Study On Venturi Tube Hydrodynamic Cavitation Assisted Extraction Of Zinc Using TBP

The traditional recovery methods of zinc have the disadvantages of low extraction efficiency,large reagent consumption and serious environmental pollution,so it is necessary to find a green and efficient method of zinc recovery.The high-speed jet and shock wave generated by hydrodynamic cavitation（HC）effect have strong stirring effect,which is conducive to the full mixing of aqueous phase and organic phase.Therefore,in this study,a method of venturi tube HC assisted extraction of zinc using tributyl phosphate（TBP）from zinc containing wastewater is proposed.First,the effects of the volume ratio of the organic and aqueous phases（O/A ratio）,Zn²⁺initial concentration,molar ratio of TBP to Zn²⁺,NaCl concentration,solution temperature,solution pH,diluent type,extractant type,impurity ions on zinc extraction were explored.Selecting the venturi tube（93 mm length,2 mm throat diameter and 10 mm throat length）under 100 mL/min flow velocity,more than 90%zinc can be extracted within 10 min.Under the same conditions,compared with the traditional extraction method without the assistance of HC,venturi HC assisted zinc ions extraction using TBP can reach the extraction equilibrium in a shorter time,and the extraction ratio of zinc is 6.64%higher than that of the traditional extraction method without the assistance of HC.When impurity ions such as Fe³⁺,Cu²⁺and Al³⁺exist in aqueous solution,it is found that the presence of Cu²⁺and Al³⁺has very little influence on zinc extraction,but the presence of Fe³⁺has great influence on zinc extraction.Therefore,in the presence of Fe³⁺,the effects of O/A ratio,solution pH,NaCl concentration,solution temperature,Fe³⁺initial concentration and molar ratio of masking agent NaF to Fe³⁺on zinc extraction assisted by venturi tube HC were explored.Finally,it is found that the extraction of Fe³⁺can be almost completely inhibited by adding moderately excessive masking agent NaF.Furthermore,the effects of reaction time,O/A ratio,HCl concentration on zinc stripping were examined.When O/A ratio was 1:2,HCl concentration was 3.0 mol/L and the reaction time was 10 min,the stripping ratio of zinc was 90.23%.Under the same conditions,compared with the traditional stripping method without the assistance of HC,the extraction ratio of venturi HC assisted extraction is nearly 20%higher than that of the traditional stripping method without the assistance of HC.During the process of zinc extraction and stripping,by comparing the HC extraction and the traditional extraction without the assistance of HC,it is found that the effect of HC extraction on zinc extraction is significantly better than that of traditional extraction.Finally,the extraction mechanism was also explored in this study.The extraction of zinc using TBP belongs to the neutral complexation extraction.With the increase of HCl concentration,H⁺will participate in the extraction reaction,H₃O⁺combines with TBP to form large cations,Zn²⁺and Cl^-combines to form ZnCl₃^-or ZnCl₄^2-.Both undergo ion-association extraction in the aqueous phase.Obviously,the venturi tube HC device has the advantages of excellent extraction effect,simple equipment,small energy consumption,simple operation and low maintenance cost.It can be used for large-scale wastewater treatment and recycle of useful substances.To sum up,in this paper,an efficient method of venturi tube HC assisted extraction of zinc using TBP is proposed.The research results can provide certain data reference and technical support for large-scale wastewater treatment and recycle of useful substances.