Preparation Of Functionalized High Sulfur Polymers And Its Adsorption Performance Research On Precious Metal Ions In Water

For a long time,precious metals have attracted great attention from consumers,financial institutions and central banks because of their unique metal properties and strong financial attributes.At the same time,the strategic nature of precious metal resources is also very prominent,which plays a vital role in economic security and reserve security.However,China’s precious metal resources are scarce,especially the platinum group metal reserves are less than five thousandths of the world’s reserves,which is seriously inconsistent with the current consumption of precious metals ranking first in the world.This has become a major constraint to China’s modernization and overall national strength.In recent years,in the production process of modern industrial products,such as electronic products,ornaments,and decorative products,the industrial waste water produced contains valuable precious metal elements.If it cannot be recycled and reused in time,it will cause a huge waste of precious metal resources and environmental pollution.Therefore,the development of green and cheap adsorbent materials with excellent performance and its application in the recovery of precious metals from industrial wastewater have attracted the attention of researchers.In this paper,On the basis of previous studies,this thesis re-studied the preparation of HSP（High-sulfur polymers）by inverse vulcanization.Then,by changing the types and ratios of porogens and modifiers,three new types were synthesized.C-HSP（Carbamide-High-sulfurpolymers）,B-HSP（Bentonite-High-sulfur polymers）and O-HSP（Oleylamine-High-sulfur polymers）,and used XRD,FT-IR,SEM/EDS,TGA,XPS and other instruments to characterize and analyze the above-mentioned polymer.The adsorption behavior in the solution containing gold,palladium and platinum-chloride was investigated and the following conclusions were drawn:（1）in the process of HSP synthesis by inverse vulcanization,porous C-HSP was prepared by using carbamide and sodium chloride as a mixed porogen.The thermogravimetric analysis of the material shows that C-HSP has good stability at room temperature,and the structure changes only when the temperature exceeds 200℃;the adsorption study of C-HSP on Au（III）in solution shows that the porogen can effectively improve the adsorption capacity of high-sulfur polymers for Au（III）.Under strong acid conditions（p H=1.0）,the saturated adsorption capacity of C-HSP for Au（III）reaches 20.98 mg g^-1.In addition,C-HSP has strong selectivity for Au（III）,and adsorption rate can still reach more than 70%after recycled three cycles;XPS results before and after adsorption showed that:strong coordination effect between Au³⁺and S was the main principle of Au（III）adsorption by C-HSP.（2）Bentonite was used as modifier to synthesize B-HSP by inverse vulcanization,and used it in the study of adsorption of Pd（II）solution.Experimental results show that bentonite does not participate in the inverse vulcanization reaction,but adheres to the surrounding of high-sulfur polymer.The addition of bentonite can effectively improve the adsorption capacity of high-sulfur polymer for Pd（II）.Under weakly acidic conditions（p H=5.0）,the saturated adsorption capacity of B-HSP for Pd（II）is 12.56 mg g^-1.The C-S bond in the HSP and-OH on the surface of bentonite play the main role.In addition,B-HSP has strong selectivity for Pd（II）,after three cycles,the adsorption rate of Pd（II）by B-HSP can still reach more than 70%;XPS results before and after adsorption showed that coordination effect was the main principles for B-HSP to adsorb Pd（II）.（3）O-HSP was synthesized by inverse vulcanization using oleylamine and sulfur powder as raw materials,carbamide,sodium chloride,and bentonite as porogens and modifiers,and was applied in the study of adsorption of Pt（IV）in solution.The results showed that under weak acid conditions（p H=3.0）,the saturated adsorption capacity of O-HSP for Pt（IV）is 11.68 mg g^-1.The C-S bond、-NH₂ of the high-sulfur polymer and-OH on the surface of bentonite play the vital role.The adsorption efficiency of Pt（IV）by O-HSP can still reach more than 60%after five cycles;XPS results before and after adsorption showed that electrostatic attraction was the main principles for O-HSP to adsorb Pt（IV）.（4）The adsorption experiment results of the above three adsorbents in a mixed solution containing 100 mg L^-1 each of gold,palladium,and platinum ions showed that planar quadrilateral Au Cl₄^-is most readily adsorbed,while Pt Cl₆^2-is most difficult due to its octahedral structure with large resistance,Pd Cl₄^2-is in the middle.In addition,the introduction of-NH₂ in O-HSP can effectively improve the adsorption performance of high-sulfur polymers for Pt（IV）.（5）The adsorption of the above functionalized high-sulfur polymer adsorbents for precious metal ions is conforms to the Langmuir isotherm adsorption model and the pseudo second order kinetics,indicating that the adsorption reaction of the high-sulfur polymer to precious metal ions is uniform single-layer adsorption,and is mainly chemical adsorption.（6）Using inverse vulcanization method to synthesize a series of high-sulfur polymer adsorbents,not only the raw materials are easy to obtain,economic and environmental protection,but also the preparation process is simple,the synthesis cycle is short,has the prospect of large-scale industrial production.