Preparation Of Uranium Adsorbent Based On Styrene-Maleic Anhydride Copolymer

With the acceleration of global economic integration,people’s increasing demand for various kinds of energy has led to the shortage of some fossil fuels.Fossil fuels causing great environmental pollution with a low utilization efficiency.Therefore,development and use of a clean and efficient new energy is crucial.Nuclear energy is a new energy with low pollution and high economic benefit.Uranium is the main fuel for generating nuclear energy,so it is imperative to develop the available uranium resources.China’s uranium resources are very scarce on land,but the coastline is vast,accompanied by thousands of times of uranium resources than land in the sea.The concentration of uranium in seawater is 3.3μg·L^-1.The extremely low concentration is a challenge to the method of uranium extraction.Therefore,the study of uranium extraction from seawater has become a topic that cannot be ignored today.Among all kinds of seawater uranium extraction methods,adsorption method is widely used because of its high adsorption efficiency,economic,environmental protection,and easy recovery.The reasonable selection of adsorbent is the key factor of adsorption method.Previous studies have shown that the introduction of carboxyl group into the adsorbent can promote the decomposition of anion carbonate and avoid its binding with uranyl,thus improving the adsorption efficiency of the material.Styrene-maleic anhydride copolymers have controllable functional groups and easy to be introduced into carboxyl groups.Therefore,in this paper,two uranium adsorbents were prepared by combining styrene-maleic anhydride copolymer with magnetic material Fe₃O₄ and porous material MIL-101,respectively.Fe₃O₄@C-SMA can be recovered magnetically,and MIL-101-SMA-AO has high specific surface area and ultra-high adsorption capacity.Confirmed the preparation of two uranium adsorbents by FR-IR,XRD,SEM,TGA and BET.For Fe₃O₄@C-SMA,a series of uranium adsorption experiments were carried out when p H=6,the adsorption capacity of Fe₃O₄@C-SMA can reach 178 mg·g^-1.After 5 adsorption-desorption cycles,the adsorption capacity remains above 80%.Due to the magnetic properties of the material,it can be easily recovered from the solution using magnets,which has excellent recycling advantages.In addition,Fe₃O₄@C-SMA has highly selective for uranium in the presence of multiple competing ions.Fe₃O₄@C-SMA adsorption process is chemical adsorption,monolayer adsorption,and adsorption process is spontaneous endothermic.XPS analysis shows that the adsorption process on Fe₃O₄@C-SMA interacts with uranium through carboxyl group and Fe₃O₄,which forms U-O bond with uranium through shared electron coordination.In simulated seawater experiments,Fe₃O₄@C-SMA still has a uranium removal rate of more than 90%.For MIL-101-SMA-AO,a series of uranium adsorption experiments were carried out when p H=7,the adsorption capacity of MIL-101-SMA-AO can reach 1086 mg·g^-1.After 5adsorption-desorption cycles,the adsorption capacity still remains above 85%.MIL-101-SMA-AO has highly selective for uranium in the presence of multiple competing ions.The analysis shows that the adsorption process of MIL-101-SMA-AO on uranium is chemical adsorption and monolayer adsorption,and the adsorption process is spontaneous endothermic.XPS analysis shows that the uranium adsorption process on MIL-101-SMA-AO was coordinated by carboxyl and amidoxime groups.In addition,MIL-101-SMA-AO still has a high selectivity for uranium in simulated seawater.In a word,Fe₃O₄@C-SMA has the advantage of magnetic recovery and is easy to recover and recycle in the adsorption process.Due to the extremely high specific surface area of the porous material MIL-101,MIL-101-SMA-AO has obtained considerable adsorption capacity and the ability to extract uranium efficiently.Both materials have feasibility and research value in actual seawater adsorption of uranium.