Study Of Removal Of Heavy Metals From Wastewater By Biosurfactant

Heavy metal pollution has become a global water pollution problem.As an efficient and economical means of water treatment,ion flotation is expected to efficiently remove heavy metal ions in water.Ion flotation has the advantages of high removal efficiency and low sludge production.Biosurfactants are environmentally friendly,can be degraded naturally,and have many coordinating groups.For heavy metal ions in water,biosurfactants are introduced in the ion flotation method as chelating agents and flotation agents for heavy metal ions(Cu²⁺and Pb²⁺).In this paper,three biosurfactants,sodium lauroyl-N-methylaminoacetate（LS）,sodium cocoylglycinate（SCG）,and sodium myristoyl glutamate（SMG）,and one chemically synthesized surfactant were selected.Sodium dialkyl sulfate（SDS）removes heavy metal ions in wastewater,and the flotation behavior and flotation mechanism of heavy metal ions are studied.The properties of the surfactants were firstly studied,and the results showed that all three biosurfactants had surface activity and foam stabilization suitable for flotation,and could be used as foaming agents and collectors in the ion flotation process.The flotation behavior of the four surfactants in a single metal ion system,the study found that the flotation time was 20 min,the ventilation rate was 50 m L/min,the heavy metal ion concentration was 4×10^-4 mol/L,and the LS,When the dosage of SDS is 1.2×10^-3mol/L,the dosage of SCG and SMG is 8×10^-4 mol/L,and the solution environment is weakly acidic,the removal rate of copper and lead ions by the four surfactants can all be improved.reach more than 98%.The mechanism of action between biosurfactants and metal ions was explored,and it was found that the carboxyl groups of the surfactants and the heavy metal ions reacted chemically to form a stable carboxylate complex,and the complex structure was loose and flocculent.Secondly,the flotation behavior of heavy metal ions of three biosurfactants in mixed metal ion system was studied.Studies have shown that when the solution environment is weakly acidic,when the dosage of LS is 1.6×10^-3 mol/L,and the dosage of SCG and SMG is 1×10^-3 mol/L,the removal rate can reach more than 95%;The coexisting ions of monovalent metal ion Na⁺have little effect on the removal rate of heavy metal ions,while divalent metal ion Ca²⁺will inhibit the removal of heavy metal ions;the selectivity to the two heavy metal ions is not affected by direct flotation with only three biosurfactants added.powerful;Finally,a biodegradable chelating agent（citric acid）was introduced to selectively separate the copper and lead mixed ions.Under the condition of:1.5:1,the removal rate of lead ions is about 90%,and the removal rate of copper ions is about 10%,and finally high selective removal is achieved.Using biosurfactant as a complexing agent for heavy metal ions and a flotation collector can efficiently remove heavy metal ions in water,which is an environmentally friendly and efficient wastewater treatment method.