Study On Transport And Separation Of Heavy Metal Ions Of Industrial Wastewater With Liquid Membrane

The discharge of wastewater is augmenting with quick economic development of industry and agriculture. Industrial wastewater contains many ingredient and usable resource. All the community pay much attention to the environment effects of the heavy metal ions in industrial wastewater because some of metal ions can cause the heavy damages to the health of human and biological balance. Liquid membrane separation technology has exhibited an excellent character on separating and enriching metal ions and organic contaminations in the wastewater due to their fast mass transport, great selectivity, high separation efficiency, convenient processes and easy automatization. It has two layer benefit of recovered resource and environmental protection by treating industrial wastewater through liquid membrane. It is necessary to develop liquid technology of separation wastewater with quick development of industry and lack of nature resource.The transport behavior through the liquid membrane, the methods on separation, enrichment and test of metal ions using different liquid membrane systems have been studied in the present treatise. The novel liquid membrane systems with high selectivity and separation efficiency have been obtained. The mathematical model of metal ions transport in liquid membrabe systems was established by the analysis of mass transfer.The results are summarized as follows:1. The transport behavior of Cu(â…¡), Pb(â…¡) and Ni(â…¡) through the bulk liquid membrane system of PC-88A/CHCl₃ is studied. The paper discussed the influencing factor upon the metal ions transfer rate. The results showed that this liquid membrane systems have marked effect upon Cu(â…¡), Pb(â…¡) and Ni(â…¡). The optimal conditions of transport are summarized as follows: stirring speed 300～400 r/min, 350～400 r/min and 300～350 r/min,respectively, feed phase pH 3.5～5.0, 2.8～3.8 and 5.3～5.8, respectively, carrier concentrations 5.0～7.5%, 5.0～6.25 %and 5.5～8.5%, respectively, reaction temperature 288～308 K, 289～303 K and 293～310 K, respectively, H₂SO₄ concentration 2.0 mol/L, 2.0 mol/L and 2.5 mol/L in stripping phase, respectively.In the conditions, treating the concentration of Cu(â…¡), Pb(â…¡) and Ni(â…¡) in wastewater the transfer rate of metal ions can reach 99%. At the same time, the three metal ions can be separated. Through the analysis of mass transfer, the driving force of transportation is differences of concentration of hydrogen ion between feed phase and stripping phase. The kinetics of transportation of metal ion through bulk liquid membrane is studied and the results indicated that the transport kinetics could be analyzed in the formalism of concatenation reaction. The rate equation of transportation was obtained. The transport kinetics parameters are calculated including k₁, k₂, t_max, R_m^max, J_a^max, J_d^max and activation energy. The kinetics equation is proved by transportation experiment.2. The transfer behavior of Cu(â…¡), Cr(â…¢), Pb(â…¡) and Ni(â…¡) were studied using the emulsion liquid membrane system of TBP-Span80-atoleine-kerosene. The influencing factors are investigated upon the metal ions transfer rate. The results showed that this emulsion liquid membrane systems have marked effect upon Cu(â…¡), Cr(â…¢), Pb(â…¡) and Ni(â…¡). The optimal transfer conditions are given as follows: Span80 7.0%, 5.0%, 6.0% and 4.0%, respectively, atoleine 5.0%, 4.0%, 5.0% and 4.0%, respectively, kerosene 80%, 84%, 81% and 83%, respectively, cartier concentrations 9.0%, 7.0%, 8.0 %and 9.0%, respectively, Roi 1:1, 1:1, 1:1 and1:1, respectively, Rew 1:4, 1:5, 1:5 and 1:5, respectively, feed phase pH 4.0～4.5, 3.5, 3.5～4.0 and 4.5～5.3, respectively.In the conditions, treating the concentration of Cu(â…¡), Cr(â…¢) and Ni(â…¡) in wastewater the transfer rate of metal ions can be reduced to 1.0 mg/L. The kinetics equation of metal ions is established through the ELM.3. The transfer behavior of Hg(â…¡), Mo(â…¥) and W(â…¥) were studied using the supported liquid membrane system of N503- kerosene. The study include analysis the effect of metal ions transport rate of soaking time, stirring rate, carrier concentration, pH of feed phase, ionic strength, reaction temperature, initial concentration of metal ion in feed phase. The transfer conditions are summarized as follows: soaking time 80 min, 60 min and 70 min, respectively, stirring speed 400～450 r/min, 350～400 r/min and 350～400 r/min, respectively, carrier concentrations 15～20%, 20～25% and 25～30%, respectively, feed phase pH 2.5～3.0, 3.5～4.0 and 5.3～5.8, respectively, ionic strength 0.4～0.8, 0.3～0.6 and 0.3～0.6, respectively, reaction temperature 288～308 K, 288～308 K and 288～308 K, respectively, stripping reagent concentration 0.3 mol/L (HCl), 0.25 mol/L (NaOH), 0.2 mol/L (NaOH), respectively.The selective separation of Hg(â…¡) and Pb(â…¡), Mo(â…¥)and W(â…¥) from aqueous solution with the SLM are explored, respectively. The results showed that Hg(â…¡) and Pb(â…¡), Mo(â…¥)and W(â…¥) are separated effective through the SLM. The kinetics equation of metal ions is established in the SLM system. The transport kinetics parametersΔ_d,Δ_o,Δχ₁ and D₂ are calculated through the SLM. The osmotic coefficient equation is obtained through the SLM. The osmotic coefficient equation is proved by transportation experiment.