Adsorption of Orthophosphates in Water by Carbonaceus of Biological Origin as Adsorbent

Abstract

The objective of this study was to evaluate the adsorption capacity calcareous skeleton of animal species (CSAS) in powder form compared to the commercial activated carbon (CAC) powder, as adsorbent for orthophosphates (P) removal from water. The experimental design selected was a factorial design with central composite rotational design (CCRD). In order to optimize the sorption process, a number of independent variables and levels were selected including: adsorption time; adsorbent/adsorbate ratio; pH and temperature. The orthophosphate (P) quantification was performed using the 4500-P E method. The P removal capacity with CAC powder varied from 0.15 to 4.86 mg/L. The maximum removal occurred at 1088 min, initial pH of 7.5, adsorbent/adsorbate ratio of 130, and temperature of 27 ºC. With the CSAS, the phosphorus removal varied from 0.70 to 6.11 mg/L. The maximum removal occurred at 735 min, with initial pH of 9.0, adsorbent/adsorbate ratio of 40 and temperature of 32 ºC. The conclusion is that the CSAS powder can become an interesting alternative as adsorbent material, both from economic and technical viewpoints in several applications, such as treatment of urban and industrial wastewaters and phosphorus removal/ retention to prevent eutrophication of recipient water bodies. Additionally, the final product (phosphorus-adsorbed CSAS powder) can be used as fertilizer and as soil pH adjustment.