An Investigation on the Possibility of Cyanide Removal from the Industrial Wastewaters Using the Smectite Clay Minerals from the Mehrjan Area, Iran

The cyanide is a highly toxic compound that is normally found in industrial wastewaters. Due to its high environmental risks, its removal is of the great importance. The clay minerals are considered to be good candidates of cyanide removal from the wastewaters. In this paper, the effect of absorbent quantity and time on the cyanide absorption using smectite clay in a batch system has been studied as well as the kinetics modeling. The clay sample from Mehrjan area with the dimension of smaller than 53 μm was used to remove the cyanide from industrial wastewaters that contains cyanide content [500±10 ppm]. The result of the XRF and semi-quantitative XRD analysis showed that the clay mineral used in this study is sodium montmorillonite with a weight percentage of 76. The effect of parameters such as different contact time and the clay quantities were investigated by clay absorbent. A 10 times increase in the clay quantity within the solution results in 38% more reduction of the cyanide content. The maximum absorption (about 80%) was observed at 6 hours of contact time using 2 grams of clay in a 50mm solution. The result of kinetics modeling showed that process was a pseudo second order adsorption reaction and the isotherms could be described by the Freundlich equation. Based on the results, several advantages of clays such as fast preparation procedure, accessibility and availability, and the reasonable price makes them appropriate replacement for activated carbon for cyanide removal from the industrial wastewaters in the future.