The water resources pollution by municipal and industrial wastewater is a considerable problem. In this research, the efficiency of Holly, Sallow and Poplar sawdust as simple, economic and abundant materials were studied for the removal of CYANIDE from aqueous solutions. The synthetic polluted water samples were prepared by using of sodium CYANIDE in distillation water with concentration of 10, 30 and 50 mg L-1 and effects of saw dust size (mesh of 20 and 70) and contact time (10-140 min) were studied. The results showed that the saw dustshad a uniform efficiency (60-70% and 71-83%) at 30 and 140 min. respectively. Also obtained results showed a direct relation with contact time and CYANIDE concentration and reversed relation with sawdust particle size. The results showed that the optimal contact time is 30 min. In this condition, the averages of adsorption capacity were obtained 1.25-1.38 and 1.34-1.52 mg CN/g sawdust for mesh 20 and 70 respectively. Based on the results, its availability and cheapness, the application of sawdust as an absorbent for the removal of CYANIDE from aqueous solutions is recommended.

In this paper the effects of experimental parameters on CYANIDE degradation in wastewater of heat treatment units has been investigated. In this process, hydrogen peroxide and CU2+ are used as oxidizing agent and catalyst, respectively. In the First steep on the desired concentration of 100mg/l CYANIDE solution in alkaline condition at 25°c, the molarity of hydrogen peroxide and catalyst concentration were optimized. Experimental results show that in molar ratio of (H2O2 :CN-)9: 1 and CU2+concentration equal to 20mg/l, CYANIDE content decreases to less than 5mg/l in 30 minutes. The practical relevance of the laboratory degradation method is demonstrated for actual wastewater with 540 mg/l CYANIDE. In 100 minutes, the CYANIDE content of the wastewater was decreased to less than 5mg/l.

In this study, removal of ferroCYANIDE and ferriCYANIDE ions from synthetic wastewater with activated red mud was studied. Two activation methods by ammonia (ABA) and cationic surfactant of cetyl trimethylammonium bromide (ABC) were used. In order to evaluate the process of CYANIDE ion adsorption and its effective parameters, 44 experiments were designed with seven variable factors using DX8 software by the response surface method. The results showed that the optimum conditions for achieving the highest adsorption capacity with ABC adsorbent were obtained as follows: pH=7. 1, adsorbent dosage of 0. 57 g, ferriCYANIDE concentration of 126 ppm, contact time of 96. 66 min, agitated speed of 120 rpm and ion strength of 0. 24 M. In optimum conditions, the absorption capacity of 19. 5 mg/g and the absorption percentage of 99. 3% were obtained. The results showed that the use of ABC adsorbent has a higher efficiency in the removal of CYANIDE ions from the synthetic wastewater. Thermodynamic studies were carried out in optimal conditions. The results showed that the negative value of Δ G◦ parameters at different temperatures indicates the spontaneity of the CYANIDE complex adsorption process on adsorbents of ABA and ABC. The spontaneity of process increased with increasing the temperature.

A simple spectrophotometric method is developed for the DETERMINATION of traces of CYANIDE ion in water samples. Toxic CYANIDE was reacted with sulfur (S8) dissolved in acetone and converted to non-toxic thiocyanate which is more stable than CYANIDE also. This product was reacted to Fe (III) to form red ferric-thiocyanate complex. The complex absorption rate in the first two minutes of its formation is related to the CYANIDE concentration. By measuring the complex absorbance at 465 nm, the CYANIDE in the range of 2. 0-16. 0 μ g/mL was determined with a detection limit of 1. 7 μ g/mL. Relative standard deviation (n = 6) for concentrations of 4. 0 and 12. 0 μ g/mL of CYANIDE was obtained 4. 2 % and 1. 5 %, respectively. To avoid interferences from other cations and anions, it is possible to isolate CYANIDE with a system converting CN-to HCN. This method was successfully applied to determine CYANIDE in various water samples.