In the field of environmental risk assessment, Cyanide is one of the most important pollutants of water, soil and air that has an important impact on the ecosystem and environment of the contaminated area. Therefore, the present study aimed to prove the biological effectiveness of Vetiveria zizanioides in phytoremediation of soils contaminated with cyanide.
This research study was conducted on a gold mine wastewater. The dried effluent samples amended with soil with various cyanide concentrations. Seven treatments with different concentrations of cyanide were obtained (mean cyanide content in G soil, 14.77 mg/kg, F soil, 10.13 mg/kg, E soil, mg/kg 8.09, D soil, mg/kg 7.53, C soil, 3.32 mg/kg, B soil, 2.52 mg/kg and A soil without cyanide (as control). After two months, the amount of cyanide in the soil, roots and leaves of the plant, as well as the total protein and proline content, and the number and length of the leaves of the plant were measured and then statistically evaluated by SPSS15 Tukey and t Paired Samples T Tests.
The results of this study showed that the increase of cyanide had a significant effect on the amount of proline (proline in the plant increased), total protein (in the plant increased), number of leaves (decrease in number) and the length (length reduction) of the leaves of the vetiver. The amount of cyanide in the leaves and roots of the plant was increased. Cyanide content was decreased in the different treatments. Cyanide content was decreased in G 50.93%, F 38.20%, E 27.19%, D 38.37%, C 17.77% and B 16.66%.
The results indicated that increase of the amount of cyanide in soil resulted in observational changes in the morphological and biochemical characteristics of the plant. However, Vetiveria zizanioides exhibited very high resistance to soil cyanide and the planting of vetiver in highly contaminated soils can lead to a reduction of cyanide up to 50 percent. Vetiveria zizanioides had higher resistance to cyanide and showed better phytoremediation than the other plants.

Cyanide is a toxic and hazardous compound for all organisms which is produced enormously by human being and causes the environment pollution. Biodegradation is the best method for cyanide elimination in industrial wastewater. The aims of this study were isolation of cyanide degrading bacteria from contaminated soil and investigation of their ability for cyanide degradation. After soil samples collection, enrichment of cyanide degrading bacteria was performed in a minimal medium containing 0.5 mM potassium cyanide. The ability of isolated bacterium to utilize the cyanide as sole carbon and nitrogen source was investigated. Cyanide degradation and ammonium production was determined in growth medium using picric acid and Nessler’s regent methods. Toxicity effect of different cyanide compounds on bacterial growth was determined using minimum inhibitory concentration. In addition, the ability of the isolated bacterium to utilize different cyanide compounds was investigated. Identification of the isolate was undertaken using morphological, physiological and biochemical characteristics and molecular analysis. A bacterium with ability to degrade cyanide as sole carbon and nitrogen source was isolated from soil. This bacterium named as isolate MF1. MF1 degraded cyanide in growth medium in alkaline condition after 40 hours. Moreover this isolate tolerated more than 7 mM potassium cyanide. The results showed that there was a direct relation between decreasing of cyanide concentration, increasing of ammonia concentration and growth of MF1. In addition, the isolated bacterium demonstrated the ability to utilize different cyanide compounds as sole carbon and nitrogen source. The results of morphological and physiological characteristics showed that this bacterium belonged to the Serratia sp. Moreover, 16S rDNA sequencing and phylogenetic analyses exhibited that MF1 strain was similar to Serratia nematodiphila with 99% homology. Discussion and The results demonstrated that the isolated bacterium is a suitable candidate for degradation of cyanide in alkaline condition. This bacterium could introduce for treatment of industrial wastewater and sites that contaminated with cyanide.

The aim of this study was to evaluate the surface modification efficiency of raw zeolite by hexadecyl trimethylammonium cationic surfactant for cyanide sorption. Properties such as mineralogy, morphology and elemental composition of sorbents were determined. Batch and column tests were performed to evaluate the sorption efficiency of raw and modified zeolite from solution and released from the cyanide polluted pulp. The presence of clinoptilolite mineral and surfactant surface coating due to modification using surfactant was confirmed by X-ray diffraction analysis and electron microscopy images. The results of isotherm experiment showed that modification of zeolite with surfactant increased the adsorption capacity of cyanide by zeolite 7 times compared to the raw sample and the maximum adsorption capacity of cyanide by modified zeolite was 3.97 mg/g. The ability of surfactant-modified zeolite to sorb more cyanide than raw zeolite was confirmed by the results of the column test on the cyanide released from the pulp. It was observed that with increasing time, the concentration of cyanide in the outlet solution increases, but this increase in the cyanide concentration in the outlet solution of the column containing the modified zeolite is less than the raw zeolite.

Cyanide is a highly toxic and hazardous pollutant commonly found in the wastewater generated by mining, electroplating, and petrochemical industries. The current research aims to evaluate the efficiency of advanced oxidation techniques such as UV, O3, and UV/O3 combination, to eliminate cyanide from synthetic wastewater. All experiments were conducted in a semi-continuous reactor to investigate the impact of various operating conditions, such as initial cyanide concentration, reaction time, reaction kinetics, and pH. In this study, degradation tests were conducted on cyanide at four different concentrations (50, 100, 200, and 250 mg/L) and two pH levels (10 and 11). The reaction duration ranged from 0 to 90 minutes, with varying lengths. All experiments maintained constant operational parameters for the process, except for the variable being tested. The UV process alone is not very effective in removing cyanide from wastewater. This is because the low absorption coefficient of cyanide in the ultraviolet region limits the performance of UV in cyanide degradation. Additionally, cyanide is a relatively stable compound that requires a high amount of energy to break bonds and destroy them. Therefore, the use of the UV process alone is insufficient for the complete and safe destruction of cyanide from wastewater. It is necessary to combine it with other advanced oxidation processes to effectively remove cyanide from wastewater. According to the results, it was found that the effectiveness of removing cyanide through a single ozonation process was higher at pH 11 as compared to pH 10. The optimal conditions for achieving the highest level of cyanide removal, which is 68%, were found to be a single ozonation process with an initial concentration of 50 mg/L and a reaction time of 80 minutes. The higher efficiency of cyanide degradation at higher pH can be attributed to the greater production of hydroxyl radicals, resulting in an increase in the oxidizing power of the process. The efficiency of cyanide degradation in synthetic wastewater can be greatly improved by using the combined UV/O3 process. In this method, the rate of cyanide degradation is higher when the pH value is lower. This is because the integrated UV/O3 method is strongly dependent on the concentration of hydroxide ions and hydroxyl radicals, which are affected by the pH value. Therefore, the effect of pH value on the efficiency of cyanide degradation by the combined UV/O3 method is significant. When UV and O3 were combined, over 50% degradation occurred in 40 minutes due to increased degradation rate. The highest efficiency for cyanide degradation was achieved at pH 10 and an initial concentration of 50 mg/L using the combined UV/O3 method. The reaction time was 50 minutes and the efficiency was 100%. First and second-order kinetic analyses were conducted for UV, ozone, and combined processes to study their effectiveness in cyanide degradation. The results showed that the combination of UV and ozone was the most effective method for total cyanide degradation from wastewater compared to the other processes studied. Therefore, UV/O3 can be considered as the optimal analytical method for cyanide degradation from wastewater.

Cyanide is a highly toxic species that found mostly in industrial effluents such as electroplating, metal mining, metallurgy and metal cleaning processes. Discharge of it into the enviroment causes very health impact. Purpose of this study was, determination of sonochemical technology for cyanide removal from aqueous solutions in the presence of hydrogen peroxide. In this study, a productive set of 500w power ultresoun waves with two frequencies 35 kHz and 130 kHz were used. Experiments were performed using different initial ratio CN-/H2O2 1/1, 1/3 and 1/5 and at initial cyanide concentrations varying from 2.5 to 75 mg/L. The effects of parameters such as pH, time and initial cyanide concentration on the sonochemical degradation have been studied. The results of the study showed that the maximom removal efficiency of cyanide was achieved 85% by sonochemical technology at frequency of 130 kHz, during of 90 min, at pH of 11, at initial cyanide concentration of 2.5 mg/l and with initial ratio of CN-/H2O2 1/5. it was also found the rates of cyanide degradation under different conditions were quite low, and also the rate of cyanide degradation was high at first but later substantially reduced. The efficiency of cyanide removal had direct relationship with pH, frequency, hydrogen peroxide concentration and time, and it had reverse relationship with cyanide concentration.

Cyanide is a hazardous compound for all living things. Cyanide compounds are commonly used in various industries and cause environmental pollution. Biodegradation is the best method for cyanide elimination in mines and industrial wastewater. The aims of this study were isolation cyanide degrading bacteria in alkaline condition from contaminated soil and investigation of their ability for cyanide degradation. Contaminated soil samples were enriched in minimal salts medium supplemented with 4.3 mM potassium cyanide. Then cyanide degradation and ammonium production was determined in growth medium using picric acid and Nessler’s regent methods. In addition the ability of the isolated bacterium to utilize different cyanide compounds was investigated. A bacterium with ability to degrade cyanide in alkaline condition was isolated and named MF3. The isolate MF3 degraded cyanide in growth medium under alkaline condition after 36 hours. The results showed that there was a direct relation between decreasing of cyanide concentration, increasing of ammonia concentration and growth of MF3. In addition, the isolated bacterium was demonstrated the ability to utilize different cyanide compounds as a sole carbon and nitrogen source. The 16S rDNA sequencing and phylogenetic analysis was exhibited that MF3 strain was similar to Bacillus safensis with 99% homology. The results of current study were demonstrated that MF3 is a suitable candidate for degradation of cyanide in alkaline condition. This isolate could introduce for elimination of cyanide from industrial wastewater and contaminated sites.

In order to detect hydrogen cyanide gene and to determine Pseudomonas fluorescent efficiency in producing hydrogen cyanide for controlling the growth of Rhizoctonia solanipathogen (the causal agent of sugar beet root and crown rot), samples were collected from sugar beet rhizosphere in Sabzevar fields. After soil sampling and purification, 31 Pseudomonas Spp. isolates were separated on specific Pseudomonas agar F medium, and Pseudomonas fluorescent strains were identified and isolated based on microbial tests. PCR results showed that three strains contained cyanide hydrogen biosynthetic gene. The qualitative evaluation of hydrogen cyanide production in microbial medium showed that all the strains were capable of producing different amounts of hydrogen cyanide. To determine the growth inhibition rate of Rhizoctonia solani by Pseudomonas fluorescent, the percentage of fungus growth in the presence of bacteria was calculated. Among the three Pseudomonas fluorescent strains, C7 showed the greatest inhibition rate and hydrogen cyanide production which can be recommended as a suitable candidate for the pathogen biocontrol.

Soil contamination by industrial pollutants has associated with increasing risks for human, the environment and other living organisms. Cyanide is considered as one of the most toxic and dangerous pollutants used for the extraction of gold. One of the most cost-effective methods to eliminate cyanide from the environment and soil is "Phytoremediation". In this research, the Physiological and biochemical responses as well as remediation, and resistance of Sorghum bicolor to different cyanide treatments were investigated Accordingly, the effluent from the gold mining was prepared from Mouteh gold mining of Isfahan and this soil was mixed with normal soil to prepare different concentrations of contaminated soil. Cyanide changes in soil, total protein content, proline and morphometric Stem length, leaf, plant length and stem diameter changes of the plants were measured after completing the vegetative phase of the plant. Plant could absorb cyanide of contaminated soils, Total protein and proline content of the plant were enhanced with increasing cyanide content. Raising the cyanide contaminated soil resulted in promoted protein and proline content in treated plants,reduced cyanide concentration in soil and increased cyanide absorption by plant Sorghum. Plant could tolerate 12.69 g/kg of cyanide. Reduction of soil cyanide as well as its accumulation in plant and morphometric changes showed that phytoremediation is an appropriate method for the remediation of cyanide contaminated soils. Therefore, Sorghum bicolor can be a useful phytoremediation plant for removing cyanide from soils contaminated with these type of pollutants.