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Industrial use of heavy metals and dyes critically depends on the effective handling of industrial effluents. Effective remediation of industrial effluents using various adsorbent materials has thus become critical. In this paper, we study two-dimensional MXenes as an adsorbent for removing Cr(VI) and methyl orange (MO) in waters. The physico-chemical performance of MXenes was studied using X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer−Emmett−Teller, scanning electron microscopy, high resolution-transmission electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy techniques. The adsorption system, including influence of contact time, pH of solutions, co-ions, and desorption experiments were performed for effective Cr(VI) and MO removal. The Cr(VI) and MO removal rate of the MXenes was very fast, and the kinetic system was driven by pseudo-second-order kinetics. The sorption isotherm closely well-tailored with the Langmuir isotherm, and the maximum removal efficiencies were 104 and 94.8 mg/g for Cr(VI) and MO, respectively. The MXenes was successfully regenerated by 0.1 M NaOH aqueous solution and can be repeatedly recycled. The uptake of Cr(VI) and MO by the MXenes was mainly due to chemical adsorption, namely electrostatic adsorption, complexation, surface interactions, and ion exchange mechanisms. This investigation demonstrates the selectivity and feasibility of the MXenes as a real adsorbent for eliminating Cr(VI) and MO from the aqueous environment.

With the advancement of modern industries and metropolitan areas, negative environmental impacts such as eutrophication have become serious issues obstructing the usage of water sources in many countries. In this study, two-dimensional (2D) MXene materials were employed for the adsorptive removal of phosphate and nitrate ions from waters. The adsorption parameters of the sorption system including reaction time, solution pH, background ions, and reusability, were evaluated in batch experiments. Material characterization techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy, thermal gravimetric analysis, Brunauer–Emmett–Teller analysis, and high-resolution transmission electron microscopy were performed. The mechanism of removing phosphate and nitrate was clearly described by various kinds of interactions such as electrostatic interactions, and the complexation was significant to elucidate the adsorption mechanism. The adsorption data for phosphate and nitrate update was determined using different isotherms and kinetic models. Reusability and field studies on the MXenes were also conducted. The above findings demonstrate that 2D MXenes could act as promising adsorbents for the elimination of toxic ions from water/wastewater.

A biopolymeric hybrid membrane, viz. lanthanum interconnected carboxymethylcellulose-bentonite (La@CMC-Bt) was prepared successfully and utilized for the remediation of phosphate and nitrate ions from water. The various adsorption influencing parameters such as agitation time, adsorbent dosage, solution pH, co-anions and temperature were optimized. The physiochemical properties of the La@CMC-Bt membrane was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermal analysis (TGA–DSC), scanning electron microscopy, energy dispersive X-ray analysis with mapping analysis, and atomic force microscopy to clarify the phosphate and nitrate adsorption mechanism. The La@CMC-Bt membrane showed superior adsorption capacity at 80.2 and 67.7 mg/g for phosphate and nitrate ions, respectively. Furthermore, the adsorption kinetic studies were calculated using reaction and diffusion-based kinetic models. The thermodynamic parameters like ΔG°, ΔS° and ΔH° have revealed that the nature of the adsorption process was favourable, spontaneous and endothermic in nature. The experimental results indicate that the possible mechanism of phosphate and nitrate adsorption onto La@CMC-Bt membrane was governed by the adsorption mechanisms like complexation, electrostatic interaction followed by ion exchange. The suitability at the field condition was carried out with the eutrophicated water sample taken from the nearby eutrophic endemic area. Therefore, based on the high efficiency and low-cost of La@CMC-Bt membrane, to be an ideal candidate to remove phosphate and nitrate ions from water/wastewater.

In recent decades, magnetic bead material has attracted considerable attention in water and wastewater purification. In this study, the potential of magnetic kaolinite immobilized in chitosan beads (MKa@CB) to remove Pb(II) and Cd(II) ions from an aqueous environment has been successfully investigated. The addition of magnetic kaolinite generates more active sites, whereas that of chitosan enhances the stability of synthesized bead materials, which enable them to effectively interact with the targeted contaminants. Various factors including agitation time, solution pH, and competitive ions were examined to optimize the removal efficiency of the MKa@CB. The adsorption kinetics and isotherm studies indicated that the adsorption fitted well to the pseudo-second-order kinetic model as well as to the Langmuir isotherm. The prepared adsorbent could be reused up to four cycles without any significant adsorption capacity loss. Thus, the synthesized MKa@4%CB can be a promising adsorbent in effectively removing Pb(II) and Cd(II) from water.

In the present work, a novel (2D/2D) accordion like CS@g‒C3N4/MX hybrid composite was prepared through one-pot hydro-thermal synthesis method and utilized as a catalyst for the degradation of organic persistent dyes such as methylene blue (MB) and rhodamine B (RhB). Because the removal of such organic compounds is a major dispute in environmental aspects. In this study, the bio-assisted g‒C3N4/MX nanosheets was utilized for the removal of organic dyes from aqueous solution under visible light irradiation, respectively. The CS@g-C3N4/MX photocatalyst showed high catalytic activity based on ~99% and ~98.5% degradation of MB and RhB within 60 and 40 min using visible light irradiation. This outcome could have resulted in greater catalytic enactment towards the degradation of other persistent pollutants with enhanced light absorption property and it can efficiently suppress photo-generated charge recombination, thus improving the interfacial charge transfer rate. The OH radical was being effective oxidative species involved in the CS@g-C3N4/MX system for the degradation of organic contaminants. Furthermore, CS@g-C3N4/MX showed excellent photo-stability over five consecutive cycles for the degradation of organic dyes with negligible loss of photocatalytic activity. Finally, the purposed catalytic mechanisms and degradation pathways of MB and RhB were systematically discussed in detail based on experimental results. Thus, the organics which oxidized into ring-opened compounds such as ethoxyethane, butadiene etc., to non-toxic products like H2O, CO2 and some mineral salts.

The presence of organic dye molecules and heavy metal ions in water causes ecological and public health problems. Therefore, remediation of water/wastewater contaminated with organic dye molecules and toxic metal ions is of importance. Herein, a reduced graphene oxide (RGO)–hydroxyapatite (Hat) (1D–2D) hybrid composite was fabricated through a hydrothermal process and applied for the adsorption of methyl orange (MO) and hexavalent chromium (Cr(VI)) from water. The as-fabricated RGO–Hat hybrids were characterized using FTIR, XRD, HR-TEM, SEM, XPS, EDAX, and TGA-DSC analytical techniques. The influencing parameters of adsorption performance, namely solution pH, contact time, and co-interfering ions, were explored to obtain the maximum adsorption capacity of contaminants from the solid–liquid interface. Batch studies revealed that MO and Cr(VI) adsorption followed the pseudo-second-order kinetic and the Langmuir isotherm models. The adsorption capacity was 49.14 and 45.24 mg g−1 for MO and Cr(VI), respectively. The adsorption of such ions over RGO–Hat hybrids was mainly driven by several uptake mechanisms viz, electrostatic force of attraction, π–π interactions, and hydrogen bonding. Thus, this study demonstrated that the RGO–Hat hybrid is a potential candidate for the treatment of MO and Cr(VI) from water.

The efficient and selective removal of toxic dye molecules from water/surface water remains a problematic task, owing to their high water solubility and low biodegradability. We fabricated the hydroxyapatite-decorated reduced graphene oxide (HA@rGO) nanocomposites via a simple hydrothermal process and used them as efficient adsorbents for the diazo dyes removal. In the batch experiments, the resultant HA@rGO nanocomposites exhibited fast and excellent removal performance for Trypan blue and Congo red dye molecules in a wide pH range and the maximum adsorption efficiencies of 146.51 and 150.09 mg/g, respectively. Several characterization analysis results demonstrated that the removal performance of the HA@rGO nanocomposites for the toxic dyes was mainly driven by electrostatic, hydrophobic, π–π interactions, and H-bonding between the adsorbents and dye molecules in the aqueous solution. Ubiquitous co-anions have significant influence on the dye removal performance of the HA@rGO nanocomposites because of the higher ionic radius and electronegativity. After adsorption, the exhausted HA@rGO nanocomposites could be regenerated in alkaline solution and reused throughout five successive adsorption–desorption cycles. We believe that the adsorbent fabricated in this work can be effectively used to remove toxic diazo dye molecules from aqueous media.

In the current industrial scenario, the dye molecules are the most rigorous contributors to water pollution, and the removal of these pollutants becomes a problematic task. Carbon adsorbents have been used as superior materials for the water/wastewater treatment process. However, the adsorption system could not use the pristine carbon materials in practical applications as it causes significantly less efficiency in adsorption. Conversely, the tuning of carbon with magnetic materials have been employed. Herein, a magnetically retrievable adsorbent was successfully fabricated using carbon-biomass from the seeds of Moringa oleifera and manganese ferrite viz.; MnFe2O4@MOAC. The organic dyes such as Reactive Blue 4 (RB4), Indigo Carmine (IC) and Acid Blue 158 (AB158) were chosen as the adsorbates for this study, and MnFe2O4@MOAC shows the adsorption efficiency of 32.45, 33.53 and 35.27 mg/g, respectively and the maximum adsorption observed in the pH range of ~3. The adsorption followed the Freundlich isotherm and the pseudo-second-order kinetics. The adsorption thermodynamics revealed that the process was endothermic and spontaneous. The fabricated adsorbent was recovered and reclaimed in five successive cycles of adsorption. Electrostatic attractions, hydrogen bonding and π-π interactions were the essential mechanisms involved in the adsorption. The newly fabricated bio-mass could be visualized as a capable adsorbent for water/wastewater treatment process since the MnFe2O4@MOAC possesses high removal efficiency towards dye molecules.

The rapid industrialization and explosion of the population result in increased usage of water and its consequent discarding causes environmental pollution. The biochar based materials are effectively employed for the removal of dyes from contaminated water. However, the pristine biochar shows less efficiency towards dye adsorption in practical applications. Herein, sulfur tethered adsorbent of Tapioca peel (S@TP) biochar was successfully fabricated and utilized for the removal of organic dyes such as Malachite Green (MG) and Rhodamine B (RhB) from water. The peel of tapioca was used as a precursor for the biochar preparation. The isotherm analysis demonstrates that the S@TP biochar has the adsorption efficiency of 30.18 and 33.10 mg/g for MG and RhB dye molecules, respectively. 25 mg/L concentration of 50 mL dye solutions were used for the adsorption study. The maximum adsorption was observed at a pH range ~8, and the adsorption attained saturation within 120 min. The adsorption followed the pseudo-second-order kinetics, and the adsorption process was composed of the Freundlich isotherm model. The newly fabricated adsorbent could be utilized as a capable adsorbent for the water/wastewater treatment process. The newly fabricated bio-mass could be visualized as a capable adsorbent for water/wastewater treatment process since the S@TP matrix possesses high removal and reusable efficiency towards dye molecules.

Contaminated waters with high contents of toxic anions are detrimental to the human health and wildlife. Thus, the quality of drinking water should be carefully monitored. Adsorption technique has been determined to be a reasonable strategy out of several methods used to remove toxic anions from water. Novel MgFe2O4-reinforced polypyrrole (Ppy@x%MgFe2O4) (x = 1%, 2%, and 5% of MgFe2O4) hybrids were synthesized from a pyrrole monomer and MgFe2O4 using a simple chemical oxidation method. The fabricated hybrids were studied for their capability to remove PO43–, NO3–, and Cr(VI) from aqueous solutions. The results showed that PO43–, NO3–, and Cr(VI) removal was highly pH-dependent. The adsorption isotherms of hybrids were fitted well by the Langmuir model, with the maximum adsorption efficiency of 116.90, 76.14, and 138.60 mg/g for PO43–, NO3–, and Cr(VI), respectively. In addition, the above-mentioned toxic anions could be efficiently desorbed from spent Ppy@x%MgFe2O4 using a 0.1 M NaOH solution, and the hybrids exhibited good regenerability. The prepared materials are promising candidates for PO43–, NO3–, and Cr(VI) removal and exhibit high adsorption efficiency, rapid adsorption–desorption behavior, and appropriate recovery from the aqueous medium under external magnetic field.

The removal of emerging contaminants including heavy metals and perfluorinated compounds has been an increasing concern globally due to their harmful effects on human health and other creatures in the environment. Mixtures of perfluorinated chemicals with heavy metals are often found in polluted areas, which is a critical challenge in water remediation. This study proposes a multifunctional magnetic adsorbent, cerium-incorporated ferrite (CMF) decorated polyaniline (PANI) (CMFx%@PANI) hybrid composites by co-precipitation followed by calcination methods. FTIR, VSM, and zeta potential measurements confirmed the successful incorporation of CMF on PANI. The textural properties and surface morphologies of CMFx%@PANI were examined using BET, FE-SEM, HR-TEM, and EDX analysis. The conventional raw forms of CMF nanoparticles and PANI were inadequate for the removal of the mentioned contaminants. However, the synchronous role of PANI with CMF nanoparticles exhibited higher adsorption capacities toward the perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and hexavalent chromium (Cr(VI)) ions than the individual forms. The sorption kinetics and isotherms indicated that adsorption behaviors of PFOA, PFOS, and Cr(VI) onto CMFx%@PANI followed a pseudo-second-order and Langmuir isotherm model, respectively. The feasible mechanisms of PFOA, PFOS, and Cr(VI) adsorption on CMFx%@PANI were investigated using XPS analysis.

In this study, we have rationally designed and grafted a bio-assisted 2D/2D TiO2/MIL-88(Fe) (TCS@MOF) heterojunction by growing granular TiO2 on the surface of MIL-88(Fe) nanosheet, as hybrid photocatalyst. The hierarchical TCS@MOF composite was prepared via the one-pot solvothermal process and employed for monocrotophos (MCP) degradation under visible light region, since its persistent nature on soil and water causes major threat to the environment. The TCS@MOF promotes a number of packed high-speed nano-tunnels in the (p-n) heterojunctions, which significantly enhance the migration of photo-induced electrons (e−) and holes (h+), respectively and thus limits the charge recombination of e−s. The optimized photocatalyst achieves significant catalytic activity of ~98.79% for the degradation of MCP within 30 min of irradiation. The prominent oxidative radicals namely •OH, •O2− etc., were involved in the oxidation of organic pesticide. Besides, TCS@MOF exhibits outstanding stability even after five repetitive cycles for the oxidation of MCP with a negligible decrease in photo-activity. The proposed mechanism and oxidative pathways of MCP were rationally deduced in detail subject to experimental results. The mechanism renders insight into the oxidation and consequent bond rupture of pollutant as well as into the formation of products such as H2O, CO2, etc. This report unveils a novel architecture of proficiently optimized TCS@MOF material structure for the perceptive oxidation of organic contaminants.

The development of industrialization and agricultural activities have carried various negative impacts to living organisms in recent decades and also, the frequent problem of inorganic pollution have been environmental anxiety to the community. Among these, Cr6+ and F− are priority poisonous pollutants from many industries. In this work, we present a low-cost synthesis procedure to obtain biocompatible zirconium incorporated chitosan-gelatin composite (CS–Zr-GEL) were fabricated and explored for the adsorptive removal of toxic Cr6+ and F− from water. The adsorption mechanism of toxic Cr6+ and F− was done by batch mode as a function of contact time, solution pH and co-existing ions. The obtained materials were extensively studied by several physico-chemical techniques to access their properties by X-ray diffraction (XRD), scanning electron microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) analysis. Additionally, the fabricated adsorbent is highly dependent on solution pH. The kinetic and isotherm data were fitted using pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacity for CS-Zr-GEL is 138.89 and 12.13 mg/g at 323K for Cr6+ and F− respectively. These findings demonstrate that the CS-Zr-GEL adsorbent represents a promising candidate that would have a practical influence on water/wastewater treatments.

A magnetic FGC composite was prepared using Fe3O4 particles and graphene oxide–carboxymethyl cellulose which were blended as the source materials. The adsorptive interactions of FGC matrix with dye molecules like Congo Red (CR), Acid Red 1 (AR1) and Reactive Red 2 (RR2) were examined and explained through various analytical techniques. The optimum conditions for the adsorption of dyes include the initial concentration of dyes (50 mg/L), volume of dyes (50 mL), adsorbent dosage (100 mg) and solution pH (3-6). In these conditions, the FGC showed extreme adsorption efficiency of 45.09, 47.32 and 46.21 mg/g for the removal of CR, AR1 and RR2 dye molecules, respectively. The Freundlich isotherm data shows better fit for dye molecules adsorption. The thermodynamic results confirmed the endothermic and spontaneous nature in adsorption. The mechanism of CR, AR1 and RR2 dyes adsorption on FGC composite follows the interactions such as electrostatic attraction, hydrogen bonding, π−π stacking, and surface complexation. The FGC composite was regenerated over 65% after five consecutive cycles using an aqueous 0.1 M NaOH solution. The FGC composite showed an enhanced adsorption capacity for the removal of toxic azo dyes. Hence, the prepared composite could be used as a potential adsorbent for the removal of dye molecules from contaminated water.

Phosphate and nitrate ions are ubiquitous pollutants in aquatic environments and phosphate and nitrate removal from water have been widely studied. Still, there exists a dilemma in developing highly selective adsorbents for the removal of phosphate and nitrate ions with enhanced removal efficiency. Herein, developed a unique and novel activated carbon-supported zinc ferrite (AC@ZnFe2O4) composite (Activated carbon derived from Muskmelon Peel) via co-precipitation method for removing phosphate and nitrate ions from water. The adsorption capacity of AC@ZnFe2O4 strongly depends on the surface properties, and this system was mainly governed by multilayer adsorption. Besides, AC@ZnFe2O4composite showed a high adsorption efficiency of 91.80 and 75.58 mg/g for phosphate and nitrate ions, respectively at 30 °C (Langmuir isotherm model). The fabricated AC@ZnFe2O4 composite was characterized using FTIR XRD, SEM, BET, EDAX and TGA-DSC analysis. The regeneration experiments revealed that the AC@ZnFe2O4 composite could potentially be reused by maintaining its high removal efficiency. The above findings suggest that AC@ZnFe2O4 composite could act as a potential low-cost adsorbent and applicable for the removal of phosphate and nitrate ions to retain the quality of water after treatments.

A hetero-structured adsorbent with outstanding adsorption performance has acquired an increased attention due to their excellent behaviour in environmental applications. Tailoring of graphene oxide and hydroxyapatite with suitable biopolymeric adsorbents would enhance the porosity, stability, specific surface area and shows high sorption performance. Herein, chitosan reinforced graphene oxide-hydroxyapatite (CS@GO-Hap) matrix was fabricated efficiently in the atmosphere of nitrogen by co-precipitation technique. Here, chitosan acted as a host in the preparation and provided the surface for a composite generation. The batch mode method was applied to investigate the adsorption performance of CS@GO-Hap composite, showed an adsorption efficiency of 43.06, 41.32 and 40.03 mg/g for the removal of the toxic Congo Red (CR), Acid Red 1 (AR1) and Reactive Red 2 (RR2) dyes from water, respectively. The composite showed enhanced adsorption at the pH of 2 and the removal efficiency of CS@GO-Hap composite decreased with increase in pH. The adsorption kinetic and isotherm fitted well with pseudo-second-order and the Freundlich model, respectively. The thermodynamic study of the adsorption of dyes showed that the process was spontaneous. The regeneration experiments emphasized that the desorption was ideal, and exhibited more than 65% regeneration ability with 0.1 M NaOH solution. The mechanism of dyes adsorption on CS@GO-Hap composite involved the electrostatic force interaction, surface complexation, hydrogen bondings and π−π stacking interactions. The findings of the study revealed the exceptional behaviour of CS@GO-Hap composite in removing the azo dyes from aqueous solutions and the great significance of the composite in the future application in water/wastewater treatment process.

The consumption of agricultural wastes as environmentally friendly and endorses green chemistry. The potential use of agricultural waste sources with additional treatment for the removal of anionic pollutants from water was examined. Herein, the removal performance of a stable inorganic-organic hybrid composite of porous carbon (Porous carbon derived from papaya seeds) was fabricated through one-pot synthesis and employed for the removal of phosphate and nitrate from water. The as-prepared hybrid composite properties were examined using FTIR, XRD, SEM, VSM, TGA-DSC, BET and EDAX with mapping analysis. The various parameters for the removal of phosphate and nitrate from water using cobalt ferrite coated-porous carbon composite (CoFe2O4@PC) were optimized. The maximum adsorption capacity is 92.34 for phosphate and 78.98 mg/g for nitrate at 303 K. Freundlich adsorption isotherm model is found to be superior fir and heterogeneous surface interaction of phosphate and nitrate ions onto the CoFe2O4@PC composite. The pseudo-second-order and intra-particle diffusion kinetic model describes the removal mechanism and rate-determining steps. Thermodynamic studies recommend that the adsorption process to be endothermic and spontaneous nature. The prepared CoFe2O4@PC composite displayed good removal capacity and was effectively utilized for the removal of phosphate and nitrate ions in real water sample. In addition, this study provides useful insights into the removal of phosphate and nitrate by magnetic separable CoFe2O4@PC composite in water/wastewater.

The main objectives of this work to elucidates the adsorption behaviour of Zn Fe LDHs impregnated OPAC (Orange Peels Activated Carbon) composite was prepared via the ultrasonic-assisted co-precipitation method and its application for the removal of phosphate and nitrate from water. The prepared composite was studied by way of FTIR, XRD, TGA, SEM, EDAX with mapping images, DSC and BET analysis. Equilibrium isotherm data of both phosphate and nitrate ions were well fitted to the Freundlich isotherm model. Thermodynamic studies shows that Zn Fe LDHs OPAC composites have a potential applicant for the removal of phosphate and nitrate from water at different temperatures. The kinetic parameters were discovered by using non-linear regression method. The regeneration study was retained up to seven cycles and 63% adsorption efficiency was observed. The applicability of Zn Fe LDHs OPAC composite at field condition was analyzed by eutrophicated water sample taken from the nearby industrial area.

A lithe zinc-aluminium layered double hydroxides were imprinted on activated carbon and fabricated Zn/Al LDHs@C composite. The composite matrix was utilized for the removal of toxic Congo Red (CR), Acid Red 1 (AR1) and Reactive Red 2 (RR2) dyes from water. The Zn/Al LDHs@C composite was characterized by Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy Dispersive X-Ray Analysis (EDAX), Brunauer-Emmett-Teller (BET), Thermogravimetric analysis-Differential scanning calorimetry (TGA-DSC) and Powder X-ray diffraction (PXRD) analytical techniques. The adsorption process was evaluated by varying the parameters such as contact time, composite dosage, pH of the solution, initial dye concentration and interfering anions. The maximum adsorption of CR, AR1 and RR2 dyes on Zn/Al LDHs@C composite were 44.09, 48.37 and 49.52 mg/g, respectively. The enhanced adsorption efficiency of the composite might be due to the existence of binding forces such as electrostatic attraction of the layered double hydroxide, hydrogen bonding sites on the Zn/Al LDHs@C and the surface complexation phenomena of the composite with the dye molecules. The Freundlich isotherm model was fit superior at the saturation point, indicating the heterogeneous surface interaction. Thermodynamic studies recommend that the adsorption process was spontaneous and endothermic in nature. The adsorption-desorption studies of Zn/Al LDHs@C composite were achieved up to five successive cycles with high efficiency. The enhanced adsorption efficiency of the Zn/Al LDHs@C composite suggested that the fabricated composite was suitable for the removal of CR, AR1 and RR2 dye molecules from water than any other developed hybrids.

In this study is to propose that for the removal of phosphate and nitrate ions from aqueous solutions using zirconium burdened carboxymethylcellulose-surfactant assisted kaolin (Zr-CMC-SKa) membrane as an effective adsorbent. The prepared membrane was synthesized by phase inversion method via polyethylene glycol as a flexible reagent and the developed membrane was extensively characterized by the details of the terms like morphological, compositional, thermal, roughness, functional and microscopic techniques. The optimization of various operating experimental conditions like the function of time, dosage, co-anions, pH, and pHZPC was studied. The adsorption kinetic phenomenon followed by pseudo-second-order and intraparticle diffusion models with good correlations. The fitting of the Freundlich adsorption isotherm model confirms multilayer adsorption of heterogeneous surface interaction between the toxic anions. Thermodynamic parameters, including the (ΔGo), (ΔSo) and (ΔHo) indicated that the phosphate and nitrate adsorption was feasible, spontaneity and endothermic in nature. The mechanistic pathway was mainly governed by electrostatic interaction, complexation followed by the ion-exchange mechanism, which was adopted for the removal of phosphate and nitrate anions from aqueous solutions. Furthermore, the applicability of the synthesized membrane towards promising results against the eutrophicated water sample by reducing the concentration of the toxic anions below the acceptable limit.

In the present work, magnetic separation is one of the most effective techniques to recovering the phosphate and nitrate ions from water using amine crosslinked magnetic banana bract activated carbon (ACM@BBAC) was prepared via magnetization and was further crosslinked by amine groups. The ACM@BBAC was extensively studied by using SEM, EDAX with mapping images, FTIR, TGA-DSC, XRD, BET, and VSM analytical techniques. The effect of various influencing parameters, i.e. adsorbent dosage, shaking time, solution pH, co-existing anions and temperature were assessed. The adsorption statics were performed by Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. Reaction and diffusion-based kinetic models were used to find the kinetic factors such as correlation coefficients, rate constants and standard deviations for each kinetic models and were also discussed. Thermodynamic parameters such as ΔG, ΔS° and ΔH° have been calculated and it could be well described for the adsorption reaction was endothermic and spontaneous in nature. Phosphate and nitrate adsorption mechanisms predominately involved by electrostatic force of interaction, ion-exchange and surface complexation with ACM@BBAC. The suitability of the ACM@BBAC at environmental condition was inspected with contaminated water sample collected from nearby eutrophic endemic area. The as-prepared ACM@BBAC is an effective adsorbent for the remediation of phosphate and nitrate ions from water/ wastewater.

In this study, we synthesized a novel 2D heterostructured composite material by substituting hexagonal boron nitride (h-BN) with polyaniline (Pani), h-BN@x%Pani, via an in situ chemical oxidative method. The h-BN@x%Pani (x = 1, 2, and 5% of aniline) can remove phosphate, nitrate, and hexavalent chromium (Cr(VI)) ions from aqueous solution, and h-BN is generally used as a supporting material because of its good stability and high specific surface area (263.68 m2/g). The physicochemical properties of the h-BN@x%Pani hybrid composite before and after adsorption of the aforementioned contaminants were investigated using various analytical techniques. After substitution of Pani onto h-BN, the surface charge density of the as-synthesized adsorbent was greatly improved, which is in good agreement with zeta-potential measurements. The adsorption mechanism of phosphate, nitrate, and Cr(VI) ions onto h-BN@x%Pani hybrid composite was mainly governed by electrostatic attraction followed by surface complexation and ion-exchange. Furthermore, the h-BN@x%Pani composite was regenerated with 0.1 M NaOH solution as a desorbing reagent without any significant loss of adsorption efficiency for five consecutive cycles. Because of their good removal behavior for phosphate, nitrate, and Cr(VI) ions, the synthesized h-BN@x%Pani hybrid composites are expected to become potential candidates in practical applications for water and wastewater remediation.

Nowadays, efficient and selective remediation of phosphate and nitrate ions from water/ wastewater is a problematical task. In this study, magnetic particles (Fe3O4) decorated GO-CMC (Fe3O4@GO-CMC) composite beads were synthesized via the one-pot process and applied for the remediation of phosphate and nitrate from aqueous medium. XRD, BET, SEM, FTIR, EDAX with mapping images and TGA analysis were done on the synthesized beads in order to examine the structural and textural properties. Batch scale adsorption experiments in phosphate and nitrate solution demonstrated the dynamic behaviours of phosphate and nitrate remediation using Fe3O4@GO-CMC composite beads under various experimental conditions such as agitation time, the influence of beads dosage, solution pH, zero point charge and co-interfering anions. The adsorption isotherm experiments, the Freundlich adsorption isotherm model showed a superior fit than the Langmuir isotherm model, yielding the maximum removal capacity of 84.90 and 76.01 mg/g for phosphate and nitrate ions, respectively. The removal mechanisms and adsorption-desorption experiments were also examined. The aptness of Fe3O4@GO-CMC composite beads at field trail was also analysed by real sample collected from nearby eutrophic endemic area. These results suggested that the Fe3O4@GO-CMC composite beads could be a suitable material for the remediation of phosphate and nitrate ions from wastewater treatments.

Inorganic anions plays an important role in biological, industrial and environmental processes. Among the several anions, phosphate and nitrate ions are highly toxic and harmful to human health and the environment. Herein, we report the porous nature of the cerium incorporated chitosan-β-cyclodextrin (Ce-CS-β-CD) microspheres were prepared and systematically studied for their adsorption performance towards these toxic anions. The connection between the most substantial parameters such as agitating time, adsorbent dosage, co-interfering ions, pH as well as ionic strength with the adsorption percentage and capacity were optimized. The prepared microspheres were broadly characterized by XRD, EDAX with mapping images, SEM, FTIR, and TGA analysis. In the single component system, the adsorption performance showed that multilayer adsorption capacity of 88.54 and 72.12 mg/g for phosphate and nitrate ions respectively. The adsorption of the pseudo-second-order kinetic model showed a superior apt than the pseudo-first-order kinetic model can be effectively defined the uptake of kinetics. The thermodynamic parameters studies shows that the nature of the adsorption is feasible, endothermic and spontaneous nature. The feasible phosphate and nitrate adsorption mechanism of the prepared microspheres were ensued by ion-exchange, complexation and electrostatic interaction. Regeneration and reusability experiments were studied up to seven cycles by 0.1 M of NaOH as a regenerant to assess the reusability of the prepared microspheres. The aptness of Ce-CS-β-CD microspheres has been tested with field condition was investigated with industrial wastewater.

Adsorbent using quaternary amino anion exchanger from agro waste such as corn husk (CHQ) and jackfruit peel (JPQ) were synthesized. The surface positive charges on the adsorbents are used for the removal of nitrate and phosphate ions from aqueous solutions. Batch adsorption parameters such as contact time, initial concentration of nitrate and phosphate solutions, dosage, solution pH, co-existing anions and temperature studies were carried out. Adsorbents were characterized using FT-IR, SEM with EDX, CHNS analyses, etc. In the adsorption isotherms study, Langmuir isotherm was found to be best for both the adsorbates and Q° of nitrate and phosphate ions were 79.09 and 100.01 mg g−1 for CHQ and 62.91 and 72.39 mg g−1 for JPQ resin at 30 °C. Studies on thermodynamic parameters revealed exothermic and spontaneous nature. It is suggested that quaternary amino anion exchanger of JPQ and CHQ are promising cost-effective adsorbents with good removal efficiency.

Phosphate and nitrate ions are emerging trace pollutants and have been perceived in groundwater, surface water, and water sources. In the present work, a layered double hydroxides (LDHs) of the binary composite Zn–Al LDHs wrapped into activated carbon (Banana bract) (BBAC@Zn–Al LDHs) composite was synthesized via co-precipitation method. The prepared adsorbent was evaluated for the removal performance of phosphate and nitrate ions from aqueous medium. The fabricated composite was examined by SEM, XRD, FTIR, TGA-DSC, EDAX with mapping images and BET techniques. The effects of adsorbent dosage, solution pH, shaking time, temperature and co-ions on phosphate and nitrate adsorption have been investigated. Kinetics of the adsorption process was studied using diffusion and reaction-based kinetic models. The equilibrium isotherm study was performed by Freundlich, Dubinin–Radushkevich and Langmuir isotherm models. BBAC@Zn–Al LDHs composite showed good reusability and stability until the five cycles but remained inactive after the seven cycles. The BBAC@Zn–Al LDHs composite and anions interacted via the following possible mechanisms: electrostatic attraction, surface complexation, and ion exchange. This study paved the new route for designing a novel LDHs wrapped porous carbon adsorbent and exposed that as an efficient and low-cost adsorbent to control the phosphate and nitrate pollution in water.

In the present work, lanthanum (III) encapsulated chitosan-montmorillonite composite (La-CS-MMT) was prepared as an adsorbent for the effective removal of phosphate ions from aqueous solution. Characterization of the adsorbent using FT-IR, XRD, SEM with EDX, TGA and DTA techniques were carried out. Batch adsorption experiments were carried out to optimize the effects of various operating parameters viz., shaking time, initial concentration of phosphate ions, dosage, competitor co-existing ions, pH and temperature. Phosphate ions adsorbed effectively on La-CS-MMT composite through hydrogen bonding and by outer-sphere complex formation mechanism. Freundlich isotherm model fit well with the equilibrium isotherm data. The experimental values of ∆G°, ∆S° and ∆H° revealed that the nature of adsorption was feasible, spontaneous and exothermic. The kinetic study was well fitted with pseudo-second-order model. Regeneration study of the spent La-CS-MMT-P composite was carried out upto five cycles and found that about 70% of adsorption efficiency was retained.