Enhanced Removal of Sulfonated Lignite from Oil Wastewater with Multidimensional MgAl-LDH Nanoparticles

Abstract

In this study, hierarchical MgAl-LDH (layered double hydroxide) nanoparticles with a flower-like morphology were prepared under a hydrothermal condition by employing worm-like micelles formed by cetyltrimethylammonium bromide (CTAB) and salicylic acid (SA) as templates. The morphology and structure of the materials were characterized by Brunauer–Emmett–Teller (BET), SEM, and XRD analyses. The performance for the adsorption of sulfonated lignite (SL) was also investigated in detail. FTIR was used to detect the presence of active functional groups and determine whether they play important roles in adsorption. The results showed that the hierarchical MgAl-LDH nanoparticles with a specific surface area of 126.31 m2/g possessed a flower-like morphology and meso–macroporous structures. The adsorption capacity was high—its value was 1014.20 mg/g at a temperature of 298 K and an initial pH = 7, which was higher than traditional MgAl-LDH (86 mg/g). The adsorption process of sulfonated lignite followed the pseudo-second-order kinetics model and conformed to Freundlich isotherm model with a spontaneous exothermic nature. In addition, the hierarchical MgAl-LDH could be regenerated and used, and the adsorption was high after three adsorption cycles. The main adsorption mechanisms were electrostatic attraction and ion exchange between the hierarchical MgAl-LDH and sulfonated lignite.

Recent Breakthrough in Layered Double Hydroxides and Their Applications in Petroleum, Green Energy, and Environmental Remediation

“…Due to the long-dependence on crude oil as a major source of energy in the last decades, a huge amount of oil-wastewater was produced from the various oil-processing steps and especially those related to oil drilling systems. The estimated oil-wastewater counts are about 250 million barrels per day, containing different organic hazards, such as sulfonated lignite of abundant functional groups, such as sulfonic acid, phenolic, hydroxyl, carboxyl, and ketone groups [109]. Sulfonated lignite is classified as a very hazardous material to humans and the environment, since it is a catching agent of heavy metals and pesticides/herbicides, and it can increase their concentration in water.…”

“…A rare work describing the role of hierarchical MgAl-LDH in the adsorptive removal of sulfonated lignite was recently published by Zhou et al [109]. The material was hydrothermally synthesized in the presence of CTAB/salicylic acid as directing agents to produce flower/worm-like morphologies of a high surface area and mesoporous structure.…”

Application of Biochar Functionalized with Layered Double Hydroxides: Improved Plant Growth Performance after Use as Phosphate Adsorbent

“…The general chemical formula of LDHs is denoted as [M 2+ 1−x M 3+ x (OH) 2 ] x+ (A n− ) x/n •mH 2 O, where M 2+ and M 3+ represent the divalent and trivalent cations, respectively, A n− is the anion in the interlayer for charge compensation, and x is equal to the molar ratio of M 3+ /(M 2+ +M 3+ ) [10]. LDHs have recently become popular for treating anionic pollutants because of their strong positive surface charge and exchangeable interlayer anions [11]. Alternatively, some studies have indicated that LDHs have been used as agrochemicals or fertilizers because of their potential to control herbicide and nutrient losses [12][13][14].…”

Water-Preserving and Salt-Resistant Slow-Release Fertilizers of Polyacrylic Acid-Potassium Humate Coated Ammonium Dihydrogen Phosphate

“…Lignite is rich in resources [ 29 ], cheap in price, and has a high content of HA organic matter. On the basis of the above background and our previous studies [ 28 ], in this paper, the HA was extracted from lignite with H 2 O 2 as an oxygenation agent.…”