Adsorption of thallium using tangerine peels and exploitation from the waste in an eco-friendly manner
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Environmental Engineering Department, College of Engineering, Mustansiriyah University, Baghdad, Iraq
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Chemical Engineering Department, College of Engineering, Mutah University, Al Karak, Jordan
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Materials Engineering Department, College of Engineering, Mustansiriyah University, Baghdad, Iraq
Corresponding author
Mohammed Nsaif Abbas
Materials Engineering Department, College of Engineering, Mustansiriyah University, Baghdad, Iraq
Ecol. Eng. Environ. Technol. 2025; 2:131-152
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ABSTRACT
Heavy metals are classified as environmentally hazardous materials, due to their toxicity to humans and other living organisms. Given the involvement of these metals in various human activities, it has become necessary to include them within international and local standards, to ensure the safety of both humans and the environment. The present study aimed to achieve the sustainability principle by investigating the ability of tangerine peels, as a readily available and low-cost material, to remove the toxic element thallium from contaminated aqueous solutions. Batch adsorption technique was used at different design parameters of acidity, temperature, contact time, initial concentration, adsorption dose and agitation speed. The obtained results showed that tangerine peels have a remarkable ability to recover thallium (III) ions from polluted water with an efficiency of 82.4% and an adsorption capacity of approximately 2 mg.g-1 at initial concentration, adsorbent dosage, contact time, pH, agitation speed, and temperature of 80 ppm, 4.5 g, 120 min, 6, 350 rpm, and 25°C, respectively. Morphological examinations indicated that the tangerine peels suffered from many changes due to thallium adsorption, as their surface area decreased by 83.5%, functional groups decreased significantly, and obvious changes in the surface structure occurred, as indicated by BET, FT-IR and SEM tests, respectively. The isothermal study showed that the best model to represent the experimental data is the Langmuir model, while the pseudo-second-order model is the closest to represent the results kinetically. Thermodynamically, adsorption is characterized as chemical, exothermic, and of decreasing randomness, in addition to being spontaneous at all studied temperatures. For the safe and comprehensive disposal of residual toxic waste, its use as a cheap and effective rodenticide has been studied, by mixing the waste at a rate of 10-25% with the diet used to feed laboratory rats. These residues caused mortality ranging from 50-100% of the animals exposed to the test in all experimental groups, which confirms the toxic effect of this metal and the necessity of providing effective and economical manners for getting rid of it.