A solar-powered electrocoagulation process with a novel CNT/silver nanowire coated basalt fabric cathode for...

Electrocoagulation (EC) has proven its high efficiency and environmental sustainability for treating several types of wastewaters. However, the primary drawbacks of the conventional EC process are the suitable electrode materials and the relatively high cost due to the requirement for electric energy. To overcome these practical challenges, this study investigated effective oil/water separation by a solar-powered electrocoagulation (SPEC) process using a novel highly conductive basalt fabric (BF) cathode. The BF cathode was fabricated using a simple approach: dip-coating in carbon nanotubes (CNT) dispersion, followed by a bath exhaustion coating in a silver nanowires (AgNws) solution, and its successful preparation was confirmed through several advanced characterization techniques. The effect of the CNT-AgNws coating on the electrical conductivity of the BF-CNT/AgNws was investigated using the four-probe tester. The BF-CNT/AgNws cathode exhibited a high conductivity of 1.66 × 10⁴ S/m, which indicates its applicability in the SPEC system. Under the operating conditions of applied voltage (25 V), SPEC time (30 min), stirring rate (150 rpm), and NaCl concentration (1 g/L), the experiment's results showed a high COD removal of 90.2 ± 0.03 %, a low energy consumption of 1.28 ± 0.01 kWh/kgCOD, and electrode consumption of 0.35 ± 0.06 kg/m³. In addition, due to the use of solar-powered energy, the overall cost was reduced by eliminating the electricity fees. Moreover, the reusability test results proved that the BF cathode has potential reusability in successive SPEC experiments while maintaining its performance. In conclusion, the obtained findings are very encouraging in designing novel EC cathodes for effective oily wastewater treatment at an industrial scale.