Adsorption of SDBS-MBAS from aqueous solutions using natural zeolite and activated carbon: A comparative study
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1
R&I Centre for the Conservation of Biodiversity and Sustainable Development, Faculty of Forestry and Natural Environment Engineering. Universidad Politécnica de Madrid, Spain
2
Department of Civil Engineering, Faculty of Engineering, The Hashemite University, PO Box 330127, Zarqa 13133, Jordan
Corresponding author
Ahmed Bdour
Department of Civil Engineering, Faculty of Engineering, The Hashemite University, PO Box 330127, Zarqa 13133, Jordan
J. Ecol. Eng. 2025; 26(5):102-113
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ABSTRACT
This study evaluates the performance of natural Jordanian zeolite and activated carbon for the removal of Methylene Blue Active Substances (MBAS) from carwash water, focusing on Sodium Dodecyl Benzene Sulfonate (SDBS), the primary component of MBAS. Comparative adsorption experiments with activated carbon were conducted under controlled conditions (pH 6.8, 25°C) to assess removal efficiency. Adsorption isotherms were constructed using multiple adsorbent dosages (0.1 to 2.0 g) and varying contact times (5 to 120 minutes) to determine maximum adsorption capacities and evaluate adsorption mechanisms. Optimization results revealed that the most efficient removal for zeolite (95.79%) was achieved at a 2.0 g dosage and a 60-minute contact time, whereas activated carbon attained a maximum removal efficiency of 99.21% under optimal conditions (2.0 g dosage, 50-minute contact time). At lower dosages (1.0 g), zeolite achieved 93.68% removal in 60 minutes, while activated carbon required only 30 minutes to reach 98.42%. When considering cost-effectiveness, natural zeolite being locally abundant and significantly less expensive than activated carbon, achieved near-optimal removal at a dosage of 1.0 g, making it a more economically viable option despite slightly lower efficiency. Removal efficiency for both materials increased with higher dosages, elevated temperatures, and lower initial SDBS concentrations. Thermodynamic analysis revealed that the adsorption process was spontaneous and endothermic, with Gibbs free energy (ΔG°) values favoring zeolite over activated carbon. Isotherm modeling indicated that adsorption data for natural zeolite fit well with both the Langmuir and Freundlich models, while activated carbon aligned more closely with the Langmuir and Pseudo-second-order models. Sorption isotherms revealed maximum adsorption capacities derived from the Langmuir model, with natural zeolite capacity increasing from 24% to 31% as the temperature rose from 25°C to 45°C and activated carbon showing a corresponding increase from 11% to 22%. These findings highlight the potential of natural volcanic tuff, an abundant and cost-effective form of zeolite in Jordan, as a sustainable alternative to activated carbon for MBAS removal from carwash wastewater.