Abstract
Because of the diversification of industries in developing cities, the phenomenon of the simultaneous contamination of various kinds of pollutants is becoming common, and the environmental process of pollutants in multi-contaminated environmental mediums has attracted attention in recent years. In this study, p-arsanilic acid (ASA), a kind of organic arsenic feed additive that contains the arsenic group in a chemical structure, is used as a typical contaminant to investigate its adsorption on iron oxides and its implication for contaminated soils. The adsorption kinetics on all solids can be fitted to the pseudo-second-order kinetic model well. At the same mass dosage conditions, the adsorption amount per unit surface area on iron oxides follows the order α-FeOOH > γ-Fe2O3 > α-Fe2O3, which is significantly higher than that for actual soil, because of the lower content of iron oxides in actual soil. Lower pH conditions favor ASA adsorption, while higher pH conditions inhibit its adsorption as a result of the electrostatic repulsion and weakened hydrophobic interaction. The presence of phosphate also inhibits ASA adsorption because of the competitive effect. Correlations between the amount of ASA adsorption in actual soil and the Fe2O3 content, total phosphorus content, arsenic content, and organic matter content of actual soil are also investigated in this work, and a moderate positive correlation (R2 = 0.630), strong negative correlation (R2 = 0.734), insignificant positive correlation (R2 = 0.099), and no correlation (R2 = 0.006) are found, respectively. These findings would help evaluate the potential hazard of the usage of organic arsenic feed additives, as well as further the understanding of the geochemical processes of contaminants in complicated mediums.
Highlights
Industries in developing cities are diversified, including agriculture, manufacturing, mining industry, etc
The results show that the adsorption kinetics and adsorption amount of inorganic arsenic were highly affected by the presence of other contaminants, especially phosphate, due to its similar chemical structure to arsenic [20,21,22]
The adsorption kinetics of arsanilic acid (ASA) on three iron oxides is investigated at various iron oxide dosages at pH 5
Summary
Industries in developing cities are diversified, including agriculture, manufacturing, mining industry, etc This diversification could lead to a multitude of sources and types of pollution to the environment. The simultaneous contamination of nutrients, heavy metals, toxic organics, Pharmaceutical and Personal Care Products, etc., in water and surface soil has been widely reported [1,2,3] Such simultaneous contamination is the joint result of domestic sewage discharge, industrial wastewater discharge, livestock and poultry industrial wastewater discharge, and agricultural non-point source pollution. The geochemical behavior of pollutants in a multi-contaminated environment has attracted attention in recent years Both competitive and cooperative effects on contaminants’ adsorption in the complex system are reported [4,5,6,7,8,9,10]. Because of the intricacy of contamination in the urban environment, studying the transportation behavior of pollutants on actual environmental mediums is of great importance
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