Organo-Montmorillonite Modified by Gemini Quaternary Ammonium Surfactants with Different Counterions for Adsorption toward Phenol

Abstract

The discharge of industrial phenol pollutants causes great harm to the natural environment and human health. In this study, phenol removal from water was studied via the adsorption of Na–montmorillonite (Na–Mt) modified by a series of Gemini quaternary ammonium surfactants with different counterions [(C11H23CONH(CH2)2N+ (CH3)2(CH2)2 N+(CH3)2 (CH2)2NHCOC11H23·2Y−, Y = CH3CO3−, C6H5COO− and Br−, 12–2–12·2Y−]. The results of the phenol adsorption indicated that MMt–12–2–12·2Br−, MMt–12–2–12·2CH3CO3− and MMt–12–2–12·2C6H5COO− reached the optimum adsorption capacity, which was 115.110 mg/g, 100.834 mg/g and 99.985 mg/g, respectively, under the conditions of the saturated intercalation concentration at 2.0 times that of the cation exchange capacity (CEC) of the original Na–Mt, 0.04 g of adsorbent and a pH = 10. The adsorption kinetics of all adsorption processes were in good agreement with the pseudo-second-order kinetics model, and the adsorption isotherm was better modeled by Freundlich isotherm. Thermodynamic parameters revealed that the adsorption of phenol was a physical, spontaneous and exothermic process. The results also showed that the counterions of the surfactant had a certain influence on the adsorption performance of MMt for phenol, especially the rigid structure, hydrophobicity, and hydration of the counterions.

Gemini Quaternary Ammonium Surfactants with Different Counterions-modified Montmorillonite for Efficient Removal of Methyl Orange

“…This is because after modified by surfactant, Mt changes from hydrophilicity to hydrophobicity, and the interlayer spacing of OMt increases sharply, thereby improving the adsorption capacity of methyl orange. However, as the amount of modifier exceeds 2.0 CEC, the interlayer spacing of OMt hardly changes or even decreases, as shown in Table 1 33) . In addition, the additional surfactant molecules lead to a densely packed, and the active sites and interlayer space originally used for adsorption is occupied, thus reducing the adsorption capacity of methyl orange 25) .…”

“…1) were synthesized as described previously 31,32) . The preparation and characterization of the modified Na-Mt (OMt-12-2-12・2Y − ) was based on our previous study 33) . According to the CEC of Na-Mt, OMts modified under 0.4, 0.8, 1.2, 1.6, 2.0, 2.4, and 2.8 CEC modifier dosages were prepared.…”

“…where m s (mg) was the amount of modifier, n represented the multiple of CEC (mmol/g) , M (g/mol) was the relative molecular weight of the modifier, and m 0 (g) was the mass of the Na-Mt. The interlayer spacing of the prepared dried OMt was calculated from the Bragg formula according to XRD patterns 33) .…”

“…It is speculated that the different counterions of the surfactant lead to different interlayer spacing of OMt. The counterion with the rigid structure, stronger hydrophobicity and stronger affinity with aliphatic long chains can result in a small interlayer spacing of OMt 33) . This is because, compared with the counterion with the flexible structures, the counterion with the rigid structure make it difficult for surfactants to enter the interlayer structure of Mt.…”

Applicability of Clay/Organic Clay to Environmental Pollutants: Green Way—An Overview

“…During this period, the method of introducing magnetic particles to remove dyes was observed. In the current year, 2023, Wei et al [121], Xie et al [122], and Hu et al [123] reported on the removal of phenol by using modified clay. Wang et al [124], Zeng et al [125], and Nazarizadeh et al [126] reported heavy metal removal by modified organoclay.…”