Presence Of Cyanides Research Articles

Efficiency of ozone microbubbles for ammonia removal from mine effluents

Several physical, chemical, and biological technologies efficiently treat ammonia nitrogen (NH3-N). However, cold temperatures and mixes of contaminants limit NH3-N removal efficiency. This study evaluated the ozone microbubbles efficiency for NH3-N removal from synthetic and five actual mine effluents. Testing was initially conducted in batch mode. Then, to confirm treatment feasibility, tests with continuous flow were performed with one synthetic and one real effluent. Results showed that the parameters of the water to be treated have significant influence on treatment efficiency. The presence of cyanides, cyanate, thiocyanate, and metals adversely influenced treatment performance. The NH3-N removal efficiency ranged from 27.8 to 99.3%. Continuous flow testing confirmed the feasibility of large-scale treatment as 99.1% of NH3-N was treated at a flow rate of 1.1 L/min over a treatment period of 570 min. Final polishing steps removed the pink color from the water after ozone microbubbles treatment, resulting in satisfactory quality of treated water.

The comet-like composition of a protoplanetary disk as revealed by complex cyanides.

Observations of comets and asteroids show that the solar nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth's surface. Unlike asteroids, comets preserve a nearly pristine record of the solar nebula composition. The presence of cyanides in comets, including 0.01 per cent of methyl cyanide (CH3CN) with respect to water, is of special interest because of the importance of C-N bonds for abiotic amino acid synthesis. Comet-like compositions of simple and complex volatiles are found in protostars, and can readily be explained by a combination of gas-phase chemistry (to form, for example, HCN) and an active ice-phase chemistry on grain surfaces that advances complexity. Simple volatiles, including water and HCN, have been detected previously in solar nebula analogues, indicating that they survive disk formation or are re-formed in situ. It has hitherto been unclear whether the same holds for more complex organic molecules outside the solar nebula, given that recent observations show a marked change in the chemistry at the boundary between nascent envelopes and young disks due to accretion shocks. Here we report the detection of the complex cyanides CH3CN and HC3N (and HCN) in the protoplanetary disk around the young star MWC 480. We find that the abundance ratios of these nitrogen-bearing organics in the gas phase are similar to those in comets, which suggests an even higher relative abundance of complex cyanides in the disk ice. This implies that complex organics accompany simpler volatiles in protoplanetary disks, and that the rich organic chemistry of our solar nebula was not unique.

Solvent extraction flow-injection manifold for the simultaneous spectrophotometric determination of free cyanide and thiocyanate ions based upon on-line masking of cyanides by formaldehyde

This study reports a sensitive solvent extraction flow-injection (FI) method for the simultaneous spectrophotometric determination of free cyanide and thiocyanate in human saliva and pralidoxime solutions. Cyanide and thiocyanate form colored ( λ max=540 nm) ternary complexes with copper and 2,2′-dipyridyl-2-quinolylhydrazone (DPQH) that are extractable into chloroform. The determination of thiocyanates in the presence of cyanides is accomplished after on-line masking of the latter with formaldehyde through a binary inlet static mixer (BISM). Total thiocyanates and cyanides are determined in a second run, without the use of the masking agent. The proposed method allows the determination of the analytes in the range of 0–4 mg l −1 thiocyanates and 0–3 mg l −1 cyanides, with the 3 σ detection limits being 0.007 and 0.004 mg l −1, respectively. The precision of the method ( s r<1.0% at 1 mg l −1 CN − or SCN −, n=12 in both cases) and the sampling rates were quite satisfactory (60 injections per hour). The method was applied to the analysis of human saliva and pralidoxime solutions and gave recoveries in the range of 98.0–102.2% for both analytes whereas the mean relative error was e r=1.7%.

Electrokinetic and Transmembrane Potentials as Factors of Cell Adaptation to Cyanide Compounds

Experimental data on the effect of Zn, Cd, Cu, Ag, Au, and Fe cyanide complexes on the electrokinetic and transmembrane potentials of bacterial cells of Pseudomonas fluorescensV-5040 are presented, and the correlation between these parameters is disclosed. Possible mechanisms of the interaction of cell membrane with the compounds studied are discussed. It was suggested that the agreement between the variations in transmembrane and electrokinetic potentials for Pseudomonas fluorescenscells is related to the specificity of given microorganism as cyanide destructor. The analysis performed allows us to consider electrokinetic and transmembrane potentials as factors of cell adaptation to the existence in the presence of cyanides and destruction of the latter.

Cyanide and metal pollution by urban snowmelt: impact of deicing compounds

Highway and road deicing operations provide traffic safety during winter driving conditions in snowbelt areas. Using large quantities of deicing chemicals causes water quality problems that need to be addressed and remediated. Two specific problems are discussed, i.e., presence of cyanides in deicing salt and decreased partitioning of metals in snowmelt resulting from high salt concentrations. Complex ferrocyanide compounds are added to salt to prevent caking. By photodecomposition, these cyanides can be broken down to free toxic cyanide compounds. For toxic metals, salt decreases partitioning between adsorbed (precipitated) and dissolved metals, resulting in an increase in dissolved metals in salt laden snowmelt and consequently increasing toxicity.

Cyanide and metal pollution by urban snowmelt: Impact of deicing compounds

Highway and road deicing operations provide traffic safety during winter driving conditions in snowbelt areas. Using large quantities of deicing chemicals causes water quality problems that need to be addressed and remediated. Two specific problems are discussed, i.e., presence of cyanides in deicing salt and decreased partitioning of metals in snowmelt resulting from high salt concentrations. Complex ferrocyanide compounds are added to salt to prevent caking. By photodecomposition, these cyanides can be broken down to free toxic cyanide compounds. For toxic metals, salt decreases partitioning between adsorbed (precipitated) and dissolved metals, resulting in an increase in dissolved metals in salt laden snowmelt and consequently increasing toxicity.

A Record of Some Recent New Hampshire Poisonings; With an Observation Concerning Possible Failure to Detect the Presence of Cyanides

A Record of Some Recent New Hampshire Poisonings; With an Observation Concerning Possible Failure to Detect the Presence of Cyanides