THE EFFECT OF SOIL PH AND ZEOLITE APPLICATION ON LEAD (PB) IMMOBILIZATION ON CONTAMINATED SOIL

Abstract

Soil application of zeolite has been shown to effectively immobilize potentially toxic elements (PTEs). Soil pH can also affect PTE availability. No previous studies have examined the interactive effect of zeolite and soil pH on Pb immobilization. Therefore, this study investigated the effect of 2 kinds of zeolite as natural zeolite (N-Z) and Mg/Al LDH zeolite (LDH-Z) applied at 3 wt%, under one control experiment (CT1) and 5 soil pH (ranging from 5 to 9) on five chemical fractions of Pb in a Pb-contaminated soil. Results showed that N-Z and LDH-Z treatments significantly enhanced Pb stabilization, which could promote Pb conversion into stable chemical fractions. Immobilization of Pb was enhanced under the soil pH of 5.0 with the application of both natural and LDH zeolite, and the figure decrease when increasing value of soil pH. Among the examined materials, Mg/Al LDH zeolite significantly gave higher rate of immobilizing exchangeable Pb in amended contaminated soil than natural zeolite. The exchangeable Pb in the control experiment was reported at 86.31%; and this figure decreased to 45.5% and 37.88% after the incubation with natural zeolite, and LDH zeolite respectively.