Effect of Chemically Modified Biowaste-Low Density Polyethylene Waste Composites for Sorption of Heavy Metals in Soil Samples collected at Waste Dumpsite in Uvwie Local Government Area of Delta State, Nigeria

Abstract

The objective of this paper was to evaluate the effect of chemically modified biowaste-low density polyethylene waste composites prepared in a 1:1 and 1:2 ratios for sorption of heavy metals in soil samples collected at waste dumpsite in Uvwie Local Government Area of Delta State, Nigeria using appropriate standard techniques. Data obtained show reduction of values of metal concentration across board, before and after treatment with sorbents. These average values of these parameters include pH (before: 6.01±0.23, after: 6.15±0.25), cadmium (before: 12.39±1.77; after: 9.24±3.24), chromium (before: 1.65±0.43; after: 1.26±0.29), iron (before: 744.38±207.77; after: 478.44±262.94), zinc (before: 12.83±3.12; after: 10.00±1.01), nickel (before: 28.72±4.70; after: 20.33±6.51), lead (before: 19.48±17.92; after: 12.85±4.44), and manganese (before: 16.41±4.46; after: 10.31±6.54). The sorption capacity of the modified sorbents was higher than that of the unmodified sorbents. Modification of the sorbents surface increases the surface characteristics thereby decreasing the concentration of heavy metals and increasing the sorption of these heavy metals from contaminated soils. The unmodified composite 1:2 (LDPE: sawdust) sorbed more metals than unmodified composite 1:1 because the increased proportion of sawdust provided a greater surface area, higher porosity, and more functional groups for metal adsorption. The modified composite 1:1 CaCO₃ and composite 1:2 Mg(OH)₂ sorbed Mn, Ni, Fe, Pb and Cd more than the other sorbents. The composite 1:1 SiO₂ and composite 1:2 Ca(NO₃)₂ sorbed Cr more than the other sorbents and least sorbents that sorbed Cr are composite 1:1 K₂CO₃ and composite 1:2 Mg(OH)₂ while composite 1:1CaCO₃ and composite 1:2 Mg(OH)₂ sorbed Zn more than the other sorbent. It is due to the varying chemical properties and interactions of the modifying agents with the specific metal ions. Each combination of composite ratio and modifying agent creates a unique sorbent with distinct sorption behaviors for different metals.