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The science and interface chemistry between the arsenic (As) anions and the different adsorbent systems have been gaining interest in recent years in environmental remediation applications. Metal-oxides and the corresponding hybrid systems have shown promising performance as novel adsorbents in various treatment technologies. The abundance, surface chemistry, high surface area (active-centres), various synthesis and functionalization methodologies, and good recyclability make these metal oxide-based nanomaterials as potential remediating agents for As oxyanions. This work critically reviews eight different platforms focused on the arsenic contamination issue, where the first classification describes the origin of arsenic contamination and presents geographical and demo-graphical considerations. The following section briefs the state-of-the-art remediation techniques for arsenic treatment with a comparative evaluation. An emphasized discussion has been provided regarding the adsorption and classification of various metal oxide adsorbents. In the next classification, various multi-synergism abilities like Redox activity, Surface functional groups, Surface area/morphology, Heterogeneous catalysis, Reactive oxygen species, Photo-catalytic/electro-catalytic reactions, and Electrosorption are detailed. The classification of various characterization tools for accessing the arsenic remediation qualitatively and quantitatively are given in the fifth chapter. The first-of-its-kind dedicated analysis has been given on the surface complexation aspects of the arsenic speciation onto various metal adsorbent systems using synchrotron results, surface-complexation modeling, and molecular simulation (e.g., DFT) in the sixth chapter. The current sensing applications of these novel nano-material systems for arsenic determination using colorimetric and electrochemical-based analytical tools and a note about the economic parameters, i.e., regeneration aspects of various adsorbent systems/the sustainable applications of the treated sludge materials, are provided in the final sections. This work makes a critical analysis of 'Environmental Nanotechnology' towards 'Arsenic Treatment'., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Arsenic mitigation behavior in aqueous systems is being evaluated for Mn-Al-Fe, Cu-Al-Fe nano adsorbents. Morphological, and vibrational spectroscopy analysis are observed with As-OH, and As-O surface complexes. XPS study of individual As(3d) spectra at different parameters is observed with multiplet peak behavior attributed to redox behavior of Mn-Al-Fe, Cu-Al-Fe. Significant proportions of As(0) signal (∼25 at.% in pH 7, ∼78 at.% in pH 2, ∼58 at.% in pH 12) implicate an environmentally stable behavior of these adsorbents to address the arsenic leaching issue. Adsorption kinetics are observed with Pseudo Second Order (PSO) model, and Freundlich model supported multilayer adsorption behavior is observed for adsorption isotherms. Trace metal voltammetry studies are observed with 75-90 % of As(III) mitigation in aliquot samples. Detailed study of Mn(2p), Cu(2p), Fe(2p), and O(1 s) spectra explains redox active, and surface ligand exchange synergism in arsenic adsorption. Low equilibrium concentrations (Ce < 10 ppb) in As(V) systems (C i ∼ 100 and 500 ppb) indicate the drinking water application of these systems. Cyclic-voltammetry (CV) studies implicate the mitigation and immobilization of arsenic species onto adsorbent by both reduction, and sorption phenomenon., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The present study is about surface complexation behavior of arsenic species adsorbed onto ternary metal oxide adsorbents (Ni-Al-Fe, Co-Al-Fe, Mn-Al-Fe, and Cu-Al-Fe). The analysis is carried out by X-ray absorption spectroscopy (XAS) tool. XANES (μ(E) vs. E) spectra close to the absorption edge (i.e., As K-edge) of all samples are observed along with the As(III) and As(V) standards. The first derivative of XANES for Ni-As(V), and Cu-As(V) samples agree with that of As(V) standards, respectively. Whereas, As(III) adsorbed adsorbent systems (i.e., Ni, Co, Mn, and Cu) are observed with mixed oxidation state of arsenic. A total of 65-85 % is observed with initial oxidation state (As(III) or As(V)), and remaining 15-35 % is observed with modified oxidation state (As(V) or As(III)) that explains the occurrence of possible charge transfer. EXAFS analysis shows the As-O bond distances in the range of 1.7-1.8 Å. The corresponding As-M bond distances are around 2.7, 3.2, and 3.6 Å which confirms the formation various edge sharing ( 2 E), and corner sharing ( 2 C, 1 V) surface complexes. Surface coverage is understood as an important parameter as bidentate attachments ( 2 E, 2 C) are evident in As(III), and As(V), but monodentate attachments ( 1 V) are only observed in As(V)., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Elastic chitosan-gelatin cryogels of varying concentration of polymer precursors have been synthesized using glutaraldehyde as a crosslinking agent. The optimum co-polymer ratio of chitosan to gelatin was found to be 1:4 at the temperature of -12 degrees C for synthesis of chitosan-gelatin hybrid cryogels. chitosan-gelatin cryogels synthesized with low viscosity chitosan were morphologically better than those formed with medium and high viscosity chitosan. Pore diameters of chitosan-gelatin cryogels as measured by scanning electron microscopy (SEM) was in the range of 30-100microm. While mercury porosimetry analysis revealed the majority of pores of the scaffold lying in the range of 30-50microm. Porosity of chitosan-gelatin cryogels was found to be greater than 90% using Archimedes's principle. Unconfined compression tests showed significant elasticity of chitosan-gelatin cryogels and maintained their physical integrity even after compressing them up to 80% of their original length. The elastic modulus varied in the range of 36-39kPa. Cyclic deformation analysis performed by compression of chitosan-gelatin cryogels with varying strains (10, 20 and 40%) showed no cracking or any significant deformation. The degradation of chitosan-gelatin cryogels was found up to 13.58+/-1.52% at 37 degrees C within 8 weeks of incubation under sterile conditions and the cryogels swelled up to 90% of their capacity within two min. Efficient cell adherence, proliferation and extracellular matrix (ECM) secretion was observed by growing fibroblast (Cos-7) cell line on chitosan-gelatin hybrid cryogels which indicate potential of the material for tissue engineering applications.