Initial Bisphenol A Research Articles

Biodegradation of Bisphenol-A in aerobic membrane bioreactor sludge

Bisphenol-A (BPA) biodegradation was studied in a membrane bioreactor under aerobic conditions. The effects of the initial BPA concentration and initial chemical oxygen demand (COD) concentration on BPA biodegradation were investigated. The degradation process followed a first-order kinetic (more than 98% of BPA was removed) with a kinetic rate constant of 1.134 h(-1) using an initial BPA concentration of 1.0 mg L(-1). The kinetic rate constant decreased to 0.611 h(-1) when the initial BPA concentration increased to 5.0 mg L(-1). The initial COD concentration (400 and 2,000 mg L(-1)) did not affect the biodegradation kinetic of BPA.

Biodegradation of bisphenol-A (BPA) in activated sludge batch reactors: Analysis of the acclimation process

In this work the effect of (a) the sludge age (SA) and the acclimation strategy on the acclimation process of activated sludge (AS) to bisphenol A (BPA), (b) the presence of biogenic substrates on the degradation of BPA, and (c) the acclimation on the degradation of biogenic substrates was studied. AS samples from reactors operated at SA of 30 and 45 d were acclimated to BPA using two strategies: constant or increasing the initial BPA concentration. Although acclimation to BPA was achieved using both strategies, no net biomass growth was detected. Specific BPA degradation rate of acclimated AS ranged between 65 and 90 mgBPA gTSS−1 d−1. BPA degradation was not affected by the biogenic substrates cheese whey or acetate; acclimation to BPA did not cause a negative effect on the biodegradation of these substrates. During the degradation of cheese whey, specific mean oxygen uptake rate (qo2mean) and specific mean substrate consumption rate (qSmean) of non-acclimated AS were similar to those corresponding to acclimated ones. When acetate was tested, qo2mean and qSmean values corresponding to acclimated AS were about twofold the values of the non-acclimated ones. This enhancement could occur because acetate is an intermediate of the metabolism of BPA.

Removal of Bisphenol A and its Oxidation Products from Aqueous Solutions by Sequential Catalytic Wet Air Oxidation and Biodegradation

Model aqueous solution of bisphenol A (BPA) of 10 mg L–1 was treated in a continuous and sequential catalytic wet air oxidation (CWAO)/aerobic bioreactor (BR) system. Wet oxidation with titanate nanotube-based catalyst resulted in nearly complete removal of BPA (>99%) at a very short space time of 0.3 min·gCAT·g–1. The main identified oxidation products in the CWAO effluent were acetic acid, formic acid and p-hydroxyacetophenone (p-HAP). All of these compounds were consequently and efficiently removed in the BR system at a hydraulic residence time (HRT) of 7.2 h. Although apparent toxicity of the CWAO effluent was found higher than of the initial BPA solution, the former could be successfully detoxified through aerobic biodegradation. The combined system thus presents a potential treatment process for the efficient removal of BPA and its oxidative derivatives from wastewaters.

Cationic surfactant hemimicelle on alginate gel for removing bisphenol A from aqueous solution

In this paper, alginate gel (AG) was prepared by cross-linking sodium alginate with calcium ion. By adding cationic surfactant cetyl trimethyl ammonium bromide (CTAB) as sorption medium, the bisphenol A (BPA) sorption from aqueous solution onto AG was investigated. The BPA removal was found to be dependent on initial pH, AG dose, CTAB concentration, BPA concentration, contact time, and temperature. The isothermal data of BPA sorption on AG conformed well to the Langmuir model, and the maximum sorption capacity (Qm) of AG for BPA was 30.96 mg/g. The BPA sorption process could be described by the pseudo-second-order rate kinetic model. The thermodynamic study indicated that the BPA sorption process was spontaneous and exothermic. The results in this research confirmed that the AG could effectively remove BPA from aqueous solution in presence of the CTAB. The following sorption mechanism was proposed. Firstly, the negatively charged AG sorbed CTAB to form hemimicelle, then BPA was sorbed on hemimicelle by hydrophobic interaction.

Degradation of bisphenol A by microorganisms immobilized on polyvinyl alcohol microspheres

In this study, microorganisms (named B111) were immobilized on polyvinyl alcohol microspheres prepared by the inverse suspension crosslinked method. The biodegradation of bisphenol A (BPA) and 4-hydro-xybenzaldehyde, a degradation product of BPA, by free and immobilized B111 was investigated. The BPA degradation studies were carried out at initial BPA concentrations ranging from 25 to 150 mg·L−1. The affinity constant Ks and maximum degradation rate Rmax were 98.3 mg·L−1 and 19.7 mg·mg−1VSS·d−1 for free B111, as well as 87.2 mg·L−1 and 21.1 mg·mg−1VSS·d−1 for immobilized B111, respectively. 16S rDNA gene sequence analyses confirmed that the dominant genera were Pseudomonas and Brevundimonas for BPA biodegradation in microorganisms B111.

Solar Photocatalytic Degradation of Bisphenol A on Immobilized ZnO or TiO2

The removal of bisphenol A (BPA) under simulated solar irradiation and in the presence of either TiO2or ZnO catalysts immobilized onto glass plates was investigated. The effect of various operating conditions on degradation was assessed including the amount of the immobilized catalyst (36.1–150.7 mg/cm2for TiO2and 0.5–6.8 mg/cm2for ZnO), initial BPA concentration (50–200 μg/L), treatment time (up to 90 min), water matrix (wastewater, drinking water, and pure water), the addition of H2O2(25–100 mg/L), and the presence of other endocrine disruptors in the reaction mixture. Specifically, it was observed that increasing the amount of immobilized catalyst increases BPA conversion and so does the addition of H2O2up to 100 mg/L. Moreover, BPA degradation follows first-order reaction kinetics indicating that the final removal is not practically affected by the initial BPA concentration. Degradation in wastewater is slower than that in pure water up to five times, implying the scavenging behavior of effluent’s constituents against hydroxyl radicals. Finally, the presence of other endocrine disruptors, such as 17α-ethynylestradiol, spiked in the reaction mixture at low concentrations usually found in environmental samples (i.e., 100 μg/L), neither affects BPA degradation nor alters its kinetics to a considerable extent.

Solar light-induced photoelectrocatalytic degradation of bisphenol-A on TiO2/ITO film anode and BDD cathode

The degradation of bisphenol-A (BPA), an endocrine disrupting compound, by means of photoelectrocatalytic (PEC), photocatalytic (PC) and electrochemical oxidation (EO) was investigated. An immobilized TiO2/ITO film, prepared by a sol–gel method, served as the photocatalyst and the anode, while boron-doped diamond (BDD) as the cathode. Photochemical reactions were induced by simulated solar radiation, while anodic bias in the range 0.04–0.32mA/cm2 was applied to evaluate its effect on PC degradation, as well as the extent of direct EO. Experiments were conducted at initial BPA concentrations between 100 and 300μg/L, solution pH between 1 and 9 and two different electrolytes, i.e. HClO4 and NaCl.Current application always improved substantially the performance of photocatalytic degradation with the extent of enhancement (computed from the pseudo-first order kinetic constants of PEC and PC) reaching values as high as 90%. The interaction between PC and EO was found to be synergistic rather than additive; this is thought to be due to (i) a more efficient separation of the photogenerated electrons and holes, and (ii) the enhanced formation of peroxide and other reactive oxygen species favored on the BDD cathode.BPA degradation rates generally increased with increasing applied current, at strongly acidic conditions and in the presence of NaCl as the supporting electrolyte; at the conditions in question, complete BPA conversion could be achieved in no longer than 60–90min of reaction.

Adsorption Studies on the Removal of an Endocrine-Disrupting Compound (Bisphenol A) using Activated Carbon from Rice Straw Agricultural Waste

In this study, we used a two-stage process and potassium hydroxide (KOH) to transform waste biomass (rice straw) into activated carbon and then evaluated the adsorption capacity of the waste for removing bisphenol A (BPA) from an aqueous solution. Activated carbon removed BPA rapidly and effectively because of its high surface area and an adsorptive capacity (181.19 mg/g) that is significantly higher than many other adsorbents that have been developed in the recent past. The native and BPA-loaded adsorbents were characterized by scanning electron microscopy, elemental analysis, and Fourier transform infrared. Different adsorption parameters, such as the initial BPA concentration, contact time, temperature, and pH for BPA adsorption, were studied using a batch system. Equilibrium adsorption isotherms (Langmuir, Freundlich, and Temkin) and kinetics were investigated. The Langmuir model fits the experimental results well, compared to the Freundlich and Temkin models, and a pseudo-second-order equation was successfully used to describe the results of the kinetic studies. This study demonstrates that activated carbon produced from rice straw can be very effective in the adsorption of BPA from aqueous solution.

Contamination of ultrapure water with bisphenol A leached from polysulfone ultrafilter

Ultrapure water produced by a water purification system is one of the most essential and widely used reagents in laboratories. However, its quality is usually the least well-characterized and often overlooked. Here we investigate the contamination of ultrapure water by bisphenol A (BPA) leached from a polysulfone (PS) ultrafilter in a water purification system. To evaluate the level of BPA in ultrapure water, we used an offline solid-phase extraction (SPE) coupled with liquid chromatography mass spectrometry (LC–MS). Initial BPA level leached from a new PS ultrafilter was 0.70±0.06ng/mL. The concentration of BPA decreased gradually with continuous dispensation of purified water and was 0.20±0.02ng/mL at 33.5-L dispensation. The total amount of extractable BPA was 64.4±1.4μg per PS ultrafilter. The cumulative amount of BPA leached during dispensation of 33.5-L water was 1.2±0.1μg, which only accounts for 2% of the total amount of extractable BPA.

Removal of bisphenol-A from spiked synthetic effluents using an immersed membrane activated sludge process

With the recent emergence of estrogenic contaminants as reclaimed wastewater quality issue, our study has investigated the removal of bisphenol-A (BPA) using a submerged membrane bioreactor. Experiments were performed at initial BPA concentrations ranging from 1.0 to 15mg/L. A very low sludge mineralization occurred in the bioreactor (with a VSS/TSS ratio around 0.8–0.9), irrespective of the variation of biomass concentration and a long retention time of solids. The specific oxygen uptake rate values recorded did not reveal any significant change in the microbial respiratory activity in the absence (2.00mgO2/gVSSh) and in the presence (1.4mgO2/gVSSh) of BPA in the synthetic effluent. The performance of the bioreactor in terms of COD removal remained constant and reached 99% irrespective of the hydraulic retention time imposed (3–6h), whereas 66–99% of COD removal was recorded while using conventional activated sludge system. The limit of the toxicity (21.6g BPA/m3/d) determined for the bioreactor membrane system was higher than that recorded for the conventional activated sludge (2.5g BPA/m3/d). BPA was effectively removed in the membrane bioreactor (abatement ⩾98% was reached) due to adsorption and biodegradation/transformation processes. Residual BPA concentrations recorded in the mixed liquor remained low (0.017–0.004mg/L), when the raw wastewater contained a concentration of 1.0mg BPA/L. This indicates that BPA was not accumulated in the membrane bioreactor, but bacteria oxidized it. Likewise, the membrane bioreactor was found to be effective in removing ammonia–nitrogen (>99% of N–NH4 removed), whereas 61% of phosphate (P–PO4) could be simultaneously removed. The membrane bioreactor was a total barrier for total suspended solid and turbidity was effectively removed (residual turbidity was lower than 1.0 NTU).

Bisphenol A oxidative removal by ferrate (Fe(VI)) under a weak acidic condition

Recently there has been increasing concerns on widespread occurrence of endocrine disrupting chemicals (EDCs) in aquatic environment. Bisphenol A (BPA) in water was oxidized as a target EDC by K 2FeO 4 (Fe(VI)) in this study. The results showed that BPA was effectively removed within a broad initial water pH range of 5.0–9.5, especially under a weak acidic condition between the initial pH 5 and 6. When the initial BPA concentration was about 1.5 mg L -1, BPA could be completely removed with a oxidation time of 30 min and a Fe(VI)/BPA molar ratio of 3.0. After Fe(VI) oxidation, UV 254 of the water samples significantly increased, indicating that BPA degradation intermediates and end products still contained phenyl ring. Further online UV scanning showed that the UV absorbance obviously changed within the UV range of 190–215 nm and 230–300 nm during Fe(VI) oxidation. The DOC of water samples reduced with the increase of Fe(VI) dosage and prolonging of oxidation time, and about 50% of BPA was mineralized after Fe(VI) oxidation under a Fe(VI)/BPA molar ratio of 4.0. The influences of coexisting constituents such as humic acids, SiO 3 2 - , HCO 3 - and tert-butanol were studied. The results showed that humic acids and SiO 3 2 - notably inhibited the BPA removal; tert-butanol slightly decreased the BPA removal; and the existence of HCO 3 - slightly enhanced the BPA removal.

Transformation of Bisphenol A in the Presence of Manganese Dioxide

Abstract This study investigates the abiotic transformation of bisphenol A (BPA) in the presence of manganese dioxide (MnO2) and under a spectrum of solution chemistry conditions using batch reactor systems. The results indicated that, at a fixed MnO2 concentration, the reaction rate decreased as a function of initial BPA concentration, and that at a fixed initial BPA concentration, the rate increased as a function of MnO2 concentration. It was also shown that the overall reaction rates decreased rapidly as the solution pH increased from 4.12 to 6.22, whereas a higher ionic strength of the background solution resulted in slower reaction rates. Both Zn2+ and Mn2+, present as background electrolytes, decreased the reaction rates likely because of their adsorption and then blocking of active sites on the MnO2 surfaces. Three products (2-[4-hydroxyl-phenyl]-ethyl, 2-[4-hydroxyl-phenyl]-propyl, and a dimer) were identified and confirmed with deuterated BPA on gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry. It was proposed that formation of dimeric products via oxidative coupling and formation of monomeric products via hydroxylation and dealkylation of BPA were the major reaction mechanisms in the oxidation of BPA by MnO2. The study indicated that oxidative reactions with MnO2 may play an important role in the fate of BPA in soil systems.

Selective adsorption and separation of BPA from aqueous solution using novel molecularly imprinted polymers based on kaolinite/Fe3O4 composites

Magnetic molecularly polymers (MMIPs) based on kaolinite/Fe3O4 composites were successfully synthesized for the selective adsorption and separation of bisphenol A (BPA) from aqueous solutions. During polymerization, the modified kaolinite/Fe3O4 (KLT/Fe3O4) not only was used as supporter but also functional monomer. The properties of MMIPs were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) analysis, and thermogravimetric analysis (TGA) and so on. The SEM graphs showed that much of KLT/Fe3O4 was successfully coated by the imprinted layer, TGA analysis suggested the grafting yield of imprinted layer to KLT/Fe3O4 was 72.51wt%. The effects of pH, initial BPA concentration, contact time and temperature of the medium on the adsorption were studied by the batch mode experiment. The equilibrium data was well described by the Langmuir isotherm model. The kinetics of adsorption followed the pseudo-second-order model and the rate constant decreased with the increase of temperature, indicating exothermal nature of adsorption process. For desorption studies, the highest desorption efficiency (95.75%) was obtained using methanol and acetic acid as eluting solution (v:v=8:2). Moreover, the selectivity of MMIPs was further demonstrated through HPLC analysis of the stimulant water samples, the result showed that MMIPs could effectively recognize BPA in mixed solution.

Solar light-induced degradation of bisphenol-A with TiO 2 immobilized on Ti

The photocatalytic degradation of bisphenol-A (BPA) was investigated over immobilized TiO 2/Ti-film catalysts irradiated by artificial solar light. Catalysts were prepared either by a sol–gel method (TIP catalyst) or deposition of Degussa P-25 slurry (P-25 catalyst) and characterized by X-ray diffraction. The effect of TiO 2 loading (0.65 and 1.3 mg), initial BPA concentration (150, 300 and 600 ppb) and initial solution pH (3, 6, 8 and 10) on degradation was studied. The latter was assessed following changes in BPA concentration by means of high performance liquid chromatography equipped with a fluorescence detector. It was found that both catalysts, consisting of about 75:25 anatase:rutile, were equally active in degrading BPA (e.g. 85% reduction at 300 ppb BPA concentration, 180 min of reaction, 0.65 mg catalyst loading and inherent pH) and conversion increase with increasing the TiO 2 loading; however, the P-25 catalyst was considerably unstable at high loadings suffering about 50% active phase dissolution. Conversion decreased with increasing BPA concentration and it was favored in the pH range 6–8. BPA degradation can be approached by a pseudo-first order rate expression with the apparent kinetic constant taking values between 6 × 10 −3 and 2 × 10 −2 s −1.

Bisphenol a Removal by Nanofiltration Process

It is well known that bisphenol A(BPA), as one EDC, has an oestrogenic effect, causing an abnormal increase in the growth of yeast cell in polycarbonate flasks. Moreover, BPA significantly contributes to the environment problem, as evidenced by a number of recent studies[1](Inoue et al., 2003). This study examined the ability of nanofiltration (NF) membranes to retain bisphenol A(BPA). In the study, BPA retention was quantified by liquid chromatography. The effect of solution chemistry, inorganic matter and pH were investigated on the rejection of BPA and its adsorption on membranes. The results indicate that BPA has a high adsorptive affinity for the membrane and more than 80% of BPA was absorbed on the membrane surface. In addition, the increase of initial BPA concentration has negative effect on BPA rejection. It also indicates that the removal of BPA is higher with lower BPA concentrations. In addition, the rejection of BPA decreases with the increase of pH when pH < 7 and increases with the increase of pH when pH ≥ 7. The experimental results of ionic strength indicate there is a slight decrease in the rejection of BPA when the ionic strength increases.

Enhanced sorption of bisphenol A on α-ketoglutaric acid-modified chitosan resins by hydrophobic sorption of hemimicelles

In this paper, α-ketoglutaric acid-modified chitosan resins (KCR) were successfully prepared. The capacity of KCR as weak cation exchanger for sorbing bisphenol A (BPA) from aqueous solution was compared with crosslinked chitosan resins (CCR) with cetyl trimethyl ammonium bromide (CTAB) as the intermediary of BPA sorbed on sorbent. The BPA removal was found to be dependent on the initial pH, KCR/CTAB dosage, BPA concentration, and contact time. The isothermal data of BPA sorption on KCR was in well agreement with the Langmuir model, and the maximum sorption capacity ( Q m) of KCR for BPA was 30.67 mg/g. The BPA sorption process could be described by the pseudo-second-order rate kinetic model.

Bisphenol A removal by the Dracaena plant and the role of plant-associating bacteria

Dracaena sanderiana and Dracaena fragrans plants, as representatives of native, tropical, evergreen plants with fibrous root systems, were evaluated for bisphenol A (BPA) tolerance and uptake capability. D. sanderiana demonstrated significantly higher BPA removal capability than D. fragrans. Therefore, it was chosen for further study. D. sanderiana tolerated BPA toxicity levels up to 80 microM, while higher BPA concentrations damaged the plant. In the sterile hydroponic system with an initial BPA concentration of 20 microM, the plant could uptake approximately 50% of the BPA. The plant's ability to translocate BPA was confirmed by the detection of BPA that accumulated at the roots and stems, but not at the leaves of the plant. Upon BPA exposure, the D. sanderiana secreted extracellular plant mucilage as a protective barrier to the toxic compound. In the non-sterile treatment, the BPA dissipation was contributed not only by the D. sanderiana plant, but also by the co-existing microbes. The BPA reached 85% of the initial concentration at 20 microM. Among the six plant-associating bacterial isolates, Bacillus cereus strain BPW4 and Enterobacter sp. strain BPW5 colonized the D. sanderiana root surface and facilitated BPA dissipation in the hydroponic treatment system. In addition, the success of the BPA treatment in the hazardous waste landfill leachate demonstrated the potential application of D. sanderiana plant in the phytoremediation of BPA contaminated wastewater or industrial leachate.

Zr-doped TiO2 for enhanced photocatalytic degradation of bisphenol A

Zr ions were successfully incorporated into the bulk lattice of TiO2 by a multi-step sol–gel process. The doping of Zr ions in TiO2 lattice reached about 30%. The Zr-doped TiO2 photocatalysts exhibited much higher photocatalytic efficiency than pure TiO2 in the degradation of bisphenol A (BPA) under UV irradiation and complete mineralization of BPA was achieved. The higher photocatalytic activity of Zr-doped TiO2 was attributed to gradually upward shift of the conduction bands with increasing Zr content, thus resulting in a stronger reduction power of photogenerated electrons and contributing to the improved photoactivity. The effects of initial BPA concentration, irradiation intensity, initial solution pH and inorganic anions on the photocatalytic performance of Zr-doped TiO2 were studied. The photodegradation of BPA was found to be optimized under a basic condition at pH 9. The addition of PO43−and SO42− anions enhanced the photocatalytic reaction but NO3−and Cl− ions showed detrimental effects.

Photocatalytic degradation of Bisphenol A (BPA) using immobilized TiO 2 and UV illumination in a horizontal circulating bed photocatalytic reactor (HCBPR)

Photocatalytic degradation of Bisphenol A (BPA) in the presence of titanium dioxide (TiO 2) and ultraviolet (UV) illumination was performed in a self-designed horizontal circulating bed photocatalytic reactor (HCBPR). TiO 2 catalyst was immobilized on the surface of polyurethane foam (PF) cubes via microwave-assisted liquid phase deposition. The effects of initial BPA concentration, initial pH, TiO 2 dosage and temperature on BPA photodegradation were investigated in order to obtain the optimum operational conditions. The results reveal that the BPA degradation efficiency can be effectively improved by increasing pH from 3.4 to 12.3 or decreasing the initial BPA concentration from 50 to 10 ppm. The optimum TiO 2 carrier dosage (the ratio of the volume of PF carriers to the effective reaction volume of HCBPR) was about 1%. Besides, the effect of temperature on BPA photodegradation was found to be unremarkable in the range of 21.2–30.5 °C. Total organic carbon (TOC) was used to evaluate the mineralization of BPA during the photodegradation process. Under the optimum conditions, 95% removal of TOC and 97% removal of BPA can be achieved after 6 h of UV radiation, which demonstrates the high photodegradation efficiency of BPA in HCBPR.

Photodegradation of bisphenol-A in a batch TiO 2 suspension reactor

In this work, the photocatalytic behaviors of bisphenol-A (BPA), which has been listed as one of endocrine disrupting chemicals, were carried out in a batch TiO 2 suspension reactor. The photodegradation efficiency has been investigated under the controlled process parameters including initial BPA concentration (i.e., 1–50 mg L −1), TiO 2 dosage (i.e., 5–600 mg/200 cm 3), initial pH (i.e., 3–11), and temperature (i.e., 10–70 °C). It was found that the optimal conditions in the photoreaction process could be coped with at initial BPA concentration = 20 mg L −1, TiO 2 dosage = 0.5 g L −1 (100 mg/200 cm 3), initial pH = 7.0, and temperature = 25 °C. According to the Langmuir–Hinshelwood model, the results showed that the photodegradation kinetics for the destruction of BPA in water also followed the first-order model well. The apparent first-order reaction constants ( k obs), thus obtained from the fittings of the model, were in line with the destruction-removal efficiencies of BPA in all the photocatalytic experiments. Based on the intermediate products identified in the study, the possible mechanisms for the photodegradation of BPA in water were also proposed in the present study.