Adsorption of ammonium ions in aqueous solution using raw and treated peat soil

Abstract

Abstract Peat exists in abundance in many parts of the world, but has low economic value. The presence of active functional groups, in the form of carboxyl and phenolic groups, makes peat an alternative sorbent having high porosity and ion exchange ability. Washing peat soil prior to adsorption has been reported to be effective in increasing its ion exchange capacity. In this study, the effect of peat washing using NaOH on its adsorption capacity for ammonium ions was investigated. The FTIR analysis indicated decreases in -OH absorption at 3300-3600 cm-1, C=O (carboxylate) at 1625 cm-1 and C-O at 1300-1000 cm-1 possibly due to the replacement of H+ by Na+ upon peat washing using NaOH. SEM analyses of peat samples showed a more homogeneous surface morphology upon washing. BET analysis results showed a reduction in surface area, pore size, and pore volume. However, the adsorption study conducted in batch mode indicated that the adsorption capacities of washed and raw peats were 28.08 mg/g and 14.48 mg/g, respectively. It can be concluded that washing peat soil using NaOH solution may alter its surface properties and may be beneficial in improving its adsorption capacity towards ammonium ions in aqueous solution.