INVESTIGATION OF LAYERED DOUBLE HYDROXIDES AND COMPOSITE MATERIALS WITH EMPHASIS ON OPTICAL PROPERTIES AND ENVIRONMENTAL ASPECTS

Abstract

The thesis mainly focuses on the low-temperature synthesis of layered double hydroxides (LDH) and their composite materials, with emphasis on optical properties and environmental aspects. Different spectroscopic techniques, i.e., PXRD, FTIR, TGA, SEM/EDX, XPS, and BET were adopted for the detailed characterization of synthesized materials. The potential application of synthesized Zn/Cu LDH for the selective and efficient removal of anionic azo dyes (CR, EBT, and MO) from synthetic and real wastewater samples was carried out and a statistical tool was employed for optimizing the process parameters involved during adsorption to get maximum efficiency. In addition, the Layered double oxide (LDO) obtained upon calcination of LDH acts as an efficient adsorbent and demonstrated high removal efficiency of 128.20 mg/g for cationic dye (Malachite green was selected as model dye). Furthermore, a smartphone-based detection technique was employed for the determination of dye concentration and the results obtained were found to be in accordance with the data obtained using UV-vis spectrophotometric analysis. Additionally, the present work summarizes the synthesis of EG-modified Zn/Cu hydroxy double salt and its adsorption behavior towards the sequestration of Congo red dye. The regeneration experiments performed revealed that the adsorbent can be efficiently reused for up to 5 regeneration cycles. Furthermore, the composites of PMMA and Polystyrene (PS) with Zn/Cu LDH were also synthesized. The PMMA/LDH composite was used as an adsorbent for the removal of food dye (brilliant black BN) and the isotherm as well as kinetics of the adsorption process were studied using different equilibrium and kinetic models. However, PS/LDH composite films showed enhanced thermal, morphological, and optical properties upon the incorporation of LDH into the polymeric matrix. The structure regaining capability, i.e., memory effect and anion ix exchange properties of Zn/Cu LDH were also studied where PANI was incorporated into the interlayer region of synthesized LDH. The PXRD, FTIR, TGA, and SEM/EDX results confirmed that the lattice demonstrated structure regaining capability as well as incorporation of PANI in interlayer region.