Adsorption of copper (II) and lead (II) ions from aqueous solution on chitosan-coated sand

Biodegradable material, known as chitosan-coated sand (CCS), was utilized for removal of copper (II) and lead (II) ions in water. Batch experiments were conducted to investigate the adsorption effect under different initial concentration (Co = 100, 500, 1000 and 2000 mg/L), solution pH (2, 3, 4, 5 and 6), and contact time (0.5, 1, 2, 4, 6, 12 and 24 h). Desorption studies were performed using diluted HCl solution (pH 1 and 3) and tap water (pH 7) on adsorbed metal ions. Langmuir and Freundlich adsorption models were used to describe static isotherms and constants. The data fitted well with Langmuir model at Qmax value of 8.18 and 12.32 mg/g CCS for Cu(II) and Pb(II) ions at 4 h contact time, respectively. Kinetic studies followed the pseudo second-order reaction, which indicated that the chemical sorption is the rate-limiting step. Results of desorption process signified potential for recovering metal ions from CCS.