Study Of Lead Ions Adsorption On Novel Hierarchical Nano-flower Composites

As the development of industry,water pollution by toxic heavy metals poses increasingly serious threat to public health and the ecosystem.Therefore,exploring an efficient,safe and advanced method to realize the water purification has been attracted significant attention in the environmental field.Nano-flower materials usually presents good adsorption capability towards heavy metal ions,but nano-ultrafine powders can't be directly applied in the water treatment due to the difficulties of solid-liquid separation and dynamical equilibrium as well as the influence of competing ions.For reaching the target of depth purification towards Pb?II?,in this dissertation,three kinds of nano-flower composites were synthesized.Every material was determined the microstructure of itself and investigated its sorption behavior for analyzing the sorption mechanism and specific adsorption towards Pb?II?.Firstly,nano-flower Mg/Al layered double hydroxides?Mg/Al-LDHs?was synthesized by traditional hydrothermal method,which was characterized by scanning electron microscope?SEM?.The results of characterization analysis presented that Mg/Al-LDHs formed excellent nano-flower structure.Besides,Mg/Al-LDHs showed fast dynamic process that would reach the kinetic equilibrium after 60 min.With existing competing ions,Mg/Al-LDHs presented a certain selective adsorption towards Pb?II?and the maximum adsorption capacity is 85.1mg/g.However,Mg/Al-LDHs showed weak performance of acid proof which weaken the Pb?II?capture by its excellent structure of surface.In order to simplify the synthesis steps and enhance the tolerance of adverse conditions,S-Cu₃?PO₄?₂ was obtained through the simple chemical precipitation method at the room temperature.S-Cu₃?PO₄?₂ with an average particle size of 30?m contains numerous petal-like lamellas.Moreover,there were countless active sites,such as-NH2 and-OH,on the surface of S-Cu₃?PO₄?₂.Therefore,S-Cu₃?PO₄?₂ exhibited excellent specific sorption to Pb?II?and quick dynamic process as well as high adsorption capacity of Pb?II??1596.5mg/g?.Besides,three kinds of competing ions,including Ca?II?,Mg?II?and Na?II?,pose little effect on the sorption behavior towards Pb?II?.Comparing with Mg/Al-LDHs,S-Cu₃?PO₄?₂ exhibited more stable and excellent sorption ability.But,nano-materials presented difficulties in solid-liquid separation and high hydraulic resistances,which hampers the application of S-Cu₃?PO₄?₂ in the water treatment.Therefore,the novel poly-dopamine covering polystyrene supported sericin hybrid copper phosphate composite?PS-PDA-S-Cu₃?PO₄?₂?was synthesized to overcome these problems.The poly-dopamine,a kind of biological “glue”,protects the decent flower-like S-Cu₃?PO₄?₂ formed on the cation exchange resin?D001?which overcome the incompatibility between organic matrix and inorganic nano-materials.The diameter range of PS-PDA-S-Cu₃?PO₄?₂ was 0.3⁰.5mm covering with flower-like S-Cu₃?PO₄?₂.Due to the negatively charged –SO3-on matrix can enrich Pb?II?from wastewater,PS-PDA-SCu₃?PO₄?₂ exhibited excellent depth removal of Pb?II?.In the Column tests,PS-PDA-S-Cu₃?PO₄?₂ presented superior treated capacity of 3450 kg wastewater /kg sorbents,which suggested that PS-PDA-S-Cu₃?PO₄?₂ had decent application prospects in heavy metal water treatment.