title: Sorption kinetics and isotherm modelling of imidacloprid on bentonite and organobentonites.
abstract: Bentonite was modified by quaternary ammonium cations viz. cetytrimethylammonium (CTA), cetylpyridinium (CP), rioctylmethylammonium (TOM) and pcholine (PTC) at 100% cation exchange capacity of bentonite and was characterized by X-ray diffraction, CHNS elemental analyser and Fourier transform infrared spectroscopy. The sorption of imidacloprid on organobentonites/bentonite was studied by batch method. Normal bentonite could adsorb imidacloprid only upto 19.31-22.18% while all organobentonites except PTC bentonite (PTCB), enhanced its adsorption by three to four times. Highest adsorption was observed in case of TOM bentonite (TOMB) (76.94-83.16%). Adsorption kinetic data were fitted to pseudo-first-order, pseudo-second-order and intraparticle diffusion models. For normal bentonite data were best fitted to pseudo-first-order kinetic, while for organobentonites fitted to pseudo-second-order kinetics. Sorption data were analysed using Freundlich, Langmuir, Temkin and Dubinin-Radushkevich isotherm models. Data were well fitted to Freundlich adsorption isotherm. Product of Freundlich adsorption constant and heterogeneity parameter (Kf.1/n) was in following order: TOMB (301.87) > CTA bentonite (CTAB) (152.12) > CP bentonite (CPB) (92.58) > bentonite (27.25). Desorption study confirmed hysteresis and concentration dependence. The present study showed that the organobentonite could be a good sorbent for removal of imidacloprid from natural water sample also. Percentage adsorption and Distribution coefficient (mL g-1) value of different adsorbent was in following order: TOMB (74.85% and 297.54) > CTAB (55.78% and 126.15) > CPB (45.81% and 84.55) > bentonite (10.65% and 11.92).
authors.affiliation: a ICAR-Division of Agricultural Chemicals , Indian Agricultural Research Institute , New Delhi , India.
authors.forename: Shailesh K
authors.initials: SK
authors.lastname: Jain
authors.affiliation: a ICAR-Division of Agricultural Chemicals , Indian Agricultural Research Institute , New Delhi , India.
authors.forename: Najam A
authors.initials: NA
authors.lastname: Shakil
authors.affiliation: a ICAR-Division of Agricultural Chemicals , Indian Agricultural Research Institute , New Delhi , India.
authors.forename: Anirban
authors.initials: A
authors.lastname: Dutta
authors.affiliation: a ICAR-Division of Agricultural Chemicals , Indian Agricultural Research Institute , New Delhi , India.|b ICAR-Directorate of Medicinal & Aromatic Plants Research , Anand , Gujarat , India.
authors.forename: Jitendra
authors.initials: J
authors.lastname: Kumar
authors.affiliation: a ICAR-Division of Agricultural Chemicals , Indian Agricultural Research Institute , New Delhi , India.
authors.forename: Mukesh K
authors.initials: MK
authors.lastname: Saini
mesh_terms: D000327:Adsorption; D001546:Bentonite / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry* / Q000302:isolation & purification; D007700:Kinetics; D008956:Models, Chemical; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000737:chemistry* / Q000302:isolation & purification; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification; D014961:X-Ray Diffraction
chemical_list: D007093:Imidazoles; D000073943:Neonicotinoids; D009574:Nitro Compounds; D014874:Water Pollutants, Chemical; D014867:Water; D001546:Bentonite; C082359:imidacloprid
keywords: Imidacloprid; isotherm; kinetics; natural water; organobentonite; sorption