Enhanced Immobilization of Cr(VI) in Soils by the Amendment of Rice Straw Char

Abstract

This study investigated the effect of rice-straw char (RSC) on the immobilization of Cr (VI) in soils. The Cr(VI) sorption experiments on the RSC and RSC-amended soils were conducted using the batch method. RSC exhibited Cr(VI) reduction capacity due to its black carbon content.The addition of RSC to the soils enhanced the overall Cr(VI) immobilization of the soils, which is primarily attributed to the Cr(VI) reduction capacity of RSC. The effects of RSC amendment on the Cr(VI) sorption of the soils increased with increasing RSC content in the soils and decreased with increasing pH or anion contents in the soil solutions. After Cr(VI) was sorbed by the soils, a portion of the Cr(VI) was converted to Cr(III) and the remainder was sorbed onto the Downloaded by [University of Auckland Library] at 08:35 05 June 2016 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 soils. The presence of RSC in the soils deceased the portion of sorbed Cr(VI) in the soils and therefore lowered the potential remobilization of Cr(VI) from the soils. The results suggested that RSC amendment can be applied to develop a cost-effective method for immobilizing Cr(VI) in polluted soils and thus lowering the environmental risk from Cr(VI) toxicity.

Immobilization of Exchangeable Cromium in a Contaminated Soil Using Natural Zeolite as an Effective Adsorbent

“…Among them, adsorption method is generally considered an effective way for immobilization of the exchangeable Cr due to its simple, flexible operation, effective and low cost [14]. The exchangeable Cr is immobilized by many adsorbents, such as natural minerals (sepiolite, montmorillonite, and attapulgite) [13], synthetic materials (FeS 2 ) [15], rice-straw biochar [16] and mixed adsorption materials (CMC-FeS@HA) [17]. Among many adsorbents, natural mineral materials have been used widely as a costeffective and environmentally friendly [13].…”