A Worksheet Based Model for Adsorption of Pollutants on Sorbents with Multiple Sites and Sorption Mechanisms

Anthropogenic compounds as pharmaceuticals constitute potential pollutants as a result of their extensive use. In places were domestic water is treated and reused, eventually part of these chemicals would arrive to wastewater treatment plants, and from there be reused or released to nature. Thus, the need for a tool for the evaluation of the fate of such pollutants due to irrigation, rain, changes in water composition or different soil properties- is crucial. This study presents a worksheet based adsorption model that considers charged and neutral sites. Adsorption to charged sites is based on a Gouy-Chapman-Stern model, whereas amounts adsorbed on neutral sites are evaluated by a combination of Langmuir and partition mechanisms. Several sites of each kind, e. g. , several clay minerals with different phisico-chemical parameters, might be considered simultaneously. Model results for metoclopramide, tetracycline and chlorpheniramine are presented. Very good fit between experimental and calculated values with a single set of adjustable parameters for each pollutant was observed. The versatility of the model combined with the fact that it is worksheet based, might make it a useful tool for environmental researchers