Adsorption of phosphate ions and reactive red 180 from aqueous solution using thermally activated lemon peels waste

• Published in: International journal of environmental science and technology (Tehran) Vol. 21; no. 2; pp. 1683 - 1696
• Main Authors: Saleh, M., Alterkaoui, A., Ozdemir, N. C., Arslan, H., Bilici, Z., Dizge, N.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2024
• Subjects: Aquatic Pollution; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Science and Engineering; Original Paper; Soil Science & Conservation; Waste Water Technology; Water Management; Water Pollution Control; Reactive red 180; Purification; Lemon peel waste; Phosphate; Activation temperature
• ISSN: 1735-1472; 1735-2630
• DOI: 10.1007/s13762-023-05246-4

Pollutants removal from water bodies has become one of the urgent issues over the world. The discharging of textile wastewater without any treatment exposes the environment to severe impacts since it contains many hazardous materials, especially dyes and phosphate. This paper explores the potential uses of lemon peels as an adsorbent for phosphate and reactive red 180 removals. The effects of activation temperature, pH, and the adsorbent dose on reactive red 180 and phosphate removal were investigated and optimized. The optimum conditions for reactive red 180 removal were pH 6.6, a concentration of 25 mg/L, an adsorbent dose of 1.75 g/L, and a contact time of 60 min (the removal efficiency reached 97.5%, and the capacity was 13.87 mg/g). Phosphate was completely adsorbed onto the thermally activated lemon peels at 900 °C with a removal efficiency and an adsorption capacity of 100% and 39.96 mg/g, respectively, after 60 min at a pH 5.9, initial concentration of 10 mg/L, and an adsorbent dose of 0.25 g/L. Both Langmuir and Freundlich had high correlation coefficients. However, Langmuir isotherm had lower error values. For both adsorbates, the Elovich’s model had the best fit data. According to Elovich’s model, the activation energy increases with the adsorption time, and the surface of the adsorbent is energetically heterogeneous. According to the thermodynamic experiments, the adsorptions of both materials were exothermic, feasible, spontaneous, and physisorption. This study suggests that employing lemon peel for phosphate may avoid the generation of second-order pollutants since the adsorbent manipulates as a natural and green fertilizer after the adsorption process. Also, reactive red 180 removal hints that lemon peel can be used for different wastewater types.