Chromium (VI) which exists in many industrial wastewater is considered highly toxic. The aim of the present investigation was to study the reduction of chromium (VI) to chromium (III) and then removing it with the help of weathered basalt andesite products. Reduction of the chromium (VI) to chromium (III) by hydrazinium sulfate was investigated. The influence of hydronium ion concentration, contact time, hydrazinium sulphate dosage and temperature has been tested in batch runs. The process was found to be acid, temperature and concentration dependent. The suitability of weathered basalt andesite products as a potential sorbent was assessed for the removal of chromium (III) following batch mode of operation. The effect of various parameters such as hydronium ion concentration, shaking time, sorbent dose, initial metal ion concentration and temperature on the removal of chromium (III) from aqueous solution was studied. Thermodynamic parameters (∆H°, ∆S° and ∆G°) for the sorption process were evaluated. Analysis of sorption obtained results showed that the sorption pattern followed the Freundlich, Langmuir and Dubinin-KaganerRadushkevich isotherms. The process follows pseudo second order rate and surface diffusion is identified as the predominating mechanism. The sorption process was shown to be reversible by the recovery of sorbed chromium (III) upon extraction with 0.5 M nitric acid. The sorbent, before and after sorption, was characterized by fourier transform infrared spectrometer, X-ray diffraction, scanning electron microscope, transmision electron microscope and thermogravimetric analyse methodes. An increase in crystallanity after sorption of chromium was observed. An industrial effluent was successfully treated with the same sorbent with convincing results.

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A chelating ion exchange resin was synthesized from 8-hydroxyquinoline and catechol using formaldehyde as a cross linking agent at 120 ± 2 ºC in DMF solution. The resin was characterized by FTIR and elemental analysis. The morphology of the synthesized resin was studied by optical photograph and scanning electron microscopy (SEM). Various kinetic parameters such as energy of activation (E a ), enthalpy of activation (H ‡ ), entropy of activation (S ‡ ), free energy of activation (G ‡ ), order of reaction (n) and pre-exponential factor (A) of various steps of thermal decomposition have been calculated from thermogravimertic results. The physico-chemical properties of the resin have been studied. The total cation exchange capacity was measured and effect of pH and metal ion concentration on ion exchange capacity were studied. The rate of cation exchange reactions and distribution coefficient values in tartaric acid media at different pH were also studied using batch equilibration method.

The suitability of weathered basaltic andesite products (WBAP) as a potential sorbent was assessed for the removal of Ni (II) from electroplating industrial wastewater. A model study based on the batch mode of operation was carried out for Ni (II) removal from aqueous solution. The effect of various parameters such as hydronium ion concentration, shaking time, sorbent dose, initial Ni (II) concentration, and temperature on the sorption process was studied. At optimised conditions of the various parameters, the industrial wastewater loaded with Ni (II) was sorbed onto WBAP. Thermodynamic parameters for the sorption process were evaluated. Freundlich, Langmuir, Temkin, and Dubinin-Kaganer-Radushkevich isotherms were applied to the sorption pattern on the WBAP. The sorption dynamics of the process was evaluated by applying Lagergren, Bangham, and Weber & Morris equations. The sorption process follows Pseudo-second-order rate of surface diffusion which is identified as the predominating mechanism. The sorption process was found to be reversible by the recovery of sorbed Ni (II) upon extraction with 0.5 MHNO3. The sorbent before and after sorption, was characterized by Fourier transform infrared (FTIR), Powder X-Ray diffraction PXRD), and Thermogravimetric analysis (TGA) methods. The change in surface morphology and crystallanity of the mineral after sorption was analyzed by Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). Based on the previous model study, an electroplating industrial effluent was successfully treated with WBAP to minimize the pollution load caused by Ni (II).