Simultaneous Silver Recovery and Cyanide Removal from Electroplating Wastewater by Pulse Current Electrolysis Using Static Cylinder Electrodes

Abstract

An effective electrochemical approach for simultaneous silver recovery and cyanide removal from electroplating wastewater was presented. Accordingly, pulse current (PC) electrolysis with parameters including voltage (4.0 V), frequency (800 Hz), and duty cycle (50%) were settled using static cylinder electrodes. Then the influences of technological conditions on the electroplating wastewater treatment process were investigated, which manifested that the concentration of silver ions in electroplating wastewater could be reduced from 221 to 0.4 mg L −1 and cyanide could be simultaneously removed from 157 to 4.9 mg L −1 after 3.0 h of PC electrolysis at pH 9.5 ± 0.5, aeration rate of 100 L h −1 , and stirring speed of 1000 rpm with NaCl addition of 0.05 mol L −1 at room temperature. The results of XRD and EDX analysis showed that the silver deposits on the cathode were crystalline in face centered cubic structure and had a high purity.

Energy efficient electrocoagulation using a new flow column reactor to remove nitrate from drinking water – Experimental, statistical, and economic approach

“…The flow column was designed to be movable that enables the operator to exclude the accumulated air bubbles on electrodes surfaces, which negatively influence the electrical resistance and the energy consumption as consequence (Gao et al, 2013).…”

Electrochemical Approaches for the Recovery of Metals from Electronic Waste: A Critical Review

“…For any given electrolyte, the peak current/voltage and the on-time and off-time pulses are the most important parameters to optimize to control the structure of the de- For any given electrolyte, the peak current/voltage and the on-time and off-time pulses are the most important parameters to optimize to control the structure of the deposits [71]. Compared to conventional DC electrodeposition, T off brings the biggest advantage to pulsed electrodeposition toward complete deposition, as it creates extra time to fill the depletion region with additional metal ions at the electrode surface [72]. Moreover, due to the presence of T off , the pulsed electrodeposition favours the initial growth of metal nuclei, increases the nuclei population density, and reduces their sizes distribution resulting in a fine grained deposit with uniformly small crystals [70].…”

“…Hence, it was reported that, in combination with the pulsed current method and the static cylindrical electrodes, most of the silver in electroplating wastewater could successfully be recovered (>99%). Meanwhile, more than 95% of the present cyanide could be removed via the electro-oxidation process at the anode [72,74]. It is also worth noting that the total energy consumption of the pulsed electrodeposition is lower than when using conventional DC methods.…”

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“…These plates are held in the required position, inside a hollow Perspex cylinder 25 cm in height and 10.5 cm in diameter, using PVC rods and spacers. The PVC rods are movable to exclude the accumulated air bubbles, which significantly influence the electrical resistance and the energy consumption as consequence (Gao et al, 2013), on the electrodes during the electrolysis process. The upper unsubmerged electrodes were used as water diffusers (no electric current was applied to them), Where, these unsubmerged electrodes convert the mass water flow into droplets that maximises the contact area between water being treated with the ambient air, which in turn enhances the aeration process.…”