| The adsorption of humic acid molecules on metal oxide (hematite) particles/water interface was studied, with humic acid used as a representative of natural organic matter. This paper mainly analyzed influences of pH values and ionic strength on the adsorption coordinate reaction, as well as on the adsorption density and the size of aggregating-particles. The adsorption density decreased with pH values increasing and increased as ionic strength increased, while the size of aggregating-particles increased firstly and then decreased with pH value increasing, and increased with the ionic strength increasing. When pH value was 4, the adsorption density was the largest, i.e. 6.22 mg/m2, while the size of aggregating-particles was the smallest. When pH value was 5, the adsorption density was smaller, but the size of aggregating-particles was larger. When pH value was 8, it reached the isoelectric point of coordination reactions, therefore the adsorption density and the size of aggregating-particles were all considerably small. When pH value was 10, the adsorption density is the smallest, i.e. 0.50 mg/m2, and the size of aggregating-particles is also smaller. Finally, the SS/SF hybrid model was introduced briefly, and used to analyze the adsorption configurations of humic acid molecules on hematite particle/water interface preliminarily. When pH value was low, the configurations were mostly train and loop, when pH value was high, the configurations were mostly tail. The higher the ionic strength was, the more train and tail configurations there were. The lower the ionic strength was, the more loop configurations there were. |
