아민기로 수식된 수용성 유기점토의 합성과 말라카이트 그린과의 제거거동

Abstract

Malachite green (4-[(4-dimethylaminophenyl)-phenyl-methyl]-N,N- dimethyl-aniline, MG), aniline green, basic green 4) is known to a toxic chemical widely used as a dye. Historically malachite green was determined as health risk to humans who eat fish contaminated with that. In addition, the United States Food and Drug Administration (FDA), detected MG in seafood imported by China, has banned in 2006 year. As a result, the development for removal techniques of MG is required. In this work, the potential feasibility of organic nanoclay which has capability for long-term trapping of MG was investlaated. Among various organic clays, aminopropyl-functionalized magnesium phyllosilicate (AMP) clay was selected due to higher solubility (dispersity) in aqueous media. This organoclay, which was initially prepared as a bulk precipitate by room temperature where hydrolysis/condensation of 3-aminopropyltriethoxysilane in ethanolic solution of MgCl2, consists of stacked sheets of a talc-like phyllosilicate with covalently attached aminopropyl groups that extend into the intarlamellar spaces. Prepared AMP clay was confirmed by X-ray diffraction. The operating variables through initial dye concentration, AMP clay dosage, initial solution pH, and temperature with MG removal were studied to equilibrium/kinetic and thermodynamic phenemina in this system. Removal of MG showed that the process was cationic exchange mechanism between magnesium ions and MG removal was strongly pH-dependent. The maximum removal percentage was obtained from pH 5 to 10. The equilibrium process was described by the Langmuir isotherm model. Maximum sorption capacity by AMP clay was to be 227.42 mg/g at pH 10.5 and room temperature. The kinetics of MG sorption on AMP clay followed the Lagergren’s pseudo-first-order model. The thermodynamics parameters of activation of Gibbs free energy, enthalpy and entropy were evaluated according to 20, 40, 60 ˚C. We found that ΔG, ΔH, and ΔS are 334.14 kJ/mol, 47.74 kJ/mol, and -0.97695 kJ/(K⦁mol) at 20 ℃ 353.28 kJ/mol, 47.58 kJ/mol, and -0.97621 kJ/(K⦁mol) at 40 ℃ 373.40 kJ/mol, 47.41 kJ/mol, -0.97849 kJ/(K⦁mol) at 60 ℃ respectively.