Cr (VI) removal from aqueous solutions by fly ash and fly ash composite filter material: Factorial experimental design

The removal of Cr(VI) from aqueous solution by batch adsorption experiments using fly ash (FA) and composite filter material made of fly ash (FACFM) as adsorbents were investigated. The influence of pH, contact time on the selectivity and sensitivity of the removal process were investigated. The effect factors such as adsorbent dosage level, initial Cr(VI) concentration and temperature were studied throughorthogonal experiment to investigate their degree of influence on the Cr(VI) adsorption process. Results show that FA and FACFM can be considered as efficient sorbents for the removal of Cr(VI) from aqueous solutions. It was also shown that increase in the adsorbent dosage level led to increase in Cr(VI) adsorption due to the increased number of adsorption sites, the adsorption process was highly pH dependent and the optimum pH was less than 3. Both adsorption rate and the removal ratio of FA were larger than that of FACFM because of its larger contact area and its powdery form, but concerning the intensity and ease of separation from aqueous solution, FACFM was more practical and can be used for wastewater treatment.         Key words: Cr (VI), fly ash (FA), fly ash composite filter material (FACFM), adsorption, orthogonal experiment.