Succinate-bonded pullulan: An efficient and reusable super-sorbent for cadmium-uptake from spiked high-hardness groundwater

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• 作者：Azhar Abbas¹ ; Muhammad Ajaz Hussain¹ ; ^{majaz172@yahoo.com" class="auth_mail" title="E-mail the corresponding author} ; Muhammad Amin¹ ; Muhammad Sher¹ ; Muhammad Nawaz Tahir² ; ^{tahir@uni-mainz.de" class="auth_mail" title="E-mail the corresponding author} ; Wolfgang Tremel²
• 关键词：Adsorption ; Cadmium ; Modified pullulan ; Succinylation ; Thermal stability
• 刊名：Journal of Environmental Sciences
• 出版年：2015
• 出版时间：1 November 2015
• 年：2015
• 卷：37
• 期：Complete
• 页码：51-58
• 全文大小：707 K

文摘

Chemically modified pullulan was evaluated for its sorption efficiency and selectivity to remove cadmium (Cd) from spiked high-hardness groundwater (GW). Pullulan esterified with succinic anhydride using dimethylaminopyridine showed a fairly high degree of substitution value as confirmed by ¹H NMR spectroscopy. Pullulan succinate (Pull-Suc) was converted into the sodium salt (Pull-Suc-Na). The effect of contact time (5–200 min) and pH (2–8) on Cd-uptake by the sorbent (Pull-Suc-Na) was investigated. The sorbent showed more than 90% Cd-removal in first 15 min from distilled water (DW) and GW solution, respectively. Comparison of Pull-Suc-Na with other polysaccharidal sorbents suggested its high efficiency (DW 476.2 mg/g and GW 454.5 mg/g) and selectivity for the removal of Cd by an ion exchange mechanism, which is further supported by the negative Gibbs free energy values calculated from Langmuir isotherms. A Langmuir isotherm kinetic model provided the best fit for the sorption of Cd using Pull-Suc-Na. The sorbent showed a negligible decrease in Cd-uptake over three regeneration cycles. The thermal stability testing of the sorbents indicated that Pull-Suc-Na (sorbent) is more stable than Pull-Suc.