Abstract
Contamination of water with organic dyes is a major environmental concern as it causes serious life-threatening environmental problems. The present research was designed to evaluate the potential of three different natural inorganic clays (NICs) i.e., Pakistani bentonite clay (PB), bentonite purchased from Alfa Aesar (BT), and Turkish red mud (RM) for malachite green (MG) dye removal from an aqueous solution. Various analytical techniques, namely X-ray fluorescence spectrometry (XRF), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller surface area measurement (BET), and thermogravimetric analysis (TGA), were used to investigate the physicochemical properties of the NICs samples. The effect of adsorption operational parameters such as contact time, aqueous phase pH, dye concentration, and amount of NICs on the adsorption behavior of MG onto NICs samples were investigated under the batch adsorption system. The equilibrium and kinetic inspection reflected the best description of MG adsorption behavior by the Langmuir isotherm model and pseudo-first-order kinetic model, respectively. The results indicated that the adsorption was favorable at higher pH. The maximum adsorption capacities calculated by Langmuir isotherm for PB, BT, and RM were found to be 243.90 mg/g, 188.68 mg/g, and 172.41 mg/g, respectively. It can be concluded that natural inorganic clays with a higher surface area can be used as an effective adsorbent material to remove the MG dye from an aqueous solution.
Highlights
In recent years, planners, environmental scientists, and decision-makers have been paying attention to sustainable resource development [1]
The chemical composition, mineralogical composition, and texture of natural inorganic clays (NICs) were determined by using X-ray fluorescence spectrometry (XRF), X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller surface area measurement (BET), and thermogravimetric analysis (TGA) analysis
It was observed that Pakistani bentonite clay (PB) clay has a quite rough surface with blunt edges and higher surface area as compared to the BT clay and red mud from Turkey (RM) clay
Summary
Planners, environmental scientists, and decision-makers have been paying attention to sustainable resource development [1]. Over 1 × 105 types of dyes and more than 7 × 105 tons per year of pigments and dyestuff are produced and used in many industries, in which 12% is lost during the manufacturing process, and 20% of dyes enter freshwater resources as industrial effluents [11] Due to their complex structures, organic dyes are mainly non-biodegradable and are resistant to environmental conditions such as heat, oxidizing agents, and light [12,13]. Most of the dyes are carcinogenic, mutagenic, and harmful to humans and aquatic biota [14] In addition their high stability towards environmental conditions and resistance to the attack of microorganisms, the presence of organic dyes causes aesthetic problems, impedes penetration of light into receiving water bodies, and depletes dissolved oxygen, thereby disturbing the ecological aquatic systems [15,16]. The obtained adsorption results were analyzed by different kinetic and isotherm models
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