Optimisation and application of plant-based waste materials for the remediation of selected trace metals (Cd, Pb and Mn) and Oxyhalides (Bro3, CIO3 and IO3) in aqueous system

Abstract

The research work is directed towards the investigation, optimization and application of some plant-based waste materials for the removal of some toxic trace metals (Cd, Pb and Mn) as well as selected oxyhalides (CIO3-,IO3- and BrO3-) in aqueous system. Waste materials from three plants; Athrixia philicoide, an indigenous bush tea; the outer covering peels of butternut Squash (Cucurbita Moschata) and pineapple (Ananas comosus) were evaluated for their sorption efficiency of the selected metals. batch and continuous experimental processes as well as conditions that might influence the sorption of the metals were investigated. These conditions include effects of pH sorption time, amount of adsorbent, volume of the aqueous medium, amount of metals etc. Qualitative and quantitative analysis of metal ions in solution was carried out using the ion chromatograph (IC) while the functional group identification present in waste materials was established using the Fourier Transform infr-red spectroscopy (FTIR), Quantitative biosorption equilibrium of 98.99% was reached within 6h at pH 6 and 100 ppm concentration of Pb metal with Athrixiaphilicoide under 30 min contact time. Applicability of the sorption process was tested on wastewater. Results revealed that > 99.93 %; 84.5 % and 64.3 % sorption efficiency was obtained for Mn, Cd and Pb respectively at pH 7 using Ananas Comosus adsorbent. For Athrixia philicoide, sorption efficiency from spiked wastewater ranged from 99.98 % for Cd; 99.96 % for Mn and 82.5 % adsorption for Pb at pH 7. For Juglans Cinerea, wastewater sorption efficiency varied between 78.76 %, 94.50 % and 96.50 % for Cd, Mn and Pb respectively at pH6. Results from the optimized method revealed the applicability of the method to environmental water samples. Possible large scale and industrial/commercial application of developed materials and methods would be explored. ) in aqueous system. Waste materials from three plants; Athrixia philicoide, an indigenous bush tea; the outer covering peels of butternut Squash (Cucurbita Moschata) and pineapple (Ananas comosus) were evaluated for their sorption efficiency of the selected metals. Batch and continuous experimental processes as well as conditions that might influence the sorption of the metals were investigated. These conditions include effects of pH, sorption time, amount of adsorbent, volume of the aqueous medium, amount of metals etc. Qualitative and quantitative analysis of metal ions in solution was carried out using the ion chromatograph (IC) while the functional group identification present in waste materials was established using the Fourier Transform infra-red spectroscopy (FTIR). Quantitative biosorption equilibrium of 96.99 % was reached within 6h at pH 6 and 100 ppm concentration of Pb metal with Athrixia philicoide under 30 min contact time. Cd and Mn adsorption by the same adsorbent under similar condition were less than 50 % for individual metal evaluation experiment. However, > 99 % adsorption was achieved with Cd in a mixture of the three (3) evaluated metals. Highest adsorption of 93 % of Pb was achieved with the Butternut Squash peel (Cucurbita moschata) at the optimal sorption pH of 6 followed by quantitative sorption of 99.2 % of Mn while Cd recorded a sorption level of 45 % all at 6 pH. The sorption efficiency of Pb, Cd and Mn using pineapple peels (Ananas comosus) also at the optimal sorption conditions of (pH 6, 30 min contact time and 100 ppm metal concentration) ranged from 98.7 %, 100 % and 99.90 % respectively.