Bisphenol A removal from water by activated carbon. Effects of carbon characteristics and solution chemistry

KOH-treated tire pyrolyzed carbon as green and easily available adsorbent for Bisphenol A and Methylene blue adsorption

The occurrence of micropollutants and dyes in water sources has sparked alarm due to their significant impacts on aquatic ecosystems and human health. This study aims to utilize the tire pyrolyzed carbon (TPC) as a source of the adsorbent for removing Bisphenol A (BPA) and Methylene Blue (MB). The adsorbent was synthesized by chemical activation of TPC with KOH at 750 °C. The activated TPC was characterized for different physical and chemical characterization techniques such as XRD, FTIR, SEM, BET, XPS, and TPD and exhibits a higher adsorption capacity of 49.2 and 72.1 mg/g respectively for BPA and MB. The effect of initial concentration, dosage of adsorbent, and initial pH are evaluated for BPA and MB. The adsorption is mainly driven by hydrophobic, electrostatic, π-π interactions, and hydrogen bonding. The removal process follows the second order and Langmuir isotherms. The adsorbent shows excellent recyclability which makes it a potential source of removal of different water-borne pollutants. The production of activated carbon from tire waste is advocated for its economic and environmental benefits.

Occurrence and sources of hormones in water resources-environmental and health impact

Within recent years, hormones have become emergent contaminants in the water environment. They easily accumulate in living organisms which in effect leads to numerous health problems (endocrine-disrupting mechanism is one of the most known toxic effects). Microbial resistance to antibiotics also became one of the emergent issues related to hormone presence. It was shown that the most common in the environment occur estrogens (E1, E2, E3, and EE2). It has been proven that large amounts of hormones are released from aquaculture as well as from wastewater treatment plants (due to the relatively low separation efficiency of conventional wastewater treatment processes). Within the article's scope, the literature review was performed. The analysis was regarding the characterization of the hormone substances present in the environment, their influence on living organisms and the environment, as well as its potential sources classification.

The Selective Removal of Bisphenol A Using a Magnetic Adsorbent Fused with Bisphenol A-Binding Peptides

The potential of bisphenol A (BPA)-binding peptides fused to magnetic beads is demonstrated as novel adsorbents that are reusable and highly selective for BPA removal from aqueous environments, in which various interfering substances coexist. Magnetic beads harboring peptides (peptide beads) showed a higher BPA removal capacity (8.6 mg/g) than that of bare beads without peptides (2.0 mg/g). The BPA adsorption capacity of peptide beads increased with the number of peptides fused onto the beads, where monomeric, dimeric, or trimeric repeats of a BPA-binding peptide were fused to magnetic beads. The BPA-adsorbing beads were regenerated using a methanol-acetic acid mixture, and after six regeneration cycles, the adsorption capacity remained above 87% of its initial capacity. The selective removal of BPA was confirmed in the presence of BPA analogs with high structural similarity (bisphenol F and bisphenol S) or in synthetic wastewater. The present work is a pioneering study that investigates the selective affinity of peptides to remove specific organics with high selectivity from complex environmental matrices.

Hierarchical Porous Activated Carbon from Wheat Bran Agro-Waste: Applications in Carbon Dioxide Capture, Dye Removal, Oxygen and Hydrogen Evolution Reactions

This work reports an efficient method for facile synthesis of hierarchically porous carbon (WB-AC) utilizing wheat bran waste. Obtained carbon showed 2.47 mmol g-1 CO2 capture capacity with good CO2 /N2 selectivity and 27.35 to 29.90 kJ mol-1 isosteric heat of adsorption. Rapid removal of MO dye was observed with a capacity of ~555 mg g-1 . Moreover, WB-AC demonstrated a good OER activity with 0.35 V low overpotential at 5 mA cm-2 and a Tafel slope of 115 mV dec-1 . It also exhibited high electrocatalytic HER activity with 57 mV overpotential at 10 mA cm-2 and a Tafel slope of 82.6 mV dec-1 . The large SSA (757 m2  g-1 ) and total pore volume (0.3696 cm3  g-1 ) result from N2 activation contributing to selective CO2 uptake, high and rapid dye removal capacity and superior electrochemical activity (OER/HER), suggesting the use of WB-AC as cost effective adsorbent and metal free electrocatalyst.

Statistical physics modeling study of an environmentally friendly and efficient adsorbent derived from the brown macroalgae Bifurcaria bifurcata for the removal of Bisphenol A

The brown macroalgae Bifurcaria bifurcata was valued and used to develop a carbonaceous material activated by H2SO4 (AC-BB@H2SO4), with the goal of assessing its adsorption ability against Bisphenol A (BPA). During the adsorption experiments, the effects of the adsorbent dose, solution pH, and contact time were examined, and the results were m = 0.4 g/L, pH = 8.3, and t = 120 min, with an elimination yield of 91.6 %. With comparatively high R2 values, the pseudo-second-order kinetic model perfectly fitted the experimental data. Langmuir's model was found to be the best appropriate for describing the adsorption equilibrium of BPA on AC-BB@H2SO4. The thermodynamic findings show that BPA adsorption on AC-BB@H2SO4 was spontaneous, favorable, and endothermic in nature. Even after six cycles of reuse, regeneration testing demonstrated that our adsorbent could eliminate BPA by >50 %. The BPA adsorption mechanism's statistical physics control parameters were determined and analyzed. BPA's adsorption energies were <40 kJ/mol, indicating that the interactions between BPA and AC-BB@H2SO4 were governed by physical forces (i.e., hydrogen bonding and van der Waals and electrostatic interactions). All of these intriguing findings indicate that our carbonaceous material might have direct ramifications in the field of wastewater treatment, notably for the clearance of BPA, which is difficult to biodegrade.

Elimination of Pharmaceutical Compounds from Aqueous Solution through Novel Functionalized Pitch-Based Porous Adsorbents: Kinetic, Isotherm, Thermodynamic Studies and Mechanism Analysis

The long-term presence of PPCPs in the aqueous environment poses a potentially significant threat to human life and physical health and the safety of the water environment. In our previous work, we investigated low-cost pitch-based HCP adsorbents with an excellent adsorption capacity and magnetic responsiveness through a simple one-step Friedel-Crafts reaction. In this work, we further investigated the adsorption behavior of the prepared pitch-based adsorbents onto three PPCP molecules (DFS, AMP, and antipyrine) in detail. The maximum adsorption capacity of P-MPHCP for DFS was 444.93 mg g-1. The adsorption equilibrium and kinetic processes were well described through the Langmuir model and the proposed secondary kinetic model. The negative changes in Gibbs free energy and enthalpy reflected that the adsorption of HCPs onto PPCPs was a spontaneous exothermic process. The recoverability results showed that the adsorption of MPHCP and P-MPHCP onto DFS remained above 95% after 10 adsorption-desorption cycles. The present work further demonstrates that these pitch-based adsorbents can be used for multiple applications, which have a very extensive practical application prospect.

Research Progress of Methods for Degradation of Bisphenol A

Bisphenol A (BPA), an endocrine disruptor widely used in industrial production, is found in various environmental sources. Despite numerous reports on BPA degradation and removal, the details remain unclear. This paper aims to address this gap by providing a comprehensive review of BPA degradation methods, focusing on biological, physical, and chemical treatments and the factors that affect the degradation of BPA. Firstly, the paper uses VOSviewer software (version 1.6.15) to map out the literature on BPA degradation published in the past 20 years, which reveals the trends and research focus in this field. Next, the advantages and limitations of different BPA degradation methods are discussed. Overall, this review highlights the importance of BPA degradation to protect the environment and human health. The paper provides significant insights for researchers and policymakers to develop better approaches for BPA degradation and removal.

Photocatalytic degradation of bisphenol A in aqueous solution using TiO2/clinoptilolite hybrid photocatalyst

Photocatalytic degradation of bisphenol A (BPA) was investigated using commercial TiO2 P25 nanoparticles supported on natural zeolite clinoptilolite (Cli). Employing ultrasound assisted solid-state dispersion method hybrid photocatalyst containing 20 wt% of TiO2, marked TCli-20, was prepared. The structural, morphological and surface properties, and particle size distribution of TCli-20 were studied by X-ray powder diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, atomic force microscopy, Brunner-Emmet-Teller method and laser diffraction. The results revealed a successful loading of TiO2 P25 nanoparticles on Cli surface and the preservation of both zeolitic structure and optical properties of TiO2. The influence of catalyst dose, pH value and the addition of hydrogen peroxide (H2O2) was evaluated. The optimal reaction conditions were 2 g/L of catalyst at near-neutral conditions (pH = 6.4) for complete BPA (5 mg/L) photodegradation after 180 min of exposure to simulated solar light. The addition of H2O2 was beneficial for the degradation process and led to the removal of BPA after 120 min of irradiation. BPA removal (60% for 180 min of irradiation) was reduced when TCli-20 was tested in bottled drinking water due to the presence of bicarbonate ions which acted as scavengers for hydroxyl radicals. Even though the photocatalytic activity of TCli-20 decreased after several cycles of usage, 70% of BPA was still successfully degraded during the fourth cycle. The reusability study showed easy separation, stability and good photocatalytic ability of investigated cost-effective hybrid photocatalyst.

Biochars and activated carbons as adsorbents of inorganic and organic compounds from multicomponent systems - A review

Biochars are obtained by biomass pyrolysis, whereas activated carbon is a biochar that has undergone chemical or physical activation. Owing to the large surface area and easy surface modification both solids are widely applied as adsorbents. They are low-costs materials, they could be regenerated and their disposal is not troublesome. Adsorption of heavy metals, dyes, pharmaceuticals on the surface of biochars and activated carbons, from simple systems of adsorbate containing only one compound, are described extensively in the literature. The present paper provides an overview of reports on adsorption of inorganic and organic compounds onto these two types of adsorbents from the mixed adsorbate systems. The described adsorbate systems have been divided into those consisting of: two or more inorganic ions, two or more organic compounds and both of them (inorganic and organic ones). The research of this type is carried out much less frequently due to the more complicated description of interactions in the mixed adsorbate systems.

Effective photocatalytic degradation of sulfamethoxazole using tunable CaCu3Ti4O7 perovskite

Sulfamethoxazole (SMX) is largely prescribed for bacterial infections but raises a major concern over generation of antibiotic-resistant bacteria in the environment. This study employed various perovskite-type photocatalysts, made by two-step synthesis procedures, to remove SMX. The as-synthesized CaCu₃Ti₄O₇ (CCTO) perovskites were characterized by XRD, SEM-EDX, and DLS. Complete degradation (∼99%; k_obs = 0.0279 min^-1) of SMX was recorded under UV-light irradiation for 90 min in the presence of CCTO. SMX removal rate was investigated under various reaction conditions including pH, catalyst dose, electrolyte (NaCl and NaBr). The astonishing rate of SMX removal (k_obs = 0.0614 min^-1) was observed with the addition of 50 mM NaBr electrolytes in the reaction, which might imply that the appearance of halogen reactive species. CCTO-MS particles were aggregated in traces when the electrolytes concentration increases, resulting in reduced rate of SMX. The SMX concentration abatement and the formation of possible intermediates during photocatalytic reaction were analyzed. The upshot of this study reveals that the inexpensive and environmentally benign CCTO perovskite photocatalyst could be applied for the treatments of emerging contaminants in the future.

Efficient Adsorption Removal of an Anionic Azo Dye by Lignocellulosic Waste Material and Sludge Recycling into Combustible Briquettes

In recent years, the removal of dyes has emerged as a significant problem that attracted several researchers. The search for green and eco-friendly adsorbents has been a never-ending task in environmental protection to overcome this issue. Herein, almond shells (AS) were used as an adsorbent to remove methyl orange (MO) from aqueous solutions. The AS was characterized using several techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). Adsorption experiments were carried out under different pH, temperature, and AS particle size conditions. Kinetic and isothermal studies revealed that MO adsorption on the AS reached equilibrium at 90 min, following the pseudo-second-order (PSO) kinetic model. The Langmuir adsorption isotherm was found the suitable adsorption model for MO adsorption on AS, showing a maximum adsorption capacity of 15.63 mg/g. Thermodynamic parameters such as the change in standard enthalpy (ΔH°), the change in standard entropy (ΔS°), and the change in standard free energy (ΔG°) indicated that the MO dye adsorption process is non-spontaneous, endothermic, and physical, which was further confirmed from FTIR analysis of AS samples after adsorption. The contaminated sludge was converted into biochar by slow pyrolysis at a temperature of 400 °C for 2 h. Biochar has been exploited for the manufacture of combustible briquettes.

The Removal of Hydrophobic Matter from Thermosensitive Poly[oligo(ethylene glycol) Monomethyl Ether Acrylate] Gel Ad-Sorbentin Alcohol–Water Mixtures

A thermosensitive gel that exhibits lower critical solution temperature (LCST) becomes hydrophilic at low temperatures and hydrophobic at high temperatures in water. A system for absorbing hydrophobic organic matters that exploits this property has been reported. While washing the gel at a low temperature with a good solvent is a possible method for removing the adsorbed matter, a process that then shrinks the gel is also required. Herein, we focused on poly[oligo(ethylene glycol) mono(m)ethyl ether acrylate] (POEGA) gels as thermosensitive gels suitable for use in this system. POEGAs are known to contain poly(ethylene glycol) (PEG) units in their side chains and exhibit upper critical solution temperature (UCST) behavior in aliphatic alcohols. By exploiting this property, we developed a method for removing hydrophobic matters that accumulate in these gels; we also evaluated the LCST and UCST behavior of POEGA gels in alcohol–water mixtures, and measured the LCSTs of these gels in water and their UCSTs in some alcohols.

Accurate Removal of Toxic Organic Pollutants from Complex Water Matrices

Characteristic emerging pollutants at low concentration have raised much attention for causing a bottleneck in water remediation, especially in complex water matrices where high concentration of interferents coexist. In the future, tailored treatment methods are therefore of increasing significance for accurate removal of target pollutants in different water matrices. This critical review focuses on the overall strategies for accurately removing highly toxic emerging pollutants in the presence of typical interferents. The main difficulties hindering the improvement of selectivity in complex matrices are analyzed, implying that it is difficult to adopt a universal approach for multiple targets and water substrates. Selective methods based on assorted principles are proposed aiming to improve the anti-interference ability. Thus, typical approaches and fundamentals to achieve selectivity are subsequently summarized including their mechanism, superiority and inferior position, application scope, improvement method and the bottlenecks. The results show that different methods may be applicable to certain conditions and target pollutants. To better understand the mechanism of each selective method and further select the appropriate method, advanced methods for qualitative and quantitative characterization of selectivity are presented. The processes of adsorption, interaction, electron transfer, and bond breaking are discussed. Some comparable selective quantitative methods are helpful for promoting the development of related fields. The research framework of selectivity removal and its fundamentals are established. Presently, although continuous advances and remarkable achievements have been attained in the selective removal of characteristic organic pollutants, there are still various substantial challenges and opportunities. It is hopeful to inspire the researches on the new generation of water and wastewater treatment technology, which can selectively and preferentially treat characteristic pollutants, and establish a reliable research framework to lead the direction of environmental science.

Adsorption behavior of bisphenol A on bentonite-loess mixtures

The leakage of chemical compounds in landfill leachate led to serious environment pollution, especially, the compounds termed endocrine disruptors such as bisphenol A (BPA). It is very important to study the adsorption behavior of endocrine disruptors in modified soil for predicting and evaluating the potential harm of endocrine disruptors to the soil. Bentonite-amended Chinese loess mixtures, with various proportions of bentonite, were used for the removal of BPA from an aqueous solution. A batch test was used to investigate the adsorption properties of bisphenol A on bentonite and Chinese loess mixtures. The influences of bentonite proportion, temperature, reaction time, pH, and soil-water ratios on the adsorption process were considered. The Fourier transform infrared spectra (FTIR) was used to clarify the change of functional groups before and after the adsorption of BPA on soil. The adsorption mechanism of BPA on soil was discussed preliminary. The results show that the addition of bentonite to the loess can improve the adsorption rate of BPA. The adsorption of BPA was mainly a spontaneous, exothermic, entropy decreasing physical adsorption process. The interaction between bentonite content and reaction concentration had a beneficial effect on BPA adsorption. The linear relationship between bentonite content and adsorption capacity was obtained. The results indicate that bentonite amended loess can provide a good liner for BPA.

Synthesis of an iso-type graphitic carbon nitride heterojunction derived from oxamide and urea in molten salt for high-performance visible-light driven photocatalysis

Thrice-modified g-C3N4 with cyano groups and an asymmetric planar heptazine/triazine-based iso-type heterojunction structure (MOCN) exhibits significantly higher photocatalytic activity.

Bisphenol A cleanup over MIL-100(Fe)/CoS composites: Pivotal role of Fe-S bond in regenerating Fe2+ ions for boosted degradation performance

Series of MIL-100(Fe)/CoS composites (MxCy) were facilely fabricated using ball-milling method. The optimum M50C50 exhibited extremely higher Fenton-like catalytic degradation activity toward bisphenol A (BPA) than the pristine MIL-100(Fe) and CoS. The significant improvement of BPA degradation was attributed to the synergetic effect between MIL-100(Fe) and CoS with the synergistic factor being 95.7%, in which the Fe-S bonds formed at the interface of the two components facilitate the Fe³⁺/Fe²⁺ cycle by improving the electron mobility both from Co to Fe and from S to Fe. Furthermore, the influence factors like co-existing inorganic ions and pH values on the catalysis activity of M50C50 were explored. The possible reaction mechanism was proposed and confirmed by both active species capture tests and electron spin resonance (ESR) determinations. It was found that M50C50 demonstrated good reusability and water stability, in which the morphology and structure were not changed obviously after five runs' operation. To our best knowledge, it is the first work concerning the interfacial interaction of Fe-MOF/MSx to promote Fe³⁺/Fe²⁺ cycle in Fe-MOFs for the purpose of organic pollutants degradation in the Fenton-like AOPs system.

Low-Cost Synthesis of Alumina Nanoparticles and Their Usage for Bisphenol-A Removal from Aqueous Solutions

Gamma-alumina nanoparticles (γANPs) were obtained from a low-cost process by using natural bauxites. The γANPs materials were characterized by X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) theory, scanning electron microscopy (SEM), atomic force microscopy (AFM), and were functionalized with N-cetyl-N, N, N, trimethylammonium bromide (CTAB), leading to CTAB modified γ-alumina nanoparticles (γANPs-CTAB). These novel functionalized γANPs-CTAB were characterized by XRPD, FTIR, and were used as an adsorbent for bisphenol-A (BPA) removal from water. Batch investigations were conducted under different experimental conditions (e.g., adsorbent dose, agitation time, initial concentration, and pH and surfactant loading) in order to optimize BPA adsorption and to identify the adsorption mechanisms in the system γANPs-CTAB-BPA. The effect of pH on the adsorption showed that the quantity of BPA removed increased remarkably until the pH value was 4, then remained almost constant until the pH value was up to 10, and then decreased for pH values greater than 10. For an initial BPA concentration of 20 mg/L and an adsorbent dose of 12.5 g/L at a pH value of 10, the removal efficiency achieved was 91.80 ± 0.21%. The adsorption mechanism was perfectly described by pseudo-second-order kinetics and the Langmuir isotherm. γANPs-CTAB materials were found to be effective adsorbents for BPA removal from water.

Enhanced removal of bisphenol A using pine-fruit shell-derived hydrochars: Adsorption mechanisms and reusability

We synthesized NaOH-activated hydrochars via hydrothermal carbonization (HTC) of Brazilian pine fruit shells at HTC residence times of 24, 48, and 72 h. The hydrochars were used as adsorbents to remove bisphenol A (BPA) from aqueous solutions. The surface area of the samples can reach up to 2220 m² g^-1, and the maximum adsorption of BPA onto the surfaces was achieved at a pH of 7.0 (708 mg g^-1). Adsorption occurred mainly via monolayer formation with a low retention time of the adsorbate (τ) on the surfaces, indicating that the BPA molecules reached the already occupied active sites and returned after undergoing heat exchange (τ > 0). Adsorption is an endothermic spontaneous process that results in a balance between entropic and enthalpic contributions. In such a reaction, ΔG°< 0, even with ΔH°> 0, the process occurs with an important increase in the entropy. The desorption was more efficient with ethanol and methanol than with HCl, NaOH, and NaCl owing to the dipole-dipole forces between the adsorbate and the alcohols. Additionally, the low desorption efficiency using acid, base, and salts can be attributed to competitive effects between the desorption agents and the active sites of the adsorbents.

Adsorption performance of modified agricultural waste materials for removal of emerging micro-contaminant bisphenol A: A comprehensive review

This review is an attempt to assess the adsorption performance of different green adsorbents derived from agricultural waste materials (AWMs) that were used for the elimination of bisphenol A (BPA) from aqueous matrices. Different processes including grafting, polymerization, activation and chemical treatment have been applied to functionalize and modify agricultural waste materials for the purposes of increasing their adsorptive performances toward BPA. The highest reported adsorption capacity of adsorbent from agricultural waste for the uptake of BPA is the highly microporous carbon adsorbent derived from Argan nut shell (1408 mg g^-1). Hydrogen bonding, hydrophobic and π-π interactions were reported in most studies as the main mechanisms governing the adsorption of BPA onto agricultural waste adsorbents. Equilibrium isotherm and kinetic studies for the uptake of BPA onto agricultural waste adsorbents were best described by Langmuir/Freundlich model and pseudo-second order model, respectively. Despite the effective elimination of BPA by various agricultural waste adsorbents, an appropriate selection of elution solvent is important for effective desorption of BPA from spent adsorbent. To date, ethanol, diethyl ether-methanol, methanol-acetic acid, mineral acids and sodium hydroxide are the most eluents applied for desorption of BPA molecules loaded onto AW-adsorbents. Looking toward the future, studies on the agricultural waste adsorbents based on polymers, activated carbons, nanoparticles and highly microporous carbons should be mostly considered by the researchers toward removing BPA. These future studies should be performed both in laboratory, pilot and industrial scales, and also should report the sustainable techniques for disposal of the spent AW-adsorbents after lose their adsorption performance on BPA.

Adsorption of bisphenol A by activated carbon developed from PET waste by KOH activation

This study deals with the preparation of activated carbon (AC) from poly(ethylene terephthalate) (PET) waste and with the physicochemical characterization of AC and its use as adsorbent of bisphenol A (BPA) in aqueous solution. AC was prepared by chemical activation with KOH and by physical activation in steam. The activation with KOH was carried out by impregnation first of PET by wet and dry routes at the PET/KOH weight ratios of 1:1, 1:3, and 1:5 and by carbonization then of the resulting products at 850 °C for 2 h in N₂ atmosphere. The activation in steam was performed by heating at 900 °C for 1 h. The ACs were characterized by N₂ adsorption at - 196 °C, mercury porosity, mercury density measurements, FT-IR spectroscopy, and measurement of pH of the point of zero charge (pH_pzc). The activation yield is 58.4-49.4% with KOH in aqueous solution, 75.8-23.9% with solid KOH, and 5.9% with steam. Using solid KOH, greater developments of a more heterogeneous porosity with increasing impregnation PET/KOH ratio are achieved. For SK1:5, S_BET is 1990 m² g^-1 and the pore volumes are 0.71 cm³ g^-1, micropores; 0.81 cm³ g^-1, mesopores; and 1.77 cm³ g^-1, macropores. The data of BPA adsorption fit better to the Ho and Mckay second order kinetic model than to the Lagergren first-order kinetic model and to the Langmuir equation than to the Freundlich equation. From the kinetic and thermodynamic standpoints, the adsorption process of BPA is more favorable for SK1:5.

Ceramic hydroxyapatite foam as a new material for Bisphenol A removal from contaminated water

Ceramic hydroxyapatite foam (CF-HAP) was prepared by combining slip-casting and foaming methods. The prepared CF-HAP was characterized by scanning electron microscopy (SEM), physisorption of N₂, Fourier transforms infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results of the specific surface area and SEM analyses revealed that the used shaping method provides CF-HAP with a wide range of porosity including macro and mesopores. Based on FTIR and XRD analyses, the CF-HAP is similar to pure well-crystallized hydroxyapatite. The adsorption results revealed that 94% of the BPA with a concentration of (40 mg/L) was effectively removed from the water and that the maximum adsorption capacity was higher in acidic than in basic medium. The thermodynamic studies indicated that the adsorption reaction was spontaneous and endothermic in nature. The adsorption capacity increased with the temperature and the BPA is chemisorbed on the ceramic foam. The isotherm data fitted slightly better with the Liu than with the Freundlich and Langmuir models suggesting that the adsorption was homogeneous and occurred only in the monolayer. The adsorption process depends largely on the BPA concentration and the results fitted well with the pseudo-first-order model. This confirms that the interaction between the BPA and the CF-HAP was mainly chemical in nature. The FTIR analysis of the used and fresh CF-HAP showed that all the hydroxyl and phosphorus bands characteristic of the hydroxyapatite shifted after adsorption of Bisphenol A. This suggests that the adsorption of Bisphenol A occurred in the sites of the hydroxyapatite. Therefore, it can be concluded that the CF-HAP has the potential to be used as an adsorbent for wastewater treatment and purification processes.

Efficient removal of various coexisting organic pollutants in water based on β-cyclodextrin polymer modified flower-like Fe3O4 particles

HYPOTHESIS

The construction of porous β-cyclodextrin polymer (β-CDP) modified flower-like Fe₃O₄ particles (CDP@Fe₃O₄) is expected to remove various organic pollutants from water, based on the larger specific surface area of flower-like Fe₃O₄ particles and the active sites provided by β-CDP. With the help of various noncovalent interactions, the removal ability of CDP@Fe₃O₄ for various water-soluble and water-insoluble organic pollutants were systematically studied.

EXPERIMENTS

CDP@Fe₃O₄ were successfully synthesized and applied for the simultaneous removal of various organic pollutants with different electrical properties, structure and hydrophobicity. Adsorption efficiency, adsorption process, adsorption mechanism and the reusability of CDP@Fe₃O₄ for single pollutant and mixed pollutants were comprehensively investigated.

FINDINGS

CDP@Fe₃O₄ exhibited excellent adsorption capabilities for various pollutants. Importantly, when these pollutants were coexisting, CDP@Fe₃O₄ still maintained a comparable removal ability for various pollutants. Efficient removal of organic pollutants was attributed to varieties of noncovalent interactions between organic pollutants and CDP@Fe₃O₄, including hydrophobic interactions, hydrogen bonds, π-π and electrostatic interactions. These results revealed that the excellent adsorption ability and convenient regeneration make CDP@Fe₃O₄ being a potential candidate in various complex organic wastewater purification.

Bifunctional Bi12O17Cl2/MIL-100(Fe) composites toward photocatalytic Cr(VI) sequestration and activation of persulfate for bisphenol A degradation

Bifunctional Bi₁₂O₁₇Cl₂/MIL-100(Fe) composite (BMx) was firstly constructed via facile ball-milling method. The optimal BM200 was highly efficient for Cr(VI) sequestration and activation of persulfate (PS) for bisphenol A (BPA) decomposition under white light illumination, which was much more remarkable than the pristine MIL-100(Fe) and Bi₁₂O₁₇Cl₂, respectively. Furthermore, the photocatalytic reduction efficiency can be significantly improved via the addition of some green small organic acids (SOAs). As well, the BPA degradation can be achieved over an extensive initial pH range of 3.0-11.0. When the PS concentration increased to more than 2.0 mM, the BPA degradation efficiency decreased due to the SO₄^-• self-scavenging effect. It was also found that the co-existence of inorganic anions like H₂PO₄^-, HCO₃^-, SO₄^2-, Cl^- and NO₃^- could decelerate the BPA degradation. The excellent photocatalytic Cr(VI) reduction and persulfate activation performances originated from both MIL-100(Fe) with excellent PS activation ability and Bi₁₂O₁₇Cl₂ with a favorable band position, which not only enabled the efficient separation of charges but also accelerated the formation of SO₄^-• radicals. The BM200 displayed prominent stability and recyclability. More importantly, the credible degradation pathway was proposed based on UHPLC-MS analysis and DFT calculation. This research revealed that the Fe-based MOFs/bismuth-rich bismuth oxyhalides (Bi_xO_yX_z, X = Cl, Br and I) composites possessed great potential in wastewater remediation.

Production of modified sunflowers seed shells for the removal of bisphenol A

In this present study, an abundant, available lignocellulosic biomass, sunflower seed shells, SSS, was used as a precursor to prepare an effective eco-adsorbent by treatment with H2SO4. A study of the surface characteristics of raw and acid-treated SSS (ACS) has shown that the addition of H2SO4 greatly affected the physicochemical properties of the obtained eco-adsorbent, improving the BET surface area from 6.106 to 27.145 m2 g-1 and surface oxygen-rich functional groups. Batch experiments were performed to assess the removal efficiency of a phenolic compound, bisphenol A (BPA), on the adsorbents. Several parameters were evaluated and are discussed (contact time, pollutant concentration, adsorbent dosage, and pH), determining that the adsorption efficiency of BPA onto SSS was notably improved, from 20.56% to 87.81% when a sulfuric acid solution was used. Different canonical and stochastic isotherm models were evaluated to predict the experimental behaviour. A dynamic study was performed based on the models of reaction kinetics and those of mass transfer. The results showed that the adsorption kinetics of BPA obey the fractal like-kinetic model of Hill for all experimental conditions. The equilibrium data are well suited to the Hill-Sips isotherm model with a determination coefficient >0.999. The kinetic modelling also indicates that the adsorption processes of BPA onto ACS are exothermic and proceed through a physical mechanism. A mass transfer study, using simplified models, proved that the process is controlled by intraparticle and film resistances to mass transfer of the BPA.

Magnetite doped metal–organic framework nanocomposites: an efficient adsorbent for removal of bisphenol-A pollutant

The removal of bisphenol-A (BPA) from the aqueous environment is a vital issue for public health due to its toxic effect.

AC, Schiller ADP, Manfrin J, Bianco LAV, Rosenberger AG. Eco-friendly, renewable Crambe abyssinica Hochst-based adsorbents remove high quantities of Zn2+ in water

Although not considered poisonous and with natural occurrence, Zn contamination is mainly related to anthropic actions. This research aim was to develop, from crambe wastes, adsorbents with high adsorption capacity of Zn²⁺. The crambe biomass was modified with H₂O₂, H₂SO₄ and NaOH 0.1 mol L^-1, resulting in four crambe-based adsorbents: C. in natura (unmodified), C. H₂O₂, C. H₂SO₄ and C. NaOH. These were studied by determination of their chemical components, SEM, FTIR, pH_PZC, thermal stability (by TG/DTG curves), SSA, pore volume and pore diameter (by BET and BJH). Adsorption studies were also carried out to evaluate its Zn removal capacity. Evaluations were taken on adsorbent dose and the influence of the pH, as well as studies on adsorption kinetics and equilibrium. These results were evaluated by pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion, Langmuir, Freundlich, Dubinin-Radushkevich and Sips (linear and nonlinear models). Results show that the crambe-based adsorbents may have functional groups such as hydroxyls, amides, carbonyls and carboxylates, which may be responsible for the Zn²⁺adsorption. The materials have heterogeneous structure, allowing the occurrence of mono and multilayer adsorption of Zn. The finest results point out the occurrence of mono and multilayer of Zn²⁺ (evidenced by Sips-nonlinear model), with an increase in Q_sat of 72% (C. H₂O₂), 22% (C. H₂SO₄) and 80% (C. NaOH). The developed crambe adsorbents have low cost of production (since the raw material is until now a solid waste) and have high removal ratio of Zn²⁺ from waters, being a promising technology.

Bio-sorption of bisphenol a by the dried- and inactivated-lichen (Pseudoevernia furfuracea) biomass from aqueous solutions

Bisphenol A (BPA), which is known as one of the endocrine-disrupting chemicals (EDCs) with hydrophilic hydroxyl groups and hydrophobic aromatic groups, has been widely used in plastic industries. The chemical waste from the industry is sometimes discharges into lakes and rivers, and then these surface waters can be polluted. So, this article aims to investigate the bio-sorption process of BPA by the inactivated lichen (Pseudoevernia furfuracea) biomass from aqueous solution. At initial, the effect of the variables such as initial BPA concentration, solution pH, temperature, contact time and recovery rate on the bio-sorption process was investigated. From the optimal results, it has been observed that the highest removal efficiency is approximately 64% at a contact time of 3-h, the bio-sorbent concentration of 9 mg/L, initial BPA concentration of 40 mg/L, and agitation speed of 150 rpm at pH 5.0. In explaining the bio-sorption potential of lichen biomass, Langmuir and/or Redlich-Peterson isotherms with two and three parameters, respectively were observed to be better fit with the experimental isotherm data (R² = 0.982). From equilibrium data based on difference between the measured and predicted results (q_{e, exp} and q_{e, pre}), it was shown that biosorption of BPA could be best described by the pseudo second order kinetic model with minimum sum of square error of 2.61%. In addition, it shows more film diffusion, and partly pore diffusion in linearity region in terms of kinetic sorption behaviors of BPA in the rate-limiting step as well as intra-particle diffusion according to Boyd's kinetic model with better regression coefficient than 0.981 when compared to the other used kinetic models, including Bangham's pore diffusion and Elovich kinetic models (with R² of 0.958 and 0.929). The thermodynamic studies showed that the biosorption process was spontaneous, and chemically feasible. Therefore, due to be low-cost, eco-friendly character, wide availability and easily accessible, the lichen biomass could be used as a promising bio-sorbent for the removal of BPA from the environment and wastewater effluents.

Reduced Graphene Oxide-Based Foam as an Endocrine Disruptor Adsorbent in Aqueous Solutions

A stable and magnetic graphene oxide (GO) foam-polyethyleneimine-iron nanoparticle (GO-PEI-FeNPs) composite has been fabricated for removal of endocrine disruptors-bisphenol A, progesterone and norethisterone-from aqueous solution. The foam with porous and hierarchical structures was synthesized by reduction of graphene oxide layers coupled with co-precipitation of iron under a hydrothermal system using polyethyleneimine as a cross linker. The presence of magnetic iron nanoparticles facilitates the separation process after decontamination. The foam was fully characterized by surface and structural scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The foam exhibits a high adsorption capacity, and the maximum adsorption percentages are 68%, 49% and 80% for bisphenol A, progesterone and norethisterone, respectively. The adsorption process of bisphenol A is explained according to the Langmuir model, whereas the Freundlich model was used for progesterone and norethisterone adsorption.

Uptake of micropollutant-bisphenol A, methylene blue and neutral red onto a novel bagasse-β-cyclodextrin polymer by adsorption process

The presence of emerging micropollutants and dyes in water resource has raised global concern about their intense effects to aquatic environments, ecosystem and human health in general. So far, various adsorbents have been suggested for reducing the levels of bisphenol A, methylene blue and neutral red contamination in wastewaters. However, a number of these adsorbents seemed to have low adsorptive capacities and regeneration performances. In view of these, batch experiment was performed to decontaminate these pollutants from aqueous solutions using an optimized bagasse-β-cyclodextrin polymer (SB-β-CD). Characterization studies of SB-β-CD were performed using FTIR, pH point of zero charge, XRD and BET methods. Adsorption of BPA, MB and NR was favored at lower temperature (298 K) and pH of 7.0, 9.0 and 6.0, respectively. The maximum adsorption capacity of BPA, MB and NR at 298 K was 121, 963 and 685 mg g^-1, respectively. Hydrogen bonding through host-guest inclusion and electrostatic interactions could respectively attribute to uptake of BPA and MB/NR onto SB-β-CD. Adsorption kinetics of three pollutants followed pseudo-second-order model. Langmuir and Freundlich models were fitted to describe the adsorption of BPA and MB/NR, respectively. Thermodynamic parameters confirmed the occurrence of physical adsorption which is spontaneous and exothermic in nature. SB-β-CD loaded with BPA and MB/NR was certainly reused by 75% ethanol and 0.1 mol L^-1 HCl solutions, respectively. Novel SB-β-CD showed better adsorptive capacity and regeneration performances; consequently can offers practical application for removal of BPA, MB and NR from wastewaters.

Transforming Waste Poly(Ethylene Terephthalate) into Nitrogen Doped Carbon Nanotubes and Its Utility in Oxygen Reduction Reaction and Bisphenol-A Removal from Contaminated Water

Till date, waste plastics are either down-cycled to cheap products like fibers or burnt in incinerators to generate heat. In this manuscript, we report a simple and effective technique for microwave induced transformation of waste polyethylene terephthalate (wPET) to carbon nano-tubes (CNT). Iron nano-particles dispersed on graphene substrate acted as catalyst for CNT growth whereas urea served the dual role of de-polymerisation of wPET and also as nitrogen doping agent. Application of our newly synthesized 3-D meso-porous graphene-nitrogen doped carbon nanotube- iron electrode (Fe@NCNT-rGO) as electro-catalyst for oxygen reduction reaction (ORR) shows a positive half-wave potential (E_1/2) of 0.75 V vs. RHE (reversible hydrogen electrode), nearly ideal four-electron pathway and excellent methanol tolerance when compared to commercial 20% Pt/C. The utility of Fe@NCNT-rGO for removal of bisphenol A from contaminated waters is also reported.

Activated Carbon from Spent Coffee Grounds: A Good Competitor of Commercial Carbons for Water Decontamination

In the framework of the circular economy, spent coffee grounds were converted into powdered activated carbon by means of pyrolysis, using potassium hydroxide as the activating agent. Its adsorption capacity on a panel of phenolic compounds was compared with those of two commercial powdered activated carbons, after preliminary studies on organic dyes with different ionic properties, to assess the affinity between adsorbates and adsorbents. Pseudo-first-order and pseudo-second-order kinetic models were carried out, together with Freundlich and Langmuir isotherms. They were useful to calculate the breakthrough at 5%, 10%, and 50% of adsorption and the partition coefficients for the comparison of performance between different sorbent systems in a less biased manner (e.g., reducing bias associated with operational settings like sorbate concentration and sorbents dosage). The results showed that the removal efficiency for SCGs-AC was comparable with that of the commercial activated carbons with the highest partition coefficients for methylene blue (12,455 mg/g/μM, adsorption capacity = 179 mg/g) and 3-chlorophenol (81.53 mg/g/μM, adsorption capacity = 3765 mg/g). The lower efficiency in bromothymol blue and bisphenol-A adsorption was due to its different morphology and surface properties.

Porous carbon materials derived from olive kernels: application in adsorption of organic pollutants

Adsorption of organic pollutants (OPs), bisphenol A, and diuron, from aqueous solutions onto porous carbon materials (CMs) prepared from olive kernels, have been investigated. The effects of initial pH, initial OP concentration, temperature, and contact time on the adsorption capacity were studied. The adsorption of bisphenol A and diuron onto CMs was found to be optimal at pH 5.6 and 6.9, respectively. It was noticed that the adsorption of those organic pollutants from aqueous solution declined with increasing temperature and the process is exothermic. The rate of adsorption followed the second order kinetic equation. The equilibrium results showed that Langmuir model fits well with the data. The maximum adsorption capacities obtained using the best CM were 476 and 434 mg g^-1 for BPA and diuron, respectively. The results showed that CMs made from olive kernels are an excellent and inexpensive biomass waste-derived sorbent. Graphical abstract.

Adsorptive Behavior of an Activated Carbon for Bisphenol A Removal in Single and Binary (Bisphenol A—Heavy Metal) Solutions

Bisphenol A (BPA) is an extensively produced and consumed chemical in the world. Due to its widespread use, contamination by this pollutant has increased in recent years, reaching a critical environmental point. This work investigates the feasibility of bisphenol A adsorption from industrial wastewater solutions, testing the reduction of bisphenol A in synthetic solutions by a commercial activated carbon, AC-40, in batch mode. Besides, mixtures of bisphenol A and different heavy metal cations were also studied. So far, no works have reported a complete study about bisphenol A removal by this activated carbon including the use of this material to remove BPA in the presence of metal cations. First, adsorption experiments were performed in batch changing pH, dose of adsorbent, initial bisphenol A concentration and contact time. Results showed greater retention of bisphenol A by increasing the acidity of the medium. Further, the percentage of bisphenol A adsorbed increased with increasing contact time. The selected conditions for the rest of the experiments were pH 5 and a contact time of 48 h. In addition, an increase in retention of bisphenol A when the dose of adsorbent increased was observed. Then, specific experiments were carried out to define the kinetics and the adsorption isotherm. Equilibrium data were adequately fitted to a Langmuir isotherm and the kinetics data fitted well to the pseudo-second-order model. The maximum adsorption capacity provided by Langmuir model was 94.34 mg/g. Finally, the effect of the presence of other heavy metals in water solution on the adsorption of bisphenol A was analyzed. Binary tests revealed competition between the adsorbates and a significant selectivity toward bisphenol A. Finally, the study of the adsorption performance in three consecutive adsorption–desorption cycles showed efficiencies higher than 90% in all cycles, indicating that the activated carbon has good reusability.

The synthesis strategy to enhance the performance and cyclic utilization of granulated activated carbon-based sorbent for bisphenol A and triclosan removal

For a potential and efficient solution in the mitigation of aquatic pollution, this study reported a well-designed and developed protected granulated activated carbon (GAC) material which ensures high strength property and adsorption performance to meet the industrial application. The prepared GAC material was shaped into a spherical core using natural binders basically assumed to constitute waste solids materials. Then after, the granulated carbon core (GAC core) was protected by a porous ceramic shell which confined the material with strong protection and high mechanical strength to resist against degeneration and pressure drop as a limiting factor for most sorbents employed in solution. The CSGAC characterization results proved that the ceramic shell has a smaller thickness (0.1 cm), good mechanical strength (2.0 MPa), and additionally, it presents larger porous channels which promote the fast and higher adsorption performance making it the desired material for the application in the real liquid environment. The test results showed that the prepared material had higher removal of triclosan (TCS) (30-40 mg/L) than BPA counterpart from the aqueous solutions. Moreover, it showed higher adsorption performance compared to the unprotected carbon materials. Furthermore, the mechanisms of BPA and TCS adsorption by core-shell granulated activated carbon (CSGAC) were discussed.

Comparative environmental assessment of end-of-life carbonaceous water treatment adsorbents

This study evaluates and compares the environmental impacts arising from the disposal of different carbonaceous sorbents used for wastewater treatment. Three different adsorption materials were considered, i.e. activated carbon, biochar and hydrochar, and three end-of-life management approaches, i.e. incineration, regeneration and landfilling. The highest overall environmental impact was of Carcinogenic effects and Freshwater Ecotoxicity due to emissions of heavy metals during production of all types of sorbents. The use of materials with higher adsorption capacities and regeneration of carbonaceous materials were considered and shown to be an efficient way for reducing the overall environmental impacts of the different adsorbents. The compensation of fossil fuel incineration by using recovered heat led to negative impacts in all categories. Recirculation of HTC process water reduced the impact on Freshwater Ecotoxicity and Eutrophication.

Sonochemical Synthesis of Copper-doped BiVO4/g-C3N4 Nanocomposite Materials for Photocatalytic Degradation of Bisphenol A under Simulated Sunlight Irradiation

Copper-doped bismuth vanadate/graphitic carbon nitride (BiVO₄/g-C₃N₄) nanocomposite materials were successfully fabricated using a sonochemical approach. Cu-doped BiVO₄/g-C₃N₄ nanocomposite photocatalysts could improve electron/hole (e^-/h⁺) pair separation, stability, and light-harvesting efficiency compared to pristine BiVO₄ or g-C₃N₄, resulting in the enhancement of photocatalytic activity. The optimal parameters, such as pH value at 10, photocatalyst dosage of 0.4 g L^-1, and 10 mol% Cu-doped BiVO₄/g-C₃N₄ photocatalyst, were determined to degrade initial concentration of 20 ppm Bisphenol A, which could be completely removed after 90 min. Furthermore, the excessive doping of copper (> 10 mol%) could not synthesize the pure monoclinic scheelite phase, which substantially resulted in the reduction of the photocatalytic activity.

Bisphenol A removal from water by biomass-based carbon: isotherms, kinetics and thermodynamics studies

Biomass-based carbon was modified and used as an efficient bisphenol A (BPA) sorbent. The simple and environmentally friendly modification method produced sorbent with a capacity of 41.5 mg/g. The raw material was modified with FeCl₃ (Fe-CR), treated with hydrochloric acid (H-CR) or modified with CaCl₂ (Ca-CR). Batch sorption experiments were performed to evaluate the effects of the initial pH, sorbent dosage, temperature, and contact time on BPA removal. BPA removal with modified carbons was notably higher than that with unmodified carbon. All sorbent materials exhibited very high sorption capacities and compared favourably to materials reported in the literature. Several isotherms were applied to describe the experimental results of Fe-CR, H-CR, and Ca-CR modified carbon residues and the Sips model showed the best fit for all sorbents. Kinetic studies for the best sorbent material (Fe-CR) showed that the sorption process follows Elovich kinetics. Desorption cycles were implemented, and sorption capacity remained with three cycles.