Determination of optimal operating conditions for AC-powered electrocoagulation process coupling green additive Tartaric Acid to remove Ni2+: Pyomo and RSM approach.

A novel Python-based open-source optimization framework, namely Pyomo (Python optimization modeling objects), alongside a conventional optimization method, RSM (response surface methodology), was utilized to determine the optimal operating conditions of an alternating current-powered electrocoagulation (ACPE) process for nickel removal. In this regard, four mutable operating factors, current density (5-9 mA/cm2), initial nickel concentration (200-400 mg/L), initial pH of the solution (5-9), and electrolysis time (30-60 min), along with a fixed amount of an additional eco-friendly substance, Tartaric Acid (155 mg/L) were considered. Metal removal efficiency (OF1) and operating costs (OF2) were monitored and evaluated as objective functions with the aim of maximization and minimization, respectively. Experiments were conducted according to the central composite design (CCD), and validation outcomes established a reasonable agreement between the predicted models and the experimental data. The multi-objective optimization process yielded two sets of 30-optimal-solution obtained through Pyomo and RSM. Accordingly, the proposed solutions by the Pyomo were found to be more flexible and eclectic, supplying the local decision maker(s) with a diverse spectrum of optimal operating conditions. Adding TA was also effective in reducing electrical energy consumption by up to 46%.

Recycling of hazardous waste as a new resource for nickel extraction.

Nickel extraction from hazardous waste by sulphuric acid leaching has been investigated. This study was performed to assess the effects of different parameters such as reaction time, acid concentrations, solid-liquid ratio, particle size, stirring speed and reaction temperature on nickel extraction from zinc plant residue, with the aim of recycling this waste and reducing its environmental impact. It was shown that the nickel extraction increased with increasing reaction time, acid concentration and temperature, and decreasing solid:liquid ratio and particle size. Leaching residues were subjected to chemical analysis, XRD and SEM studies, and the results indicated that it is possible to extract more than 96% nickel content by optimization of leaching conditions. These results provided important data on the recovery of nickel from toxic hazardous waste, and leaching is a suitable method for this waste management. The results also showed that this waste can be used as a secondary resource for nickel extraction.