Thiocyanate Concentration Research Articles

THIOCYANATE COMPLEXES OF d-METALS: INFLUENCE OF CONCENTRATION OF KNCS AND NH4Cl ON A TYPE OF COORDINATION OF SCN-IONS BY FTIR SPECTROMETRY

By IR spectrometry thiocyanates aqueous solutions of divalent cations of cadmium, mercury, nickel, manganese, iron, zinc and cobalt were studied. It was found that cadmium (II), mercury (II), nickel (II), iron (II) thiocyanate ions coordinated by type thiocyanate, zinc (II) − according to the type isothiocyanate; cobalt (II) and manganese (II) coordination mode change depending on the concentration of potassium thiocyanate in a solution. These results are consistent with the theory of hard and soft acids and bases. Co2+ ions are intermediate acids, so they can coordinate with SCN− into two types; Zn2+ ions, although they belong to intermediate acids but have a strong affinity to nitrogen atoms, so thiocyanate group coordinated through nitrogen with Zn2+. Cations Hg2+ and Cd2+ are typical soft acids, so only coordinated SCN− ions through sulfur (as a mild base). Mn2+ ions can coordinate SCN− by two types. The effect of additives of the ammonium chloride ions on thiocyanate ions (0.5 mol/l) coordination with cobalt (II) ions was studie. With the increasing concentration of ammonium chloride in a solution a change occurs of coordination type with thiocyanate to isothiocyanate. It has been suggested that the increase in the concentration of potassium thiocyanate leads to the increase in the proportion of Co(NCS)42− and reduce the proportion of «free» water (unrelated with ions in the solution). Therefore, SCN− ions in the case Mn2+ and Co2+ oriented so that the hydrophobic sulfur atoms are external ones.Forcitation:Matveichuk Yu.V., Rakhman′ko E.M. Thiocyanate complexes of d-metals: influence of concentration of KNCS and NH4Cl on a type of coordination of SCN− ions by FTIR spectrometry. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 7. P. 34-41.

Optimization of the Double Loop Electrochemical Potentiokinetic Reactivation Method for Detecting Sensitization of Nickel Alloy 690

Nickel alloy 690 (UNS N06690) is one of the current choices for nuclear power plant steam generator tubing. The severity of certain stress corrosion cracking submodes in Ni-Cr-Fe alloys, such as Alloy 690, may be a function of the alloy sensitization condition. Sensitization results from chromium carbide precipitation at or near grain boundaries when the alloy is exposed to temperatures from 500°C to 800°C, which causes local chromium depletion in the adjacent matrix. The objective of this work was to study the parameters that control the double loop electrochemical potentiokinetic reactivation (DL-EPR) method and to develop an optimized test routine for Alloy 690. Alloy 690 specimens were tested under different thermal treatments, tailored to obtain a variety of concentrations of chromium in solid solution near the grain boundary (GB) region. The DL-EPR method was applied to Alloy 690 in solutions with different concentrations of sulfuric acid and potassium thiocyanate, at 30°C and 50°C. The optimal condition for detecting sensitization of Alloy 690 was 0.5 M H2SO4 + 0.001 M KSCN, at 30°C. Optical micrographs confirmed an intergranular type of attack under thermally aged (sensitized) conditions. The ratio of the reactivation to the activation peak intensities (Ir/Ia) obtained in the DL-EPR test agreed well with mass loss obtained in boiling nitric acid solution with Cr(VI) additions (modified Huey test). Chromium depletion profiles near the GB of thermally treated specimens under different conditions were measured with the energy dispersive x-ray spectroscopy technique, performed on a transmission electron microscope. A model available in the literature was fitted to those results. The Ir/Ia ratio for Alloy 690, obtained when using the optimal DL-EPR testing conditions, correlated well with the Cr depletion zone width and depth near the GB.

Cognitive and motor performance in Congolese children with konzo during 4 years of follow-up: a longitudinal analysis.

SummaryBackgroundKonzo is an irreversible upper-motor neuron disorder affecting children dependent on bitter cassava for food. The neurocognitive ability of children with konzo over time has yet to be fully documented.MethodsWe did a longitudinal study in a konzo outbreak zone continuously affected by konzo since 1990, in the district of Kahemba, southern Bandundu Province, Congo. We enrolled children with a record of neurological diagnosis of konzo in Kahemba town. For all study children with konzo enrolled in the final sample for the baseline assessment, a neurological exam was done by neurologists to confirm konzo diagnosis using the 1996 WHO criteria at 2 years and 4 years. In the initial baseline sample for each child with konzo, we attempted to get consent from a comparison child without konzo (1996 WHO criteria) within 2 years of age, from a neighbouring household who met inclusion criteria. The neuropsychological assessments were the Kaufman Assessment Battery for Children, second edition (KABC-II), and the Bruininks-Oseretsky Test of Motor Proficiency, second edition (BOT-2).FindingsData collection occurred between Oct 12, 2011, and Aug 14, 2015, in the town of Kahemba. 123 children from the Congo with konzo and 87 presumably healthy children without konzo from neighbouring households were enrolled. The planned assessments were completed by 76 children with konzo and 82 children without konzo at 2-year follow-up, and by 55 children with konzo and 33 children without konzo at 4-year follow-up. Boys with konzo did worse than those without konzo on the KABC-II Learning (p=0·0424) and on the Mental Processing Index (MPI; p=0·0111) assessments at 2-year follow-up, but girls did not. These differences observed in boys might have been caused by stunting. At 4-year follow-up, the difference in KABC-II MPI score between boys or girls with or without konzo was not significant. Both boys and girls with konzo had lower scores on BOT-2 than children without konzo at both follow-up times (p<0·0001). These differences were not attenuated when controlling for physical growth. Boys with and without konzo declined on BOT-2 fine motor proficiency at 2-year follow-up (boys with konzo p=0·0076; boys without konzo p=0·0224) and KABC-II MPI performance at 2-year follow-up and 4-year follow-up (2 years: boys with konzo p<0·0001, boys without konzo p=0·0213; 4 years: boys with konzo p=0·0256, boys without konzo p=0·10), but that was not the case for the girls with scores remaining stable regardless of konzo status. For boys, increases in urinary thiocyanate concentration was significantly associated with reductions in BOT-2 motor proficiency (p=0·0321), but was not significantly associated in girls and urinary thiocyanate concentration was not associated with KABC-II MPI score for either boys or girls.InterpretationMotor and cognitive performance continues to be significantly impaired in boys with konzo at 2-year follow-up compared with boys without konzo. Because these impairments are associated in part with exposure to poorly processed cassava as measured by urinary thiocyanate, interventions are urgently needed to ensure improved processing of cassava to detoxify this food source.FundingUS National Institutes of Health.

Effect of stimulating the acupoints Feishu (BL 13) and Dazhui (GV 14) on transdermal uptake of sinapine thiocyanate in asthma gel

ObjectiveTo investigate the effect of stimulating the acupoints Feishu (BL 13) and Dazhui (GV 14) on the transdermal uptake of sinapine thiocyanate contained in a gel used for the management of asthma. MethodsThirty Sprague-Dawley rats were randomly divided into three equal groups using a random number table: the Feishu (BL 13) acupoint group, the Dazhui (GV 14) acupoint group, and the nonacupoint group or control group. Using microdialysis technology, preprocessed skin probes were implanted into the rats at Feishu (BL 13), Dazhui (GV 14), and a nonacupoint site. Asthma gel was then placed on the skin at Feishu (BL 13), Dazhui (GV 14) acupoints, and the nonacupoint for all groups. Dialysate was collected every 30 min for 12 h. The normalized concentration of sinapine thiocyanate in the skin was determined by high-performance liquid chromatography. ResultsThe rat in vivo transdermal experiment demonstrated that the quantity-time equation showed a good linear correlation with zero-order kinetics (r > 0.99). The transdermal behavior was in accordance with the first-order rate open model in which the transdermal penetration rates and the accumulative amounts of sinapine thiocyanate in the skin at the acupoint sites were greater than those through the skin of the nonacupoint site. The systemic maximum concentration and the area under the curve of sinapine thiocyanate in the acupoint groups were significantly greater than in the nonacupoint group. A lag time was observed in both acupoint groups, but not in the nonacupoint group. ConclusionStimulating the acupoints promotes the percutaneous absorption of sinapine thiocyanate and also controls its release, reducing concentration fluctuations in the blood.

Determination of Iron Content in Iron Deficiency Drugs by UV-Visible Spectrophotometer

The objective of this work was to validate a simple, precise and accurate spectrophotometric method for the determination of iron in the iron deficiency drugs, namely are Feroglobin B12, Ferose-F and Ferose. The proposed method is based on the reaction of iron with ammonium thiocyanate after the wet digestion of the drugs under study with HNO 3 and H 2 O 2 . Effects of pH, temperature, standing time and thiocyanate concentration on the determination of iron in drugs containing iron have been investigated. The λ max was 430 nm and the molar absorptivity of 0.0399 L mol -1 cm -1 . The linear regression was in the range 0.5 - 60 μg/mL for iron content in hemoglobin. The detection limit and the limit of quantification were found to be 0.040 and 0.122 µg mL -1 for the iron respectively, and with a linear regression correlation coefficient of 0.998. Recovery measurements ranged from 99.63-100.20%. This method is simple and fast can be used for the determination of iron in the iron deficiency drugs in pharmaceutical laboratories. DOI: http://dx.doi.org/10.17807/orbital.v9i3.953

Finish line plant-insect interactions mediated by insect feeding mode and plant interference: a case study of Brassica interactions with diamondback moth and turnip aphid.

There are gaps in our understanding of plant responses under different insect phytophagy modes and their subsequent effects on the insect herbivores' performance at late season. Here we compared different types of insect feeding by an aphid, Lipaphis erysimi, and a lepidopteran, Plutella xylostella, and how this affected defensive metabolites in leaves of 2 Brassica species when plants gain maturity. Thiocyanate concentrations after P. xylostella and L. erysimi feeding activities were the same. Total phenolics was higher after the phloem feeder feeding than the folivore activity. The plants compensatory responses (i.e., tolerance) to L. erysimi feeding was significantly higher than the responses to P. xylostella. This study showed that L. erysimi had higher carbon than P. xylostella whereas nitrogen in P. xylostella was 1.42 times that in L. erysimi. Population size of the phloem feeder was not affected by plant species or insect coexistence. However, there was no correlation between plant defensive metabolites and both insects' population size and biomass. This suggests that plant root biomass and tolerance index after different insect herbivory modes are not necessarily unidirectional. Importantly, the interaction between the folivore and the phloem feeder insects is asymmetric and the phloem feeder might be a trickier problem for plants than the folivore. Moreover, as both plants' common and special defenses decreased under interspecific interference, we suggest that specialist insect herbivores can be more challenged in ecosystems in which plants are not involved in interspecific interference.

Liquid milk exposure and risk assessment of thiocyanate in Chinese populations

Objective: To analyze liquid milk exposure of thiocyanate among Chinese population and preliminarily assess its health risk. Methods: A total of 2 059 raw milk samples were collected during 2013 and 2014 from 12 Chinese provinces, New Zealand and Netherlands. Farms were chosed according to the main sources of dairy companies, the distribution of farms and the yield of milk. Content of thiocyanate were detected by ion chromatography. Liquid milk consumption data were taken from Chinese beverage and alcoholic beverage consumption survey in 18 cities or counties in 9 provinces, including 16 775 subjects older than 3. A simple distribution model was used to estimate the exposure of thiocyanate from liquid milk. The tolerable daily intake (TDI) of thiocyanate was made 0.08 mg·kg(-1)·d(-1). Then the exposures of different age groups were compared with TDI. Results: Finally, 1 331 samples out of 2 059 were detected to contain thiocyanate. The detection rate was 65%. The average concentration of thiocyanate was 2.11 mg/kg, with a range of 0.10-16.20 mg/kg. The general population's consumption of thiocyanate by drinking liquid milk was 0.001 mg · kg(-1) · d(-1), which was lower than TDI. The P(95) of general population and consumers were 0.009 mg · kg(-1) · d(-1) and 0.020 mg·kg( -1)·d(-1) respectively, which were also lower than TDI. Mean exposures of population aged 3-6, 7-12, 13-17, 18-59 as well as elderly aged 60 and above were 0.007, 0.003, 0.002, 0.001 and 0.001 mg · kg(-1)·d(-1) respectively, which were all lower than TDI. Conclusion: The results suggested that the health risk of thiocyanate exposure by drinking liquid milk among Chinese population was at a low level. However, milk products for children deserve more concern.

Integrated DNA and RNA extraction using magnetic beads from viral pathogens causing acute respiratory infections

Current extraction methods often extract DNA and RNA separately, and few methods are capable of co-extracting DNA and RNA from sputum. We established a nucleic acid co-extraction method from sputum based on magnetic beads and optimized the method by evaluating influencing factors, such as the guanidinium thiocyanate (GTC) and dithiothreitol (DTT) concentrations, magnetic bead amount, incubation temperature, lysis buffer pH and RNA carrier type. The feasibility of the simultaneous nucleic acid co-extraction method was evaluated by amplifying DNA and RNA viruses from a single clinical specimen with a multiplex RT-qPCR method. Both DNA and RNA were most efficiently extracted when the GTC and DTT concentrations were 2.0 M and 80 mM, respectively, 20 μl magnetic beads were added, the incubation temperature was 80 °C, the pH was 8 or 9, and RNA carrier A was used. Therefore, we established a simple method to extract nucleic acids from two important respiratory viruses compared with other commercial kits. This magnetic beads-based co-extraction method for sputum followed by a multiplex RT-qPCR can rapidly and precisely detect DNA and RNA viruses from a single clinical specimen and has many advantages, such as decreased time, low cost, and a lack of harmful chemicals.

Novel Mechanism of Decyanation of GDC-0425 by Cytochrome P450.

GDC-0425 [5-((1-ethylpiperidin-4-yl)oxy)-9H-pyrrolo[2,3-b:5,4-c']dipyridine-6-carbonitrile] is an orally bioavailable small-molecule inhibitor of checkpoint kinase 1 that was investigated as a novel cotherapy to potentiate chemotherapeutic drugs, such as gemcitabine. In a radiolabeled absorption, distribution, metabolism, and excretion study in Sprague-Dawley rats, trace-level but long-lived 14C-labeled thiocyanate was observed in circulation. This thiocyanate originated from metabolic decyanation of GDC-0425 and rapid conversion of cyanide to thiocyanate. Excretion studies indicated decyanation was a minor metabolic pathway, but placing 14C at nitrile magnified its observation. Cytochrome P450s catalyzed the oxidative decyanation reaction in vitro when tested with liver microsomes, and in the presence of 18O2, one atom of 18O was incorporated into the decyanated product. To translate this finding to a clinical risk assessment, the total circulating levels of thiocyanate (endogenous plus drug-derived) were measured following repeated administration of GDC-0425 to rats and cynomolgus monkeys. No overt increases were observed with thiocyanate concentrations of 121-154 µM in rats and 71-110 µM in monkeys receiving vehicle and all tested doses of GDC-0425. These findings were consistent with results from the radiolabel rat study where decyanation accounted for conversion of <1% of the administered GDC-0425 and contributed less than 1 µM thiocyanate to systemic levels. Further, in vitro studies showed only trace oxidative decyanation for humans. These data indicated that, although cyanide was metabolically released from GDC-0425 and formed low levels of thiocyanate, this pathway was a minor route of metabolism, and GDC-0425-related increases in systemic thiocyanate were unlikely to pose safety concerns for subjects of clinical studies.

Iron (II) as catalyst for thiocyanate wet oxidation: Mechanism and modelization

This study investigates, for the first time ever, the performance of iron(II) as homogeneous catalyst during the catalytic wet oxidation of thiocyanate. The results revealed the suitability of iron salts as cheap, non-toxic catalysts for the homogeneous wet oxidation of thiocyanate in acidic medium, greatly enhancing the oxidation rate and achieving efficiencies above 95% (75min, 3.58mM of catalyst). Ammonium, sulphate and bicarbonate were identified as the main reaction products. Other toxic intermediates such as cyanide, cyanate, nitrates or nitrites were not detected at any reaction time. According to the results obtained, a complete reaction pathway, based on the formation of two iron (III)-thiocyanate complexes, was proposed for the degradation of thiocyanate. Finally, a kinetic model, including the effect of the main operating conditions (temperature, pressure and initial concentrations of iron and thiocyanate), was successfully fitted to the experimental data.

Approach for Modulation of the Permselective Properties of Ni(II) Porphyrin Polymers

AbstractThe electropolymerization of Ni(II) Protoporphyrin (polyNiPP) onto glassy carbon electrodes is performed in different experimental conditions, varying the supporting electrolytes, solvent, and oxidative potentials. The AFM images show different average thickness for each polymer, polyNiPP(TBAP) (0.6 μm) and polyNiPP(LiClO4) (0.1μm). The polyNiPP(LiClO4) describes a straight line plot of EMF versus log (C) for NO2−, with the slope of 37 mV per concentration decade while the same film is not sensitive to the thiocyanate concentration. For polyNiPP(TBAP) the slope for thiocyanate progressively increase when is oxidized in aqueous solution. A sub‐Nernstian response (59 mV /decade) is obtained at 1000 mV. The Nyquist plots confirm that the method of preparation establishes the properties of films related to the movement of the ions.

Determining an effective operating window for a thiocyanate-degrading mixed microbial community

Thiocyanate-laden effluents are generated during the cyanidation stage of gold production. Thiocyanate (SCN−) is difficult to remove using conventional treatment processes. Biological alternatives, such as the activated sludge tailings effluent remediation (ASTER™) process have been developed to treat thiocyanate and cyanide laden process water, but their application has been limited. Driven by the desire to broaden the commercial application of the technology, research was conducted to define the effective operating window with respect to pH, temperature and thiocyanate concentration. Biodegradation of SCN− by the mixed microbial community was assessed in batch experiments at an initial SCN− concentration of up to 1800mg/L. A concentration dependent period of apparent inactivity was observed when the unacclimitized stock culture was exposed to elevated SCN−. Exposure to elevated SCN− levels induced floc formation, presumably as a stress response. The effect of temperature, across a range from 10 to 45°C, was assessed at SCN− concentrations between 60 and 180mg/L, with optimum degradation occurring between 30°C and 40°C. The effect of solution pH on SCN−degradation was investigated between pH 5.0–10.0, with optimum performance at pH 7.0. A significant decrease in degradation rates was observed below pH 6.5 and above pH 8.5. This research has helped to establish an effective operating window for the ASTER™ process.

Structural, vibrational, thermal, electrical properties of PVP–PVC blend NH4SCN

Polymer blending is one of the most important methods used to obtain new polymeric materials, and it is a useful technique for designing electrolyte materials with required modifications in the properties, such as electrical, thermal and mechanical. PVP–PVC blend membrane doped with different molar weight percentage of NH4SCN has been prepared by solution casting technique using DMF as solvent. XRD, FTIR, DSC and AC impedance studies have been made for the above membrane. XRD studies reveal the amorphous nature of membrane. A complex formation has been confirmed by FTIR studies. Differential scanning calorimetry shows that the thermal stability and the glass transition temperature decreases with the increase in concentration of ammonium thiocyanate. The maximum proton conductivity of the polymer electrolyte is determined by AC impedance spectroscopy. A maximum conductivity of 4.01 × 10−4 S cm−1 has been observed for the composition of 70PVP:30PVC:0.3 M wt% of NH4SCN. Dielectric and modulus behaviors have been studied for the above membrane and the relaxation frequency (τ) is calculated from the loss tangent spectra (tan δ). The primary proton battery with configuration Zn + ZnSO4·7H2O/70PVP:30PVC:0.3 M wt% NH4SCN/PbO2 + V2O5 are fabricated.

Population Survey of Iodine Deficiency and Environmental Disruptors of Thyroid Function in Young Children in Haiti.

Iodine deficiency is the leading cause of preventable neurodevelopmental delay in children worldwide and a possible public health concern in Haiti. To determine the prevalence of iodine deficiency in Haitian young children and its influence by environmental factors. Cross-sectional study, March through June 2015. Community churches in 3 geographical regions in Haiti. 299 healthy Haitian children aged 9 months to 6 years; one-third each enrolled in a coastal, mountainous, and urban region. Urinary iodide, serum thyrotropin (TSH), goiter assessment, and urinary perchlorate and thiocyanate. Mean age was 3.3±1.6 years, with 51% female, median family income USD 30/week, and 16% malnutrition. Median urinary iodide levels were normal in coastal (145 μg/L, interquartile range [IQR] 97 to 241) and urban regions (187 μg/L, IQR 92 to 316), but revealed mild iodine deficiency in a mountainous region (89 μg/L, IQR 56 to 129), P < 0.0001. Grade 1 goiters were palpated in 2 children, but TSH values were normal. Urinary thiocyanate and perchlorate concentrations were not elevated. Predictors of higher urinary iodide included higher urinary thiocyanate and perchlorate, breastfeeding, and not living in a mountainous region. Areas of mild iodine deficiency persist in Haiti's mountainous regions. Exposure to two well-understood environmental thyroid function disruptors is limited.

Effect of feeding water soaked rapeseed-mustard cake (Brassica juncea) based diet on the performance of lactating cows

"The study was carried out to ascertain the effect of feeding water soaked rapeseed-mustard cake (RMC) based diet on the performance of lactating cows. Eighteen Holstein Friesian crossbred lactating cows were randomly allocated to 3 dietary treatments of 6 each viz. Control, RMC-dry and RMC-sani, respectively for an experimental period of 90 days. The glucosinolates (GLS) content of raw RMC was 149.50 µmol/g DM and it gets reduced by 31.96 per cent to 101.72 µmol/g DM in overnight water soaked (1:3 w/v ratio) RMC. The daily intake of concentrate and total DM by lactating cows did not differ significantly (Pgreater than0.05) irrespective of the dietary treatments. The digestibility coefficient (%) of DM, OM, CP, EE, NDF and ADF; nutrient density (%) and intake (g/kgW0.75) of composite diets in terms of DCP and TDN did not differ significantly (P&gt;0.05) irrespective of dietary treatments. Milk yield and its basic quality parameters including milk fat, milk protein, total solids and SNF content were comparable among the dietary treatments. Though thiocyanate (CNS) concentration of blood serum (8.65 to 12.65 µg/ml) and milk (24.77 to 39.84 µg/ml) was significantly (P less than 0.01) increased in RMC fed groups as compared to control, it was significantly (P less than 0.01) reduced in RMC-sani as compared to RMC-dry. The serum T3 (2.07 - 2.15 nmol/L) and T4 (70.62 - 73.67 nmol/L) concentrations were comparable among the dietary treatments. Alongwith substantial reduction in the GLS content of water soaked RMC, no adverse effect could be noticed by feeding raw or water soaked RMC based diet on the performance of lactating cows and CNS excretion in the body fluids get reduced by dose dependent intake of dietary GLS.

The Vitamin B12 Analog Cobinamide Is an Effective Antidote for Oral Cyanide Poisoning.

Cyanide is a major chemical threat, and cyanide ingestion carries a higher risk for a supra-lethal dose exposure compared to inhalation but provides an opportunity for effective treatment due to a longer treatment window and a gastrointestinal cyanide reservoir that could be neutralized prior to systemic absorption. We hypothesized that orally administered cobinamide may function as a high-binding affinity scavenger and that gastric alkalinization would reduce cyanide absorption and concurrently increase cobinamide binding, further enhancing antidote effectiveness. Thirty New Zealand white rabbits were divided into five groups and were given a lethal dose of oral cyanide poisoning (50mg). The survival time of animals was monitored with oral cyanide alone, oral cyanide with gastric alkalinization with oral sodium bicarbonate buffer (500mg), and in combination with either aquohydroxocobinamide or dinitrocobinamide (250mM). Red blood cell cyanide concentration, plasma cobinamide, and thiocyanate concentrations were measured from blood samples. In cyanide ingested animals, oral sodium bicarbonate alone significantly prolonged survival time to 20.3±8.6min compared to 10.5±4.3min in saline-treated controls, but did not lead to overall survival. Aquohydroxocobinamide and dinitrocobinamide increased survival time to 64±41 (p<0.05) and 75±16.4min (p<0.001), respectively. Compared to aquohydroxocobinamide, dinitrocobinamide showed greater systemic absorption and reduced blood pressure. Dinitrocobinamide also markedly increased the red blood cell cyanide concentration. Under all conditions, the plasma thiocyanate concentration gradually increased with time. This study demonstrates a promising new approach to treat high-dose cyanide ingestion, with gastric alkalinization alone and in combination with oral cobinamide for treating a supra-lethal dose of orally administered cyanide in rabbits.

Removal of thiocyanates and heavy metal ions from simulated wastewater solutions by electro- and peroxyelectrocoagulation

A procedure for treatment of simulated wastewater solutions to remove Cu2+, Ni2+, and SCN− ions using various combinations of aluminum and iron electrodes in the electro- and peroxyelectrocoagulation processes was studied. The influence exerted by the current density, pH of solution, and concentrations of impurities and hydrogen peroxide on the efficiency of removal of these ions was analyzed. Electrocoagulation using aluminum anode does not lead to a significant decrease in the thiocyanate concentration. In the peroxyelectrocoagulation process, the efficiency of removal of SCN− ions increases with an increase in the [H2O2]: [SCN−] ratio. The electrocoagulation efficiency with the Fe/Fe electrode pair reaches 87% for SCN− and 99.5% for Cu2+ and Ni2+ at a current density of 20 mA cm–2 and electrolysis time of 20 min.

Electrochemical Hydrogen Permeation Tests Under Potentiostatic Hydrogen Charging Conditions Conventionally Used for Hydrogen Embrittlement Study

Electrochemical hydrogen charging is a commonly used method for hydrogen embrittlement study of high strength steels as well as immersion in ammonium thiocyanate solutions. Hydrogen concentration in specimens in wide range, from low hydrogen concentration simulating that caused by atmospheric corrosion to relatively high hydrogen concentration to emphasize the effect of hydrogen on hydrogen embrittlement fracture, can be obtained either by changing hydrogen charging solutions with/without catalyst poisons and by controlling current density and potential applied to specimens. However, in many cases, hydrogen concentration is controlled in a trial-and-error manner. To understand the behavior of hydrogen entry in various hydrogen charging conditions and to obtain guidelines for efficient electrochemical hydrogen charging, electrochemical hydrogen permeation tests were performed in galvanostatic hydrogen charging conditions and the effects of current density and solution were reported in our previous study. In the present study, aiming at the same purpose, potentiostatic hydrogen charging was carried out using varied conditions and the hydrogen entry was monitored by means of electrochemical hydrogen permeation test and the results were compared with that obtained by using galvanostatic hydrogen charging. In the same way of the previous study, 0.5 mm-thick pure Fe sheet specimens set in a Devanathan-Stachurski cell were used in this study. The hydrogen input side of the specimen was potentiostatically polarized in 3 wt% NaCl solutions containing varied concentration of ammonium thiocyanate and a 0.1 M NaOH solution, open to air at room temperature. The Ni-plated hydrogen output side was polarized at 20 mV vs. Hg/HgO in a 0.1 M NaOH solution and the electrochemical hydrogen permeation current density was monitored in various potentiostatic hydrogen charging conditions. Hydrogen permeation current density was increased almost linearly with decrease in hydrogen charging potential. Exceptionally, at relatively high potential region the hydrogen permeation current density was lower than the extrapolation of the line probably because oxygen reduction decreases the efficiency of hydrogen entry. The efficiency of hydrogen entry expressed by the ratio of hydrogen permeation current density to hydrogen charging current density at the applied potential was decreased with decrease in potential accompanied with increase in cathodic current density. The increase in ammonium thiocyanate concentration led to enhancement of hydrogen entry drastically. These results were almost the same as that obtained for galvanostatic hydrogen charging in the previous study, and the relationship between hydrogen charging potential and hydrogen permeation current density of the potentiostatic hydrogen charging was similar to the relationship between potential of hydrogen input side resulted by galvanostatic hydrogen charging and hydrogen permeation current density. The relationship obtained in the present study can be used as guidelines for potentiostatic hydrogen charging. Though it is assumed that potentiostatic and galvanostatic hydrogen charging are similar to each other in principle, stability of hydrogen permeation current density showed some differences. In the presentation, stability of hydrogen permeation current density under the potentiostatic and galvanostatic hydrogen charging will be also discussed.

Effects of thiocyanate on granule-based anammox process and implications for regulation

The feasibility of using anaerobic ammonium oxidation (anammox) process to treat industrial wastewater containing thiocyanate (SCN−) was examined in this study. Anammox activity decreased with increasing thiocyanate concentration and pre-exposure time in batch tests. A typical noncompetitive model was used to fit the data for thiocyanate inhibition, and the 50% inhibition concentration (IC50) of thiocyanate on anammox was 620.4mgL−1 at 200mgL−1 total nitrogen level. The influent thiocyanate concentration of test reactor (R1) in phase II gradually increased from 10 to 120mgL−1, and the average nitrogen removal efficiency (NRE) of R1 was maintained at 83.0±7.82%. This robustness was attributed to the self-adaptation ability of anammox biomass through long-term acclimatization. The NRE was decreased to 57.1% under 130mgL−1 thiocyanate within two days. However, the NRE of control reactor (R0) in absence of thiocyanate was 91.23±4.11% in this phase. Under thiocyanate stress, the specific anammox activity, settling velocity and heme c content of the granules significantly decreased, and the extracellular polymeric substances content slightly increased. The short- and long-term performance inhibition could be reversed in the presence of 10mgL−1 Fe(III).

Investigation of concentration of thiocyanate ion in raw cow’s milk from China, New Zealand and the Netherlands

Thiocyanate ion is a natural component of cow’s milk (hereinafter as milk) which may be artificially augmented to activate the lactoperoxidase milk preservation system. This study presents a survey of thiocyanate levels in raw milk and proposes a naturally occurring baseline concentration of thiocyanate in milk, which is the basis for market supervision. 1669 raw milk samples from China, 270 samples from New Zealand and 120 from the Netherlands were collected in the survey. 65% of the samples contained thiocyanate above the detection limit. The average concentration of thiocyanate was 2.11mg/kg (0.10–16.20mg/kg). Differences in the concentrations of thiocyanate were found among three countries, the 12 selected provinces in China, and between summer and winter. The baseline concentration of thiocyanate found in raw cow’s milk was statistically calculated and rounded to 9.0mg/kg. Thiocyanate in milk at this level does not present a food safety concern.