Mehdi Soleymani Gharegol - Civil Engineering Department, Engineering Faculty, Urmia University, Urmia, Iran, Iran
Kazem Badv - Civil Engineering Department, Engineering Faculty, Urmia University, Urmia, Iran, Iran
Behzad Nemati akhgar - Mining Engineering Department, Engineering Faculty, Urmia University, Urmia, Iran

This paper carried out the study on removing cyanide from aqueous solutions by modified zeolite with hexadecyltrimethylammonium bromide. After determining the properties of the prepared adsorbent by the XRD, SEM, FTIR, and BET techniques, the effect of parameters such as the initial concentration of cyanide, pH, contact time, temperature, and the ionic strength of cyanide was examined by batch tests, and the effects of bed depth and flow rate on the performance of cyanide adsorption was investigated by column process. The XRD analysis showed the presence of clinoptilolite mineral in the structure of the raw zeolite, and the surface coating of raw zeolite by surfactant was detected by the SEM method. The FT-IR results confirmed the adsorption of cationic surfactant on the surface of the modified zeolite. The Langmuir, Freundlich and Tamkin adsorption models showed an excellent ability to describe the cyanide adsorption isotherm using the studied adsorbent. The adsorption capacity of cyanide by modified zeolite was ۳.۹۷ mg/g, significantly increased compared to the maximum adsorption capacity of raw zeolite cyanide (۰.۵۴ mg/g). The pseudo-second-order model has an excellent ability to describe the adsorption kinetics of cyanide contaminants using natural and modified zeolites. Maximum cyanide uptake capacity was achieved at pH value ۸. Cyanide removal decreased with increasing pH and ionic strength of the stock solution and increased with an increase in solution temperature. Column study results confirmed that the adsorption capacity increased with the increasing bed depth, and decreased with increasing flow rate. Yoon-Nelson curves are closer to the experimental curves with high R۲ values.

Cyanide, Surfactant, Adsorption isotherms, Kinetics, Gold tailings dam