Adsorption of chlorpyrifos, penconazole and metalaxyl from aqueous solution by modified clays

• Published in: Journal of environmental science and health. Part B, Pesticides, food contaminants, and agricultural wastes Pesticides, food contaminants, and agricultural wastes, 2009-08, Vol.44 (6), p.525-532
• Main Authors: Suciu, Nicoleta A, Capri, Ettore
• Format: Article
• Language: English
• Subjects: Adsorption; Agronomy. Soil science and plant productions; Alanine - analogs & derivatives; Alanine - chemistry; Aluminum Silicates - chemistry; aqueous solutions; Bentonite - chemistry; Biological and medical sciences; Cations; chlorpyrifos; Chlorpyrifos - chemistry; clay; Fundamental and applied biological sciences. Psychology; Kinetics; maximum adsorption; metalaxyl; Micelles; Modified clays; montmorillonite; natural montmorillonite; penconazole; pesticide; Pesticides - chemistry; Pesticides - isolation & purification; process design; Soil and water pollution; Soil science; Solutions - chemistry; sorption isotherms; Surface Properties; Surface-Active Agents - chemistry; Thermodynamics; Triazoles - chemistry; Waste Disposal, Fluid - methods; wastewater treatment; Water - chemistry; water pollution
• ISSN: 0360-1234; 1532-4109
• DOI: 10.1080/03601230902997543

Sorption of three pesticides (chlorpyrifos, metalaxyl and penconazole) has been measured on a commercial clay montmorillonite and on the same mineral modified with either of two cationic-surfactant micelles. Both micelle-clay complexes, commercial names Cloisite 20A and Cloisite 30B, showed a good capacity to sorb all three pesticides from water, whereas their sorption on the natural montmorillonite was not described by an isotherm. Modelling sorption on both micelle-clay complexes showed that the Freundlich sorption constant (K F ) was higher for chlorpyrifos on Cloisite 20A (K F = 7.76) than on Cloisite 30B (K F = 5.91), whereas the sorption of metalaxyl was stronger on Cloisite 30B (K F = 1.07) than on Cloisite 20A (K F = 0.57). Moreover the micelle-clay complex Cloisite 20A also showed a good affinity for penconazole, the maximum quantity adsorbed (q m ) of 6.33 mg g −1 being 45% more than that on Cloisite 30B. Single-batch adsorption of each pesticide onto both micelle-clay complexes was studied using the Freundlich isotherm for chlorpyrifos and metalaxyl and the Langmuir isotherm for penconazole. The Cloisite 20A micelle-clay complex was predicted to require 23% less adsorbent to treat certain volumes of wastewater containing 30 mg L −1 chlorpyrifos, 43% more to treat metalaxyl similarly and 57% less to treat penconazole compared with Cloisite 30B.