Study On Adsorption Performance Of Nano-Hydroxy Fe Modified Biochar For Cd(Ⅱ) In Wastewater

Industrial growth has improved people’s living standards while introducing massive heavy metals pollutant in water.Wastewater containing a high amount of heavy metal can cause severe adverse effects in environment and human.Adsorption is a green removal method with high efficiency,no secondary pollution and low energy.In the work,corn stalks,bamboo and rice straw biochar were pretreated with KMn O₄and selected biochar after adsorption experiments to prepare（n Fe OOH@BC）.And studying on adsorption performance for Cd（Ⅱ）in Wastewater.The conclusion is as follows:（1）Biochar（corn stalks,bamboo and rice straw biochar）has a weak adsorption capacity for Cd.However,after pretreatment,the removal capacity of biochar is improved,in which the removal rate of Cd on corn stalks biochar increased 2 times rather than raw.After loading n Fe OOH,structural properties of corn stalks biochar was promoted,surface roughness was increased.The pore size distribution results show that the pores of biochar are mainly micropores and mesopores.（2）The uptake of n Fe OOH@BC on Cd is affected by p H,dosage,concentration.The maximum Cd sorption occurred at a p H of 7;The removal rate of 0.3 g dosage can reach 96.13%;n Fe OOH@BC have the potential to remove the high-concentration cadmium（Cd（Ⅱ）=150 mg/L～300 mg/L）.（3）The uptake of Cd on n Fe OOH@BC reached equilibrium in 360 min,and the experimental equilibrium adsorption capacity was 12.40 mg/g,which was close to the theoretical value（12.132 mg/g）;Cd sorption followed pseudo second-order kinetics（R²=0.999）;Similarly,Langmuir isotherms had a better fit than the Freundlich isotherms,with maximum sorption capacities 33.445 mg/g;Ion exchange and group complexation are the main removal mechanisms,and the groups involved in adsorption are C-O,C=O/C-O-C,C-H,etc.（4）n Fe OOH@BC can efficiently remove Pb（Ⅱ）,Cu（Ⅱ）,Cd（Ⅱ）.However,the coexisting ions influence each other seriously,and the n Fe OOH@BC preferentially adsorbed Pb（Ⅱ）in the mixed system.Binary system,the removal of target heavy metals will be affected by the concentration of coexisting ions.And Pb severely affects the removal of Cu（Ⅱ）;Cu（Ⅱ）had the most pronounced effect on Cd;Cd has a weak effect on Pb.After three cycles of adsorption,the removal rate of Cd（Ⅱ）by n Fe OOH@BC can be maintained at about 55%,with a reusability.