In order to increase diatomite adsorption capacity, polypropylene acetamide (PAM) and barium chloride(BaCl2) were employed to modify the diatomite. Experiments were conducted to investigate surface chemistry characterization and adsorption capacity of the diatomite before and after modification, and adsorption capacity of Pb2+ onto raw diatomite, PAM modified diatomite, zeolite, vermiculite and red soil. The results obtained show that the best concentrations of PAM and BaCl2 for diatomite modification were 20 g·L-1 and 0.2 mol·L-1, respectively. PAM and BaCl2 removed most of the impurities on the diatomite, improved surface chemistry characterization and porous structure of the diatomite. Experimental data obtained from the present study indicated that the best condition for Pb2+ adsorption on the dry diatomite (diatomite dosage) was 50 g·L-1, pH value was 7, adsorption time was 120 min, and initial concentration of Pb2+ was 200 mg·L-1. The present data also indicate that adsorption capacity of PAM modified diatomite and BaCl2 modified diatomite increased by percentages of 23.4 and 28.5%, respectively when compared with raw diatomite. PAM modified diatomite was the most effective and available adsorbent for adsorption of Pb2+.
Key words: Diatomite, modification, Pb2+, adsorption capacity.
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