Selective Separation And Enrichment Of Precious Metal Ions Based On WS₂ Microcrystals And Its Composites

Precious metal,which serves as the indispensable of industry due to its unique features,is closely related to the development of contemporary high technology.With the development of industrialization worldwide,the loss of precious metals with e-waste and industrial residues has become a major obstacle to sustainable development and environmental protection.Increasing attention to the sustainable development of precious metal resources requires the development of advanced materials and technologies for efficient enrichment.Among many precious metal separation and enrichment strategies,adsorption technology has shown great advantages.Hopefully,two-dimensional lamellar materials similar to graphene could provide an attractive,efficient approach to selective capture of precious metal ions from aqueous solutions.Particularly,two-dimensional transition metal sulfide?TMDs?,such as WS₂,which constructed from single or multilayer that are bridged byweak out-of-plane van der Waalsinteractions,are a marvelous class layered nanomaterials for diverse applications.Their unique features,such as an ultrahigh intrinsically interlaminar clearance characteristic and abundant exposed binding sites,have extremely facilitated them to be competent in catching various molecules or ions.However,attempts to employ WS₂ to precious-metals enrichment are rarely explored.In search of advanced adsorption material,we apply WS₂ as object for intensively investigated.Based on the aerogel of graphene oxide,a compositeaerogel with interconnected 3D network structure and synergistic effect of tungsten sulfide was designed to enrich the precious metals inaqueous solutions.Based on these studies,this paper mainly summarizes the following two aspects.1. flower-like WS₂ microcrystals?F-WS₂ MCs?were prepared through a one-step hydrothermal strategy,which was comprehensively featured by SEM,TEM,and other related techniques.The capture ability of flower-like WS₂ for 13 kinds of metal ions was investigated,including common heavy metals and precious metals.And the adsorption capacity of the first three metal ions with strong adsorption capacity was systematically studied.The optimal adsorption conditions for metal ions by WS₂ crystallites were obtained by investigating the adsorption factors such as the amount of adsorbent,adsorption time,p H,and ionic strength of the adsorption environment.The theory was obtained through the research of adsorption isotherm,adsorption kinetics,and thermodynamics Maximum adsorption capacity.The results indicated that Au?III?,Ag?I?,and Pd?II?were capable of quickly adsorbing by F-WS₂ MCs,and the adsorption efficiency of Au?III?,Ag?I?,and Pd?II?were 94.1%,86.8%and 27.6%,the kinetic data fitted well with the pseudo-second-order model.Meanwhile,the maximum adsorption capacities of Au?III?,Ag?I?and Pd?II?were 1340.6 mg g^?1,186.22 mg g^?1,and 67.29 mg g^?1,respectively.In addition,the mechanism of WS₂ microcrystals for metal ions capturing was studied by relevant means,and the selectivity of F-WS₂ MCs material under the coexistence of multiple metal ions were proved to be favorable.In conclusion,this paper not only verified the feasibility of the application of WS₂ microcrystals in metal ion capture or removal,but also provided the necessary data support and theoretical basis for the application of WS₂microcrystals in metal enrichment and environmental restoration2. A facile hydrothermal method was optimized to prepare WS₂nanosheets?P-WS₂?successfully,the growth process under controlled conditions of the materials was analyzed. The P-WS₂/GA designed and constructed possessed a 3D structure with an interpenetrating network,which wascombined with the aerogel advantages of GO and WS₂ sheets.The adsorption properties of pure GO aerogel,P-WS₂ and its composite aerogel were comparativelyinvestigated.The feasibility and practicality of the applicationof Au?III?was evaluated.The results confirmed that the addition of WS₂ greatly improves the enrichment ability of aerogels.The adsorption process of P-WS₂,GA and WS₂-doped graphene oxide composite aerogels?P-WS₂/GA?dominated by the chemical processes.According to the adsorption model,the theoretical maximum adsorption capacity of P-WS₂/GA reach 1265.8mg g^?1,and the adsorption process of the three materials can be described by pseudo-second-order.The simple enrichment device showed aexcellent enrichment effect on Au?III?,and the bulk aerogel demonstrated the potential of separating directly fromwater solvent after adsorption.In addition,the dye removal capacity of WS₂ aerogel was explored.Since the F-WS₂ MCs structure shows great advantages in improving the availability of adsorption sites.The 3D functional aerogels obtained ensure the effectiveness of the adsorption sites,and easy to be separated.WS₂ materials will play a greater role in the future.