Adsorption of crystal violet dye from aqueous solution using mesoporous materials synthesized at room temperature

Abstract

In this work, batch adsorption experiments are carried out for crystal violet dye using mesoporous MCM-41 synthesized at room temperature and sulfate modified MCM-41 prepared by impregnation method using H 2 SO 4 as sulfatising agent. The surface characteristics, pore structure, bonding behavior and thermal degradation of both the MCM-41 samples are characterized by nitrogen adsorption/desorption isotherms, X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) spectroscopy and thermo gravimetric analysis (TGA). The adsorption isotherm, kinetics and thermodynamic parameters are investigated for crystal violet (CV) dye using the calcined and sulfated MCM-41. Results are analysed using Langmuir, Freundlich and Redlich-Peterson isotherm models. It is found that the Freundlich model is an appropriate model to explain the adsorption isotherm. The highest adsorption capacity achieved is found to be 3.4 × 10 −4 mol g −1 for the sulfated MCM-41. The percentage removal of crystal violet dye increases with increase in the pH for both the MCM-41 adsorbents. Kinetics of adsorption is found to follow the second-order rate equation. From the thermodynamic investigation, it is evident that the adsorption is exothermic in nature. CVCrystal Violet CTAB Cetyltrimethylammonium Bromide TEOS Tetraethylorthosilicate a 0 Unit cell Parameter (nm)Pseudo-first-order rate constant (min −1 ) k 2 Pseudo-second-order rate constant (gmol −1 min −1 ) k d Diffusion coefficient (dimensionless) K F Freundlich isotherm constant (mol/g(dm 3 /mol) 1/n ) K L Langmuir constant (dm 3 mol −1 ) K RP Redlich-Peterson constants (mol g −1 ) m Mass of the adsorbent (g) n Adsorption intensity (dimensionless) q e Amount of dye adsorbed at equilibrium (mol g −1 ) Q max Maximum adsorption capacity (mol g −1 ) S 0 Entropy (KJ mol −1 K −1 ) S BET BET surface area (m 2 g −1 ) V Volume (dm 3 ) V mes Mesoporous volume (cm 3 g −1 )Greek letters βFull width at half maximum (degrees) θAngle of diffraction (degrees) λ Wavelength (nm) λ max Maximum absorbance wavelength (nm) Adsorption (2009) 15: 390-405 391

Kinetics and Thermodynamic Study of Malachite Green Adsorption on Seeds of Dates.

“…The minimum removal of dye was thus found at pH 2, which is probably due to the H + ions competing favorably with the cationic groups of the dye molecule for adsorption sites on SD. Similar observations have been reported by other authors [22,23]. The insignificant higher removal of the dye, observed at pH between 7.0 and 12.0, was noted to be accompanied by a drop in the original pH of the dye solution at adsorption equilibrium.…”

“…pH has been related with changes in the structural stability and color intensity of the dye molecule [23]. The removal of MG dye by SD over a range of 2-12 was noted to increase with the increase in pH of the dye solution, appreciably up to pH 7.0 (Fig.…”

Adsorption capability of activated carbon synthesized from coconut shell

“…The sample was collected at different time intervals, and the dye concentration (C t ) was calculated with the Varian CARY 50 probe type UV-vis spectrophotometer (Agilent Technologies Inc., Santa Clara, CA, USA). The amount of dye adsorbed (q t ) onto the activated carbon was calculated with the following formula [35,36]: (2) here, C 0 and C t represent, respectively, the initial and equilibrium concentrations of methyl orange solution in (mg L…”

Review of the use of mesoporous silicas for removing dye from textile wastewater

“…The most frequently used equations for describing isotherms of the adsorption of dye by MPSs in solid/ liquid systems are the Langmuir (Joo et al 2009;Chen et al 2012;Chang et al 2013a;Liu et al 2013), Freundlich (Monash and Pugazhenthi 2009;Anbia and Salehi 2012), Redlich-Peterson (Monash and Pugazhenthi 2009;Yang and Feng 2010a;Wu et al 2012) and Temkin Mahmoodi et al 2011). The mathematical equations of these models are presented in Table 7.…”