Self-Template Etching Synthesis of Urchin-Like Fe3O4 Microspheres for Enhanced Heavy Metal Ions Removal

Hierachical Fe₃O₄ microspheres with superparamagnetic properties are attractive for their superior structural, water-dispersible, and magnetic separation merits. Here self-template etching route was developed to create optimal porous structure in superparamagnetic Fe₃O₄ microspheres by using the oxalic acid (H₂C₂O₄) as etching agent. A plausible formation mechanism of the urchin-like Fe₃O₄ microspheres was proposed based on systematic investigation of the etching process, which involved two stages including pore-forming step based on size-selective etching and pore-expanding step based on further etching. The as-synthesized Fe₃O₄ microspheres exhibited urchin-like structure with specific surface area and pore-size tunable, water-dispersible, and superparamagnetic properties. The optimal urchin-like Fe₃O₄ microspheres demonstrated superior performance including fast magnetic separation and high removal capabilities for the heavy metals ions like Pb²⁺ (112.8 mg g^-1) and Cr(VI) (68.7 mg g^-1). This work will shed new light on the synthesis of urchin-like microspheres for superior performance.

Arsenic removal from water/wastewater using layered double hydroxide derived adsorbents, a critical review

Arsenic pollution has become a worldwide environmental concern. Dangerous arsenic concentrations in natural waters threaten the health of millions of people, and this has received significant attention. Among the various technologies that have been developed for arsenic removal from water, the use of adsorption technology is considered to be a prevailing method, because the adsorption approach usually has high removal efficiency and the advantage of convenience of handling. In recent years, layered double hydroxides (LDHs) have become prime candidates for arsenic removal, due to their hydrophilic nature and cationic layered structures. Research on arsenic removal using LDHs is mainly focused on (1) the influence of the synthesis method and composition of the LDH, (2) the influence of the particle size of the LDH, (3) the influence of the Mg/Al ratio in LDHs, (4) LDH-based hybrids and (5) the competition with other anions. This paper provides a review of the currently available literature focusing on arsenic removal using LDHs for the five parts mentioned above. In addition, based on this overview, a closing section will suggest research efforts for future work. It is expected that this review will provide a summary of the main research in this area, and will also shed light on the direction of future development.

Performance of synthesized cast and electrospun PVA/chitosan/ZnO-NH2 nano-adsorbents in single and simultaneous adsorption of cadmium and nickel ions from wastewater

The performance of synthesized cast and electrospun polyvinyl alcohol/chitosan/zinc oxide/aminopropyltriethoxylsilane (PVA/chitosan/ZnO-APTES) nano-adsorbents were compared in removal of Cd(II) and Ni(II) ions from wastewater. The adsorbents were characterized by SEM, BET, FTIR and TGA analyses. Furthermore, the swelling investigations were carried out to study the adsorbent stability in aqueous solution. The effect of several parameters such as contents of ZnO-NH₂, contact time, initial Cd(II) and Ni(II) concentration and temperature on the adsorption capacity was investigated in a batch mode. In comparison with cast adsorbent, nanofiber adsorbent indicated the better adsorption performance. The experimental data well fitted the double-exponential kinetic model. In single metal ion system, the maximum adsorption capacity of nanofiber for Cd(II) and Ni(II) ions is estimated to be 1.239 and 0.851 mmol/g, respectively, much higher than q_m of cast adsorbent for Cd(II) (0.625 mmol/g) and Ni(II) (0.474 mmol/g) ions. Thermodynamic parameters were investigated to identify the nature of adsorption process. In binary system of Cd(II)-Ni(II) ions, the inhibitory effect of competitive Cd(II) ion on the Ni(II) adsorption was greater than the inhibitory effect of competitive on the Cd(II) adsorption. The selectivity adsorption of both nanofiber and cast adsorbents was in order of Cd(II) > Ni(II).

Solid-liquid separation: an emerging issue in heavy metal wastewater treatment

Solid-liquid separation (SLS) plays a dominant role in various chemical industries. Nowadays, low efficiency of SLS also become a significant problem in heavy metal (HM) wastewater treatment, affecting the effluent quality (HM concentration and turbidity) and overall process economy. In this context, we summarize here the occurrence of solids in HM wastewater, as well as typical SLS operations used in HM wastewater treatment, including sedimentation, flotation, and centrifugation. More important, this article reviews the improvement of the SLS operations by some technologies, including coagulation, flocculation, ballasted method, seeding method, granular sludge strategy, and external field enhancement. It is noted that abiological granular sludge strategy and magnetic field enhancement often possess higher SLS efficiency (faster settling velocity or shorter separation time) than other methods. Hence, the two strategies stand out as promising tools for improving SLS in HM wastewater treatment, but further research is required regarding scalability, economy, and reliability.

Preparation of Functionalized Magnetic Fe₃O₄@Au@polydopamine Nanocomposites and Their Application for Copper(II) Removal

Polydopamine (PDA) displays many striking properties of naturally occurring melanin in optics, electricity, and biocompatibility. Another valuable feature of polydopamine lies in its chemical structure that incorporates many functional groups such as amine, catechol and imine. In this study, a nanocomposite of magnetic Fe₃O₄@Au@polydopamine nanopaticles (Fe₃O₄@Au@ PDA MNPs) was synthesized. Carboxyl functionalized Fe₃O₄@Au nanoparticles (NPs) were successfully embedded in a layer of PDA through dopamine oxypolymerization in alkaline solution. Through the investigation of adsorption behavior to Cu(II), combined with high sensitive electrochemical detection, the as-prepared magnetic nanocomposites (MNPs) have been successfully applied in the separation and analysis of Cu(II). The experimental parameters of temperature, Cu(II) concentration and pH were optimized. Results showed that the as-prepared MNPs can reach saturation adsorption after adsorbing 2 h in neutral environment. Furthermore, the as-prepared MNPs can be easily regenerated by temperature control and exhibits a good selectivity compared to other metal ions. The prepared Fe₃O₄@Au@PDA MNPs are expected to act as a kind of adsorbent for Cu(II) deep removal from contaminated waters.

A review of functionalized carbon nanotubes and graphene for heavy metal adsorption from water: Preparation, application, and mechanism

Carbon-based nanomaterials, especially carbon nanotubes and graphene, have drawn wide attention in recent years as novel materials for environmental applications. Notably, the functionalized derivatives of carbon nanotubes and graphene with high surface area and adsorption sites are proposed to remove heavy metals via adsorption, addressing the pressing pollution of heavy metal. This critical revies assesses the recent development of various functionalized carbon nanotubes and graphene that are used to remove heavy metals from contaminated water, including the preparation and characterization methods of functionalized carbon nanotubes and graphene, their applications for heavy metal adsorption, effects of water chemistry on the adsorption capacity, and decontamination mechanism. Future research directions have also been proposed with the goal of further improving their adsorption performance, the feasibility of industrial applications, and better simulating adsorption mechanisms.

Magnetite and Green Rust: Synthesis, Properties, and Environmental Applications of Mixed-Valent Iron Minerals

Mixed-valent iron [Fe(II)-Fe(III)] minerals such as magnetite and green rust have received a significant amount of attention over recent decades, especially in the environmental sciences. These mineral phases are intrinsic and essential parts of biogeochemical cycling of metals and organic carbon and play an important role regarding the mobility, toxicity, and redox transformation of organic and inorganic pollutants. The formation pathways, mineral properties, and applications of magnetite and green rust are currently active areas of research in geochemistry, environmental mineralogy, geomicrobiology, material sciences, environmental engineering, and environmental remediation. These aspects ultimately dictate the reactivity of magnetite and green rust in the environment, which has important consequences for the application of these mineral phases, for example in remediation strategies. In this review we discuss the properties, occurrence, formation by biotic as well as abiotic pathways, characterization techniques, and environmental applications of magnetite and green rust in the environment. The aim is to present a detailed overview of the key aspects related to these mineral phases which can be used as an important resource for researchers working in a diverse range of fields dealing with mixed-valent iron minerals.

Simultaneous removal of tetracycline and Cu(ii) by adsorption and coadsorption using oxidized activated carbon

The enhanced coadsorption of TC and Cu(ii) was likely due to the formation of a TC–Cu(ii) complex bridging.

Silica based inorganic–organic hybrid materials for the adsorptive removal of chromium

We employed polymer functionalized silica gel as an adsorbent for the removal of Cr(vi) from water. The chains of 2-aminoethyl methacrylate hydrochloride (AEMA·HCl) polymer were grown from the surface of silica gel via surface-initiated conventional radical polymerization and the resulting hybrid material exhibited high affinity for chromium(vi). To investigate the adsorption behavior of Cr(vi) on diverse polymer based hybrid materials, the removal capacity of (SG-AEMH) was compared with our previously reported branched polyamine functionalized mesoporous silica (MS-PEI). The adsorption capacities of polymer based materials were also compared with their respective monolayer based platforms comprising a 3-aminopropyltriethoxysilane (APTES) functionalized silica gel (SG-APTES) and mesoporous silica (MS-APTES). The polymer based systems showed excellent Cr(vi) adsorption efficiencies compared to monolayer counterparts. The structural characteristics and surface modification of these adsorbents were examined by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The experimental data were analyzed using the Langmuir and Freundlich models. Correlation coefficients were determined by analyzing each isotherm. The kinetic data of adsorption reactions were described by pseudo-first-order and pseudo-second-order equations. Thermodynamic parameters, i.e., change in the free energy (ΔG°), the enthalpy (ΔH°), and the entropy (ΔS°), were also evaluated. The synthesized hybrid materials exhibited a high adsorption capacity for chromium ions. Furthermore, they could be regenerated and recycled effectively.

We employed and compared polymer functionalized silica gel and mesoporous silica as adsorbents for the removal of Cr(vi) from water.

An eco-friendly approach for heavy metal adsorbent regeneration using CO2-responsive molecular octopus

Perennial problems of adsorption in wastewater treatment include adsorbent recycling, generation of waste sludge and secondary pollution because harmful concentrated acids, bases or strong chelators are often used for adsorbent regeneration and adsorbate recovery. We report, for the first time, an eco-friendly regeneration concept demonstrated with a CO₂-responsive octopus-like polymeric adsorbent. Various heavy metals can be scavenged at very high Q_e by such adsorbent through coordination. Most importantly, the rapid and complete regeneration of the adsorbent and recovery of the heavy metal ions can be readily achieved by CO₂ bubbling within a few minutes under mild conditions, i.e., room temperature and atmospheric pressure. The adsorbent can then be restored to its adsorptive state and reused upon removal of CO₂ by simply bubbling another gas. This eco-friendly, effective, ultra-fast and repeatable CO₂-triggered regeneration process using CO₂-responsive adsorbent with versatile structure, morphology or form can be incorporated into a sustainable closed-loop wastewater treatment process to solve the perennial problems.

Highly Efficient Water Decontamination by Using Sub-10 nm FeOOH Confined within Millimeter-Sized Mesoporous Polystyrene Beads

Millimeter-sized polymer-based FeOOH nanoparticles (NPs) provide a promising option to overcome the bottlenecks of direct use of NPs in scaled-up water purification, and decreasing the NP size below 10 nm is expected to improve the decontamination efficiency of the polymeric nanocomposites due to the size and surface effect. However, it is still challenging to control the dwelled FeOOH NP sizes to sub-10 nm, mainly due to the wide pore size distribution of the currently available polymeric hosts. Herein, we synthesized mesoporous polystyrene beads (MesoPS) via flash freezing to assemble FeOOH NPs. The embedded NPs feature with α-crystal form, tunable size ranging from 7.3 to 2.0 nm and narrow size distribution. Adsorption of As(III/V) by the resultant nanocomposites was greatly enhanced over the α-FeOOH NPs of 18 × 60 nm, with the iron mass normalized capacity of As(V) increasing to 10.3 to 14.8 fold over the bulky NPs. Higher density of the surface hydroxyl groups of the embedded NPs as well as their stronger affinity toward As(V) was proved to contribute to such favorable effect. Additionally, the as-obtained nanocomposites could be efficiently regenerated for cyclic runs. We believe this study will shed new light on how to fabricate highly efficient nanocomposites for water decontamination.

Self-Assembled Exopolysaccharide Nanoparticles for Bioremediation and Green Synthesis of Noble Metal Nanoparticles

Continuing efforts have been made to explore novel exopolysaccharides (EPSs) for valuable applications. In this research, we report for the first time that a novel non-glucan EPS named EPS-605 can self-assemble to form spherical nanosize particles of ∼88 nm in diameter, expanding both the range of EPS type and structural type that EPSs self-assemble into. Characterization of EPS-605 shows that it is composed of mannose, glucose, and galactose with several modifications including acylation, phosphorylation, sulfation, and carboxylation, and a highly negative charge. EPS-605 showed a record biosorption capability for Pb²⁺, Cu²⁺, Cd²⁺, and methylene blue as compared to that of other reported EPSs, biosorbents, and nanosorbents. The adsorption ability of EPS-605 is affected by pH, temperature, the initial adsorbate concentration, the contact time, and the presence of background electrolytes. The mechanism of EPS-605 adsorbing heavy metals seems to be different to that for dyes. Moreover, EPS-605 can serve as the reductant in the synthesis of Au nanoparticles (AuNPs) and AgNPs enabling good monodispersity within the shortest time (of 30 min) compared to that from other EPSs and without any extra pretreatment. Our research advances the development of novel EPSs and provides a new, eco-friendly, and renewable platform for both the bioremediation and green synthesis of nanomaterials.

Graphene-Supported Spinel CuFe₂O₄ Composites: Novel Adsorbents for Arsenic Removal in Aqueous Media

A graphene nanoplate-supported spinel CuFe₂O₄ composite (GNPs/CuFe₂O₄) was successfully synthesized by using a facile thermal decomposition route. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Electron Dispersive Spectroscopy (EDS), X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the prepared composite. The arsenic adsorption behavior of the GNPs/CuFe₂O₄ composite was investigated by carrying out batch experiments. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, where the sorption kinetics of arsenic adsorption by the composite were found to be pseudo-second order. The selectivity of the adsorbent toward arsenic over common metal ions in water was also demonstrated. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled column filter test. The GNPs/CuFe₂O₄ composite exhibited significant, fast adsorption of arsenic over a wide range of solution pHs with exceptional durability, selectivity, and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solution. The highly sensitive adsorption of the material toward arsenic could be potentially employed for arsenic sensing.

Review on nanoadsorbents: a solution for heavy metal removal from wastewater

Elimination of heavy metals from contaminated streams is of prime concern due to their ability to cause toxic chaos with the metabolism of flora and fauna alike. Use of advanced nano-engineered technologies such as the innovative combination of surface chemistry, chemical engineering fundamentals and nanotechnology opens up particularly attractive horizons towards treatment of heavy metal contaminated water resources. The obtained product of surface engineered nanoadsorbent produced has successfully proven to show rapid adsorption rate and superior sorption efficiency towards the removal of a wide range of defiant heavy metal contaminants in wastewater. The use of these materials in water treatment results in markedly improved performance features like large surface area, good volumetric potential, extra shelf-lifetime, less mechanical stress, stability under operational conditions with excellent sorption behaviour, no secondary pollution, strong chelating capabilities and they are easy to recover and reuse. This review intends to serve as a one-stop-reference by bringing together all the recent research works on nanoparticles synthesis and its advantages as adsorbents in the treatment of heavy metal polluted wastewater that have so far been undertaken, thereby providing researchers with a deep insight and bridging the gap between past, present and future of the elegant nanosorbents.

Amorphous boron-doped sodium titanates hydrates: Efficient and reusable adsorbents for the removal of Pb2+ from water

Amorphous titanium hydroxide and boron-doped (B-doped) sodium titanates hydrates were synthetized and used as adsorbents for the removal of Pb²⁺ from water. The use of sodium borohydride (NaBH₄) and titanium(IV) isopropoxide (TTIP) as precursors permits a very easy synthesis of B-doped adsorbents at 298K. The new adsorbent materials were first chemically characterized (XRD, XPS, SEM, DRIFT and elemental analysis) and then tested in Pb²⁺ adsorption batch experiments, in order to define kinetics and equilibrium studies. The nature of interaction between such sorbent materials and Pb²⁺ was also well defined: besides a pure adsorption due to hydroxyl interaction functionalities, there is also an ionic exchange between Pb²⁺ and sodium ions even working at pH 4.4. Langmuir model presented the best fitting with a maximum adsorption capacity up to 385mg/g. The effect of solution pH and common ions (i.e. Na⁺, Ca²⁺ and Mg²⁺) onto Pb²⁺ sorption were also investigated. Finally, recovery was positively conducted using EDTA. Very efficient adsorption (>99.9%) was verified even using tap water spiked with traces of Pb²⁺ (50ppb).

Synthetically modified nano-cellulose for the removal of chromium: a green nanotech perspective

Existing processes for the decontamination of heavy metals from water are found to be cost-prohibitive and energy-intensive which is totally against the sustainable concept of development. Green nanotechnology for water purification for ecosystem management, agricultural and industry is an emerging as leading global priority and occupies better position over the current state of water purification. Herein, the diafunctionalised polyaniline modified nanocellulose composite sorbent (PANI-NCC) has been used to introduce amine and imine functionalities for the removal of trivalent and hexavalent chromium from water bodies. The fabricated nanobiomaterial has been authenticated by modern spectroscopic, microscopic techniques. The modified PANI-NCC is rod-like in shape, ~60 nm in size. The roughness and crystallinity index is also quantified and found to be 49.67 nm and 84.18%, respectively. The optimised experimental finding provides the efficient removal of trivalent [Cr(III)] (47.06 mg/g; 94.12%) and hexavalent [Cr(VI)] (48.92 mg/g; 97.84%) chromium from synthetic waste water. The fabricated nano biosorbent is deemed to be a potent biosorbent for technological development to remove the toxic metals in the real environmental water samples.

Fabrication of a GNP/Fe-Mg Binary Oxide Composite for Effective Removal of Arsenic from Aqueous Solution

Graphene nanoplates (GNPs) can be used as a platform for homogeneous distribution of adsorbent nanoparticles to improve electron exchange and ion transport for heavy-metal adsorption. In this study, we report a facile thermal decomposition route to fabricate a graphene-supported Fe-Mg oxide composite. The prepared composite was characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. Batch experiments were carried out to evaluate the arsenic adsorption behavior of the GNP/Fe-Mg oxide composite. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, in which the sorption kinetics of the arsenic adsorption process by the composite was found to be pseudo-second-order. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled-column filter test. The GNP/Fe-Mg oxide composite exhibited significant fast adsorption of arsenic over a wide range of solution pHs, with exceptional durability and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solutions.

Preparation of dithiocarbamate polymer brush grafted nanocomposites for rapid and enhanced capture of heavy metal ions

A core-brush nanocomposite for rapid and enhanced adsorption of heavy metal ions was explored by combining SI-ATRP and DTC functionalization.

Removal of Cd(ii) and Pb(ii) ions from natural water using a low-cost synthetic mineral: behavior and mechanisms

A low-cost synthetic mineral (LCSM) was prepared by mechanochemical treatment of a solid-state mixture containing potassium feldspar, wollastonite, gypsum, limestone and dolomite powder at a molar ration of 1 : 1 : 1 : 6 : 3 and hydration process.

Synthesis of chelating polyamine fibers and their adsorption properties for nickel(ii) ions from aqueous solution

In this work, a novel fibrous material PA–PVAF has been prepared. In the adsorption experiments of Ni(ii), the fibrous material PA–PVAF showed excellent adsorption performance, which can be used as a promising adsorbent.

A microscopic and spectroscopic study of rapid antimonite sequestration by a poorly crystalline phyllomanganate: differences from passivated arsenite oxidation

Surface passivation during the adsorption of Mn(ii) and the formation of Mn(iii) was the predominant cause for the decrease in the As(iii) oxidation rate, whereas it may not have been the limiting factor during Sb(iii) oxidation.

Effective removal of Pb(ii) using a graphene@ternary oxides composite as an adsorbent in aqueous media

A one-pot hydrothermal method to prepare a graphene@Fe–Mg–Cu ternary oxide composite and the proposed adsorption mechanism for removal of Pb(ii) ions.

Study on the performance of micro-flow injection preconcentration method on-line coupled to thermospray flame furnace AAS using MWCNTs wrapped with polyvinylpyridine nanocomposites as adsorbent

An adsorbent nanocomposite based on multi-walled carbon nanotubes and polyvinylpyridine is used in the development of a micro-flow injection preconcentration method coupled to TS-FF-AAS for the determination of very low levels of Cd.

Quasi-reverse-emulsion-templated approach for a facile and sustainable environmental remediation for cadmium

Highly efficient and sustainable decontamination of heavy metal ions is achieved by nanostructured hierarchical hollow α-Fe₂O₃ chestnut buds and nests.

An arginine functionalized magnetic nano-sorbent for simultaneous removal of three metal ions from water samples

The feasibility of using eco-friendly biodegradable arginine functionalized magnetic nanoparticle entrapped chitosan beads (AFMNPECBs) for simultaneous removal of three metal ions from water samples was evaluated under different conditions.

Modeling packed bed sorbent systems with the Pore Surface Diffusion Model: Evidence of facilitated surface diffusion of arsenate in nano-metal (hydr)oxide hybrid ion exchange media

This study explores the possibility of employing the Pore Surface Diffusion Model (PSDM) to predict the arsenic breakthrough curve of a packed bed system operated under continuous flow conditions with realistic groundwater, and consequently minimize the need to conduct pilot scale tests. To provide the nano-metal (hydr)oxide hybrid ion exchange media's performance in realistic water matrices without engaging in taxing pilot scale testing, the multi-point equilibrium batch sorption tests under pseudo-equilibrium conditions were performed; arsenate breakthrough curve of short bed column (SBC) was predicted by the PSDM in the continuous flow experiments; SBC tests were conducted under the same conditions to validate the model. The overlapping Freundlich isotherms suggested that the water matrix and competing ions did not have any denoting effect on sorption capacity of the media when the matrix was changed from arsenic-only model water to real groundwater. As expected, the PSDM provided a relatively good prediction of the breakthrough profile for arsenic-only model water limited by intraparticle mass transports. In contrast, the groundwater breakthrough curve demonstrated significantly faster intraparticle mass transport suggesting to a surface diffusion process, which occurs in parallel to the pore diffusion. A simple selection of DS=1/2 DP appears to be sufficient when describing the facilitated surface diffusion of arsenate inside metal (hydr)oxide nano-enabled hybrid ion-exchange media in presence of sulfate, however, quantification of the factors determining the surface diffusion coefficient's magnitude under different treatment scenarios remained unexplored.

Ion exchange induced removal of Pb(ii) by MOF-derived magnetic inorganic sorbents

Nanoporous adsorbents of ZnO/ZnFe2O4/C were synthesized by using a metal organic framework (Fe(III)-modified MOF-5) as both the precursor and the self-sacrificing template. The adsorption properties of ZnO/ZnFe2O4/C toward Pb(ii) ions were investigated, including the pH effect, adsorption equilibrium and adsorption kinetics. The adsorption isotherms and kinetics were well described by using the Langmuir isotherm model and pseudo-second-order model, respectively. The MOF-derived inorganic adsorbents exhibited high absorption performance with a maximum adsorption capacity of 344.83 mg g(-1). X-ray powder diffraction and high-resolution X-ray photoelectron spectroscopy suggest that Zn(ii) was substituted by a significant portion of Pb(ii) on the surface of ZnO nanocrystals. Microscopic observations also demonstrate the effect of Pb(ii) ions on ZnO crystals as reflected by the considerably reduced average particle size and defective outer layer. Quantitative measurement of the released Zn(ii) ions and the adsorbed Pb(ii) ions indicated a nearly linear relationship (R(2) = 0.977). Moreover, Pb-containing ZnO/ZnFe2O4/C adsorbents are strongly magnetic allowing their separation from the water environment by an external magnet.

Aluminum substituted nickel ferrite (Ni–Al–Fe): a ternary metal oxide adsorbent for arsenic adsorption in aqueous medium

In this article synthesis and characterization of ternary metal oxide of aluminum substituted nickel ferrite and its adsorption capability for arsenic [(As(iii)) and (As(v))] species have been reported.

Adsorptive removal of Ni(ii) ions from aqueous solution and the synthesis of a Ni-doped ceramic: an efficient enzyme carrier exhibiting enhanced activity of immobilized lipase

We report the successful removal of Ni²⁺ from aqueous solution via entrapment by chitosan nanoparticles, followed by calcination with a ceramic matrix to construct a novel carrier for lipase immobilization with enhanced activity.

Etching synthesis of iron oxide nanoparticles for adsorption of arsenic from water

Nano-iron oxide prepared by an etching method is good adsorbent for arsenic removal from water.

Quaternary ammonium bearing hyper-crosslinked polymer encapsulation on Fe3O4 nanoparticles

Crosslinked anionic polymer encapsulation formed on Fe₃O₄ nanoparticles has been found to be selective towards the least hydrated competing anions.

Surfactant modification of banana trunk as low-cost adsorbents and their high benzene adsorptive removal performance from aqueous solution

The banana trunk was modified using different surfactants (cationic, anionic and non-ionic surfactants), such as ​CTAB, SDS, Pluronic 123, and Triton X-100 to develop a novel low-cost adsorbent for benzene removal from aqueous solution.