Biosorption of Pb(II) ions from aqueous solution using alginates extracted from Djiboutian seaweeds and deposited on silica particles

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Pure Appl. Chem
High-molecular alginates were extracted from Djiboutian brown seaweeds, Sargassum sp. (S) and Turbinaria (T) and isolated as sodium salts in 31.0 and 42.7% yield by weight. 1H NMR analysis of the uronic acid block-structure indicates mannuronic/guluronic M/G ratios of 0.49 and 3.0 for the alginates extracts, respectively. The resulting alginates were deposited onto native Aerosil 200 silica, amine-functionalized and carboxyl-functionalized silica particles to enhance the mechanical strength providing Alg.(T/S)+SiO2) Alg.(T/S)+SiO2NH2) and Alg.(T)+SiO2CO2H) composites. Taking Pb(II) as examples for toxic heavy metal ions, the effects of the pH, adsorption kinetics, and isotherms have been studied systematically. The best uptake achieved was 585 mg Pb2+ ion/g using Alg.S+SiO2NH2. Furthermore, the Pb(II) ions were successfully desorbed in several cycles from Alg.T+SiO2 using 0.5 M hydrochloric acid. Therefore, Alg.T+SiO2 may be considered as a low-cost biosorbent that quickly adsorbs and easily desorbs analyte lead ions. A comparison of the adsorption capacity of our biopolymer-coated particles with that of other adsorbents reported in the literature reveals that our materials are among the best performing for the adsorption of Pb(II).
adsorption, alginates, biopolymer, kinetic studies, lead, POC-17, silica, UD College of Engineering, CoE_Djibouti, Université de Djibouti, Djibouti, Engineering, Marielle Franchi, Michael Knorr
Pure Appl. Chem