Increase In Cyanide Concentration Research Articles

The stability of cyanide in human biological samples. A systematic review, meta-analysis and determination of cyanide (GC-QqQ-MS/MS) in an authentic casework 7 years after fatal intoxication

A 30 year old man was found with no signs of life in front of the house. The cyanide concentration in blood and urine was determined five years after the man’s death. What is more, a stability study was conducted for 730 days in an authentic casework blood sample. Sample preparation procedure included precipitation with methanol:water mixture, solid phase extraction (SPE) and derivatization with the use of PFB-Br (pentafluorobenzyl bromide). The sample was analyzed using GC-QqQ-MS/MS (gas chromatopraphy coupled with tandem mass spectrometry) isotope dilution method. Separation was done using a SH-RXI-5MS column (30 m x 0.25 mm, 0.25 µm). Detection of PFB-CN and PFB-13CN was achieved using a triple-quadrupole mass spectrometer with an electron ionization (EI) ion source in multiple reaction monitoring (MRM) mode. After 5 years from the man’s death, cyanide concentration was: 1900 ng/mL in blood and 500 ng/mL in urine. Stability study performed in an authentic blood sample 6 and 7 years after the man’s death revealed cyanide concentrations of 1898.2 ng/mL and 1618.7 ng/mL, respectively. While spectrophotometric and colorimetric methods recorded both decrease and increase in cyanide concentration over time, newer chromatographic methods mainly indicate a decrease. The studies presented in this paper seem to confirm this trend. However, in order to interpretate the results of cyanide concentration in biological material reliably, more research is still necessary.

Potassium Fertigation With Deficit Irrigation Improves the Nutritive Quality of Cassava

Water deficit limits cassava (Manihot esculenta Crantz) productivity in drought-prone areas and alters the nutritive quality of the crop. Potassium (K) may mitigate the effects of water deficit and improve the nutritional content of cassava, which would alleviate malnutrition among the human population in the tropics who depend on cassava as a staple food. Pot experiments were conducted under controlled glasshouse conditions to investigate the influence of deficit irrigation and K fertigation on the nutritive and anti-nutritive quality of biofortified cassava during the early growth phase. Treatments initiated at 30 days after planting were three irrigation doses (30%, 60%, 100% pot capacity) that were split to five K (0.01, 1, 4, 16 and 32 mM) concentrations. Plants were harvested at 90 days after planting, and the starch, energy, carotenoid, crude protein, fiber, minerals and cyanide concentration of the leaves and roots were determined. Irrigation and K treatments showed significant (P < 0.05) interactions for starch, carotenoid, energy and cyanide concentration. An irrigation dose of 30% together with 0.01 mM K resulted in the lowest starch, carotenoid, energy, and fiber content, but highest cyanide concentration, relative to full-irrigated (100%) plants together with 16 mM K. When the K application rate was 16 mM the best nutritional quality was obtained, with the lowest cyanide concentration, regardless of irrigation dose. Moreover, nutritional traits showed strong positive associations, whereas cyanide concentration correlated negatively with all the nutritional traits. Notably, an irrigation dose of 60% together with 16 mM K reduced the nutritional content the least and showed minimal increase in cyanide concentration. The results indicate that K fertigation with adjusted irrigation may improve the dietary quality of young cassava and reduce antinutrients, which could enhance the nutrient bioavailability of cassava grown in drought-prone areas.

Biological cyanide removal from industrial wastewater by applying membrane bioreactors

AbstractBACKGROUNDThis work investigates whether the membrane bioreactor (MBR) process can effectively treat industrial wastewater containing high cyanide concentrations; cyanide may inhibit the biological processes, rendering such processes inadequate. In this work, the changes in process performance and microbial activity under gradually increased free cyanide (CN−) concentrations (1,3 and 10 mgCN−L−1) were investigated in two pilot‐scale MBR configurations. The MBR systems consisted of two parallel operating lines: a single aerobic (MBR1) and an aerobic/anoxic (MBR2).RESULTSCyanide removal was not adversely affected by the increase in cyanide concentration since removals up to 90% were obtained. Despite the inhibition that occurred, ammonia and organic carbon removal efficiency did not decrease, even at the highest cyanide concentration of 10 mgCN−L−1, and it remained high (&gt;95%) in both systems. Nitrification (sAUR) was inhibited by 35%, 54%, and 64% in MBR1 and by 16%, 25%, and 36% in MBR2, with the addition of 1, 3, and 10 mgCN−L−1, respectively. The aerobic respiration (sOUR) was inhibited considerably less with an inhibition of 19%, 37%, and 45% in MBR1 and 9%, 16%, and 21% in MBR2. The biomass maintained under both aerobic and anoxic conditions (MBR2) was more tolerant to cyanide compared to the biomass that was acclimated under only aerobic conditions (MBR1).CONCLUSIONAt high cyanide load conditions, the MBR systems showed satisfactory removal of both cyanide and conventional pollutants despite the inhibition observed, indicating that MBR systems can successfully respond to the treatment of industrial wastewater that is heavily contaminated with cyanide. © 2020 Society of Chemical Industry

Cyanide adsorption from cassava wastewater onto calcined periwinkle shell

Local cassava processing industries produce large quantities of wastewater containing cyanide which is toxic in nature with negative impacts on the environment when disposed without treatment. In this study calcined periwinkle shell (CPS) was prepared, characterized and used to adsorb cyanide present in cassava wastewater. Equilibrium studies were conducted in batch set ups to investigate the influence of process variables such as adsorbent dosage, pH, temperature, contact time and initial cyanide concentration on the adsorption process. The highest removal rate of cyanide from cassava wastewater was found to be 78.34% with equilibrium reached at fixed adsorbent dosage of 3.0 g at contact time of 80 minutes. Cyanide adsorption was also observed to be dependent on pH with the maximum adsorption of cyanide occurring at a pH 10. The percentage of cyanide removed decreased with increase in cyanide concentration. Results from the study confirm calcined periwinkle shell as low cost and effective adsorbent which can be used for the removal of cyanide from cassava wastewater

Oxidative damage mediated iNOS and UCP-2 upregulation in rat brain after sub-acute cyanide exposure: dose and time-dependent effects

Cyanide-induced chemical hypoxia is responsible for pronounced oxidative damage in the central nervous system. The disruption of mitochondrial oxidative metabolism has been associated with upregulation of uncoupling proteins (UCPs). The present study addresses the dose- and time-dependent effect of sub-acute cyanide exposure on various non-enzymatic and enzymatic oxidative stress markers and their correlation with inducible-nitric oxide synthase (iNOS) and uncoupling protein-2 (UCP-2) expression. Animals received (oral) triple distilled water (vehicle control), 0.25 LD50 potassium cyanide (KCN) or 0.50 LD50 KCN daily for 21 d. Animals were sacrificed on 7, 14 and 21 d post-exposure to measure serum cyanide and nitrite, and brain malondialdehyde (MDA), reduced glutathione (GSH), glutathione disulfide (GSSG), cytochrome c oxidase (CCO), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and catalase (CA) levels, together with iNOS and UCP-2 expression, and DNA damage. The study revealed that a dose- and time-dependent increase in cyanide concentration was accompanied by corresponding CCO inhibition and elevated MDA levels. Decrease in GSH levels was not followed by reciprocal change in GSSG levels. Diminution of SOD, GPx, GR and CA activity was congruent with elevated nitrite levels and upregulation of iNOS and UCP-2 expression, without any DNA damage. It was concluded that long-term cyanide exposure caused oxidative stress, accompanied by upregulation of iNOS. The upregulation of UCP-2 further sensitized the cells to cyanide and accentuated the oxidative stress, which was independent of DNA damage.

Batch growth kinetic studies of locally isolated cyanide-degrading Serratia marcescens strain AQ07.

The evaluation of degradation and growth kinetics of Serratia marcescens strain AQ07 was carried out using three half-order models at all the initial concentrations of cyanide with the values of regression exceeding 0.97. The presence of varying cyanide concentrations reveals that the growth and degradation of bacteria were affected by the increase in cyanide concentration with a total halt at 700ppm KCN after 72h incubation. In this study, specific growth and degradation rates were found to trail the substrate inhibition kinetics. These two rates fitted well to the kinetic models of Teissier, Luong, Aiba and Heldane, while the performance of Monod model was found to be unsatisfactory. These models were used to clarify the substrate inhibition on the bacteria growth. The analyses of these models have shown that Luong model has fitted the experimental data with the highest coefficient of determination (R2) value of 0.9794 and 0.9582 with the lowest root mean square error (RMSE) value of 0.000204 and 0.001, respectively, for the specific rate of degradation and growth. It is the only model that illustrates the maximum substrate concentration (Sm) of 713.4 and empirical constant (n) of 1.516. Tessier and Aiba fitted the experimental data with a R2 value of 0.8002 and 0.7661 with low RMSE of 0.0006, respectively, for specific biodegradation rate, while having a R2 value of 0.9 and RMSE of 0.001, respectively, for specific growth rate. Haldane has the lowest R2 value of 0.67 and 0.78 for specific biodegradation and growth rate with RMSE of 0.0006 and 0.002, respectively. This indicates the level of the bacteria stability in varying concentrations of cyanide and the maximum cyanide concentration it can tolerate within a specific time period. The biokinetic constant predicted from this model demonstrates a good ability of the locally isolated bacteria in cyanide remediation in industrial effluents.

Protective efficacy of various carbonyl compounds and their metabolites, and nutrients against acute toxicity of some cyanogens in rats: biochemical and physiological studies.

Cyanogens are widely used in industries and their toxicity is mainly due to cyanogenesis. The antidotes for cyanide are usually instituted for the management of cyanogen poisoning. The present study reports the protective efficacy of 14 carbonyl compounds and their metabolites, and nutrients (1.0 g/kg; oral; +5 min) against acute oral toxicity of acetonitrile (ATCN), acrylonitrile (ACN), malononitrile (MCN), propionitrile (PCN), sodium nitroprusside (SNP), succinonitrile (SCN), and potassium ferricyanide (PFCN) in rats. Maximum protection index was observed for alpha-ketoglutarate (A-KG) against MCN and PCN (5.60), followed by dihydroxyacetone (DHA) against MCN (2.79). Further, MCN (0.75 LD50) caused significant increase in cyanide concentration in brain, liver and kidney and inhibition of cytochrome c oxidase activity in brain and liver, which favorably responded to A-KG and DHA treatment. Up-regulation of inducible nitric oxide synthase by MCN, PCN and SNP, and uncoupling protein by PCN and SNP observed in the brain was abolished by A-KG administration. However, no DNA damage was detected in the brain. MCN and SNP significantly decreased the mean arterial pressure, heart rate, respiratory rate and neuromuscular transmission, which were resolved by A-KG. The study suggests a beneficial effect of A-KG in the treatment of acute cyanogen poisoning.

Cyanide removal simulation from wastewater in the presence of titanium dioxide nanoparticles

One of the methods of removing cyanide from wastewater is surface adsorption. We simulated the removal of cyanide from a synthetic wastewater in the presence of Titanium dioxide nano-particles absorbent uses VISUAL MINTEQ 3.1 software. Our aim was to determine the factors affecting the adsorption of cyanide from synthetic wastewater applying simulation. Synthetic wastewater with a concentration of 100 mg/l of potassium cyanide was used for simulation. The amount of titanium dioxide was 1 g/l under the temperature of <TEX>$25^{\circ}C$</TEX>. The simulation was performed using an adsorption model of Freundlich and constant capacitance model. The results of simulation indicated that three factors including pH, nanoparticles of titanium dioxide and the primary concentration of cyanide affect the adsorption level of cyanide. The simulation and experimental results had a good agreement. Also by increasing the pH level of adsorption increases 11 units and then almost did not change. An increase in cyanide concentration, the adsorption level was decreased. In simulation process, rising the concentrations of titanium dioxide nanoparticles to 1 g/l, the rate of adsorption was increased and afterward no any change was observed. In all cases, the coefficient of determination between the experimental data and simulation data was above 0.9.

The β-cyanoalanine pathway is involved in the response to water deficit in Arabidopsis thaliana

The β-cyanoalanine pathway is primarily responsible for detoxification of excess cyanide produced by plants. Recent evidence suggests that cyanide detoxification via this pathway may be involved in the response and tolerance to water deficit in plants. The aim of this study was to explore this role in Arabidopsis thaliana in greater detail. The first objective was to establish responsiveness of the pathway to the magnitude and duration of water deficit. The second objective was to examine how interruption of single genes (AtCysA1, AtCysC1 and AtNIT4) encoding enzymes of the pathway influenced the ability to metabolize cyanide and withstand water deficit. Arabidopsis plants were exposed to conditions which emulated acute and chronic water deficit, followed by measurement of tissue cyanide concentration, activity of enzymes, and physiological parameters. The results for wild-type Arabidopsis demonstrated a transient increase in cyanide concentration and β-cyanoalanine synthase activity, followed by a decrease in both. The increase in enzyme activity was localized to the tissue in direct proximity to the stress. The knockdown AtCysA1 mutant did not differ from wild-type while AtCysC1 mutants were slightly more sensitive to water deficit. The AtNIT4 mutant was the most sensitive showing decreased growth along with altered chlorophyll content under water deficit as compared to wild-type. Collectively, the results indicated that the pathway is responsive to water deficit although the severity of stress did not alter the nature of the response, implying that the capacity to remove cyanide generated during water deficit may contribute to tolerance to this stress in Arabidopsis.

Packed cage rotating biological contactor system for treatment of cyanide wastewater

The aim of this work was to study the efficiency of the packed cage rotating biological contactor (RBC) system with synthetic wastewater (SWW) containing 800 mg/l BOD 5 with various cyanide residue concentrations and hydraulic loading time. The results showed that cyanide had a negative effect to both the system’s efficiency and bio-film quality. An increase in cyanide concentration led to a decrease in bio-film growth and the consequent reduction in the removal efficiency of the system. Also, the effluent suspended solids (SS) of the system was increased with increasing cyanide concentrations because the bio-film detached from the media due to the toxicity of the cyanide residue. The system showed the highest COD, BOD 5, TKN and cyanide removal efficiencies of 94.0 ± 1.6%, 94.8 ± 0.9%, 59.1 ± 2.8% and 95.5 ± 0.6%, respectively, with SWW containing 5 mg/l cyanide under HRT of 8 days, while they were only 88.8 ± 0.7%, 89.5 ± 0.5%, 40.3 ± 1.1% and 93.60 ± 0.09%, respectively, with SWW containing 40 mg/l cyanide. In addition, the effluent ammonia, nitrite and nitrate were increased with increases in cyanide concentration or loading. However, the system with SWW containing the highest cyanide concentration of 40 mg/l showed almost constant COD and BOD 5 removal efficiencies of 89% and 90%, even when the system was controlled under the lowest HRT of 8 h.

Adsorption of cyanide from aqueous solutions at pyrophyllite surface

The adsorption of cyanide from aqueous solutions at pyrophyllite mineral surface has been studied by investigating the effect of initial concentration of adsorbate, amount of adsorbent, pH and temperature of test solutions. The adsorption efficiency is observed to be 99% in dilute solutions but decreases down to 40% with increase in cyanide concentration to 10 ppm. The adsorption is observed to be maximum from neutral solutions and is observed to increase with increase in temperature. The adsorption data have been fitted in Langmuir and Freundlich isotherms and the adsorption has been found to be endothermic in nature in the temperature range 30–60°C.