Removal And Enrichment Metal Ions And Heterocyclic Compounds From Aqueous By Organic Anionic Modified Layered Double Hydroxides

In this work,phytate intercalated layered double hydroxides(Phytate-LDH)and dodecylsulfonate intercalated layered double hydroxides(DSO-LDH)were prepared by hydrothermal method and anion exchange method.They were applied to the metal ions enrichment and furan separation from aqueous solution,respectively.The influence of experimental conditions on experimental results was explored by changing contact time,initial concentration of pollutants,the dosage of LDHs,pH value,temperature and so on.XRD,FT-IR,SEM were used to characterize the morphology of LDHs before and after experiment,the enrichment/separation mechanisms were also explored.The concentrations of metal ions and furan in aqueous solution were measured by ICP and HPLC,respectively.Phytate-LDH has a highly complexation ability for many metal ions and can be used to selectively enrich metal ions in mixed solution,such as Pb2+?Co2+?Pr3+ and Ce2+.Phytate-LDH has good enrichment performance for these ions in single metal ion solutions.At low concentration(below 10 mg/L),all the capture rates of the four metal ions were more than 97%,for the highly toxic Pb2+ even up to nearly 100%,and maintained a high capture rate(99.87%)for Pb2+ at a high concentration(100 mg/L).When all the four metal ions are co-exist in aqueous solution,the selectivity order is Pb2+?Pr3+ ? Ce3+>Co2+.In a solution containing mixtures of the three metal ions of Pr3+,Ce3+ and Co2+,the selectivity order is Pr3+ ? Ce3+?Co2+,and in a solution containing mixtures of Pr3+ with Co2+ and Ce3+ with Co2+,the selectivity orders are Pr3+?Co2+ and Ce3+?Co2+,respectively.And the selectivity is due to the difference of binding energy between metal ion and Phytate-LDH.Moreover,Phytate-LDH can maintain a high selective enrichment ability at wide temperature and pH range.Therefore,the Phytate-LDH is promising for the enrichment and/or purification of Pb2+?Co2+?Pr3+ and Ce3+ from aqueous solution.DSO-LDH has a high separation performance for furan under a wide pH range.The separation capacities can reach ultrahigh 413.4 mg/g.When the initial concentration of furan was 100 mg/L,after separation by DSO-LDH,the residual concentrations of furan was 4.16 mg\L,which is lower than the safety standard of wastewater of China.When initial concentration is 5 mg/L,the residual concentrations can't be detected by high performance liquid chromatography.It is mainly due to the organic modified LDHs can makes furan easier to dissolve into interlayer of LDHs.The kinetics model and equilibrium isotherms model of separation processes are matching with pseudo-second order kinetics model and linear model,respectively.After separation,furan was recycled by extraction with acetone,the DSO-LDH still have good separation performance after 10 adsorption-desorption cycles.Therefore,DSO-LDH is a green and efficient adsorbents for the separation and recycle of furan from aqueous solution.