摘要
本试验研究了土壤、矿物对Cr(Ⅲ)的吸附和沉淀作用,结果表明:在pH4.0时,三种土壤对Cr(Ⅲ)的吸附量是青紫泥>黄筋泥>旱地红镶。Cr(Ⅲ)的吸附量和沉淀量之和随pH的变化曲线可分为四个区域。在Cr(Ⅲ)吸附或吸附一沉淀区域的pH范围内(pH<6.0),土壤对Cr(Ⅲ)的吸附分量随溶液中pH升高而减少,沉淀分量则随pH升高而增加;溶液中富啡酸和柠檬酸的存在可以增加Cr(Ⅲ)的沉淀量。
r(III) removal in solutions with different pH values was measured under
con-ditions of adding and without adding soils and minerals. With pH increasing insoil solution,
the amounts of Cr(III) removal by adsorption and precipitation incre-ased when pH < 10.5, but
decreased when PH > 10.5. The curve of Cr(III) removalby soils and minerals could be divided
into four ranges: (1) pH range of Cr(III)adsorption when pH < about 4.0, (2) pH range of Cr(III)
adsorption-precipitationwhen pH 4-6, (3) pH range of Cr(III) stable precipitation when pH 6-10.5,
and(4) pH range ol Cr(III) hydrolysis when PH > 10.5.Organic acids such as citric acid and fulvic
acid existing in soils would raiseCr(III) dissolubility and stability in pH range of 4-7. The pH
value causing pre-cipitation of fulvic acid-Cr(III) was about pH 7.0 and rose by 3 pH unites
comparedwith that of Cr(III) precipitation. Whereas, little effect on Cr(III) dissolubility wasfound
for humic acid existing in soil solution. The existence of phosphate in sol-ution would lower the
PH value causing stable precipitation of Cr(III).The amounts of Cr(III) adsorbed by three soils at
pH 4.0 followed the sequ-ence: stagnogleyed paddy soil > submergic paddy soil from red soil >
upland redsoil.Cr(III) adsorption isotherms fit Langmuir and Freundlich equations in
theniontmorillonite-Cr(III) system, but did not fit Langmuir and Freundlich equationsin the
soil-Cr(III) system.
出处
《土壤学报》
CAS
CSCD
北大核心
1994年第1期77-85,共9页
Acta Pedologica Sinica
关键词
铬
土壤
吸附作用
沉淀作用
Chromium (III), Soii adsorption, Precipitation, Soil Pollution.