Initial Bisphenol A Concentration Research Articles

Transformation fate of bisphenol A in aerobic denitrifying cultures and its coercive mechanism on the nitrogen transformation pathway.

Bisphenol A (BPA) is a commonly used endocrine-disrupting chemical found in high levels in wastewater worldwide. Aerobic denitrification is a promising alternative to conventional nitrogen removal processes. However, the effects of BPA on this novel nitrogen removal process have rarely been reported. Herein, we investigated the removal and interaction effects of BPA (0, 0.1, 1, and 10 mg/L) in aerobic denitrifying cultures. Our experimental results demonstrated that the aerobic denitrification system could remove 66%-86% of BPA from wastewater. Fourier transform infrared spectroscopy revealed that polysaccharides and amides were the primary sites for adsorption. An increase in the type and number of intermolecular hydrogen bonds might enhance the ability of aerobic denitrifying cultures to adsorb BPA. Adsorption kinetics analysis demonstrated that inhomogeneous multilayer adsorption was the leading cause of BPA removal. Adsorbed BPA decreased the sedimentation, flocculation, and hydrophobicity of aerobic denitrifying cultures, triggering changes in the levels of proteins and polysaccharides in extracellular polymeric substances. As the influent BPA increased from 0 to 10 mg/L, the nitrate-nitrogen and total organic carbon in the reactor effluent increased from 0.4 ± 0.2 and 26 ± 7.9 mg/L to 18.8 ± 9.3 and 116.2 ± 55.6 mg/L, respectively. BPA (initial concentration range: 1-10 mg/L) significantly influenced the abundance of genes involved in the nitrogen transformation pathway, contributing to the increase in the abundance of gaseous NOx-transformed genes and altering the relative abundance of denitrifying bacteria, particularly Thauera. Correlation analyses revealed that Pseudomonas, Thauera, and AKYH767 are important for maintaining systemic nitrogen transformations and BPA adsorption.

Construction of novel dual wave-absorbing ZnFe2O4/CNTs nanoparticles with more hotspots for enhanced microwave-induced catalytic activity：Performance and mechanism

In this study, novel dual wave-absorbing ZnFe2O4/CNTs nanoparticles were successfully fabricated using a microwave hydrothermal method and applied for enhanced microwave-induced catalytic degradation of bisphenol A (BPA) in aqueous solution. The effects of various process parameters, including Fe3+ concentration (mass ratio of ZnFe2O4 to CNTs), MW irradiation time, MW power, initial BPA concentration, and catalyst dose on the degradation process were thoroughly assessed. The results indicate that ZnFe2O4/CNTs nanoparticles effectively utilize MW energy to generate more hot spots and exhibit superior MW catalytic activity at a 1.0:10.0 mass ratio (ZnFe2O4:CNTs), due to the synergistic effect between ZnFe2O4 nanoparticles and CNTs under MW irradiation. Additionally, hydroxyl radicals (·OH) play a major role in the degradation process, while superoxide radicals (·O2−) and holes (h+) play relatively minor roles. Potential intermediates and degradation pathways in the ZnFe2O4/CNTs/MW system have also been identified. Thus, the integrated ZnFe2O4/CNTs/MW technology shows great promise for treating environmental endocrine disruptors (EEDs) in water and wastewater.

Multi-win situation of wastewater purification, carbon emission reduction and resource utilization: Conversion of refractory organics and nitrate to urea and ammonia in a flow-through electrochemical integrated system

The advanced oxidation process is an efficient technology for the degradation and detoxification of refractory organics to ensure water safety. However, most researches focus on improving pollutant degradation but overlook carbon emission and resource utilization. In this study, a flow-through electrochemical integrated system was constructed to simultaneously realize bisphenol A (BPA) oxidation into small non-toxic organics and CO2, and generated CO2 coupled with nitrate-containing wastewater conversion to urea and ammonia on a porous cathode (Zr-Fe/CN). The synergistic effect between anodic BPA oxidation with cathodic CO2 and NO3−reduction improves the electron utilization efficiency and thus increasing the BPA degradation, urea yield rate (UYR) and NH3 yield rate (NYR) by 13.4 % 18.4 % and 8.3 %, respectively. Furthermore, the flow-through operation mode significantly increased the mass transfer efficiency and quickly carried generated CO2 from the anode into the cathode to improve CO2 utilization efficiency. Compared to the parallel plate electrode reactor, the BPA degradation efficiency, UYR and NYR in the flow-through reactor increased from 59.46 % to 84.49 % (the initial concentration of BPA was 40 mg/L), 9.94 mmol h−1g−1 to 19.55 mmol h−1g−1, and 80.31 mmol h−1g−1 to 106.06 mmol h−1g−1 within 60 min, respectively. Moreover, the total carbon conversion efficiency (from BPA to urea) increased from 20.2 % to 42.4 % and the total Faraday efficiency (FE) increased from 78.6 % to 96.3 %. This work provides a multi-win strategy of harmless, resource-based and carbon emission reduction for wastewater treatment.

Removal of bisphenol A (BPA) from aqueous solution by potassium carbonate modified wetland plant biochars

Bisphenol A (BPA) is a known endocrine disruptor that is acutely toxic to the living organisms. In this study, the wetland plants Phragmites australis and Typha orientalis were subjected to carbonize at 500 °C for different durations (4, 5, and 6 h) and varying mass ratios of wetland plants to potassium carbonate (1:2, 1:1, and 2:1). The prepared modified biochars were used to treat BPA in solution to explore the effect of contact time and initial concentration of BPA on adsorption performance. Both adsorption kinetic models and isotherm models were also studied. The results demonstrated a gradual increase in the adsorption capacity of Phragmites australis and Typha orientalis biochars for BPA with prolonged contact time. Furthermore, an enhancement in the adsorption capacity was observed with increasing initial BPA concentration. The modified biochars significantly enhanced BPA removal and adsorption capacities for BPA compared to the unmodified biochars. L55C (Phragmites australis carbonized at 500 °C for 5 h with a mass ratio of 2:1) and X54C (Phragmites australis carbonized at 500 °C for 4 h with a mass ratio of 2:1) exhibited the largest total surface areas, total pore volumes, microporous surface areas and microporous volumes, and achieved maximum adsorption capacities of 8.547 and 8.117 mg/g, respectively. The adsorption processes were fitted with pseudo-second-order adsorption kinetic models and Langmuir models. The adsorption processes were monolayer chemical adsorption.

Facile synthesis of activated biomass loaded with ZnCl2 as eco-friendly adsorbent for BPA and BPS removal: Comparative study on Batch, column and breakthrough performance

The presence of endocrine-disrupting chemicals (EDCs) in water bodies presents hazards to human health and the environment, hence it is important to research methods that are cost-effective and eliminate these pollutants. In this work, untreated coir pith (CP-N), activated coir pith at 700 °C (ACP), and Zinc chloride activation with ACP (ACP-Zn1.5) adsorbents were compared for efficient removal of bisphenol A (BPA) and bisphenol S (BPS) in a single and binary system for batch study. Furthermore, the parameters related to isotherms, thermodynamics, and kinetics were established. The ACP-Zn1.5 exhibited a maximum sorption capacity of 42.58 and 32.25 mg/g for BPA and BPS. The isotherms and kinetics correspond to the Freundlich model and pseudo-second-order kinetics for both BPA and BPS. For binary systems, BPA and BPS exhibit combative and mutual effects by achieving a maximum sorption capacity of 39.69 and 19.45 mg/g. To assess the effectiveness of ACP-Zn1.5, studies in a fixed bed column were also conducted with variations in the flow velocity, bed height, and initial BPA and BPS concentration. The adsorption mechanism investigations have demonstrated that the main forces underlying the process are surface interactions such as the formation of hydrogen bonds and π-π interactions. As a result, the obtained ACP-Zn1.5 shows considerable potential for removing bisphenols by adsorption from the aqueous system.

A novel integrated membrane bioreactor-stirred tank bioreactor system for simultaneous biodegradation of bisphenol A contaminated wastewater and biopolyol production: An approach towards circular bioeconomy

The present work examined the biodegradation of bisphenol A (BPA) under batch and continuous modes using hydrocarbonoclastic bacterium, Pseudomonas aeruginosa PR3. The strain showed great biodegradation potential under batch shake flask and stirred tank reactor. Bacterial growth was considerably inhibited at initial BPA concentrations > 50 mg/L. Further, membrane bioreactor (MBR) for BPA biodegradation was also evaluated under different inlet BPA concentration and hydraulic retention time (HRT) and the maximum BPA removal efficiency of 94.4 % was attained with an influent BPA concentration of 25 mg/L at 5 d of HRT. MBR also showed better performance under shock loading conditions. Identification of BPA biodegraded pathways was also performed using liquid chromatography-mass spectrometry, elucidating the different metabolites and end products formed. A subsequent enhancement in BPA removal efficieny was also observed owing to the microfiltration system of MBR that was applied to separate bacterial biomass from effluent. The maximum removal efficiency was further enhanced to 98.5 % under the same operational schedule. As the strain has the ability to produce extracellular diol synthase enzyme which transforms oleic acid into the biopolyol 7,10-dihydroxy-8(E)-octadecenoic acid, the effluent containing the enzymes was supplemented with 1 % (v/v) oleic acid under whole cell and cell-free approaches. Cell-free technique showed an enhanced bioconversion efficiency in comparison to the traditional whole cell approach. Further, the produced biopolyol was characterized using Fourier transform infrared spectroscopy, thermogravimetry, differential scanning calorimetry, and 1H nuclear magnetic resonance analyses and also depicted the antibacterial activity.

Porous activated carbons derived from waste Moroccan pine cones for high-performance adsorption of bisphenol A from water

Porous-activated carbons (ACs) derived from Moroccan pine cones (PC) were synthesised by a two step-chemical activation/carbonisation method using phosphoric acid (PC-H) and zinc chloride (PC-Z) as activating agents and used for the adsorption of bisphenol A (BPA) from water. Several techniques (TGA/DTA, FT-IR, XRD, SEM and BET) were used to determine the surface area and pore characterisation and variations during the preparation of the adsorbents. The modification significantly increased the surface area of both ACs, resulting in values of 1369.03 m2 g−1 and 1018.86 m2 g−1 for PC-H and PC-Z, respectively. Subsequent adsorption tests were carried out, varying parameters including adsorbent dosage, pH, initial BPA concentration, and contact time. Therefore, the highest adsorption capacity was observed when the BPA molecules were in their neutral form. High pH values were found to be unfavourable for the removal of bisphenol A from water. The results showed that BPA adsorption kinetics and isotherms followed pseudo-second-order and Langmuir models. Thermodynamic studies indicated that the adsorption was spontaneous and endothermic. Besides, the regeneration of spent adsorbents demonstrated their reusability. The adsorption mechanisms can be attributed to physical adsorption, hydrogen bonds, electrostatic forces, hydrophobic interactions, and π-π intermolecular forces.

Effective adsorption of bisphenol A from aqueous solution using phosphoric acid-assisted hydrochar.

Sycamore leaf biochar (PSAC) was prepared by a two-step phosphoric acid-assisted hydrothermal carbonization combined with a short-time activation method. The characterization results showed that the introduction of phosphoric acid molecules and thermal activation resulted in a substantial increase in the specific surface area (994.21 m2/g) and microporous capacity (0.307 cm3/g) of PSAC. The batch adsorption results showed that the adsorption process of PSAC on bisphenol A (BPA) was best described by the pseudo-second-order kinetic model and Sips isothermal model, with a maximum adsorption capacity of 247.42 mg/g. The adsorption of BPA onto PSAC was determined to be a spontaneous endothermic process. The equilibrium adsorption capacity of PSAC exhibited an upward trend with increasing initial BPA concentration and temperature while decreasing with higher adsorbent dosage and pH value. Coexisting cations and humic acids in water have little impact on the adsorption performance of PSAC for BPA. The adsorption mechanism of BPA by PSAC was mainly governed by pore filling and hydrogen bonding interactions, π-π interactions, and intraparticle diffusion. Furthermore, PSAC demonstrated good reusability by its sustained adsorption capacity of BPA, which remained at 82.6% of the initial adsorption capacity even after four adsorption-desorption cycles. These findings highlight the potential of utilizing low-cost sycamore leaf biochar as an effective adsorbent for the removal of the endocrine disruptor BPA.

Response surface methodology-artificial neural network application for bisphenol A treatment using carbon nanotubes manganese oxide composite

Bisphenol A (BPA) is an emerging pollutant that easily escapes conventional treatment techniques. It requires application of novel composite materials along with mathematical modelling for optimisation and evaluation of the treatment process. In the present study, manganese (IV) oxide (MnO2) nanoparticles were doped onto the surface of multi-walled carbon nanotubes to develop an adsorptive–oxidative composite. The composite was characterised using transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and surface area analysis to confirm composite formation and study its properties. Conventional optimisation of pH (4–10), initial BPA concentration (10–50 mg/l) and contact time (0–60 min) was carried out and found to fit well with the Freundlich isotherm model (R 2 > 0.99) and followed a pseudo-second-order kinetic reaction. A central composite design model was applied using response surface methodology (RSM) to study individual parameters and their interaction effects to enhance process efficiency. Further, the experimental data sets and their responses from RSM were analysed using an artificial neural network. From random experimental sets (80%) of which (10%) each to train, validate and test were selected to analyse the variance of models for higher efficiency using Levenberg–Marquardt back-propagation (LM-BP) algorithm. Additionally, BPA-spiked simulated pharmaceutical waste water was treated with the composite to explore its treatment potential. This systematic experimental and computational approach aided in optimising treatment efficiency for real-time application.

Tungsten-based nanocatalysts with different structures for visible light responsive photocatalytic degradation of bisphenol A

Environmental pollution, such as water contamination, is a critical issue that must be absolutely addressed. Here, three different morphologies of tungsten-based photocatalysts (WO3 nanorods, WO3/WS2 nanobricks, WO3/WS2 nanorods) are made using a simple hydrothermal method by changing the solvents (H2O, DMF, aqueous HCl solution). The as-prepared nanocatalysts have excellent thermal stability, large porosity, and high hydrophilicity. The results show all materials have good photocatalytic activity in aqueous media, with WO3/WS2 nanorods (NRs) having the best activity in the photodegradation of bisphenol A (BPA) under visible-light irradiation. This may originate from increased migration of charge carriers and effective prevention of electron‒hole recombination in WO3/WS2 NRs, whereby this photocatalyst is able to generate more reactive •OH and •O2– species, leading to greater photocatalytic activity. About 99.6% of BPA is photodegraded within 60 min when using 1.5 g/L WO3/WS2 NRs and 5.0 mg/L BPA at pH 7.0. Additionally, the optimal conditions (pH, catalyst dosage, initial BPA concentration) for WO3/WS2 NRs are also elaborately investigated. These rod-like heterostructures are expressed as potential catalysts with excellent photostability, efficient reusability, and highly active effectivity in different types of water. In particular, the removal efficiency of BPA by WO3/WS2 NRs reduces by only 1.5% after five recycling runs and even reaches 89.1% in contaminated lake water. This study provides promising insights for the nearly complete removal of BPA from wastewater or different water resources, which is advantageous to various applications in environmental remediation.

Lactiplantibacillus sp. D10-2: potential bacteria for eliminating bisphenol A and reducing BpA-induced lipid accumulation.

Bisphenol A (BpA) is an endocrine-disrupting substance commonly found in plastics and resins. It is reported that BpA exposure induces lipid accumulation in humans, similar to obesogenic compounds. The main objective of this study is to investigate the removal of BpA using Lactiplantibacillus sp. D10-2, and to examine its potential for reducing BpA-induced lipid accumulation in 3T3-L1 cell line model. The heat-dried cells of Lactiplantibacillus sp. D10-2 showed 69.7% removal efficiency for initial BpA concentration of 10μg/mL, which was 30.5% higher than the live cells. The absence of metabolites or intermediates in BpA removal studies indicates that the Lactiplantibacillus sp. D10-2 strain removed BpA by adsorption process. The hydrophobic interactions of heat-dried Lactiplantibacillus sp. D10-2 cells were observed to be higher with 33.7% compared to live cells (15.0%), suggesting a stronger ability to bind with BpA. Although the BpA binding onto Lactiplantibacillus sp. D10-2 was not affected by pH, it was confirmed that as the temperature increases, the binding ability got decreased due to mass transfer and diffusion of BpA molecules. Treatment with Lactiplantibacillus sp. D10-2 (0.1, 0.25, 0.5, 1%) reduced lipid accumulation by 61.7, 58.0, 52.7 and 60.4% in 3T3-L1 cells exposed with BpA. In addition, it was confirmed that Lactiplantibacillus sp. D10-2 treatment suppressed the protein expression levels of lipogenesis-related PPARγ and C/EBPα in 3T3-L1 cells. The results of the study suggest that the Lactiplantibacillus sp. D10-2 strain can remove BpA and reduce BpA-accelerated lipid accumulation in 3T3-L1 cells.

Catalytic polymerization of bisphenol A using a horseradish peroxidase immobilized microporous membrane reactor.

Bisphenol A (BPA) is one of the most widely used chemical products, which is discharged into rivers and oceans, posing great hazards to organisms such as reproductive toxicity, hormone imbalance and cardiopathy induction. With the expansion harm of BPA, people have paid more attention to the environmental effects. In this paper, the degradation of BPA from the synthetic wastewater using the immobilization of horseradish peroxidase membrane reactor (HPR) was investigated. The immobilized HRP microporous membrane was prepared by the porous calcium alginate method. In addition, the reuse of the immobilized HPR membrane and the measurement of membrane flux showed that the membrane has good activity and stability. Finally, the experimental parameters including reaction time, pH, the concentration of BPA and the dosage of H2O2 were optimized to remove the BPA, and about 78% degradation efficiency of BPA was achieved at the optimal condition as follows: H2O2 to BPA molar ratio of 1.50 with an initial BPA concentration of 0.1 mol/L, the HPR dosage of 3.84 u/mL, the initial solution pH of 7.0, a temperature of 20 °C and a contact time of 10 min.

Enhanced biodegradation of endocrine disruptor bisphenol A by food waste composting without bioaugmentation: Analysis of bacterial communities and their relative abundances

Composting with food waste was assessed for its efficacy in decontaminating Bisphenol A (BPA). In a BPA-treated compost pile, the initial concentration of BPA 847 mg kg-1 fell to 6.3 mg kg-1 (99% reduction) over a 45-day composting period. The biodegradation rate was at its highest when bacterial activity peaked in the mesophilic and thermophilic phases. The average rate of total biodegradation was 18.68 mg kg-1 day-1. Standard methods were used to assess physicochemical parameters of the compost matrix and gas chromatography combined with mass spectrometry (GC/MS) was used to identify BPA intermediates. Next-generation sequencing (NGS) was used to detect BPA degraders and the diverse bacterial communities involved in BPA decomposition. These communities were found consist of 12 phyla and 21 genera during the composting process and were most diversified during the maturation phase. Three dominant phyla, Firmicutes, Pseudomonadota, and Bacteroidetes, along with Lactobacillus, Proteus, Bacillus, and Pseudomonas were found to be the most responsible for BPA degradation. Different bacterial communities were found to be involved in the food waste compost biodegradation of BPA at different stages of the composting process. In conclusion, food waste composting can effectively remove BPA, resulting in a safe product. These findings might be used to expand bioremediation technologies to apply to a wide range of pollutants.

Application of iron-intercalated graphite for modification of nickel foam cathode in heterogeneous electro-Fenton system: Bisphenol A removal from water at neutral pH

The presence of bisphenol A (BPA) in natural waters can be highly harmful due to its high persistence and adverse effects, raising concerns to remove this hazardous compound. Herein, an electro-Fenton system is proposed to eliminate BPA, wherein the iron source in the Fenton reaction is provided by its intercalation into the carbon layers of graphite. The produced heterogeneous catalyst was then coated onto the nickel foam serving as a cathode. The magnetic graphite intercalated compound (mGIC) and the modified cathode (before and after experiments) were characterized by FE-SEM, EDX, XPS, and XRD analyses. Some effective parameters, namely pH (3–9), current density (0–20 mA cm−2), and BPA concentration (0.5–20 mg L−1) were studied. At pH 3, the removal of BPA was 95.52%, and under neutral circumstances, the BPA and TOC removals were 85.70 and 58.12%, respectively at the initial BPA concentration of 10 mg L−1. The proposed system was also applied to several water sources spiked with BPA at the concentration of 5 mg L−1 under neutral pH, which exhibited considerable removal of 99.74%, 99.72%, and 92.70% for groundwater, municipal effluent wastewater, and tap water, respectively. The proposed system was applied for 15 consecutive cycles without showing significant changes in BPA removal, indicating its excellent stability and reusability. Furthermore, based on the analysis of intermediates, a possible decomposition pathway was proposed, indicating a reduction in overall toxicity. By using the proposed heterogeneous electro-Fenton system, iron waste is avoided, and operational costs of treatment can be reduced due to the absence of iron sludge production and catalyst loss.

Pulsed gas–liquid discharge plasma catalytic degradation of bisphenol A over graphene/CdS: process parameters optimization and O3 activation mechanism analysis

In the present work, pulsed gas–liquid hybrid discharge plasma coupled with graphene/CdS catalyst was evaluated to eliminate bisphenol A (BPA) in wastewater. The optimization of a series of process parameters was performed in terms of BPA degradation performance. The experimental results demonstrated that nearly 90% of BPA (20 mg l−1) in the synthetic wastewater (pH = 7.5, σ = 10 μS m−1) was degraded by the plasma catalytic system over 0.2 g l−1 graphene/CdS at 19 kV with a 4 l min−1 air flow rate and 10 mm electrode gap within 60 min. The BPA removal rate increased with increasing the discharge voltage and decreasing the initial BPA concentration or solution conductivity. Nevertheless, either too high or too low an air flow rate, electrode gap, catalyst dosage or initial solution pH would lead to a decrease in BPA degradation. Moreover, optical emission spectroscopy was used to gain information on short-lived reactive species formed from the pulsed gas–liquid hybrid discharge plasma system. The results indicated the existence of several highly oxidative free radicals such as ·O and ·OH. Finally, the activation pathway of O3 on the catalyst surface was analyzed by density functional theory.

Peroxymonosulfate activated by natural porphyrin derivatives for rapid degradation of organic pollutants via singlet oxygen and high-valent iron-oxo species

The activation of peroxymonosulfate (PMS) by sodium ferric chlorophyllin (SFC), a natural porphyrin derivative extracted from chlorophyll-rich substances, was systematically investigated for facile degradation of bisphenol A (BPA). SFC/PMS is capable of degrading 97.5% of BPA in the first 10 min with the initial BPA concentration of 20 mg/L and pH = 3, whereas conventional Fe2+/PMS could only remove 22.6% of BPA under identical conditions. It demonstrates a prominent flexibility to a broad pH range of 3–11 with complete pollutant degradation. A remarkable tolerance toward concomitant high concentration of inorganic anions (100 mM) was also observed, among which (bi)carbonates can even accelerate the degradation. The nonradical oxidation species, including high-valent iron-oxo porphyrin species and 1O2, are identified as dominant species. Particularly, the generation and participation of 1O2 in the reaction is evidenced by experimental and theoretical methods, which is vastly different from the previous study. The specific activation mechanism is unveiled by density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations. The results shed light on effective PMS activation by iron (III) porphyrin and the proposed natural porphyrin derivative would be a promising candidate for efficient abatement of recalcitrant pollutants toward complicated aqueous media in wastewater treatment.

Laccase encapsulation immobilized in mesoporous ZIF-8 for enhancement bisphenol A degradation.

Endocrine disruptors (EDCs) such as bisphenol A (BPA) have many adverse effects on environment and human health. Laccase encapsulation immobilized in mesoporous ZIF-8 was prepared for efficient degradation of BPA. The ZIF-8 (PA) with highly ordered mesopores was synthesized using trimethylacetic acid (PA) as a template agent. On account of the improvement of skeletal stability by cross-linking agent glutaraldehyde, ZIF-8 (PA) realized laccase (FL) immobilization within the mesopores through encapsulation strategy. By replacing the template agent, the effect of pore size on the composite activity and immobilization efficiency by SEM characterization and kinetic analysis were investigated. Based on the physical protection of ZIF-8(PA) on laccase, as well as electrostatic interactions between substances and changes in surface functional groups (e.g. -OH, etc.), multifaceted enhancement including activity, stability, storability were engendered. FL@ZIF-8(PA) could maintain high activity in complex systems at pH 3-11, 10-70°C or in organic solvent containing system, which exhibited an obvious improvement compared to free laccase and other reported immobilized laccase. Combined with TGA, FT-IR and Zeta potential analysis, the intrinsic mechanism was elaborated in detail. On this basis, FL@ZIF-8(PA) achieved efficient removal of BPA even under adverse conditions (removal rates all above 55% and up to 90.28%), and was suitable for a wide range of initial BPA concentrations. Combined with the DFT calculations on the adsorption energy and differential charge, the mesoporous could not only improve the enrichment performance of BPA on ZIFs, but also enhance the interaction stability. Finally, FL@ZIF-8(PA) was successfully applied to the degradation of BPA in coal industry wastewater. This work provides a new and ultra-high performances material for the organic pollution treatment in wastewater.

Preparation of Chitosan-Carbon Nanotubes Decorated with ZnO@laccase: Application in the Removal of Bisphenol A from Aqueous Solution

Bioremediation with immobilized enzymes has been established as the method for restoring contaminated ecosystems with the help of biological tools on a global scale. The purpose of this work is to immobilize the laccase enzyme for increasing the biocatalyst′s ability in order to remove bisphenol A (BPA). Initially, the nanocatalyst was prepared by immobilizing laccase on chitosan using carbon nanotubes decorated with zinc oxide. Subsequently, Fourier transformed infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and dot mapping were employed to characterize the prepared nanocomposites. Laccase activity, immobilization yield (%), thermal and storage stability, and reusability of laccase immobilized on chitosan-coated carbon nanotubes (CNTs)/ZnO nanocomposites were also measured. The chitosan (CS)-CNTs/[email protected] nanocatalyst performance in different operational conditions (initial concentrations of bisphenol A, amount of nanobiocatalyst, pH, and irradiation time) on the photodegradation process of bisphenol A were also investigated and optimized using the response surface methodology (RSM)-central composite design (CCD) model. The RSM design and experiments demonstrated that 94.51% of BPA was removed under optimal conditions (initial BPA concentration of 100 mg L−1, nanocatalyst amount of 1 g L−1, pH=9, and 40 min of contact exposure). Laccase was a critical factor in this process, and after five recycling cycles, immobilized laccase retained 61% of its original activity, indicating that this nanobiocatalyst can be used in purification processes as a durable and robust catalyst.

Development of Bi2WO6 and Bi2O3 - ZnO heterostructure for enhanced photocatalytic mineralization of Bisphenol A.

Present study proposed the synthesis of mixed p-type and n-type nanocomposite heterostructures by co-precipitation method. The as-synthesized heterostructures were characterized through different characterization techniques. The as-synthesized Bi2WO6 and Bi2O3-ZnO heterostructures were tested as photocatalysts during the photodegradation of Bisphenol A (BPA). The Bi2O3-ZnO heterostructure nanocomposite was found to be a more effective photocatalyst than Bi2WO6. The effect of operating parameters including catalytic dose (0.02-0.15 gL-1), initial BPA concentration (5-20 mgL-1), temperature change (5-20 °C) and solution pH changes (4, 5, 7, and 8) were evaluated with Bi2O3-ZnO under UV-light irradiation by selecting a 300 W Xe lamp. More than 90% BPA was degraded with 0.15 gL-1 Bi2O3-ZnO, keeping 1.0 mM H2O2concentration fixed in 250 mL of reaction suspension. The HPLC and GC-MS were used to detect the reaction intermediates and final products. A plausible degradation pathway was proposed on the basis of the identification of reaction intermediates. Repeatability test analysis confirmed that the as-synthesized catalyst showed superb catalytic performance on its removal trend. The kinetics of degradation of BPA were well fitted by the power laws model. With the order of reaction being 0.6, 0.9, 1.2, and 1.3 for different operating parameters, i.e., catalyst dose, initial pH, temperature, and initial BPA concentration.

Nitrogen-doped carbon nanosheets for efficient degradation of bisphenol A by H2O2 activation at neutral pH values

Metal-free carbonaceous materials exhibit great potentials as heterogeneous catalysts for Fenton-like degradation of organic pollutants, because of their high stability and free of secondary pollution of leaching metals. However, the low catalytic activity of carbonaceous materials toward H2O2 activation limits their applications. Herein, we report on a facile two-step thermal annealing method of preparing a kind of nitrogen-doped carbon nanosheets (NCN), which shows efficient degradation of bisphenol A (BPA) via H2O2 activation under neutral conditions. Almost 100% of BPA was removed in 30 min by NCN catalysts in the presence of 12 mmol/L H2O2 at neutral pH values. This NCN catalyst shows good stability with negligible activity decay during recycle use. The influencing factors including the H2O2 addition, NCN dosages, initial BPA concentration, and initial pH values to the removal of BPA by NCN were explored. The radical quenching experiment coupled with an electron spin resonance (ESR) spectrometer demonstrated that singlet oxygen (1O2), and superoxide radical (·O2–) served as primary active species for the pollutant degradation. Pyrrolic N served as adsorption active sites for BPA; Ketonic CO, unsaturated carbon bonds of CC and CC, and graphic C/N are supposed to be active sites for the catalytic reaction. This work provides a new sight in the preparation of carbon-based heterogeneous catalysts and their activation of H2O2 for the removal of organic pollutants from water.