Improvement of the desorption of the pesticide 2,4-D via complexation with HP-β-cyclodextrin

✍ Scribed by José I Pérez-Martínez; Juan M Ginés; Esmeralda Morillo; María L González-Rodríguez; José R Moyano Méndez

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 184 KB
• Volume: 56
• Category: Article
• ISSN: 1526-498X
• DOI: 10.1002/(sici)1526-4998(200005)56:5<425::aid-ps156>3.0.co;2-w

✦ Synopsis

Inclusion complex formation of 2,4-dichlorophenoxyacetic acid (2,4-D) with hydroxypropylb-cyclodextrin (HP-b-CD) has been proposed as a way of modifying the behaviour of the pesticide in the soil environment. The present study assesses the effect of complex formation on 2,4-D physicochemical properties (aqueous solubility, crystallinity and dissolution rate) and its behaviour on soils.

The solid complexes were prepared using different methods (spray drying, kneading and heating in a sealed container). To con®rm the complex formation in the solid state differential scanning calorimetry, hot stage microscopy and x-ray diffraction techniques were employed. Complex formation in solution was studied by phase solubility. The presence of HP-b-CD increased the 2,4-D solubility nine times approximately. The apparent stability constant was determined as 98.6 M À1 . The dissolution rates of the 2,4-D/HP-b-CD complexes were examined and compared with that of the pure pesticide. The results indicated that the complex may have great utility as a rapid way of dissolving the pesticide. Batch experiments were performed to study the adsorption±desorption of 2,4-D on soils and the in¯uence of the HP-b-CD over these processes. The results showed that HP-b-CD could increase the desorption of 2,4-D previously adsorbed on soils.