Treatment of River Sediments with Calcium Lignosulfonate and Nitric Acid

Single,compound,order extractions with nitric acid and calcium lignosulfonate at various concentrations were adopted for the treatment of heavy metals contaminated sediments,and the effects of different treatment were compared.The results showed that the removal efficiency of heavy metals was low in single treatment with calcium lignosulfonate,but higher in single treatment with nitric acid.The removals of Cr,Cu,Ni and Zn were 15.9%,60.8%,73.4% and 75.8% respectively at 0.1 mol/L nitric acid.The removal of heavy metals in compound extraction with nitric acid and calcium lignosulfonate was similar for that in single extraction with nitric acid.For order extraction,extraction with calcium lignosulfonate followed by nitric acid was ineffective for removal of heavy metals,and the effect of calcium lignosulfonate on the extraction of heavy metals with nitric acid was inhibition.The total removals of heavy metals were lower than that in single extraction with nitric acid.Extraction with nitric acid followed by calcium lignosulfonate was effective,and the effect of nitric acid on the extraction with calcium lignosulfonate was promotion.The total removals of Cr,Cu,Ni and Zn in two steps amounted to 29.8%,83.1%,98.5% and 100%.