ADSORPTION OF NATURAL ORGANIC MATTER (NOM) IN PEAT WATER BY LOCAL INDONESIA TROPICAL CLAY SOILS

Abstract

A series of experiment on the adsorption of natural organic matter (NOM) originated from peat
water in Central Kalimantan, Indonesia by local peat clay soils had been carried out. A selected local peat clay
soil (LPC) and activated local peat clay soil (ALPC) had been used as adsorbents. The activation of the local
peat clay soil was carried out by immersing it in 1 M HCl solution at 900 oC. The effects of pH on the adsorption
capacities were investigated. It has been found that at lower pHs (3-5) the adsorption capacities increased
significantly. A rotary shaker was set at 180 rpm as an agitator in performing the kinetically behaviour and
adsorption isotherm of NOM onto the LPC and the ALPC. It was found that the equilibration time for the LPC
and the ALPC were 180 and 150 minutes, respectively. The kinetics equation model that most fitted to the
adsorption experimental data for the both adsorbents was pseudo-second order kinetics model (r2 > 0.99). The
Dubinin-Radushkevich depicted the data more accurately to describe the NOM-LPC and NOM-LAPC
adsorption isotherms (r2 > 0.99). Further analysis on the peat water NOM characteristics and local clay (LPC and
ALPC) suggested that physical adsorption, mainly electrostatic interactions enhanced adsorption process and
hydrophobic or solute driven adsorption dominated in the early stage of the process, followed by a chemical
adsorption process.