The influence of temperature, pH/molarity and extractant on the removal of arsenic, chromium and zinc from contaminated soil

Abstract

Purpose Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/ high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate-citrate (OC) and dithionite-citrate-oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated. Materials and methods A two-level, full-factorial design with a centre point was implemented. Two factors, concentration and temperature,were evaluated in NaOH extractions, and pH and temperature for OC and DCO solutions. In all cases, the extraction temperature was 20°C, 30°C and 40°C. The studied NaOH concentrations were 0.05, 0.075 and 0.1 M. The pH in OC solutions was 3, 5 and 7, and in DCO solutions, 4.7, 6.3 and 6.7. Water-

The Release Characteristics of Cr(Ⅵ) in Contaminated Soil by Dynamic Simulation of Acid Rain

“…The release of Cr(VI) from soil spiked by inorganic salts was much faster for the initial few days and then it became slower (Fig 2). Initially rapid release possibly due to a higher mobility of Cr(VI) in soil which depends largely on adsorption of soil colloids[ 23,24 ]. For example, Cr(VI) can be more easily absorbed by ferric oxide and iron oxide hydrate than kaolinite and montmorillonite [25,26] .…”