title: An efficient calix[4]arene based silica sorbent for the removal of endosulfan from water.
abstract: The present work explores sorption behavior of calix[4]arene based silica resin to remove α and β endosulfan isomers from aqueous solution. The efficiency of resin was checked through both batch and column sorption methods. In both methods, the sorption parameters, i.e. pH, equilibrium time, shaking speed and sorbent dosage were optimized as 2, 60 min, 125 rpm and 50 mg, respectively. Freundlich and Langmuir sorption isotherm models were applied to validate the sorption process. The data obtained in both models reveal that the sorption is favorable. Column sorption data were analyzed through Thomas model to calculate kinetic coefficient k(TH) and maximum sorption capacity q(o) of the resin, which were found to be 6.18 and 5.83 cm(3) mg(-1) min(-1) as well as 1.11 and 1.08 mg g(-1) for α and β endosulfan, respectively. Kinetics of sorption shows that it follows pseudo second order rate equation. The optimized method has also been applied to real water samples and the results show that calix[4]arene based silica resin is an effective sorbent to remove endosulfan from waste waters.
authors.affiliation: Dr. M. A. Kazi Institute of Chemistry, University of Sindh, Jamshoro 76080, Pakistan.
authors.forename: Sibghatullah
authors.initials: S
authors.lastname: Memon
authors.forename: Najma
authors.initials: N
authors.lastname: Memon
authors.forename: Shahabuddin
authors.initials: S
authors.lastname: Memon
authors.forename: Yawar
authors.initials: Y
authors.lastname: Latif
mesh_terms: D000327:Adsorption; D000465:Algorithms; D047250:Calixarenes / Q000737:chemistry*; D004726:Endosulfan / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007306:Insecticides / Q000302:isolation & purification*; D008855:Microscopy, Electron, Scanning; D008956:Models, Chemical; D010636:Phenols / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D018508:Water Purification / Q000379:methods*
chemical_list: D007202:Indicators and Reagents; D007306:Insecticides; D010636:Phenols; C121325:calix(4)arene; D047250:Calixarenes; D012822:Silicon Dioxide; D004726:Endosulfan