Adsorption characteristics of composite modified biochar and its passiva-tion effect on farmland soil with light to moderate cadmium pollution
Cadmium(Cd)pollution in farmland soil leads to excessive Cd in crops,which can be trans-ferred to humans through the food chain,posing a signifi-cant threat to human health.Therefore,it is urgent to take reasonable countermeasures.The purpose was to mix dif-ferent materials(potassium hydroxide:K,attapulgite:A,calcium magnesium phosphate fertilizer:M,polyacrylamide:P)with biochar for ball milling modified(Q)treatment.The Cd adsorption performance of the modified biochar and its passivation effect on Cd-contaminated agricultural soils were investigated through adsorption equilibrium and pot experi-ments.The results showed that the modified biochar had richer functional groups and mineral elements than the unmodified biochar(YC).The adsorption kinetics curve of Cd adsorption was in accordance with the proposed second-order kinetic e-quation.The adsorption mode of Cd was mainly monolayer adsorption.The increase of pH value and temperature could im-prove the adsorption capacity of cadmium ions by biochar.The addition of biochar to the soil significantly increased the soil pH value and nutrient content,and reduced the bioavailable cadmium content in the soil.Among them,the application of biochar+potassium hydroxide+attapulgite+calcium-magnesium-phosphorus fertilizer+polyacrylamide ball-milled modi-fied biochar(QKAMP)and biochar+potassium hydroxide+attapulgite+polyacrylamide ball-milled modified biochar(QKAM)significantly reduced the bioavailable Cd content by 25.5%and 23.4%(P<0.05),respectively,compared with the control(CK),and significantly reduced the bioavailable Cd content by 16.84%and 14.57%(P<0.05),respectively,compared with unmodified biochar(YC)treatment.Meanwhile,the addition of QKAMP and QKAM significantly reduced the cadmium content in Brassica rapa var.chinensis(Linnaeus)Kitamura aerial part by 36.1%and 33.6%,respectively,compared with the control(CK),and by 21.6%and 18.6%,respectively,compared with the unmodified biochar treat-ment.It can be seen that,as a heavy metal passivation material,QKAMP is more effective in reducing the bioavailability of cadmium in cadmium-contaminated soils(pH 7.07,cadmium content≤1.75 mg/kg)and ensuring the safe production of agricultural products.
NETL
NSTL
万方数据
维普
