Removal of turbidity, lead and cadmium ions from wastewaters using products derived from mangifera indica kernel
Kariuki, John Njuguna
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Lack of sufficient safe drinking water remains a major challenge world over. Further, population growth and subsequent growth in agriculture, industry and technology continues to contribute to increased contamination of the little available clean water everyday. Major contaminants include, agro-chemical residuals, industrial effluents, acids, dyes and toxic heavy metals. Heavy metals of concern includes lead and cadmium because at even very low levels are toxic and have no known metabolism in the body. Literature findings have established a direct correlation between the level of turbidity and microbial load. convectional methods fall short because they are expensive or not readily available. The current work sought to establish a low cost effective adsorbent by utilizing mango (Mangifera indica L.) kernels agricultural waste as a resource to prepare adsorbent materials. Biomass, MBM was obtained by grinding dried kernels, ash, MKA was obtained by burning M.indica kernels in presence of oxygen in a furnace at 600ºC. Carbon, MKC and activated carbon, MKAC, were prepared by pyrolysis of dried kernels and activated kernels in a furnace at 400ºC, respectively. The materials obtained were utilized for the adsorption of lead and cadmium ions and turbidity from wastewaters. Batch experiments were carried out to determine the effect of contact time, initial concentration of metal ions, dosage, temperature and pH on the percentage removal of Pb2+, Cd2+ and turbidity on the four adsorbents. The adsorption capacity for Pb2+ was 8.73 for MKAC, 5.69 for MKC, 9.69 for MKA and 4.69 for MBM and 12.76, 7.13, 12.71 and 3.8 for MKAC, MKC, MKA and MBM, respectively for Cd2+. MKAC, MKC and MKA fitted well in Freundlich adsorption isotherm model for Pb2+ and Cd2+ with R2 values of 0.989 for MKAC, 0.993 for MKC and 0.978 for MKA with Pb2+ and 0.974, 0.987 and 0.914 for MKAC, MKC and MKA, respectively for Cd2+. MBM fitted in the Langmuir model with R2 value of 0.983 and 0.997 for Pb2+ and Cd2+, respectively. Highest percentage turbidity removal were 54.82, 31.63, 97.37 and 59.97 for MKAC, MKC, MKA and MBM, respectively. Products derived from M. indica kernel were found to be effective adsorbents.