts for effective tartrazine degradation

Nanocomposites of carbon quantum dots, molybdenum disulfide, and dendritic silver (MoS2/CQD/dendritic Ag) were synthesized via a facile and inexpensive procedure and utilized to investigate photocatalytic degradation of tartrazine (TZN) in aqueous medium. The nanocomposites and their individual components were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectrometry (EDS), mapping, X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). The optimum conditions for TZN degradation obtained were TZN concentration of 20 mg/L and a solution pH of 6.5. Electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) analysis were employed to evaluate the TZN degradation by the prepared MoS2/CQD/dendritic Ag nanocomposites. XRD of CQDs, MoS2 and Ag NPs showed amorphous, hexagonal phase and face-centered cubic structures, respectively. Band gaps of 3.3 and 1.9 eV for CQDs and MoS2, respectively as obtained from UV–Vis DRS.The enhanced photo-degradation of TZN was achieved due to the synergistic effects between the nanocomposite constituents. Complete degradation of TZN occurred within 30 min with a rate constant value of 0.172 min−1, wherein oxygen radicals played a significant role compared to other species during the process of degradation.

Degradation of organic compounds in the dark using pre-illuminated Ag/TiO2 as a reusable Fenton-like material

Organic compounds were successfully degraded using silver-deposited titanium dioxide (Ag/TiO2) and hydrogen peroxide (H2O2). Electrons accumulate in Ag deposits on the surface of TiO2 under UV light (λ > 320 nm) illumination; therefore, pre-illuminated Ag/TiO2 activates H2O2 to hydroxyl radicals (•OH) and induces the degradation of 4-chlorophenol (4-CP) under dark conditions. In the presence of pre-illuminated Ag/TiO2 and H2O2 at [4-CP] = 50 μM, [H2O2] = 1 mM, and [pre-illuminated Ag(3.0 wt%)/TiO2] = 0.5 g/L, 64% of 4-CP was degraded after 90 min. The UV light-induced electron storage in Ag deposits and the electron transfer from the Ag deposits to H2O2 in the dark were confirmed by measuring the UV-visible absorption spectra of Ag/TiO2 before and after UV light illumination and the addition of H2O2. The verification of •OH production via a pre-illuminated Ag/TiO2-mediated Fenton reaction was performed using fluorescence spectroscopy, and coumarin was used as a chemical probe. Experiments conducted under various conditions suggest that the optimal conditions for maximum degradation are [H2O2] = 1.0 mM, [Ag/TiO2] = 0.5 g/L, and [Ag content] = 5.0 wt%. The H2O2 activation ability of the used Ag/TiO2 was completely restored through UV light illumination. Additionally, all the tested organic compounds, including 4-CP, 2-chlorophenol, 2,4-dimethylphenol, bisphenol A, sulfisoxazole, sulfamethoxazole, and furfuryl alcohol, were efficiently degraded in a suspension of pre-illuminated Ag/TiO2 and H2O2. Pre-illuminated Ag/TiO2 can be proposed as a practical Fenton-like material for water treatment owing to its high stability and reusability.

Optimization of azithromycin degradation: Integrating ANN-PSO modeling, intermediates analysis, identification, and microbiological assessment

BackgroundThis study aims to identify the by-products generated during the degradation process of azithromycin (AZM), a prevalent antibiotic during the COVID-19 pandemic, via a novel chlorine/ferrous-based advanced oxidation process. MethodsThe optimal conditions for AZM degradation were determined using a neural network coupled with particle swarm optimization modeling. The by-products generated during the process were identified using QuEChERS based on dispersive solid-phase extraction and direct-infusion high-resolution mass spectrometry analysis techniques. The efficacy of the proposed method was validated through microbiological assays conducted pre- and post-degradation of AZM. Significant findingsThe optimal values determined were [NaClO] = 200 μM, [AZM] = 35.37 mg L–1, [FeSO4] = 3.5 mg L–1, and a pH 2.51, providing a predicted yield of 99.9%. Five photoproducts, Azit-DP1 through Azit-DP5, were successfully identified with respective m/z values of 357.11533, 159.06552, 146.08127, 100.07701, and 83.04969. A proposed mechanism for the degradation pathway was presented. The biotests results confirmed that as the quantity of AZM in the medium decreases due to degradation, its antimicrobial effectiveness diminishes accordingly, eventually disappearing completely after 4 h of the degradation process. The results of the performed biotests confirmed the effectiveness of the proposed low-cost system in removing azithromycin and its by-products from the aqueous medium.

Isolation and Characterization of the Wastewater Micropollutant Phenacetin-Degrading Bacterium Rhodococcus sp. Strain PNT-23.

Phenacetin, an antipyretic and analgesic drug, poses a serious health risk to both humans and aquatic organisms, which is of concern since this micropollutant is frequently detected in various aquatic environments. However, rare pure bacterial cultures have been reported to degrade phenacetin. Therefore, in this study, the novel phenacetin-degrading strain PNT-23 was isolated from municipal wastewater and identified as a Rhodococcus sp. based on its morphology and 16S rRNA gene sequencing. The isolated strain could completely degrade 100 mg/L phenacetin at an inoculum concentration of OD600 1.5 within 80 h, utilizing the micropollutant as its sole carbon source for growth. Strain PNT-23 exhibited optimal growth in LB medium at 37 °C and a pH of 7.0 with 1% NaCl, while the optimal degradation conditions in minimal medium were 30 °C and a pH of 7.0 with 1% NaCl. Two key intermediates were identified during phenacetin biodegradation by the strain PNT-23: N-acetyl-4-aminophenol and 4-aminophenol. This study provides novel insights into the biodegradation of phenacetin using a pure bacterium culture, expands the known substrate spectra of Rhodococcus strains and presents a potential new candidate for the microbial removal of phenacetin in a diverse range of environments.

Characterisation of a Bacillus sp. Isolated from Soils Near Lake Maninjau Capable of Degrading Glyphosate

Glyphosate and other soil toxins can be ecologically and financially sustainable bioremediation. When it pollutes the environment, the herbicide glyphosate—used extensively for weed control—poses serious dangers to animals and their ecosystems. A rice field that had been treated with glyphosate for several years was the subject of this investigation into the bioremediation capabilities of soil bacteria. We provisionally identified the most promising isolate as Bacillus sp. strain Unand1 using partial identification methods. Under ideal circumstances, this bacterium demonstrated considerable promise for degrading glyphosate. Bacterial experiments showed that the optimal conditions for glyphosate degradation were a pH of 6.0–7.0, a glyphosate concentration of 0.5–0.6 g/L, 30 °C, and a 1% (v/v) inoculum size. At 0.5 g/L glyphosate, the bacterium showed a two-day lag phase before degrading over 90% after six days of incubation. There was a remarkable 99% and 95% suppression rate of bacterial growth, respectively, when exposed to heavy metals such as Hg(II) and Ag(I). According to this study, this bacterium has bioremediation capability for glyphosate-contaminated settings. Full characterisation and optimization of this bioremediation approach require additional research, especially using molecular identification techniques. This method has the potential to greatly reduce the negative effects of glyphosate pollution on ecosystems and agricultural sustainability.

Eco-friendly Biodegradation of Hydrocarbons Compounds from Crude Oily Wastewater Using PVA/Alginate/Clay Composite Hydrogels

Immobilized microorganisms especially bacteria are most used rather than free cells to be protected from the environmental conditions when being used for the bioremediation of environmental pollutants. Herein, two marine’s bacterial isolates were tested for their ability to decompose crude oil. The optimum conditions for effective bacterial degradation e.g., pH, temperature, and inoculum size were investigated. PVA-alginate-clay composite hydrogel beads with different types of incorporated mineral clays were prepared and tested as bacterial carrier for potential bioremediation. Synthesized composite hydrogels were physico-chemically characterized by FTIR, SEM, and thermal analyses. Results showed that, embedded degrading bacteria in PVA-alginate beads recorded degradation rates as 74 and 66.6% for both tested bacterial isolates (S and R) compared to 61.2 and 53% degradation rates by free cells, respectively. Where, attapulgite clay-containing beads recorded maximum degradation% as 78.8 and 75% for both bacterial isolates, when added to immobilization matrices and these percentages could be enhanced under optimal conditions. The 16S rRNA gene of the two marine oils degrading bacterial isolates were amplified and sequenced, where both isolates were identified as Pseudomonas stutzeri and Rhodococcus qingshengii with submitted accession numbers of ON908963 and ON908962, respectively. These results are referring to the ability of using both tested isolates for crude oil bioremediation process and embedded them into PVA-alginate-clay beads as hydrogel carrier under the optimum conditions.

Pseudomonas aeruginosa based concurrent degradation of beta-cypermethrin and metabolite 3-phenoxybenzaldehyde, and its bioremediation efficacy in contaminated soils

Beta-cypermethrin is one of the widely used pyrethroid insecticides, and problems associated with the accumulation of its residues have aroused public attention. Thus, there is an urgent need to effectively remove the beta-cypermethrin that is present in the environment. Biodegradation is considered a cost-effective and environmentally friendly method for removing pesticide residues. However, the beta-cypermethrin-degrading microbes that are currently available are not optimal. In this study, Pseudomonas aeruginosa PAO1 was capable of efficiently degrading beta-cypermethrin and its major metabolite 3-phenoxybenzaldehyde in water/soil environments. Strain PAO1 could remove 91.4% of beta-cypermethrin (50 mg/L) in mineral salt medium within 120 h. At the same time, it also possesses a significant ability to metabolize 3-phenoxybenzaldehyde—a toxic intermediate of beta-cypermethrin. The Andrews equation showed that the maximum substrate utilization concentrations of beta-cypermethrin and 3-phenoxybenzaldehyde by PAO1 were 65.3558 and 49.6808 mg/L, respectively. Box–Behnken design-based response surface methodology revealed optimum conditions for the PAO1 strain-based degradation of beta-cypermethrin as temperature 30.6 °C, pH 7.7, and 0.2 g/L inoculum size. The results of soil remediation experiments showed that indigenous micro-organisms helped to promote the biodegradation of beta-cypermethrin in soil, and beta-cypermethrin half-life in non-sterilized soil was 6.84 days. The bacterium transformed beta-cypermethrin to produce five possible metabolites, including 3-phenoxybenzyl alcohol, methyl 2-(4-hydroxyphenoxy)benzoate, diisobutyl phthalate, 3,5-dimethoxyphenol, and 2,2-dimethyl-1-(4-phenoxyphenyl)propanone. Among them, methyl 2-(4-hydroxyphenoxy)benzoate and 3,5-dimethoxyphenol were first identified as the intermediate products during the beta-cypermethrin degradation. In addition, we propose a degradation pathway for beta-cypermethrin that is metabolized by strain PAO1. Beta-cypermethrin could be biotransformed firstly by hydrolysis of its carboxylester linkage, followed by cleavage of the diaryl bond and subsequent metabolism. Based on the above results, P. aeruginosa PAO1 could be a potent candidate for the beta-cypermethrin-contaminated environmental bioremediation.

A Novel Study on Anionic Surfactant Degradation Potential of Psychrophillic and Psychrotolerant Pseudomonas spp. Identified from Surfactant-contaminated River Water.

The Yamuna River, a tributary of the holy Ganga, is heavily polluted in the Delhi-NCR region, India and has been gaining attention due to the excessive foaming of the river over the past few years. This can be directly or indirectly related to the overuse of surfactants and the discharge of untreated domestic and textile wastewater into the river. To determine the surfactant load and investigate potential surfactant-degrading bacteria in the region, 96 water samples from four sites in the Okhla Barrage stretch of the river were collected and analysed. The results showed that the selected sites have surfactant concentrations more than the permissible limit (1.00 mgL-1). Also, at most of the sites, the concentration crossed the desirable limit of BIS (0.2 mgL-1) during the period of analysis. The concentration of anionic surfactant reported in the region was found in the range of 0.29 mgL-1 and 2.83 mgL-1. A total of 38 different bacteria were isolated using selective media from the same water samples, out of which 7 bacterial isolates were screened for sodium dodecyl sulphate (SDS) tolerance activity. Based on 16S rRNA gene sequencing, 2 species, namely Pseudomonas koreensis YRW-02 and Pseudomonas songnenensis YRW-05 have been identified and their degradation potential was assessed at different SDS concentrations. The results showed that our strains YRW-02 and YRW-05 degraded 78.29 and 69.24% of SDS respectively. Growth optimization was also performed at different substrate concentrations, pH, and temperature to investigate optimum degradation conditions. This study plays a significant role in assessing the surfactant load and also gives a promising background for future use in in-situ bioremediation experiments.

Natural marmatite photocatalyst for treatment of mineral processing wastewater to help zero wastewater discharge

Mineral processing wastewater (MPW) with large discharge and high toxicity affects environmental safety, and the realizing zero discharge of MPW is of great significance for reducing environmental pollution, saving water resources, and promoting the sustainable development of the mining industry. In this study, we reported natural marmatite (NM) as a low-cost and efficient photocatalyst for the treatment of MPW to help zero wastewater discharge. The photocatalytic activity of NM was evaluated by the removal of total organic carbon (TOC) from MPW under visible-light illumination, and the optimal degradation conditions were discussed. Results showed that superoxide free radicals (·O2−) were the dominant active species responsible for organic pollutants degradation, and 74.25% TOC removal was obtained after 120 min reaction under the optimum treatment conditions. Meanwhile, the wastewater treated by NM photocatalysis can be reused in the flotation system without adverse impact on the product index. Based on these findings, a model of zero wastewater discharge for flotation with the help of photocatalytic treatment was established, it indicated that the water of the whole system can be balanced without affecting the ore dressing index, which showed that visible light-driven photocatalyst has a promising application prospect in the treatment and recycling of industrial wastewater.

Complete degradation of di-n-butyl phthalate by Glutamicibacter sp. strain 0426 with a novel pathway.

Di-n-butyl phthalate (DBP) is widely used as plasticizer that has potential carcinogenic, teratogenic, and endocrine effects. In the present study, an efficient DBP-degrading bacterial strain 0426 was isolated and identified as a Glutamicibacter sp. strain 0426. It can utilize DBP as the sole source of carbon and energy and completely degraded 300mg/L of DBP within 12h. The optimal conditions (pH 6.9 and 31.7°C) for DBP degradation were determined by response surface methodology and DBP degradation well fitted with the first-order kinetics. Bioaugmentation of contaminated soil with strain 0426 enhanced DBP (1mg/g soil) degradation, indicating the application potential of strain 0426 for environment DBP removal. Strain 0426 harbors a distinctive DBP hydrolysis mechanism with two parallel benzoate metabolic pathways, which may account for the remarkable performance of DBP degradation. Sequences alignment has shown that an alpha/beta fold hydrolase (WP_083586847.1) contained a conserved catalytic triad and pentapeptide motif (GX1SX2G), of which function is similar to phthalic acid ester (PAEs) hydrolases and lipases that can efficiently catalyze hydrolysis of water-insoluble substrates. Furthermore, phthalic acid was converted to benzoate by decarboxylation, which entered into two different pathways: one is the protocatechuic acid pathway under the role of pca cluster, and the other is the catechol pathway. This study demonstrates a novel DBP degradation pathway, which broadens our understanding of the mechanisms of PAE biodegradation.

Preparation of Hypoallergenic Whey Protein Hydrolysate by a Mixture of Alcalase and Prozyme and Evaluation of Its Digestibility and Immunoregulatory Properties.

Whey protein (WP) has nutritional value, but the presence of β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) cause allergic reactions. In this study, hypoallergenic whey protein hydrolyate (HWPH) was prepared by decomposing β-LG and α-LA of WP using exo- and endo-type proteases. The enzyme mixing ratio and reaction conditions were optimized using response surface methodology (RSM). Degradation of α-LA and β-LG was confirmed through gel electrophoresis, and digestion, and absorption rate, and immunostimulatory response were measured using in vitro and in vivo systems. Through RSM analysis, the optimal hydrolysis conditions for degradation of α-LA and β-LG included a 1:1 mixture of Alcalase and Prozyme reacted for 10 h at a 1.0% enzyme concentration relative to substrate. The molecular weight of HWPH was <5 kDa, and leucine was the prominent free amino acid. Both in vitro and in vivo tests showed that digestibility and intestinal permeability were higher in HWPH than in WP. In BALB/c mice, as compared to WP, HWPH reduced allergic reactions by inducing elevated Type 1/Type 2 helper T cell ratio in the blood, splenocytes, and small intestine. Thus, HWPH may be utilized in a variety of low allergenicity products intended for infants, adults, and the elderly.

Uncovering the metabolic pathway of novel Burkholderia sp. for efficient triclosan degradation and implication: Insight from exogenous bioaugmentation and toxicity pressure

Triclosan (TCS), a synthetic and broad-spectrum antimicrobial agent, is frequently detected in various environmental matrices. A novel TCS degrading bacterial strain, Burkholderia sp. L303, was isolated from local activated sludge. The strain could metabolically degrade TCS up to 8 mg/L, and optimal conditions for TCS degradation were at temperature of 35 °C, pH 7, and an increased inoculum size. During TCS degradation, several intermediates were identified, with the initial degradation occurring mainly through hydroxylation of aromatic ring, followed by dechlorination. Further intermediates such as 2-chlorohydroquinone, 4-chlorocatechol, and 4-chlorophenol were produced via ether bond fission and C–C bond cleavage, which could be further transformed into unchlorinated compounds, ultimately resulting in the complete stoichiometric free chloride release. Bioaugmentation of strain L303 in non-sterile river water demonstrated better degradation than in sterile water. Further exploration of the microbial communities provided insights into the composition and succession of the microbial communities under the TCS stress as well as during the TCS biodegradation process in real water samples, the key microorganisms involved in TCS biodegradation or showing resistance to the TCS toxicity, and the changes in microbial diversity related to exogenous bioaugmentation, TCS input, and TCS elimination. These findings shed light on the metabolic degradation pathway of TCS and highlight the significance of microbial communities in the bioremediation of TCS-contaminated environments.

Synthesis of Solar Light Active Reduced Graphene Oxide-ZnS Nanomaterial for Photocatalytic Degradation and Antibacterial Applications.

Good water quality is essential for life; therefore, decolorizing and detoxifying organic dye wastes (textile effluents) have gained immense environmental importance in recent years. Thus, the degradation of wastewater has become a potential need for our environment. This research aims to synthesize and investigate a ceramic-based nanomaterial catalyst for the degradation of dye solution under exposure to sunlight. A reduced graphene oxide-ZnS (rGO-ZnS) nanomaterial was qualitatively synthesized using a solvothermal method. The prepared nanomaterial was characterized using XRD, SEM, HR-TEM, EDX, XPS, and FT-IR techniques. The photocatalytic activity of the rGO-ZnS nanomaterial was checked using oxidative photocatalytic degradation of naphthol blue black dye (NBB) under direct sunlight irradiation. Here, the rGO/ZnS composite showed a significant photocatalytic performance to degraded NBB (93.7%) under direct solar light. Chemical Oxygen Demand (COD) measurements confirmed the mineralization of the dye. The influence of different radical scavengers on NBB degradation was studied. Optimum conditions for efficient degradation were determined. The antibacterial property of the prepared catalyst was studied.

Preparation of a novel Ti/TNAs/PbO2-PVDF-Er2O3 anode by Ti3+ self-doping TNAs and its electrocatalytic performance for hydroquinone degradation

A new type of Ti/TNAs/PbO2-PVDF-Er2O3 electrode was prepared in this research via composite electrodeposition method with Ti3+ self-doped modified titanium dioxide nanotubes arrays (TNAs) as the intermediate layer, and co-deposition of PVDF and rare earth Er (Ⅲ) into PbO2, which is expected to be used for efficient degradation of hydroquinone (HQ) wastewater. The research results indicate that the Ti/TNAs/PbO2-PVDF-Er2O3 electrode is composed of more compact β-PbO2, possesses the largest hydrophobicity (97.8°) among the series electrodes. Additionally, the electrode exhibits remarkable electrocatalytic performance with the largest oxygen evolution potential (2.012 V), the largest electrochemical active surface area (ECSA), and the smallest electron transfer resistance (1.054 Ω·cm2). Furthermore, the Ti/TNAs/PbO2-PVDF-Er2O3 electrode is used for the degradation of HQ, and the experiments results reveal that the degradation process is mainly controlled by the indirectly oxidation of ·OH generated on the surface of the electrode, which is presumed to be oxidized to benzoquinone and various fatty acids by ·OH in combination with GC-MS, and finally mineralized to CO2 and H2O. Meanwhile, under the optimum degradation conditions (pH:7, temperature: 30 ℃, Na2SO4: 0.1 M, current density: 50 mA.cm‐2), the degradation rate is up to 94.5%, demonstrating the best electrocatalytic degradation efficiency.

Photocatalytic Degradation of Sulfamethoxazole from a Synthetic Pharmaceutical Wastewater Using Titanium Dioxide (TiO2) Powder as a Suspended Heterogeneous Catalyst

Some medications in aquatic media pose a serious environmental risk. Sulfamethoxazole (SMX) is a member of the sulfonamide group. Photocatalysis offers a promising technique to degrade organic pollutants into environmentally friendly substances. This study examined the effect of operating conditions (pH, time, and temperature) of the ultraviolet (UV)/TiO2 photocatalytic process on the degradation of SMX in an aqueous solution. Decreasing the pH value positively affects SMX degradation, and better removal values were obtained at a pH equal to 4. The optimum operating conditions for complete degradation in a solution containing 500 mg/L of SMX, TiO2 0.5 mg/L irradiation time of 420 min, and pH 4. Under these conditions, Chemical Oxygen Demand (COD) removal was 62.6% at a temperature of 25 ℃. The effect of temperature was studied at three temperatures (25, 40, and 60 ℃) with pH 4. The elevation of temperature increased the COD removal rate to 99.62% at 60 ℃. Finally, the results of the reaction kinetics study showed that a first-order kinetics model described organic contamination removal data over time, and the obtained activation energy was 42.195 kJ/mol.