Fabrication Of The Thermo-sensitive Hydrogel Carboxymethyl Cellulose/poly(N-isopropylacrylamide-co-acrylic Acid) For U(?) Removal From Aqueous Solution

The technology of dissolution and leaching is widely used in uranium mining and metallurgy,and a large amount of low-concentration uranium-containing radioactive wastewater can be generated from these industrial processes,which could pose a serious potential risk to the environment and the health of those involved.Traditional methods such as reverse osmosis,ion exchange,and evaporation have the demerits of complexity,high energy consumption,and cumbersome operation.The adsorption method,which possesses the characteristics of a wide source of materials,low cost,high selectivity,fast treatment rate,and large capacity would provide a possibility for the efficient uptake of uranium-bearing wastewater.In this work,the thermo-sensitive materials N-isopropylacrylamide?NIPAM?and acrylic acid?AA?were crosslinked with carboxymethyl cellulose?CMC??CMC/P?NIPAM-co-AA??via a free radical polymerization method for the removal of U???from aqueous solution.The L16?4⁵?orthogonal experiments were designed for the optimization of the synthesis condition.The optimal combination are 0.1g of CMC,0.15g of AA,0.06g of ammonium persulfate?APS?,0.03g of N,N-methylene bis acrylamide?BIS?under the polymerization temperature of 0?.The adsorption performance of the CMC/P?NIPAM-co-AA?hydrogel for the uptake of U???from simulated wastewater was also investigated.The adsorption reached equilibrium within 1 h.Under the reaction of pH=6 and a temperature of 298K,an initial concentration of U???of 5 mg·L^-1,and 10 mg of the CMC/P?NIPAM-co-AA?hydrogel,the maximum adsorption capacity was14.69 mg g^-1.The kinetics fitted perfectly with the pseudo-second-order model,and the isotherms for the composite hydrogel adsorption of U???was in accordance with the Langmuir model.After chemical modification the U???adsorption was reduced by 15.58%,13.01%and 9.46%after carboxyl groups,hydroxyl groups and acylamino groups being shielded,correspondingly.The chemical modification confirmed that the acylamino group played an important role in uranium adsorption.The results of functional group shielding test and XPS spectrum showed that the oxygen-containing functional groups had complexation on U???.By investigating the desorption effect of CMC/P?NIPAM-co-AA?hydrogel at 20⁵0?,it was shown that 50?was the most suitable desorption temperature.The desorption and reusability study revealed that the resolution rate was still available at approximately 77.74%after five alternate heating cycles at 20 and 50°C of adsorption-desorption.