Equilibrium, Thermodynamics, Kinetics of Adsorption of CO32- and SO42- Ions on Modified Plantain Peels
Abstract
To reuse treated wastewater, water quality must be improved. Adsorption is a simple, cost-effective method for eliminating toxicities and poisnous anions. The adsorbent's features and properties determine the method's effectiveness. This research examines the adsorption of carbonate and sulphate anions onto plantain peels modified with 2-amino-4,6- dihydridoxypyrimidine. Characterization was done using SEM, XRD, and FTIR. UV-visible spectroscopy was used to measure initial and equilibrium concentrations, and Langmuir and Fremdliuch isotherms were used to analyze the data. The best parameters for adsorbing 150 mg/L CO3 2- and SO4 2- were: pH 2, and 4, 0.8 g adsorbent, 120 min contact time, and 330 K temperature. Kinetic study used pseudo-first-order reaction equations, and both ion uptake processes followed pseudo-firstorder rate expression. ΔG (-3.772 kJ/mol) for CO3 2- and ΔG (-3.047 kJ/mol) for SO4 2- were negative, and ΔH (-22.04 kJ/mol) and (-39.92 kJ/mol) were also negative, indicating the adsorption process was feasible, spontaneous, and exothermic. Modified plantain peels had high adsorptivity and were a cost-effective adsorbent for CO3 2- and SO4 2- from aqueous solutions.
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Introduction
Toxic anions polluting groundwater is a global problem endangering drinking water. Excessive use and discharge of phosphorus, nitrogen, and sulphur compounds raise nutrient levels in surface and groundwater. When toxic metals enter the environment, metal ions accumulate in humans through direct ingestion or food chains. Water is a fundamental resource for humanity, and its protection is essential for present and future societies. Human activities, like industrial practices, domestic waters, and agricultural uses (e.g. fertilizers, compost, wastewater treatment effluent) often contaminate water with nitrate, sulphate, and phosphate[1]. Recent technological and economic developments are creating toxic pollutants in the different sources of natural water and this is constituting a major hazard to human health [3]. With over 1.2 billion people lacking access to clean, unpolluted, and safe drinking water, water-related issues especially as regards the ever-increasing water scarcity and water pollution remains one of the most topical issues of environmental [2]. Higher levels of sulfate in drinking water lead to its bitter taste and digestive problems as well as corrosion of sewer pipes in addition to causing problems in the anaerobic wastewater treatment processes [4].
Improving water quality is essential for wastewater reuse. Health risks must be taken into account, which could lead to stricter water quality standards [5]. Common mercury removal techniques include adsorption [6], ion exchange, flocculation, and ultrafiltration. Adsorption is a simple, adaptable, and established technique for removing heavy metals, including mercury, from industrial wastewater [7]. It is cost-effective and does not require advanced technology. Deep filtration, macro-filtration, and adsorption can remove some toxic anions, while disinfection eliminates the rest [7].
Wastewater purification using adsorption is a simple, economical way to remove toxins and metals. The adsorbent's features and properties determine the method's effectiveness. Adsorption isotherm is the fundamental concept in adsorption. Equilibrium between pressure/concentration in the bulk fluid phase and adsorbed quantity is known as adsorption
Conclusion
Research showed modified natural adsorbents can remove anion pollutants from water, with effectiveness depending on adsorbent dose, temperature, concentration, pH, and contact time. The pseudo-first-order kinetic model and Langmuir model fit the adsorption and equilibrium isotherm data well, respectively. RL values indicated modified plantain peels were suitable for anion adsorption. Thermodynamic analysis revealed the reaction was spontaneous, exothermic, and physisorption. Thus, modified plantain peels are a promising, low-cost adsorbent for carbonate and sulphate ion removal from aqueous solutions.