Usha Jha

The co‐occurrence of fluoride and arsenate in groundwater is a growing global concern owing to their synergistic adverse effect on human health. Thus, development of materials capable of capturing fluoride and arsenate simultaneously from aqueous medium is of much need. Moreover, it is a matter of great research importance to develop sustainable adsorbents by recycling solid wastes. Keeping this in mind, herein a novel pseudoboehmite nanoparticles (PBN) were synthesized by chemical valorization of disposable waste aluminium pan for simultaneous removal of fluoride and arsenate in aqueous medium. The physicochemical properties of the material were confirmed using analytical techniques such as XRD, BET, FT‐IR, FESEM etc. Batch study confirms the maximum monolayer adsorption of 90.10 mg g ⁻¹ and 94.84 mg g ⁻¹ of fluoride and arsenate respectively, which shows comparable affinity of the material for both contaminants. The selectivity of the adsorbent towards fluoride and arsenate was further evaluated by set of kinetic experiments in both single‐ion and mixture‐ion environment. The synthesis of pseudoboehmite nanomaterial using disposal waste Al pan and its high efficacy for removal of fluoride and arsenic even in presence of competing anionic environments provide a new direction of waste management for sustainable remediation of groundwater contaminants.

This work presents the synthesis of a hybrid core–shell structured Fe(0)@Fe oxide and Mn(0)@Mn oxide (ZVIM) nanocomposite by an ultrasonically assisted hydrothermal process for decontamination of arsenic in groundwater. Our material possesses a unique core–shell structure with zero-valent Fe and Mn in the core encapsulated by a thin layer of their respective oxides. Herein, the synthesized material utilizes the synergetic effect of Mn-oxide layers of zero-valent manganese (ZVM) to oxidize As(III) to As(V) and iron oxide layers of zero-valent iron (ZVI) for sequestration of total arsenic. The maximum adsorption capacity of ZVIM is calculated to be 58.9 mg g⁻¹ and 101.95 mg g⁻¹ for As(III) and As(V), respectively, which is greater than that of the individual zero-valent manganese and zero-valent iron. The uptake kinetics of both As(III) and As(V) show >80% removal within a reaction time of 20 minutes. The adsorption kinetics follow a pseudo-second order model, suggesting the chemisorption nature of the adsorption process. FTIR and XPS analyses reveal the mechanism of surface interaction of the adsorbent with arsenic species. Furthermore, the effectiveness of our adsorbent is revealed by groundwater tests where the final arsenic concentrations in samples were reduced below the WHO limit for drinking water.

This work describes the preparation of core–shell structured zero valent manganese (ZVM) for sequestration of total arsenic from drinking water. The material was synthesized using an ultra-sonication assisted hydrothermal route and the prepared material was characterized by using various analytical techniques such as FTIR, XRD, FE-SEM, EDS, AFM, TEM, TGA-DTA, BET and XPS. A combination of data shows successful fabrication of core–shell structured ZVM which consists of core zero-valent manganese (Mn⁰) encapsulated by layers of manganese oxides (Mn₃O₄–MnO₂). XPS analysis provides information regarding the surface interaction of arsenic species with the adsorbent material. The adsorbent was tested for arsenic removal with variation of the solution parameters in a batch technique. Both As(III) and As(V) could be removed over a wide pH range where the maximum sorption capacity was found to be 30.9 mg g⁻¹ and 72.5 mg g⁻¹ for As(III) and As(V), respectively. It was observed that the sorption kinetics and adsorption isotherm follow a pseudo second order kinetic model and D–R isotherm model, respectively. The presence of co-anions in a competitive environment had little effect on the arsenic removal properties of the material. Moreover, the exceptional arsenic adsorption capacity of ZVM in ground water and high reusability make it a promising adsorbent material in the removal of total arsenic from aqueous solution.

Summary: Alumina has wide applications in industry, automobiles, electrical appliances etc. However its application as biomaterial has started recently. We propose to improve the bio‐physical, bio‐chemical and bio‐medical properties of alumina for its application as biomaterial by nitrogen ion implantation. Alumina is implanted with nitrogen ions at different energies (30 keV to 90 keV) and various ion doses (1 × 10¹⁵ ions/cm² to 5 × 10¹⁷ ions/cm²). The microstructural changes and surface roughness of the specimens are characterized using Optical Microscope, Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM). Nano‐layered compound formation of nitrides & oxynitrides were observed using Glancing angle X‐ray Diffraction (GXRD). Mechanical changes like hardness are studied using nanoindentation method. It is observed that corrosion resistance studied using Electrochemical analyzer (ECA) increases at lower energy and at intermediate ion dose. At higher energy and higher ion doses corrosion resistance deteriorates which is in co‐ordinance with the micrstructural analysis. Bio‐medical characterization of the specimens has been carried out by Wettability and Thrombogenicity tests. Wettability decreases in comparison with unimplanted samples. The thrombogenicity of unimplanted and implanted samples were evaluated using a whole blood kinetic clotting time method. From thrombogenicity test, it is concluded that at lower energy, thrombogenicity increases whereas for higher energy thrombogenicity decreases in comparison with the unimplanted samples. On the basis of all the above studies, best suitable energy and ion‐dose is decided for the hard tissue replacement by alumina.