PREPARATION AND CHARACTERISATION OF PLANTAIN WASTE BASED CELLULOSIC NANOCOMPOSITES FOR THE REMOVAL OF SELECTED HEAVY METALS FROM BATTERY EFFLUENT

Abstract

In this study, Ag NPs and Ag-CNCs impregnated on CNTs nano adsorbents were developed using a combination of green chemistry protocol and chemical vapor deposition techniques and subsequently characterized using, HRTEM, HRSEM, XRD, EDS and SAED. The adsorption capability of silver-carbon nanotubes (Ag-CNTs) and silver-cellulose nanocrystals are modified multiwalled carbon nanotube (Ag-CNTs-CNCs), the nanocomposites are for rapid and efficient removal of selected heavy metals (Fe, Cu, Ni, Zn and Pb) as well as analysis of physico-chemical parameters such as, pH, total dissolved solids (TDS), chemical oxygen demand (COD), biochemical oxygen demand (BOD), nitrates, sulphates, and chlorides from battery effluent using a batch process. The aim of the study is the preparation and characterization of plantain waste based cellulosic nanocomposites for the removal of selected heavy metals from battery effluent. The result showed successful deposition of Ag and the grafting of CNCs into the matrix of CNTs as confirmed by the microstructures, morphology, crystalline nature, and elemental characteristics of the Ag-CNTs-CNCs. Optimum batch adsorption parameters include; contact time (90 min) and adsorbent dosage (0.03 g) for Ag-CNTs and contact time (90 min), adsorbent dosage of (0.02 g) for Ag-CNTs-CNCs. The adsorption capacities were obtained as follows; Fe2+ (105.263 mg/g), Cu2+ (238.095 mg/g) Ni2+ (166.667 mg/g), Zn2+ (121.951 mg/g) and Pb2+ (119.048 mg/g), for Ag-CNTs. Langmuir isotherm and pseudo-second order kinetic model best described the experimental data in the batch adsorption with Ag-CNTs adsorbent. The adsorption capacities using the Ag-CNTs-CNCs adsorbent were obtained as follows; Fe2+ (200.000 mg/g), Cu2+ (263.158 mg/g) Ni2+ (238.095 mg/g), Zn2+ (169.492) and Pb2+ (181.818mg/g), with a higher adsorption capacity following more physical adsorption, electrostatic interactions and surface complexation. On the contrary, the Freundlich isotherm and pseudo-second order kinetic model best described the experimental data in batch adsorption for Ag-CNTs-CNCs, which validated the chemisorption and multilayered nature of the adsorption process. The high physico-chemical parameters in the effluent were successfully analyzed in the batch systems to fall within WHO permissible concentrations. This study establishes that Ag-CNTs-CNCs is efficient for the treatment of industrial effluent when compared to Ag-CNTs.