Bisphenol A Removal Efficiency Research Articles

Enhanced electrocatalytic degradation of bisphenol A by graphite/β-PbO2 anode in a three-dimensional electrochemical reactor

In this study, the electrocatalytic synergy of the graphite/β-PbO2 anode and granular activated carbon (GAC) particles electrodes for bisphenol A (BPA) degradation are investigated in a three-dimensional electrochemical reactor (3DER). The graphite/β-PbO2 anode was prepared by anodic deposition method and the electrocatalytic properties of lead oxide film were studied by FESEM, XRD, EDX-mapping, linear sweep voltammetry and accelerated lifetime test techniques. The effect of five independent variables including pH, Na2SO4 concentration, current density, GAC amount, and reaction time on the system response was optimized by an orthogonal central composite-genetic algorithm (OCCD-GA). The results showed that β-PbO2 crystals were deposited as completely compact pyramidal clusters on the graphite surface. In addition, the service life and oxygen evolution potential (OEP) for the electrocatalytic layer of β-PbO2 were 90 h and 2 V, respectively. Based on the developed quadratic model (R2 > 0.99 and p-value < 0.0001), the optimal points for pH, Na2SO4 concentration, current density, GAC amount, and reaction time were predicted to be 4.6, 0.074 mol L−1, 35.7 mA cm−2, 25 g, and 80 min, respectively. Under optimal conditions, BPA removal efficiency in 3DER system and separate application of electrocatalytic degradation and GAC were obtained 98.8%, 72.2% and 9.75%, respectively. Thus, the electrocatalytic synergy of 3DER system due to lead oxide layer and GAC particle electrodes in BPA degradation was calculated to be 35.5%. LC-MS analysis was used to identity the intermediates formed during BPA degradation. The final degradation intermediates were short-chain acids including adipic acid, malonic acid and, acetic acid.

Immobiling enzyme-like ligand in the ultrafiltration membrane to remove the micropollutant for the ultrafast water purification

Water security is one of the most pressing global challenges due to its effects on human health. To face the challenge of water pollution, membrane technology was widely applied for the removal of pollutants and desalination. In this work, an enzyme-like ligand, Iron (III)-tetraamidomacrocyclic ligand (Fe(III)-TAML), was for the first time immobilized into a polyethersulfone (PES) membrane for the catalytic oxidation removal of micropollutants during the ultrafiltration process. Through the introduction of graphene oxide-polyethyleneimine (GO-PEI), Fe(III)-TAML was successfully immobilized into the membrane. Results shown that porosity and hydrophilicity of the PES membrane were significantly enhanced after GO-PEI modification. Furthermore, about 100% of bisphenol A (BPA) in the feed water was removed after filtration using the Fe(III)-TAML immobilized membrane at a high flux of 192 L/m2 h, which was attributed to the generation of high valence Fe through activating Fe(III)-TAML by H2O2. Moreover, the Fe(III)-TAML in the membrane could be simply regenerated by a re-adsorption process, and the flux and removal efficiency of BPA were stabled during five cycles. Additionally, the TAML/GO-PEI/PES membrane maintained a high water flux and BPA removal efficiency for the filtration of actual surface water. Overall, these results highlight the potential of enzyme-like ligand catalytic oxidation coupled with ultrafiltration to remove micropollutants at a high flux for ensuring the water safety.

Investigation of Electrocoagulation Process for Efficient Removal of Bisphenol A from the Aqueous Environment: Promising Treatment Strategy

Introduction: Endocrine disruptive compounds as a class of organic contaminants in the aquatic environment received severe attention in the last decades. The release of bisphenol A (BPA) as a hazardous organic chemical into the environment has caused high health and environmental concerns. Therefore, its removal from aquatic environments is strongly recommended. The present study deals with BPA removal efficiency from an aqueous environment using the electrocoagulation process (ECP). Materials and Methods: The effects of parameters including BPA concentration (1-10 mg L-1), current density (3-15 mA cm-2), pH (4-10), and reaction time (5-30 min) on the treatment process were investigated. Response surface methodology (RSM) was employed for optimization of the ECP. The significance of the developed model was investigated by the obtained F-value and P-value. Results: The maximum BPA removal of 98.2% was attained at pH of 8.5, BPA concentration of 3.25 mg L-1, the current density of 12.0 mA cm-2, and reaction time of 23 min. The significance of the developed model was confirmed by the high F-value of 46.69 and the very low P-value of &lt; 0.0001. Furthermore, the electrical energy consumption of the process was found to be 0.308 kWh m-3 in the optimum condition. Conclusion: The obtained experimental results revealed that the co-precipitation and the adsorption process through the electrostatic interactions as the main removal mechanisms controlled the treatment process.

Magnetic porous carbon nanopolyhedron modified rGO composites as recyclable sorbent for effective removal of bisphenol A from water

The effective removal of endocrine disruptors from water is important for human health. Herein, magnetic sorbents, composed of ZiF-67-derived carbon polyhedrons containing Co nanocrystals (Co-C) modified reduced graphene oxide (rGO) nanosheets (Co-C/rGO), were synthesized. The optimized Co-C/rGO-2 exhibited a high adsorption capacity of 175.1 mg g−1 for removal of bisphenol A (BPA) from water because of the optimized porous structure including micropores, mesopores and macropores as well as high surface area of 284.4 m2 g−1. In addition, the adsorption equilibrium of BPA was almost reached within 3 h and showed almost stable at pH 2–7. Existence of humic acid, Ca2+, K+, Na+ had little effect, while the Al3+ showed negative on the adsorption of BPA. Furthermore, the magnetic Co-C/rGO-2 can be easily recovered and showed high reuse performance remaining 83.7% of the initial adsorption capacity after the 4th recycling. The fixed-bed experiment indicated that the removal efficiency of BPA (10 μg L–1) from water can reach almost 100% at bed volume lower than 4000. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results revealed that the adsorption of BPA was mainly dominated by the π-π interaction.

Activation of peroxymonosulfate by sewage sludge biochar-based catalyst for efficient removal of bisphenol A: Performance and mechanism

Activation of peroxymonosulfate (PMS) for organic-contaminated water remediation is a promising strategy. In this study, a sludge-derived biochar (SBC) was prepared as an efficient and low-cost metal-free catalyst to activate PMS for the abatement of bisphenol A (BPA) in water. The results demonstrate that BPA could be rapidly oxidized by the combination of SBC and PMS. Compared with the slight adsorption (8.1%) by SBC alone and limited direct oxidation (2.4%) by sole PMS, the removal efficiency of BPA was boosted to 94.5% within 60 min in the presence of both SBC and PMS. Active species participating in the rapid elimination of BPA were investigated via both chemical quenching experiment and electron paramagnetic resonance (EPR) technique. The results indicate that non-radical rather than radical process plays an important role in BPA abatement in the SBC/PMS system. The electron-transfer non-radical process was further verified by the open circuit potential test. It is proposed that PMS is bound to SBC to form a surface reactive complex (SBC-PMS*), which would abstract the electrons from the adsorbed BPA through the conductive carbon tunnel. The present work provides an alternative of controlling waste by waste.

Sulfate radicals based heterogeneous peroxymonosulfate system catalyzed by CuO-Fe3O4-Biochar nanocomposite for bisphenol A degradation

Magnetic CuO-Fe3O4-Biochar (CuO-Fe3O4-BC) nanoparticles were successfully synthesized by two steps of coprecipitation and calcination and were characterized as a heterogeneous catalyst to activate peroxymonosulfate for bisphenol A (BPA) degradation. The reaction process and mechanism of heterogeneous catalyst adsorption and synergistic catalytic oxidation for the removal of BPA in CuO-Fe3O4-BC/PMS system were extensively evaluated in view of the practical applications. Results indicated that the addition of CuO achieved a high removal efficiency of BPA in a wide pH range. BPA removal efficiency reached 100 % in 30 min by using 2.0 g/L CuO-Fe3O4-BC and 5 mM PMS at a pH of 9.0, and SO4− played an essential role in the degradation process. The synergistic effect of copper ions and iron ions accelerated the circulation of Fe (II)/Fe (III) and Cu (I)/Cu (II), which improved the electron transfer on the catalyst surface and increased the free radical generation rate. CuO, Fe3O4 and BC achieved a synergistic effect between adsorption and catalysis. The stability and reusability of CuO-Fe3O4-BC/PMS system offer an approach in organic pollutant wastewater treatment since it has great advantages of high removal efficiency, conducting under neutral conditions, energy-saving and avoiding the common issues in traditional Fenton reactions.

Efficient piezocatalytic removal of BPA and Cr(VI) with SnS2/CNFs membrane by harvesting vibration energy

Piezocatalysis that converts mechanical energy into chemical energy plays an important role in environmental purification and energy regeneration. In this work, a piezoelectric membrane of carbon nanofibers coated by few-layers SnS 2 nanosheets, a typical layered transition metal dichalcogenides (TMDs), for the first-reported piezocatalysis of hexavalent chromium (Cr (VI)) and bisphenol A (BPA). A boosted removal efficiency of Cr (VI) and BPA under ultrasonication are 3 and 4 times higher than that under illumination, respectively, which is attributed to the built-in electric field and band bending derived from the piezoelectricity of SnS 2 as well as the outstanding electronic liquidity of CNFs substrate. It was also found that the most oxidizing ·OH can be generated in SnS 2 /CNFs for piezocatalytic oxidative degradation of BPA compared to the absence of ·OH under illumination. Finally, the possible piezocatalytic mechanism of SnS 2 /CNFs is proposed. So it provides a new view on piezocatalysis of TMDs for environmental remediation by collecting mechanical energy. A piezoelectric membrane was firstly reported by coating few-layers SnS 2 nanosheets on carbon nanofibers for piezocatalytic reduction of Cr(VI) and degradation of BPA in water, which provides a new insight of piezocatalytic sulfide for mechanical-energy-driven environmental remediation. • SnS 2 /CNFs film was prepared for piezocatalyic Cr(VI) reduction and BPA degradation for the first time. • The piezoelectric-assisted catalysis realizes the energy conversion from mechanical energy to chemical energy. • The piezoelectric effect promoting free carries separation and transfer efficiently. • The most oxidizing ·OH can be generated under ultrasound compared to the absence of ·OH under illumination. • Mechanism of piezocatalytic Cr(VI) reduction and BPA degradation by SnS 2 /CNFs film was well proposed.

Enhanced removal of phenolic endocrine disrupting chemicals from coastal waters by intertidal macroalgae

The phytoremediation of phenolic endocrine disrupting compounds (EDCs) in coastal waters by intertidal macroalgae was firstly investigated. The results showed that intertidal macroalgae could remove bisphenol A (BPA) and nonylphenol (NP) at environmental relevant concentration, and Ulva pertusa was the most efficient one. In most cases, the order of EDCs removal efficiency could be expressed as: green algae > brown algae > red algae. The in-situ monitoring using a charge‐coupled device imaging system confirmed the accumulation of EDCs in the intertidal macroalgae. The removal mechanisms included the initial rapid biosorption process, followed by the slow accumulation and biodegradation. The removal efficiency of BPA and NP was slightly dependent on temperature and nutrient concentration. A linear relationship was observed between the initial concentration and the average removal rate (R2 > 0.99). The BPA and NP at the environmental relevant concentration (100 μg L−1) could be removed efficiently using Ulva pertusa even after three cycles in pilot-scale experiments. The high removal efficiency of NP and BPA was also confirmed by the field investigation from the intertidal zone with abundant Ulva pertusa. These findings demonstrated that intertidal macroalgae could play essential role for the phytoremediation of phenolic EDCs in coastal waters.

Peroxydisulfate Activation and Singlet Oxygen Generation by Oxygen Vacancy for Degradation of Contaminants.

Oxygen vacancies (OVs) play a crucial role in the catalytic activity of metal-based catalysts; however, their activation mechanism toward peroxydisulfate (PDS) still lacks reasonable explanation. In this study, by taking bismuth bromide (BiOBr) as an example, we report an OV-mediated PDS activation process for degradation of bisphenol A (BPA) employing singlet oxygen (1O2) as the main reactive species under alkaline conditions. The experimental results show that the removal efficiency of BPA is proportional to the number of OVs and is highly related to the dosage of PDS and the catalyst. The surface OVs of BiOBr provide ideal sites for the inclusion of hydroxyl ions (HO-) to form BiIII-OH species, which are regarded as the major active sites for the adsorption and activation of PDS. Unexpectedly, the activation of PDS occurs through a nonradical mechanism mediated by 1O2, which is generated via multistep reactions, involving the formation of an intermediate superoxide radical (O2•-) and the redox cycle of Bi(III)/Bi(IV). This work is dedicated to the in-depth mechanism study into PDS activation over OV-rich BiOBr samples and provides a novel perspective for the activation of peroxides by defective materials in the absence of additional energy supply or aqueous transition metal ions.

Utilization of the Corncob Agro-Industrial Residue as a Potential Adsorbent in the Biosorption of Bisphenol-A

The presence of plastic waste in water bodies has led to a growing concern due to the impact on human health. Among the most important plastic additive molecules is bisphenol-A (BPA). On the other hand, micro-pollutant removal processes that make use of agro-industrial waste have aroused the interest of researchers. This is because the accumulation of lignocellulosic materials is also an environmental problem. The objective of this work is to use corncob agro-industrial residue (CC) as an adsorbent in the removal of BPA in aqueous matrix. The adsorption studies were carried out in reaction media containing the ground vegetable fiber and BPA solution in concentrations of 10, 25 and 50 mg L-1, as well as at pHs 3, 5, 7 and 9. Isotherms models and kinetic models were evaluated. The results showed that CC is a potent BPA adsorbent in aqueous solution, leading to about 90% of removal. The adsorption kinetics followed the pseudo-second order model and isotherm that best suited was the Lagmuir model, and the maximum adsorption capacity was 51.25 mg per gram of adsorbent fiber, after 20 min of contact. The thermogravimetric analysis allowed us to conclude that CC is a material resistant to high temperatures, due to the presence of a considerable amount of lignin. Finally, the best results of BPA removal efficiency by CC compared to activated carbon corroborate its high biosorption capacity.

Self-nitrogen doped carbons aerogel derived from waste cigarette butts (cellulose acetate) for the adsorption of BPA: Kinetics and adsorption mechanisms

The fabrication of highly porous functionalized carbon materials is the demand of current scenario for the removal of toxic pollutants form aqueous solution. Therefore, waste cigarette butts that consist of cellulose acetate and other nitrogen rich compounds, such as nicotine and harmine have been used for the fabrication of N-doped carbon aerogel (NDC) via hydrothermal and carbonization process. As-fabricated NDC was characterized via, elemental analysis, FTIR, Raman, TGA, XRD, BET, SEM and XPS and used for the adsorption of bisphenol –A (BPA). The outcomes of adsorption essay and its kinetics support that the adsorption of BPA over NDC was carried out via pseudo-second-order kinetic model and via Langmuir model isotherm. The values for ΔG and ΔH were found negative and positive respectively, and support that the adsorption process is spontaneous and endothermic. The nature of adsorbent as well as in-situ and post characterization of the adsorbent support the adsorption mechanism, and the conclusions support that the hydrogen bonding, electrostatic as well as the π-π interactions were employed between the BPA and NDC during adsorption. In addition, the regeneration of the NDC was efficiently achieved and BPA removal efficiency remained high (92.47%) after seven cycles.

Efficient removal of bisphenol A with activation of peroxydisulfate via electrochemically assisted Fe(III)-nitrilotriacetic acid system under neutral condition

In this work, an innovative electrochemically assisted Fe(III)-nitrilotriacetic acid system for the activation of peroxydisulfate (electro/Fe(III)-NTA/PDS) was proposed for the removal of bisphenol A (BPA) at neutral pH with commercial graphite electrodes. The efficient BPA decay was mainly originated from the continuous activation of PDS by Fe(II) reduced from Fe(III)-NTA complexes at the cathode. Scavenger experiments and electron paramagnetic resonance (EPR) measurements confirmed that the removal of BPA occurred through graphite adsorption, direct electron transfer (DET) and radical oxidation. Sulfate and hydroxyl radicals were primarily responsible for the oxidation of BPA while graphite adsorption and DET played a minor role in BPA removal. The influence of Fe(III) concentration, PDS dosage, input current, NTA to Fe(III) molar ratio as well as coexisting inorganic anions (Cl−, NO3−, H2PO4− and HCO3−) on BPA elimination was explored. The BPA removal efficiency reached 93.5 % after 60 min reaction in the electro/Fe(III)-NTA/PDS system under the conditions of initial pH 7.0, 0.30 mM Fe(III), 0.15 mM NTA, 5 mM PDS and 5 mA constant current. Overall, this research provided a novel perspective and potential for remediation of organic wastewater using NTA in combination with electrochemistry in the homogeneous Fe(III)/persulfate system.

Designing a new reaction system by stacking use of Ti mesh supported Ag/N-TiO2 nano-sheets for enhanced photocatalytic degradation of bisphenol A

In this work, Ag nano-particles deposited and N-doped TiO2 nanosheets grown on the Ti mesh (Ag/N-TiO2/Ti mesh) were synthesized through combination of a hydrothermal process and a photo-reduction deposition strategy, and then applied to photocatalytic (PC) degradation of bisphenol A (BPA). The physicochemical performances of Ag/N-TiO2/Ti mesh were investigated by a series of characterizations. Results showed that N doping promoted the formation of rutile, and increased the thickness of TiO2 nanosheets (30 nm–40 nm). Furthermore, N element was existed in the form of substitutional nitrogen state (O-Ti-N) in the lattice of TiO2, generating N2p doping energy level. The Ag nanoparticles were deposited on the surface of N-TiO2 in the form of Ag0. The PC removal efficiency of BPA by Ag/N-TiO2/Ti mesh was 90.5% within 60 min, much higher than that of N-TiO2/Ti mesh (78.0%) and TiO2/Ti mesh (59.5%). The N adulteration and surfaceplasmaresonance of Ag0 significantly enhanced the visible-light absorbance and photo-excited electrons-holes separation, which accounted for the improved PC degradation of BPA. By using the light transmittance performance of Ti mesh to stack three Ag/N-TiO2/Ti mesh (named 3-Ag/N-TiO2/Ti mesh) in a distance interval of 0.5 cm constructed a new reaction system, and it removed over 99.99% of BPA within 30 min, which was significantly higher than that of Ag/N-TiO2/Ti mesh system (59.5%). This was mainly ascribed to the effective optical energy utilization and the enhanced mass transfer. This study not only indicated that Ag/N-TiO2/Ti mesh was a promising photocatalyst, but also offered useful information for designing specific reactor in practical application (such as amplified cylindrical reactor).

Efficient Removal of Bisphenol A Using Nitrogen-Doped Graphene-Like Plates from Green Petroleum Coke.

Green petroleum coke, a form of industrial waste produced in the oil-refining process, was used to synthesize nitrogen-doped graphene-like plates (N-GLPs) together with melamine. In this study, characterization and batch experiments were performed to elucidate the interaction mechanism of N-GLPs and bisphenol A (BPA). Structural analysis of N-GLPs, including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS), showed an obvious graphene-like structure and successful nitrogen doping. In addition, compared with 8.0 m2/g for green petroleum coke, the BET surface area of N-GLPs markedly increased to 96.6 m2/g. The influences of various factors, including contact time, temperature, and initial pH on BPA removal efficiency were investigated. It was found that 92.0% of BPA was successfully removed by N-GLPs at 50 °C. Based on the adsorption experiments, it was shown that electrostatic attraction, hydrogen bonding, and π-π interaction enhanced the adsorption capacity of N-GLPs for BPA. According to the thermodynamic data, the adsorption process was spontaneous, physical, and endothermic in nature. Therefore, N-GLPs are efficient adsorbent material to remove BPA from wastewater.

Bisphenol A Removal by Graphene Oxide Applied in Different Processes

Bisphenol A (BPA) is a commonly used plasticizer incorporated into the parent plastics during manufacturing. It is classified as an emerging contaminant that is continually detected in aquatic environments and is listed as an endocrine disrupting chemical confirmed to be associated with cardiovascular disease and reproductive disorder. The hazardous aspects of BPA require the development of innovative methods for its degradation. Among these techniques, adsorption and electrochemical degradation are considered to be particularly attractive due to their high efficiency, versatility and environmental friendliness, since they do not require any other chemicals. The use of graphene oxide (GO) was investigated as an adsorbent and as a particle electrode for the removal of BPA from aqueous solutions. The adsorptive behaviors of GO toward BPA were investigated in batch mode under darkness, visible light and UV light conditions. GO was used as particle electrode in a three-dimensional electro-oxidation (3D-EO) process established by an Ru/TiO2 anode and the effects of current density values ranging from 10 to 50 mA/cm2 were investigated. The obtained results revealed that the 3D electrochemical degradation process achieved a higher BPA removal efficiency than adsorption, showing that 3D-EO with a graphene oxide particle electrode may significantly improve BPA removal efficiency.

Catalytic wet air oxidation of high BPA concentration over iron-based catalyst supported on orthophosphate.

The catalytic performance of Fe supported on nickel phosphate (NiP) was evaluated for the removal of bisphenol A (BPA) by catalytic wet air oxidation (CWAO) at 140°C and 25bar of pure oxygen pressure. The prepared NiP and Fe/NiP materials were fully characterized by XRD, N2-physisorption, H2-TPR, TEM, and ICP analysis. Iron (Fe/NiP) impregnation of NiP support enhanced the BPA removal efficiency from 37.0 to 99.6% when CWAO was performed. This catalyst was highly stable given the operating conditions of acidic medium, high temperature, and high pressure. The Fe/NiP catalyst showed an outstanding catalytic activity for oxidation of BPA, achieving almost complete removal of BPA in 180min at a concentration of 300mg/L, using 4g/L of Fe/NiP. No iron leaching was detected after the CWAO of BPA. The stability of Fe/NiP was performed over three consecutive cycles, noting that BPA conversion was not affected and iron leaching was negligible. Therefore, this catalyst (Fe/NiP) could be considered as an innocuous and effective long-lasting catalyst for the oxidation of harmful organic molecules.

Cobalt promoted bifunctional graphene composite (Co@pGSC) for heterogeneous peroxymonosulfate activation

We report, synthesis of Co@graphene on common grinded river sand for peroxymonosulphate (PMS) activation. As prepared catalysts characterized in TEM, XPS, Raman, BET and XRD for their surface and bulk properties confirmed that the composite material has enough surface area, and Co3O4 nanoparticles are well dispersed (20–40 nm) on graphene sand composite (pGSC). The PMS activation and its oxidation efficiency of prepared catalysts were evaluated for Bisphenol-A (BPA) as a model organic pollutant in aqueous phase. The formation of SO4− and OH radical in the PMS with catalysts system proved using DMPO radical trapping agent by EPR technique. The catalyst (Co@pGSC_0.02) loaded with 0.02 M cobalt concentration showed higher percentage (98.1%) of BPA removal efficiency among the studied concentration. The oxidative-cleavage of BPA and its intermediate by-products were further verified by GC–MS analysis. The reusability of catalyst depicted greater than 90% removal efficiency and the surface, crystalline properties remained same as fresh catalyst (evidenced spent catalyst XRD and XPS analyses) over 12 cycles. The significant catalytic performance may be ascribed to synergetic effect of electron transfer between graphene and Co3O4 over sand.

Insights into endocrine-disrupting Bisphenol-A adsorption from pharmaceutical effluent by chitosan immobilized nanoscale zero-valent iron nanoparticles

Bisphenol A (BPA) in the aquatic environment have adverse effects on human health and other living organisms. BPA at low traces can lead to cardiovascular disease, type II diabetes, and impaired hepatic enzymes. For efficient BPA removal, chitosan immobilized nanoscale zero-valent iron (nZVI-chitosan) nanoparticles were synthesized and used as adsorbent. Since the BPA removal efficiency depends on independent process variables like nZVI-chitosan dosage, initial BPA concentration, pH and contact time, experiments were conducted systematically. To characterize the interaction effect of these variables, the experimental matrix is designed using response surface methodology (RSM). The isothermal and kinetic model parameters are estimated using differential evolution optimization (DEO), and these parameters better represent adsorption behaviour. The batch adsorption experiments indicated that the BPA adsorption on to nZVI-chitosan follows pseudo 1st order kinetic models. The maximum extent of BPA adsorption was 65.16 mg/g based on the Langmuir isotherm model. DEO based model parameters better fit the non-linear models with high R2 and lower RMSE. The regenerability experiments indicate that synthesized nZVI-chitosan adsorbent can be used up to three cycles with removal efficiency over 50%. The thermodynamic studies indicated that ΔG° is negative signifying a favourable and spontaneous adsorption process. The inhibition effects of coexisting ions on BPA adsorption followed the order of Mn2+ > Ca2+ > Mg2+ > Fe2+ for cations and of SO42− > NO3− > Cl− for anions. The BPA removal from real pharmaceutical wastewater is 93.8% obtained for optimal initial BPA concentration of 6 mg/L, an adsorbent dosage of 1.5 g/L, with solution pH of 3 and adsorption time of 1 h, whereas this removal efficiency is 95% for synthetic wastewater.

Immobilization of horseradish peroxidase on Fe3O4 nanoparticles for enzymatic removal of endocrine disrupting chemicals.

The modified Fe3O4 nanoparticles were used as a support for the immobilization of horseradish peroxidase (HRP). The immobilized enzyme (HRP@Fe3O4) was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectrometer (FTIR), and vibration sample magnetometer (VSM). According to the results, the optimum concentration of glutaraldehyde (GA) and agitation time were 300μL and 7h. HRP was well loaded on the surface of the Fe3O4. There was no change in the crystal structure of HRP@Fe3O4 compared with Fe3O4. The removals of bisphenol A (BPA) and 17α-ethinylestradiol (EE2) using HRP@Fe3O4 had been investigated. The degradation efficiencies of BPA and EE2 catalyzed by HRP@Fe3O4 were higher than that of soluble HRP. In addition, HRP@Fe3O4 can be reused through magnetic separation. After the fifth repeated use, the removal efficiencies of BPA and EE2 were up to 56% and 48%, respectively. Batch studies of catalyzed oxidation and coagulation on the degradation of BPA and EE2 in the presence of humic acid (HA) were also investigated. The order of the removal efficiencies was HRP+PACl (polyaluminum chloride)+SDS (lauryl sodium sulfate)>HRP+PACl>HRP>HRP+PAM (Polyacrylamide)>HRP+PAM+SDS. The coagulation effect of HRP@Fe3O4 and PACl was better than that of HRP@Fe3O4 and PAM. The removals of BPA and EE2 were 90.3% and 64.5% by use HRP@Fe3O4 and PACl as coagulant, while the removals were 78.7% and 57.6% by use HRP@Fe3O4 and PAM as coagulant. SDS had a positive effect on PACl, while a negative effect on PAM. Moreover, the products generated by enzymatic oxidation reaction can be effectively removed after coagulation.

Enhanced removal of the endocrine disruptor compound Bisphenol A by adsorption onto green-carbon materials. Effect of real effluents on the adsorption process

The high exposure to the endocrine disrupting compounds (EDC) in water represents a relevant issue for the health of living beings. The xenoestrogen Bisphenol A (BPA), a suspected EDC, is an industrial additive broadly used for manufacturing polycarbonate and epoxy resins. Due to its harmful effect in humans and the aquatic environment, an efficient method to remove BPA from wastewater is urgently required. The present work aims to study the adsorption of BPA from aqueous solutions onto carbonaceous materials, e.g., a synthesized carbon xerogel (RFX), a chemical-activated carbon from Kraft lignin (KLP) and a commercial activated carbon (F400) for comparative purposes. Batch kinetic and adsorption tests of BPA in ultrapure water were accomplished, finding higher adsorption capacities of BPA onto both F400 activated carbon (qsat = 407 mg g−1) and the biochar KLP (qsat = 220 mg g−1), versus to that obtained for the xerogel (qsat = 78 mg g−1). Furthermore, kinetic experiments revealed faster kinetic adsorption for RFX and KLP materials, achieving the equilibrium time within 24 h, attributed to their more-opened porous structure. Pseudo-first order, pseudo-second order, Elovich, intra-particle diffusion and film diffusion models were used to fit the experimental data. Thus, the BPA adsorption isotherms were analysed by Langmuir, Freundlich, Sips, Redlich-Peterson and Dual-site Langmuir (DLS) isotherm models.In addition, the influence of different aqueous matrices, such as a hospital wastewater, a wastewater treatment plant (WWTP) effluent and a river water, on BPA removal efficiency has been explored. These adsorption tests revealed a clear competitive effect between the target compound (BPA) and the natural organic matter content (NOM) present in the matrices for the active sites, resulting in a high decreasing of BPA adsorption removal.