Fabrication and Application of Low-Cost Thiol Functionalized Coal Fly Ash for Selective Adsorption of Heavy Toxic Metal Ions from Water

Abstract

A novel thiol modified coal fly ash (CFA-SH) is successfully synthesized by a facile, efficient, and environmentally friendly process using 3-mercaptopropyltrimethoxysilane (MPTS). Various techniques have been used to characterize thoroughly the structure, the surface property, and the presence of the mercaptopropyl groups. The synthesized material proves to be an effective and selective adsorbent for removal of Hg 2+ and Cd 2+ ions from aqueous solution. The effect of time, pH, sample dose, speed, temperature, and metal ion concentrations were investigated thoroughly to optimize the sorption process. The kinetics data fitted in accordance with the pseudo-second-order model. It is also noticed that the Langmuir equation provides an accurate description of these sorption data, implying that monolayer sorption took place during adsorption. The quick and excellent uptake capacities (q m of 361.01 mg g −1 for Hg 2+ within 50 min at pH 8 and 106.38 mg g −1 for Cd 2+ within 60 min at pH 8) of the sorbent can be described on the basis of the hard and soft acid−base principle (HSAB) and electrostatic attraction. Moreover, both adsorbents and adsorbates can be reused using concentrated HCl. Finally, the low cost of the developed sorbent is also the prime point of interest in this experiment.

Facile Preparation of Tannic Acid–Poly(vinyl alcohol)/Sodium Alginate Hydrogel Beads for Methylene Blue Removal from Simulated Solution

“…37 Introparticle diffusion can reflect changes in the removal rate of a target contaminant. Therefore, the Weber–Morris equation eq 3 could be used to identify the controlled rate, as follows 38 where k id (mg/g min 0.5 ) is the intraparticle diffusion rate constant and C is the intercept.…”

Green Preparation of Nanoporous Pyrrhotite by Thermal Treatment of Pyrite as an Effective Hg(Ⅱ) Adsorbent: Performance and Mechanism

“…where q t (mg/g) represents the adsorbed amount at time t, k (mg/(g·min 1/2 )) represents the rate constant, and c represents a constant. As shown in Figure 4B, the multilinear plots indicate that more than one mechanism might be responsible for Hg(II) adsorption onto MPy-600 [5]. The adsorption process can consist of two stages.…”

“…Furthermore, trace amounts of Hg(II) in water are puzzling due to its complexation and mobility features at low concentrations, bioaccumulation during metabolic processes, wide distribution, and control difficulties. The United States Environment Protection Agency set a mandatory discharge limit of 10 µg/L for the total mercury content in wastewater, and the limit in drinking water is 1 µg/L [5]. Hence, it is very important to remove Hg(II) effectively from wastewater [6,7].…”

“…Among them, adsorption methods have been widely studied because they are cost-effective, environmentally friendly, and easy to conduct. Numerous adsorbents have been extensively studied, such as activated carbon [9,10], lichens [11], amine-modified attapulgite [8], poly(2-aminothiazole) [12], and mesoporous silica [5]. However, those adsorbents are either too costly or have low adsorption capacity.…”

Efficient Removal of Lead Ions from Water by a Low-Cost Alginate-Melamine Hybrid Sorbent

“…Over the past decade, many low-cost lead ion adsorbents have been developed to replace activated carbon [6][7][8], such as clay minerals, zeolites, chitosan and its derivatives, industrial waste and so on. However, these adsorbents often have one or more of the following deficiencies in the application process, for example: (1) less binding sites (functional groups such as -COOH, -NH 2 , -OH, -COO, -CHO, etc.)…”