Natural Organic Matter Removal by Adsorption onto Carbonaceous Nanoparticles and Coagulation

Abstract

Nanoparticles have emerged as promising adsorbents for water purification. In this study, nanoscale carbon black was employed to remove natural organic matter (NOM) from water in the presence and absence of coagulation. Standard Suwannee River NOM was employed as the targeted pollutant. In the absence of coagulation, more than 60% NOM removal was achieved by carbon black adsorption. A higher hydrogen ion concentration (pH) (3–5) was favorable for NOM removal. More than 35% NOM was removed by carbon black adsorption in the first 20 min, and the adsorption of NOM onto carbon black occurred within about 2 h. Proper stirring was essential for the mixture of NOM and carbon black, while insufficient stirring or overstirring decreased NOM removal efficiency. When low dosages of coagulants were used in combination with carbon black at pH 6–7, the removal efficiency of NOM increased significantly. Depending on the coagulant, the sequencing of adsorption and coagulation can be important. Almost 90% NOM was removed in 15 min by carbon black adsorption and alum coagulation, which is a higher removal than for conventional treatment. This study indicated that carbon black might be an important adsorbent for NOM removal in water treatment in combination with low doses of alum.