Insight into the Effect of Sulfonation Techniques on the Adsorption Properties of −SO₃H Surface-Functionalized Coal as Adsorbent for Malachite Green Dye: Steric and Energetic Investigation

Abstract

Natural coal (N.C) was sulfonated with sulfuric acid by normal stirring (MS.C) and sonication waves (SS.C) to obtain −SO3H functionalized coal as enhanced adsorbents of malachite green dye (MG). The sulfonated products exhibit enhanced surface area (MS.C (27.2 m2/g) and SS.C (45.8 m2/g)) as compared to N.C. SS.C achieved higher acid density (14.2 mmol/g) and sulfur content (13.2 wt. %) as compared to MS.C. The impact of the sulfonation processes on the adsorption of MG was assessed based on the monolayer isotherm model of one energy. The MG Q sat of N.C (121.3 mg/g), MS.C (226.3 mg/g), and SS.C (296.4 mg/g) validate the significant effect of the sulfonation processes by the sonication waves. This is in agreement with the active site densities that reflect the saturation of SS.C by more active sites (180.74 mg/g) than MS.C (120.38 mg/g) and N.C (70.84 mg/g). The MS.C and SS.C can adsorb three MG molecules as compared to two molecules per site of N.C. The Gaussian energy (<8 kJ/mol) and adsorption energy (<40 kJ/mol)) reflects the physisorption of MG involving van der Waals forces, hydrogen bonding, and dipole bonding forces. The thermodynamic functions demonstrate the uptake of MG by exothermic, spontaneous, feasible reactions.

Synthesis and Characterization of Iron-Rich Glauconite Nanorods by a Facile Sonochemical Method for Instantaneous and Eco-friendly Elimination of Malachite Green Dye from Aquatic Environments

“…In recent times, the accelerated growth of industries has resulted in significant environmental challenges, notably the issue of water pollution and its consequential impacts on both aquatic ecosystems and human health. , Various types of pollutants are discharged into the surroundings as a result of industrial operations, including dyes, pesticides, heavy metals, antibiotics, petrochemicals, and bacteria. , All of these aforementioned concerns possess substantial gravity, representing catastrophic challenges that pose a direct threat to the well-being of both human beings and all other forms of life . Synthetic dyes are aromatic organic compounds that serve as crucial coloring agents for various sectors such as paper, plastic, leather, printing, and textiles. , Hence, it has been stated that an estimated quantity of over 7 × 10 5 tons annually of dyes manufactured is being discharged as contaminants into the natural environment and aquatic ecosystems .…”

“…The majority of synthetic dyes are known to possess toxicity and nondegradability, leading to a range of adverse consequences, including dermatitis, allergies, cancer, teratogenicity, skin irritation, carcinogenicity, and kidney damage. , Furthermore, the migration of dye molecules has adverse effects on the aquatic ecosystem, specifically impacting the photosynthetic activity and overall bioactivity of the species present. This pertains to the inhibitory effect of the dye surface on the penetration of sunlight into the deeper layers of water. , Malachite green (MG) is a frequently used dye, characterized as a synthetic organic molecule (C 23 H 25 ClN 2 ) with a green hue. However, despite the widespread use of the MG dye in several industries, including the aquaculture, food, and pharmaceutical disinfection sectors, it has been recognized as a highly hazardous compound. ,, Insufficient treatment of MG results in a substantial release of this molecule into the aquatic environment, leading to a decrease in the oxygen levels in the water.…”

“…This pertains to the inhibitory effect of the dye surface on the penetration of sunlight into the deeper layers of water. , Malachite green (MG) is a frequently used dye, characterized as a synthetic organic molecule (C 23 H 25 ClN 2 ) with a green hue. However, despite the widespread use of the MG dye in several industries, including the aquaculture, food, and pharmaceutical disinfection sectors, it has been recognized as a highly hazardous compound. ,, Insufficient treatment of MG results in a substantial release of this molecule into the aquatic environment, leading to a decrease in the oxygen levels in the water. Moreover, the presence of MG at high concentrations poses notable health risks, including mutagenesis, pulmonary toxicity, chromosomal fractures, tumor formation, and teratogenicity. , …”

“… 1 , 2 Various types of pollutants are discharged into the surroundings as a result of industrial operations, including dyes, pesticides, heavy metals, antibiotics, petrochemicals, and bacteria. 3 , 4 All of these aforementioned concerns possess substantial gravity, representing catastrophic challenges that pose a direct threat to the well-being of both human beings and all other forms of life. 5 Synthetic dyes are aromatic organic compounds that serve as crucial coloring agents for various sectors such as paper, plastic, leather, printing, and textiles.…”

“…This pertains to the inhibitory effect of the dye surface on the penetration of sunlight into the deeper layers of water. 4 , 8 Malachite green (MG) is a frequently used dye, characterized as a synthetic organic molecule (C 23 H 25 ClN 2 ) with a green hue. However, despite the widespread use of the MG dye in several industries, including the aquaculture, food, and pharmaceutical disinfection sectors, it has been recognized as a highly hazardous compound.…”