Application of ANN and RSM for Rhodamine B and Safranine‑O\nDecolorization on Zinc-Carbon Battery Waste Derived Ag/CoFe-LDH/rGO\nCatalyst

The present work is first aimed at\nrecovering graphite from carbon\nrods of waste zinc-carbon (Zn-C) batteries for applications such as\nwastewater treatment, in order to contribute to the development of\na sustainable environment. Then, a composite material, cobalt-iron\nlayered double hydroxide combination with reduced graphene oxide,\nand with subsequent Ag nanoparticles deposition via NaBH<sub>4</sub> reduction method (Ag/CoFe-LDH/rGO) was prepared for the catalytic\nactivity of Rhodamine B (RhB) and Safranine-O (SO) as model contaminants\nfrom aquatic media. The catalytic activity of RhB and SO by Ag/CoFe-LDH/rGO\nin the presence of NaBH<sub>4</sub> was studied to model and optimize\nthe process parameters (NaBH<sub>4</sub> amount, reaction time, initial\ndye concentration (<i>C</i><sub>o</sub>), and catalyst dosage)\nvia central composite design (CCD)-response surface methodology (RSM).\nAlso, an artificial neural network (ANN) model was developed to estimate\nthe catalytic activity of each dye using an RSM data set. The catalytic\nactivities of 99.54% and 99.96% were obtained for RhB and SO dyes,\nrespectively, under the optimal conditions: NaBH<sub>4</sub> amount\n12.32 mM, reaction time 3.19 min, <i>C</i><sub>o</sub> 33.46\nmg/L, and catalyst dosage 1.24 mg/mL for RhB dye; NaBH<sub>4</sub> amount 16.76 mM, reaction time 3.06 min, <i>C</i><sub>o</sub> 15.10 mg/L, and catalyst dosage 1.46 mg/mL for SO dye. The\noptimum conditions of process parameters by ANN with gray wolf optimizer\n(GWO) were in good agreement with the points determined the RSM-CCD.\nThese results demonstrate that RSM and ANN approaches can be applied\npractically and efficiently to maximize the catalytic activity of\nRhB and SO by Ag/CoFe-LDH/rGO in the existence of NaBH<sub>4</sub>. On the other hand, from the kinetic and thermodynamic studies,\nthe positive activation enthalpy, Δ<i>H</i><sup>#</sup> and the negative activation entropy, Δ<i>S</i><sup>#</sup> values for each dye demonstrated that the catalytic performance\nwas endothermic and less random at the solid/liquid interface.