The influence of temperature, pH/molarity and extractant on the removal of arsenic, chromium and zinc from contaminated soil
2011 (engelsk)Inngår i: Journal of Soils and Sediments, ISSN 1439-0108, E-ISSN 1614-7480, Vol. 11, nr 8, s. 1334-1344Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]
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-washed and medium coarse soil fraction of arsenic, chromium and zinc contaminated soil was agitated for 15 min with the extraction solution. Results and discussion: In NaOH extractions, the temperature and (less strongly) NaOH concentration significantly affected As and Cr mobilisation, but only the latter affected Zn mobilisation. Both pH and temperature significantly (and similarly) influenced As and Cr mobilisation in OC extractions, while only the pH influenced Zn mobilisation. In contrast, the extraction temperature (but not pH) influenced As, Cr and Zn mobilisation in DCO extractions. Conclusions: For all extractants, mobilisation was most efficient at elevated temperature (40°C). None of the extractants reduced the soil's As content to below the Swedish EPA's guideline value. Use of DCO is not recommended because dithionite has a short lifetime and residual arsenic contents in DCO-extracted soil are relatively high. Instead, sequential extraction with NaOH followed by OC solutions (affording significant reductions in As, Cr and Zn levels in the soil with short extraction times) at 40°C is recommended.
sted, utgiver, år, opplag, sider
2011. Vol. 11, nr 8, s. 1334-1344
Emneord [en]
Extraction, Factorial design, Mobilisation, Polluted soil, Soil washing, Water-washed soil
HSV kategori
Forskningsprogram
Tillämpad geologi; Avfallsteknik
Identifikatorer
URN: urn:nbn:se:ltu:diva-11249DOI: 10.1007/s11368-011-0411-yISI: 000297257100004Scopus ID: 2-s2.0-81355149684Lokal ID: a2d7fd26-23a1-4ec7-8207-554787f6be9cOAI: oai:DiVA.org:ltu-11249DiVA, id: diva2:984198
Prosjekter
Pilotskale utvärdering av jordtvätt för sanering av arsenik-kontaminerad jord
Merknad
Validerad; 2011; 20110823 (learas)
2016-09-292016-09-292022-08-31bibliografisk kontrollert