Preparation Of Novel Nanocomposite Hydrogels And Their Studies Of Characteristics Of Adsorption To Tl(Ⅲ)、cr(Ⅲ)、 Fe(Ⅲ)ions

With the speeding up of urbanization and industrialization,the excessive release of heavy metals has become a global environmental problem.Unlike the organic contaminants,heavy metals are not biodegradable and tend to accumulate in living organisms and many heavy metal ions are known to be toxic or carcinogenic.In recent years,our country’s heavy metal pollution incidents often occur,such as thallium pollution event of beijiang river,Guangdong Province,chromium pollution event of nanpan river,Yunnan Province.Therefore,treatment and control of heavy metal polluted water is very important in our country.The choice of the adsorbent has a decisive effect on removal efficiency.Thecarboxymethylcellulose-g-poly（acrylicacid）/acrylamide（CMC-g-PAA/AM）hydrogel was synthesized by solution grafting copolymerization of carboxymethyl cellulose,acrylic acid and acrylic amide with using ammonim peroxodisulphate as an initiator and N,N’-methylenebisacrylamide as crosslink agent in this paper.A novel organic-inorganic nanocomposite hydrogel—carboxymethylcellulose-g-poly（acrylicacid）/acrylamide/attapulgite（CMC-g-PAA/AM/ATP）—was synthesized,in presence of the attapulgite.The surface morphology,group,elemental composition,theral stability and swelling performance of hydrogels were analysized by scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）,fourier transform infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscopy（XPS）,thermogravimetric analysis（TGA）characterization methods.The two hydrogels were applied in the Tl（Ⅲ）,and Cr（Ⅲ）,and Fe（Ⅲ）ion adsorption from aqueous solution.The adsorption performances of the hydrogels were studied through bath experiments investigating the effects of pH,reaction time,reaction temperatureand initial metal ion concentration.The desorotion and reuse of hydrogels was explored by using different desorbents.And the adsorption mechanism of hydrogels is discussed by SEM,EDS,FT-IR,and XPS characterization methods.The conclusions were as follows:（1）The analysis results of SEM-EDS,FTIR and XPS showed that the ATP was introduced on CMC-g-PAA/AM;the analysis results of TGA showed that thermal stability of CMC-g-PAA/AM/ATP was better than CMC-g-PAA/AM;（2）The result of swelling performance of hydrogels showed two hydrogels were able to maintain a good swelling in the pH 4 to 8.And the welling ratio decreases with the increase of inorganic salt solution concentration.In different valence metal salt solution,the order of swelling performance is KCl>NaCl>CaCl₂>FeCl₃;（3）The initial pH of solution had important influence on adsorption performance for heavy metal ions.The adsorption kinetics and isotherms of Tl（Ⅲ）,Cr（Ⅲ）and Fe（Ⅲ）on two hydrogels were found to follow pseudo-second order model,and Langmuir model,respectively.The adsorption mechanisms are mainly complexation and ion exchange;（4）CMC-g-PAA/AM and CMC-g-PAA/AM/ATP can be effective in removing Tl（Ⅲ）,Cr（Ⅲ）and Fe（Ⅲ）,and had better regeneration.