ASSESSMENT OF THE EFFICIENCY OF SAWDUST FROM THREE HARDWOOD SPECIES AS LOW-COST ADSORBENT FOR THE REMOVAL OF CADMIUM FROM CONTAMINATED WATER

Abstract

A lot of wastes are generated in the wood industries which constitute series of negative environmental effects. Nevertheless, sawdust has some organic compounds which can remove heavy metal ions from an aqueous solutions using the adsorption procedure. This investigated the potentials of three hardwood species for the removal of cadmium ion from contaminated water. The wood species utilized in this study include Triplochiton scleroxylon, Brachystegia eurycoma, and Blighia sapida sawdust. The sawdust samples were sieved before the pretreatment to remove both impurities and extractives. The experiments were conducted in batches for adsorption in order to determine the effect of pH solution, contact time, on adsorption of cadmium ions. The experiment was laid out in a 3 × 2 × 4 factorial experimental design. The results revealed that the adsorption capacity for (treated and untreated species, Triplochiton scleroxylon, Brachystegia eurycoma and Blighia sapida (treated and untreated) were 92.40±6.42% and 82.66±13.25%, 85.43±17.21%, and 78.00±24.15%, 78.00±20.08% and 80.75±17.07% respectively at the different pH levels (1-4). The results at the optimum pH (2) also revealed that the adsorption capacity for treated and untreated species of Triplochiton scleroxylon, Brachystegia eurycoma and Blighia sapida were 96.99±1.76% and 96.99±1.68%, 97.94±1.20% and 98.48±0.66%, 97.73±1.59% and 99.10±0.81% respectively at the different contact time (30, 60, 90 and 120). This research revealed that pre-treated sawdust adsorbed metal ions faster even at a low time interval compared to untreated samples. Also, it was observed that the highest adsorption capacity (%) of cadmium took place at pH 2 for all samples of sawdust both (treated and untreated). Hence, the selected wood species were found appropriate for the extraction of cadmium from contaminated water and therefore recommended for use.