Adsorption Behavior of DOM by PACs with Different Particle Sizes

Abstract

Particle size of powdered activated carbon (PAC) is an important factor influencing the adsorption behavior of organic matter, but the effect of PAC particle size on the removal of different fractions of dissolved organic matter (DOM) is still not well understood. In this work, natural water from a site with anthropogenic influence was used as test water, and the adsorption behavior of different DOM fractions onto three PACs with different particle size was investigated. The results demonstrated that the DOM removal was enhanced 83.3% when the PAC particle size decreased from 76.0 to 19.1 µm. The majority of increased adsorption capacity could be ascribed to microbial by‐product and humic‐like fractions, or to mid‐molecular weight fraction DOM. With the decrease of PAC particle size, the adsorption kinetic constant of low‐molecular fraction was greatly enhanced, but the adsorption capacity was enhanced less significantly. By comparing the Brunauer–Emmett–Teller surface area and pore size distribution of PACs with different particle sizes, it was confirmed that the improvement of adsorption by reducing PAC particle size could be attributed to the increase of accessible PAC surface area and decrease of diffusion distance for DOM molecules.