Samaneh Salmani; Hassan Rezaei; Hajar Abyar
Abstract
Agricultural product processing generates substantial quantities of agricultural waste and their disposal has become a critical concern, threatening human health and the environment. The pyrolysis process is an upgrading technology for producing valuable products from waste feedstocks. Hence, the potential ...
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Agricultural product processing generates substantial quantities of agricultural waste and their disposal has become a critical concern, threatening human health and the environment. The pyrolysis process is an upgrading technology for producing valuable products from waste feedstocks. Hence, the potential of eco-friendly biochar derived from cotton waste was comprehensively investigated for methylene blue removal. The cotton-based biochar contained various pore sizes and functional groups on the surface verified by SEM and FTIR analyses. The impacts of adsorbent dose, methylene blue concentration, temperature, pH, and contact time on the adsorption of methylene blue were assessed to highlight the efficiency of the cotton-based biochar. The results revealed >90% removal under 10 mg/l methylene blue concentration, 0.7 g adsorbent dose, pH of 6, and contact time of 60 min at a temperature of 20 ⁰C. The adsorption isotherm was well-fitted with the Freundlich model, indicating the multilayer methylene blue adsorption. The adsorption process was chemisorption and endothermic based on kinetic and thermodynamic modeling. Summing up, it can be suggested that the cotton-based biochar can be easily and efficiently applied for methylene blue removal from aqueous solutions, and further investigations are required to modify its specific surface area by a green synthesis approach.
Zohreh Jahannia; Hassan Rezaei; Hajar Abyar; Somayeh Namroodi
Abstract
Cost-effective dye wastewater treatment approaches are critically required for the long-term sustainability of textile industries. To fill the gaps, multiple high-potential adsorbents derived from biomass have been proposed. For this purpose, this study was conducted to present an applicable and cost-effective ...
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Cost-effective dye wastewater treatment approaches are critically required for the long-term sustainability of textile industries. To fill the gaps, multiple high-potential adsorbents derived from biomass have been proposed. For this purpose, this study was conducted to present an applicable and cost-effective biochar synthesized from cow dung to remove methylene blue from the aqueous solutions. The potential of cow dung-based biochar was optimized under various pH, biochar dose, methylene blue concentration, contact time, and temperature. The maximum removal was 96% achieved at optimum conditions, 20 mg/l methylene blue concentration, 0.2 g biochar dose, pH of 6, and 90 min contact time at ambient temperature. The methylene blue adsorption process followed the Freundlich isotherm (R2=0.9827) and pseudo-second-order (R2=0.999) kinetic models, implying multilayered adsorption on the heterogenous surface and chemisorption mechanism, respectively. Furthermore, the adsorption process was spontaneous and exothermic due to negative Gibbs free energy (ΔG0) and enthalpy (ΔH0) with the reduction at randomness of methylene blue molecules and adsorbent interaction based on negative entropy (ΔS0). Regarding the high efficiency of cow dung-based biochar to adsorb methylene blue, it is recommended that further investigations consider the biochar activation and functionalization intending to upgrade its adsorption capacity.
