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Zhang X.-F.,Guangzhou University | Zhang X.-F.,Guangdong Province Key Laboratory of Radioactive Pollution Control and Resource | Chen D.-Y.,Guangzhou University | Chen D.-Y.,Guangdong Province Key Laboratory of Radioactive Pollution Control and Resource | And 5 more authors.
Huanjing Kexue/Environmental Science | Year: 2015

In order to explore how the modification of succinic acid improves the adsorption of tea oil tree sawdust for uranium, the tea oil tree sawdust was modified by succinic acid, after the pretreatments of crushing, screening, alkalization and acidification. Infrared analysis indicated carboxylic acid groups and ester groups were added to the sawdust after modification, and scanning electron microscope demonstrated after modification the appearance of tea oil tree sawdust was transferred from the structure like compact and straight stripped into the structure like loose and wrinkled leaves, which meant modification increased its inner pores. By the static experiments, effects of reaction time between adsorbent and solvent, dosage of adsorbent, temperature, pH value and initial concentration of uranium were investigated. The results showed that after the modification by succinic acid, the absorption rate of tea oil tree sawdust for uranium increased significantly by about 20% in 12.5 mg·L-1 initial concentration uranium solution. Adsorption equilibrium was achieved within 180 min, and the kinetic data can be well described by the pseudo-second-order kinetic model. The experimental adsorption isotherm followed the Langmuir and Freundlich models. In addition, the maximum adsorption amounts of tea oil tree sawdust after modification calculated from Langmuir equation raised from 21.4133 to 31.5457 mg·g-1 at 35℃ and pH 4.0. ©, 2015, Science Press. All right reserved.


Zhang X.-F.,Guangzhou University | Zhang X.-F.,Guangdong Province Key Laboratory of Radioactive Pollution Control and Resource | Chen D.-Y.,Guangzhou University | Chen D.-Y.,Guangdong Province Key Laboratory of Radioactive Pollution Control and Resource | And 4 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2015

P-calix[4]arene acetate was synthetized by the main reaction substrates, p-tert-butyl-calix[4]arene and ethylbromoacetate, subsequently loaded onto zeolite. Infrared spectra demonstrated that the synthetized compound had the structure characteristics of p-calix[4]arene acetate; Scanning electron microscope analysis indicated that p-calix[4]arene acetate was loaded on zeolite successfully, evenly and dispersedly. By the static experiments, the results showed that when the pH = 4, absorbent dosage was 0.5 g, initial uranium concentration was 10 mg/L, p-calix[4]arene acetate/zeolite = 0.025/1, and the reaction time was 30min, the adsorption efficiency of zeolite increased from about 30% to 93% after loadeding p-calix[4]arene acetate. Besides, the adsorption reactions of uranium by zeolite and zeolite loaded with p-calix[4]arene acetate (Referred to as the loaded zeolite) could be both described by pseudo-second-order kinetic model, while the absorption rate of loaded zeolite was faster than that of zeolite. Moreover, both of the 2 absorption reactions followed the Langmuir adsorption isotherm, whereas the maximum adsorption amount inferred by Langmuir model ascended from 16.8919 to 32.5733 mg/g, which was due to fact that zeolite had increased the absorption sites on its surface after loading p-calix[4]arene acetate. In addition, infrared spectra analyses before and after adsorbing uranium demonstrated that the loaded zeolite mainly depended on the strong complexion of p-calix[4]arene acetate and the sorption of Si-O and Al-O to remove uranium, and these 2kinds of functions affected synergistically to speed up the rate of adsorption and increase adsorption amount. ©, 2015, Chinese Society for Environmental Sciences. All right reserved.

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