A novel type of adsorbent, TiO2 impregnated pomegranate peels (PP@TiO2) was successfully synthesized and its efficacy was investigated based on the removal of As(III) from water. The adsorbent was characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometer (EDS), X-ray Diffraction (XRD) analysis, and Fourier Transform Infrared (FTIR) Spectroscopy, to evaluate its morphology, elemental analysis, crystallinity, and functional groups, respectively. Batch experiments were conducted on PP@TiO2 for As(III) adsorption to assess the adsorption isotherm, effect of pH, and adsorption kinetics. Characterization data suggested that TiO2 was successfully impregnated on the biomass substrate. The equilibrium data better fitted to the Langmuir isotherm model having a maximum adsorption capacity of 76.92 mg/g and better distribution coefficients (KD) in the order of ~103 mL/g. The highest percentage of adsorption was found at neutral pH. The adsorption kinetics followed the pseudo-2nd-order model. X-ray Photoelectron Spectroscopy (XPS) of the adsorption product exhibited that arsenic was present as As(III) and partially oxidized to As(V). PP@TiO2 can work effectively in the presence of coexisting anions and could be regenerated and reused. Overall, these findings suggested that the as-prepared PP@TiO2 could provide a better and efficient alternative for the synergistic removal of As(III) from water.

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Hexavalent chromium (Cr(VI)) is a critical pollutant with high toxicity, even at trace concentrations. Cr(VI) is possibly carcinogenic and mutagenic and can produce serious health issues. Hence, it is necessary to remove Cr(VI) from the water before releasing it into the environment. Currently, numerous removal techniques were used. Adsorption is the best method compared to others because it is simple, cheap, highly efficient, and can be used in water having trace concentrations of contaminants. Biomass-based waste materials (BMWs) are found as far better adsorbents than commercially and other available adsorbents. In this study, the existing Cr(VI) removal techniques are reviewed and, a broad range of current research studies of Cr(VI) removal from water by using BMWs are evaluated. This review can be helpful to develop a more efficient, cheap, reliable, and environmentally benign bio-adsorbent. It is obvious after the literature review given herein that BMWs exhibited potential adsorbents for the removal of Cr(VI). Also, the chemically modified adsorbents exhibited a higher adsorption capacity than unmodified adsorbents.

Cuprous oxide nanoparticles were synthesized by the reduction of copper sulphate pentahydrate salt at different concentration using sodium borohydride as a reducing agent, polyethylene glycol-6000 as a stabilizer by simple, chemical co-precipitation methods and the effect of concentration on particle size were also studied. The crystalline size and phase of Cu2O nanoparticles (NPs) were authenticated by X-ray diffraction (XRD), morphology and structure by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and elemental analysis was carried out by energy-dispersive X-ray spectroscopy (EDX). The concentration-dependent antimicrobial properties of Cu2O NPs were studied for a different strain of bacteria. XRD and selected area electron diffraction studies (SAED) patterns confirmed the formation of face-centered-cubic Cu2O nanoparticles with size 4.77 nm and 8.02 nm at two different concentrations of 0.01 M and 0.1 M CuSO4, respectively. SEM and TEM images showed that the nanoparticles were uniform, in the form of clusters, and homogeneously distributed. EDX confirmed that synthesized nanoparticles were in pure form having copper and oxygen ratio 3:1 based on the atomic percentage of the chemical species. Cu2O nanoparticles showed excellent antibacterial activity against both bacterial strains Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli). The antibacterial activities of Cu2O NPs were found to be concentration-dependents and large bactericidal effect were seen for Gram-positive (Staphylococcus aureus) bacteria at higher concentrations of Cu2O NPs.

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