RESUMEN
Among the various methods for the removal of azo dye, electrocoagulation is recognized to be highly efficient. However, the process is associated with high operation and maintenance cost, which demands the need for reducing the electrolysis time without compromising the performance efficiency. This can be achieved by adopting hybrid electrocoagulation process with a low-cost but effective process, such as adsorption. The study investigated the performance of a hybrid electrocoagulation-biocomposite system (H-EC-BC) for removing methyl orange dye. Firstly, the operating parameters of electrocoagulation process were optimized and a removal efficiency of 99% has been attained using Fe-SS electrodes at a pH of 6 for a reaction time of 30 min. The performance of EC process was found to be decreasing with increase in dye concentration. Secondly, biocomposite was synthesized from Psidium guajava leaves and characterized using SEM, FTIR, EDAX, and XRD analyses. The results suggested that it is having a porous nature and cellulose crystal structure and confirmed the presence of chemical elements such as carbon (65.2%), oxygen (29.1%) as primary with Fe, Cl, Na and Ca as secondary elements. The performance of the biocomposite was evaluated for the dye adsorption using spectrophotometric methods. Various operating parameters were optimized using experimental methods and a maximum removal efficiency of 65% was achieved at a pH of 6, dosage of 5 g/L and an adsorption contact time of 120 min. The maximum efficiency (92.78%) was obtained with Fe-SS electrodes and KCl as a sustaining electrolyte under acidic circumstances (pH 6). The biocomposite was observed to be more efficient for higher dye concentration. Langmuir and Freundlich adsorption isotherms were fitted with the experimental results with R2 values as 0.926 and 0.980 respectively. The adsorption kinetics were described using Pseudo-first and Pseudo-second order models, wherein Pseudo-second order model fits the experimental results with R2 value of 0.999. The energy consumption of electrocoagulation (EC) process in the hybrid H-EC-BC system was compared to that of a standard EC process. The results demonstrated that the hybrid system is approximately 7 times more energy efficient than the conventional process, thereby implicating its adaptability for field application.
RESUMEN
Emerging pollutants, particularly microplastics, present a significant threat to both the environment and human health. Traditional treatment methods lack targeted strategies for their removal. This study thoroughly investigated the efficacy of electrocoagulation as a method for efficiently extracting microplastics from water. Various critical operational parameters, including electrode combinations, pH levels, electrolyte concentrations, electrode geometries, configurations, current intensities, and reaction times, were systematically examined. The study systematically examined the impact of different combinations of aluminium (Al) and stainless steel (SS) electrodes, including Al-Al, SS-SS, Al-SS, and SS-Al. Among these combinations, it was found that the Al-Al pairing exhibited outstanding efficiency in microplastic removal, while simultaneously minimizing energy consumption. Initial pH emerged as a critical parameter, with a neutral pH of 7 demonstrating the highest removal efficiency. In the pursuit of optimizing parameters like electrolyte concentrations, electrode geometry, and configuration, it's noteworthy that consistently achieving removal efficiencies exceeding 90% has been a significant achievement. However, to ascertain economic efficiency, additional factors such as energy consumption, electrode usage, and post-treatment conductivity must be taken into account. To tackle the complexity posed by various parameters and criteria, using multi-criteria decision-making tools like TOPSIS is essential, as it has a track record of effectiveness in practical applications. The electrolyte concentration of 0.5 g L-1 is identified as optimal by TOPSIS analysis Additionally, the TOPSIS highlighted the superiority of cylindrical hollow wire mesh electrodes and established the monopolar parallel configuration as the most effective electrode connection method. The investigation carefully evaluated the effect of reaction time, determining that a 50-min window provides optimal microplastic removal efficiency. This refined system exhibited remarkable proficiency in eliminating microplastics of varying size ranges (0-75 µm, 75-150 µm, and 150-300 µm), achieving removal efficiencies of 90.67%, 93.6%, and 94.6%, respectively, at input concentration of 0.2 g L-1. The present study offers a comprehensive framework for optimizing electrocoagulation parameters, presenting a practical and highly effective strategy to address the critical issue of microplastic contamination in aquatic environments.
