Adsorption of paraquat from water by insoluble cyclodextrin polymer crosslinked with 1,2,3,4-butanetetracarboxylic acid

• Published in: Iranian polymer journal 2019-03, Vol.28 (3), p.213-223
• Main Authors: Junthip, Jatupol, Promma, Warangkana, Sonsupap, Somchai, Boonyanusith, Chaichat
• Format: Article
• Language: English
• Subjects: Adsorption; Carbon 13; Ceramics; Chemical synthesis; Chemistry; Chemistry and Materials Science; Composites; Crosslinking; Cyclodextrins; Enthalpy; Exothermic reactions; Fourier transforms; Free energy; Gibbs free energy; Glass; Infrared analysis; Infrared reflection; Ion exchange; Microscopy; Natural Materials; NMR; Nuclear magnetic resonance; Original Research; Paraquat; Pesticides; Polymer Sciences; Polymers; Reaction kinetics; Regeneration; Scanning electron microscopy; Stereoscopy; Thermogravimetric analysis
• ISSN: 1026-1265; 1735-5265
• DOI: 10.1007/s13726-019-00692-9

An insoluble polymer was elaborated by crosslinking reaction between β-CD (β-cyclodextrin) and BTCA (1,2,3,4-butanetetracarboxylic acid) and it was firstly applied in adsorption of paraquat (PQ) from water. This insoluble polymer was synthesized at 180 °C for 30 min which displayed 74.1% of reaction yield, 3.80 mmol g − 1 of ion exchange capacity (IEC) and 0.18 mmol g − 1 of β-CD content. Physicochemical properties were evaluated by attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR), carbon-13 nuclear magnetic resonance ( 13 C NMR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) method and stereoscopic microscopy. The optimal pH was 8 and the equilibrium time was 120 min. At 30 °C, the adsorption capacity was enhanced (10.8, 19.7, and 25.8 mg g − 1 ) when the initial concentration of paraquat was increased (25, 50 and 200 mg L − 1 , respectively). Adsorption kinetics was described by the pseudo-second-order model and adsorption isotherm was appropriated to the Langmuir model. The negative standard enthalpy change (∆ H º) showed an exothermic process, the positive standard entropy change (∆ S º) displayed an increased disorder and the negative standard Gibbs free energy change (∆ G º) indicated a spontaneous adsorption method. Ultimately, the regeneration efficiency of polymer in methanol was 87.3% after four cycles. This polymer could be used as a potential adsorbent for removal of other cationic pesticides.