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| Comparison of Cd2+ adsorption onto BS+DT and BS+SDS in complex modified red soil |
| Received:March 18, 2019 |
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| KeyWord:complex modification;red soil;Cd2+;adsorption |
| Author Name | Affiliation | E-mail | | ZHANG Ling-kai | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China | | | ZHANG Yang | Xi′an Solid Waste Management Office, Xi′ an 710000, China | | | YEK Sambath | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China | | | MENG Zhao-fu | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China
Key Lab of Plant Nutrition and Agro-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China | zfmeng1996@263.net | | REN Shuang | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China | | | LU Hao-yuan | College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China | |
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| Abstract: |
| In order to compare the difference of cadmium ion(Cd2+)adsorption on two amphoteric complex modified red soils, amphotericcationic complex modified red soil was prepared with an amphoteric modifier dodecyldimethyl betaine(BS)and a cationic modifier dodecyldimethylammonium bromide(DT). Amphoteric-anionic complex modified red soil was also prepared with BS and anionic modifier sodium dodecyl sulfonate(SDS). The Cd2+ adsorption isotherm and its thermodynamic properties was conducted by batch experiments, and the influence of total modifier ratios, temperature, pH and ionic strength was investigated. The results indicated that the cationic complex modifier DT showed an opposite effect against anionic complex modifier SDS, and the Cd2+adsorption capacity decreased when the modifier ratio of DT was increased, while it increased with an increase in the modifier ratio of SDS. The maximum adsorption capacity of Cd2+ was ordered by BS+SDS > BS > CK(red soil) > BS+DT. The Sips model was the best model for describing Cd2+ adsorption isotherms on different modified soils. The adsorption of Cd2+in both BS-DT and BS-SDS modified red soil increased with an increase of both temperature and pH, but decreased with an increase of ionic strength. The adsorption of Cd2+ was a spontaneous process with endothermic and entropy increment characteristics. The low negative charge of variable charge soils is the key factor for deciding the difference of Cd2+ adsorption on amphotericcationic and amphoteric-anionic modified soil. |
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