Due to the widespread use of cyanide in mining operations, the recovery and destruction of cyanide is important both from the environmental aspects of wastewater and effluent treatment and from the economic aspects associated with the high reagent consumption by the process itself. A photoelectrocatalytic detoxification technique with titanium dioxide microelectrodes is one of the most innovative ways for the treatment of wastewater containing cyanide. However, this technique has a disadvantage for industrial application; the separation of titanium dioxide after the photocatalytic degradation of cyanide is rather difficult due to fineness of the particle and, therefore, the reuse of the titanium dioxide has not been used for the treatment of cyanide-containing wastewater. To alleviate this weak point, an Electrocoagulation (EC) technique was used to recover the titanium dioxide from its aqueous suspensions. The process was studied under various parameters: cyanide concentration, TiO_2 concentration, current density values and other operational conditions. The results show that photodegradation of cyanide was 93 % in 30 minutes using a 450 W halogen lamp. The recovery of anatase with the EC process was 98 %. The results indicate that this technique has the potential to serve as a reliable and economical method because sunlight could be used efficiently as the source power. Langmuir isotherms were used to obtain the thermodynamic parameters such free energy, enthalpy and entropy, the evaluation of this parameters (ΔG°= -37 kJ/mol, ΔH° = -54 kJ/mol and ΔS° = 0.524 kJ/mol K) indicated a spontaneous and exothermic nature of the adsorption of anatase particles on the iron species.
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