Cyanide Concentration Research Articles

Cyanide removal from cassava wastewater onto H3PO4 activated periwinkle shell carbon

The continuous generation of waste resulting from the industrial activities of humans has significantly been on the rise, especially liquid wastes emanating from cassava processing mills, which is a major cause for concern in developing countries. This study focused on the preparation of H3PO4 activated periwinkle carbon (APSC) and use in the removal of cyanide in cassava wastewater. The influence of variables such as pH, adsorbent dosage, contact time, and different cyanide concentrations was investigated in batch procedures. Results from the batch studies reveal a strong pH-dependent adsorption process with optimum cyanide removal occurring at pH 8. An equilibrium time of 80 min and adsorbent dosage of 3.0 g gave the highest percentage of cyanide adsorbed at 83.93%. The Pseudo-first-order, Pseudo-second-order, and Elovich kinetic models were used for the analysis of experimental data while equilibrium data analysis using Langmuir, Freundlich, and Redlich–Peterson was carried out to determine the best-fit isotherm model. The Coefficient of determination (r2), Sum of square error (SSE), and Chi-square (chi^{2}) were used to estimate the error deviations between the predicted and the experimental models using nonlinear regression analysis to determine models that best explain the adsorption process. Kinetic data fitted well to the Elovich and Pseudo-second-order kinetic model which implies chemisorption as the dominant adsorption process. The Redlich–Peterson and Langmuir model best describes the adsorption process suggesting mono-layer adsorption with the monolayer adsorption capacity of APSC found to be 2.856 mg.g−1.

Diagnosis of lethal cyanide poisoning. Analysis by Anion-Exchange Chromatography with Pulsed AmperometricDetection.

Cyanide is a poison widely used in cases of suicide or homicide. Although various methods to identify and quantify this substance are reported in the literature, they are mainly validated on biological fluids (e.g., blood and urine). In the present study, the Anion‐Exchange Liquid Chromatography with Pulsed Amperometric Detection (IC‐PAD) method was validated on blood and, for the first time, on gastric content, and organs (brain, lung, and liver). For each matrix, linearity, accuracy, precision, limit of detection (LOD), lower limit of quantification (LLOQ), matrix interferences, and carryover were assessed. The samples were extracted by steam distillation in acid environment for the following analysis by IC‐PAD. Furthermore, cyanide values found in two real poisoning cases are reported. For each investigated matrix, the analytical method satisfied all acceptance criteria for validation: it showed a good precision and accuracy, selectivity, and sensitivity with no carryover and matrix interference. The extraction by steam distillation in acid environment REDUCED the interference of the matrices and ALLOWED to perform the analysis with good precision and accuracy. In case #1, analysis showed a blood cyanide concentration of 0.99 μg/ml. In case #2, cyanide concentrations were 1.3 μg/g in brain, 0.8 μg/g in lung, 1.6 μg/g in liver, and 1.2 μg/g in gastric content. The cyanide concentrations found in the two reported cases have been suitable to cause death by poisoning.

ARBUSCULAR MYCORRHIZAE FUNGI AND SUSTAINABILITY OF ARTISANAL GOLD MINING WASTE DISPOSAL SITE REVEGETATION

Mining areas is associated with barren, highly altered soil structure, poor soil nutrients and high heavy metals concentration. Those condition, in some way may influence plant and its microbial symbion adaptation in order to establish vegetation. Arbuscular Mycorrhizae Fungi (AMF) form symbiosis to plant and provide both side beneficial. Because of its importance, AM F are addressed as important aspect in revegetation. In this paper we describe about AMF present in Artisanal Gold Mining (AGM) waste disposal site and furthermore we review about AMF adaptation in facing climate change. AMF spore and colonization were observed under microscope. Generally, 5 AMF species from genus Glomus and Acaulospora had been found. AMF Spore density varied from 8-162 spore/ 150 gram soil. Root colonizations were found in 8 plant species with percentage range from very low to high category. The highest concentration of mercury (135,4 ppm), Pb (51,4 ppm), and Cyanide (5,6 ppm) is followed by supreme AM diversity (4 species), spore density ( 162/150 gram soil), colonization percentage (high category), and plant diversity (6 species). The plant diversity was decreasing along with the low diversity and abundance of AMF. This results indicate that indigenous AMF can colonizes and promote plant diversity in tailing and potentially can be used to promote revegetation. Elevated C seems play role in enchancing AMF colonization but in soil with low available nitrogen, AMF are indicated to promote carbon loss. Furthermore, higher temperature may result in lower glomalin, protein produced by AMF which function in water-stability of soil aggregate.

Effects of Frying Time on the Concentration of Cyanide in Garri (A Fermented Cassava Product)

The study investigated the effects of frying time on the cyanide content of garri, a cassava meal commonly consumed in many parts of the world especially, Africa. Tubers of cassava were obtained from Umuna Okigwe, peeled and ground. The pulp was packed into a cotton bag, dewatered and allowed to ferment under pressure using locally fabricated mechanical press. A calculated quantity (80 g) of the semi-dried pulp, was placed in a metallic basin and placed on a fireplace and fried. 15 g each of the roasting sample were removed after 10-, 20-, 30- and 35-minutes frying intervals and subjected to alkaline titration method to determine their cyanide content. Results showed that at 10mins, 20 mins, 30 mins and 35 minutes of frying reduced the cyanide content to 19.44, 10.8, 10.8 and 9.72mg/kg respectively. It is therefore strongly recommended that the frying time of garri be maximized to effectively reduce the cyanide contents of the product.

Effects of Roasting Periods on the Nutritive Value of Telfaira occidentalis (Fluted Pumpkin) Seeds

Effect of roasting on the proximate composition, anti-nutrients, and selected mineral components of fluted pumpkin seeds were obtained by extracting the seeds from the pod, sun drying, and dividing them into three portions, one untreated and the other two roasted for 30 and 60 minutes, respectively. The samples were pulverized separately using a mechanical grinder and chemically analyzed. After employing different roasting time ranging from 0 minutes to 60 minutes; moisture content reduced from 0.86-0.27% with a coefficient of variation (CV) of 53%, crude protein reduced from 30.28-21.46% with a CV of 19%, crude fiber 2.06-2.49% with a CV of 10%, ash content 4.13-4.33% with a CV of 5%, fat content 38.13-37.75% with a CV of 1.2%, and carbohydrate 24.54-32.70% with a CV 16%. Copper changed from 0.303 to 0.114% with a CV of 100%, lead from 1.070 to 0.007% with a CV of 128%, potassium from 7.54 to 7.62% with a CV of 0.68%, and calcium from 0.513-0.20% with a CV of 20.62%. The anti-nutrient, on the other hand, exhibited a steady reduction. Oxalate concentrations changed from 148.5-104.5% with a CV of 17%, cyanide concentrations from 0.5 to 0.4% with a CV of 14%, and phytate concentrations from 425.1-175.0% with a CV of 45%. On the other hand, processing times increased the amount of ash, crude fiber, carbohydrate, lead, potassium, and calcium in the product. The anti-nutrient decreased as the processing time grew. As a result of processing fluted pumpkin seeds for 60 minutes, fluted pumpkin seeds of greater protein content are produced, which can be used as a food supplement.

Leaching of complex gold ore using a cyanide-glycine solution

In this research, the leaching of complex gold ore was studied using cyanide and glycine. In the absence of glycine, the gold dissolution increases from 6.47 to 62.21% with increasing the cyanide concentration from 250 to 4500 g/t. The ore contains sulfide minerals and base metals, such as copper, zinc, and silver, which are high cyanide consumers. At 2000 g/t cyanide concentration, the gold dissolution significantly increases from 30 to 92% with adding 0.5 mol/L of glycine. A further increase in the glycine concentration has no significant effect on the dissolution of gold. At 2000 g/t cyanide and 0.5 mol/L glycine concentrations in the absence of H2O2, the dissolution of gold is 78%, which increases to 88% and 93% with increasing the H2O2 concentration to 1 and 1.5%, respectively. The solid content is very effective in the range of 20–25%. Further increases in the solid content to 30, 35, and 40% do not have a significant effect on the gold dissolution. When only glycine is in the system, the gold dissolution is very low, and when only cyanide is in the system, the gold and copper dissolutions are almost the same. The solubility of copper in the presence of cyanide and glycine is the same, but the solubility of gold in cyanide is much higher than glycine.

Reprocessing of ore heap leach tailings at the Vasilkovsky GOK, Kazakhstan

Purpose. Representation in a generalized form of the conducted research on the development of technology for heap leaching of gold-bearing tailings at the Vasilkovsky GOK (Altyntau Kokshetau), which can be used to recover gold from technogenic deposits in Kazakhstan. Methods. The research on the gold recovery from the ore beneficiation tailings at the Vasilkovsky deposit is conducted using direct cyanidation. Experiments are performed in open heat-resistant beakers equipped with a mechanical agitator. The preparation of the material for cyanidation consists of the following operations, such as grinding, water washing and alkaline treatment followed by cyanidation. The optimal cyanidation parameters are determined by performing a series of experiments with a change in one parameter at a constant value of others. After the optimal process duration is determined, a series of experiments are conducted with a change in the solids content in the pulp of 20, 25, 33, 50 and 100%. The concentration of cyanide in the solution is 0.1-1.0 g/dm3. The concentration of sodium thiosulphate in the cyanide solution is 0.5-5.0 g/dm3. The process temperature varies within 20, 30, and 40°С. The content of the nutrient medium is the sodium thiosulphate for the used culture T10. Findings. It has been determined that with an increase in the solids content in the pulp, the degree of gold recovery from tai-lings increases, reaching a maximum of 97.5%, with a ratio of (solid : liquid) S:L = 1:1. When the solids content in the pulp is below 50%, a longer agitation leaching of the pulp is required to achieve a recovery of at least 85-90%, which, in turn, leads to high operating costs. Originality. For the first time it has been found that the optimal solids content for maximum gold recovery in the pulp can be considered 50% (or S:L = 1:1). Practical implications. Increasing the solids content in the pulp contributes to the duration of the solvent contact with the ore mass, which allows the use of less concentrated solutions of the leaching agent.

Effect of Rhodanese Enzyme Addition on Rumen Fermentation, Cyanide Concentration, and Feed Utilization in Beef Cattle Receiving Various Levels of Fresh Cassava Root

Fresh cassava root is not recommended for animal feeding due to high quantities of hydrocyanic acid (HCN), which produces symptoms of poisoning. The purpose of this study was to find out how a rhodanese enzyme addition affects rumen fermentation, HCN content, feed utilization, and blood metabolites in beef calves fed fresh cassava root. Four Thai native beef cattle with an initial body weight (BW) of 95 ± 10.0 kg (1–1.5 years old) were randomly allocated to receive fresh cassava root containing HCN at 0, 300, 450, and 600 ppm according to a 4 × 4 Latin square design. Rice straw was the basal diet. The rhodanese enzyme was combined with concentrated feeds at a concentration of 1 mg/104 ppm HCN. The fresh cassava root was cleaned to remove dirt and chopped into 3 to 5 mm sized pieces before being fed to the animals at their various levels. The total feed intake of beef cattle increased when fed with fresh cassava root (p < 0.05). The digestibility of crude protein (CP) was different among various fresh cassava root levels (p < 0.05). Ruminal ammonia-N levels were measured 4 hours after feeding, and the average concentration declined considerably in animals fed fresh cassava root at 300–600 ppm HCN (p < 0.05). Cyanide concentration in the rumen was linearly increased by 270.6% (p < 0.05) when it was supplemented with a high level of fresh cassava root. Blood urea-N concentration was altered and decreased when supplemented with fresh cassava root (p < 0.01). The blood thiocyanate concentration was altered by the levels of fresh cassava root and rhodanese enzyme, which ranged from 4.1 to 27.9 mg/dL (p < 0.01). Cattle given fresh cassava root showed no influence on total volatile fatty acid, acetic acid, or butyric acid concentrations in the rumen (p > 0.05). However, the concentration of propionic acid increased slightly (p < 0.05) 4 hours after feeding. Supplementing fresh cassava root up to 600 ppm HCN/day improved N absorption, retention, and the proportion of N retention to N intake (p < 0.05). Therefore, increasing the inclusion of fresh cassava root with a rhodanese enzyme addition improves total feed intake, CP digestibility, nitrogen utilization, blood thiocyanate, and propionate concentrations, which may remove HCN without harming animal health.

Studies of the rate of gold sorption by the AM-2B anionite from cyanide-alkaline solutions

The paper presents the results of studies on the sorption leaching of gold-containing ore of the Vasilkovskoye deposit. Kinetic dependences of the sorption of gold and associated metals from cyanide-alkali solutions under different physical and chemical factors were obtained. It was found that gold on the AM-2B resin sorbed at a higher rate than, for example, copper and zinc. The solutions were analyzed using modern devices of a new generation: FT-IR spectrometer "Avatar 370". Laboratory studies were performed to determine the gold sorption rate by the AM-2B anionite from cyanide-alkaline solutions. It was found in the process of sorption of gold from multicomponent cyanide-alkali solutions on AM-2B anionite of mixed basicity, with the macroporous structure containing benzyl dimethylamine and dibenzyl dimethyl ammonium functional groups, that an important factor of qualitative and quantitative separation of gold and impurity metals is the concentration of cyanide and hydroxyl ions in solution. The temperature effect on the sorption rate of gold from cyanide-alkali solutions was studied with the temperature dependences F of t, Bt, of t, ln (l - F) of t, and D of t that show that the sorption process of dicyanoaurate ions is controlled by mixed diffusion.

Thiocyanate toxicity: a teaching case

Introduction: Thiocyanate can cause gastrointestinal, neurologic, and cardiovascular toxicity. Additionally, it interferes with multiple laboratory assays. We present a case of acute thiocyanate toxicity. Case: A 17-year-old female presented with an intentional thiocyanate ingestion. Her course was notable for delirium, wide complex tachycardia, and presumed seizure activity with concurrent lactatemia, acidemia, and narrowing of her arterio-venous oxygen gradient. She received lipid emulsion therapy (LET). While hemodialysis was considered, she recovered without additional treatment. After resolution of her critical illness, a serum cyanide concentration was 0.21 mcg/mL. She had laboratory testing notable for hyperchloremia, hypocalcemia, hypokalemia, and an elevated salicylate concentration attributed to interference by thiocyanate. The thiocyanate was eliminated via first-order kinetics with a half-life of 61.6 hours. Discussion: Thiocyanate poisoning may cause cardiac and neurologic toxicity. Laboratory evidence of impaired cellular respiration in this case suggests possible in vivo conversion to cyanide, however this is not proven. Cyanide antidotal treatment was not administered for this patient, however LET was given based on thiocyanate’s lipophilicity. Hemodialysis is known to effectively remove thiocyanate from the blood, however the patient improved without it. The patient’s laboratory derangements were due to thiocyanate interference with ion selective electrode and colorimetric analyzer technology. Conclusions: Thiocyanate can cause cardiac and neurologic toxicity, and interferes with several laboratory assays. Theoretically, LET and cyanide antidotal treatment may be useful, but this requires further investigation. Thiocyanate toxicity should be managed supportively, and hemodialysis may be used in severe cases.

Fenton oxidation as pretreatment for biomass gasification condensate: cost and biomass inhibition evaluation

Abstract Gasification transforming organic compounds into energy-rich pyrolytic gas, is a climate-friendly treatment option for biological solid wastes. The condensates arising from the pyrolytic gas valorization is owing to high concentrations of small molecular phenols, cyanides, nitrogen-heterocyclics, aromatics and ammonium, posing an environmental and health hazard. In this paper, the watery phase of the biomass gasification condensate from spent mushroom compost (SMC), with a chemical oxygen demand (COD) of 16.4 g/L and total nitrogen of 2.3 g/L, was pretreated by Fenton oxidation. The experiments were conducted at room temperature with an initial pH value of 3, 5 and 8.9, hydrogen peroxide (H2O2) dosages between 15 and 100% of the normalized stoichiometric ratio (NSR), and Fe2+ dosages corresponding to molar ratio of H2O2:Fe2+ between 10 and 30. Through respiration inhibition assays, the best operational condition for detoxification was determined at an initial pH 5 with 30% NSR H2O2 dosage and molar ratio of H2O2:Fe2+ at 15:1. The specific operational cost of the Fenton oxidation was calculated at 2.17 €/kg CODelimination. In respiration inhibition assay, the oxygen consumption of wastewater after Fenton oxidation was increased by 316% in 3 days. In a 20 days’ biogas production test, the biogas production was increased by 81%.

Assessment of the principal factors influencing the silver cyanidation process by using Plackett-Burman experimental design

For decades, the cyanidation process is frequently used for gold and silver extraction, as well as metal extraction as a sub-product of lead, zinc, and copper metallurgy. The present study focuses on the factors that influence silver extraction efficiency, which represents the rate of silver dissolution in a sodium cyanide solution. The screening design of Plackett and Burman has been performed to investigate the variables that have the most impact on the extraction of metal namely temperature, pH, free cyanide concentration, dissolved oxygen level, pulp density, lead nitrate ratio (Pb(NO3)2ratio), and setting time.To evaluate the meaning of the seven variables, twelve experiments were carried out and the result revealed that for a 95% confidence level, the chosen parameters for the model are meaningful in their whole. The following three factors were significant (P<0.05) when it comes to the silver cyanidation process including, setting time, pulp density, and free cyanide concentration. The variance analysis (ANOVA) using a Fisher test has shown that the setting time was considered to have the most significant effect for a significance level of 1% (Fstatistics=22.8328 > Fc=21.2). Likewise, for a 95% confidence level, both pulp density and free cyanide concentration have a major influence on the response. The Pareto diagram results clearly show that pulp density and setting time represent 20% of factors that have 80% effect on the silver extraction. Model validation verified that no statistically relevant distinction was made between the predicted and experimental results with the determination coefficient R2=0.93, this mean that the metal extraction is better fitted to the model and the predictability of the model is adequate to explain 93% of the variation in the dependent variable as a function of factor variation.

Integrated Membrane Process Coupled with Metal Sulfide Precipitation to Recover Zinc and Cyanide

In gold cyanidation plants, which include a zinc cementation process, there is a progressive increase in zinc content in the solution and a higher cyanide concentration in leaching tailings. Consequently, there are opportunities to: (i) recover zinc and cyanide from these solutions, (ii) generate a saleable ZnS by-product, and (iii) reduce cyanide consumption and cyanide concentration in leaching tailings. Previous studies have proposed the use of the SART (Sulfidization, Acidification, Recycling, and Thickening) process for this purpose; however, this process has disadvantages that must be addressed. This study presents the results of the experimental assessment of an alternative process, the SuCy process, which uses an integrated membrane process. The SuCy process is composed of a metal sulfide precipitation coupled with a membrane filtration stage, a membrane contactor step to recover and concentrate cyanide, and a final neutralization and ultrafiltration stage. The flux obtained for zinc sulfide separation was around 0.01 L/m2s, with cyanide recovery of 95% at 60 min, whereas flux for ultrafiltration was 0.22 L/m2s. A comparison with an experimental study of the SART process at laboratory scale showed that the SuCy process could obtain a higher zinc recovery and can reduce the solid–liquid separation equipment by around five times. Therefore, the SuCy process could be a promising alternative for zinc and cyanide recovery in gold cyanidation.

Purifying cyanide-bearing wastewaters by electrochemical precipitate process using sacrificial Zn anode

With the rapid development of society, wastewaters, such as cyanide-containing wastewaters (CBWs) have caused environmental problems. In the present work, an electrochemical approach using sacrificial Zn anode was investigated for the removal of cyanides from CBWs. The effects of operational parameters, such as current density, pH, initial cyanide concentration, and ionic strength, on the cyanides removal from synthetic solution were discussed in turn. Under the optimal conditions obtained, the treatment of industrial CBWs was considered. Subsequently, more attentions were paid to elucidate the removal mechanisms of cyanide ions and the corresponding metal-cyanide (copper and iron) complexes by a combination of cyclic voltammetry (CV), pHPZC, X-Ray diffractometer (XRD), scanning electron microscope with energy disperse spectroscopy (SEM/EDS) and X-ray photoelectron spectrometer (XPS) characterizations. Experimental results demonstrated that the removal efficiency of total cyanide (CNT), Cu, and Fe from industrial CBWs are 98%, 91%, and 96%, respectively, with an anode consumption of 1.78 kg/m3 and energy consumption of 2.50 kW·h/m3, of which 72% of Cu was collected on the cathode and almost all of Fe was in the precipitate. Removal mechanisms suggested that free cyanide (CN–) mainly presented as Zn(CN)2 into the electrolytic precipitate. The replacement of Zn2+ and electroreduction promoted 72% of Cu(I) to be reduced, while 57% of the remaining portion of Cu(I) was oxidized to Cu(II) and 43% of Cu(I) could form CuSCN into the precipitate by XPS analysis. With respect to Fe, it was mainly ascribed to the formation of Zn2Fe(CN)6 precipitate to be removed. From above, this work provided a method for enriching cyanides from wastewaters into the precipitate, while valuable metal Cu was deposited on the cathode, facilitating the separation and recovery of valuable resources.

Rapid measurements of hydrogen cyanide concentration in combustion gas via terahertz spectroscopy

The development of a real-time measurement system to determine the concentrations of combustion gases mixed with smoke particles in fire environments is an essential technical issue in the fire safety field. In this study, the absorption line for the J = 8–7 rotational transition at 708.9 GHz of hydrogen cyanide (HCN) produced by the combustion of silk is rapidly measured in a 1 m cell during repeat scans (seven times a minute) via terahertz spectroscopy. The obtained time profile of HCN concentrations agrees well with the time profile obtained via Fourier transform infrared (FT-IR) spectroscopy. The maximum concentrations derived via terahertz spectroscopy are consistent with those derived via FT-IR within an accuracy of 10%. The minimum sensitivity of HCN is 100 ppm as detected via terahertz spectroscopy. The repetition rate, the accuracy, and the sensitivity for the scans demonstrate the potential of terahertz spectroscopy to rapidly diagnose combustion gas flow concentrations in fire environments.

New insights into the role of cyanide in the promotion of seed germination in tomato

BackgroundCyanide is a natural metabolite that exists widely in plants, and it is speculated to be involved in the regulation of various growth and development processes of plants in addition to being regarded as toxic waste. Previous studies have shown that exogenous cyanide treatment helps to improve seed germination, but the mechanism is still unclear. In this study, tomato (Solanum lycopersicum cv. Alisa Craig) was used as the material, and the effects of cyanide pretreatment at different concentrations on tomato seed germination were investigated.ResultsThe results showed that exogenous application of a lower concentration of cyanide (10 μmol/L KCN) for 12 h strongly increased the tomato seed germination rate. RNA-Seq showed that compared with the control, a total of 15,418 differentially expressed genes (P<0.05) were obtained after pretreatment with KCN for 12 h, and in the next 12 h, a total of 13,425 differentially expressed genes (P<0.05) were regulated. GO and KEGG analyses demonstrated that exogenous KCN pretreatment was involved in regulating the expression (mainly downregulation) of seed storage proteins, thereby accelerating the degradation of stored proteins for seed germination. In addition, KCN pretreatment was also involved in stimulating glycolysis, the TCA cycle and oxidative phosphorylation. Notably, it is shown that KCN acted on the regulation of plant hormone biosynthesis and perception, i.e., down-regulated the gene expression of ABA biosynthesis and signal transduction, but up-regulated the expression of genes related to GA biosynthesis and response. Consistent with this, plant hormone measurements confirmed that the levels of ABA were reduced, but GA levels were induced after pretreatment with KCN.ConclusionThese findings provide new insights into the regulation of seed germination by cyanide, that is cyanide-mediated seed germination occurs in a time- and dose-dependent manner, and is related to the mobilization of energy metabolism and the regulation of some plant hormone signals.

In Vitro Effect of Aqueous Extract of Fresh Cassava Leaves (Manihot Esculenta, Crantz) on The Larvae of Haemonchus Contortus as an Intestinal Parasite of Sheep

Cassava is frequently fed to animals. In the case of sheep, the producer relates consumption to a reduction in the parasite load. The literature has proven the effect of phenolic compounds as an anthelmintic in vivo, but no evidence for cyanogenic compounds, also present in all parts of the cassava plant, was found. A controlled in vitro bioassay was used to evaluate the aqueous extract of fresh cassava leaves. The efficiency parameter was the immobility of Haemonchus contortus larvae at the L3 stage, also used to evaluate commercial anthelmintics. Cell culture plates with 100 active L3-stage larvae per well were used, being each replicate constituted by three wells. Aqueous extract of fresh cassava leaves (FCL), Ivomec® 0.01% (PCI) as the positive control, and distilled water as negative control (NCW), were placed in the culture plate wells. Considering the immobility of the larvae as a positive anthelmintic effect, the results showed that in NCW treatments all larvae were mobile, while in PCI all 300 larvae were immobile. FCL produced a gradient of larval inactivation correlation (R2 0.996). The best-fit equation was y = -33.39ln(x) + 40.517, a logarithmic equation, which allowed the calculation of the Lethal Concentration (CL) of 3.44 µg CN- ml, or 80.0 mg of fresh cassava leaves per milliliter of water, with a performance equivalent to ivermectin. This concentration of free cyanide is compatible with the safe consumption of fresh leaves by live weight of sheep. The exact amount of cassava roots, leaves, or shoots, consumed to provide an effective dose for controlling H. contort should be established in vivo. Although phenolic compounds must also be present in the extract, the immobility was attributed to cyanogenic compounds since the correlation was proportional to the increase in the cyanide concentration. It can be concluded that the consumption of fresh cassava leaves has the potential as an anthelmintic agent to be evaluated in vivo by feeding sheep and goats. Local use could also add value to the production of fresh cassava leaves, with an average potential production of 2.5 tonnes ha-1, available throughout the year, with greater production at the beginning of cultivation and in the summer months. These leaves could be used after the roots harvesting or even after pruning for this purpose. Currently, this amount of good quality protein material remains without use in the field.

Ag3PO4/Ag nanocomposite for selective and sensitive cyanide determination in food samples through catalytical colorimetry using a paper-based test kit

A paper-based test kit for selective and sensitive determination of cyanide was successfully developed using a Ag3PO4/Ag nanocomposite for catalytic colorimetry. The Ag3PO4/Ag nanocomposite synthesized via a one-step chemical bath method could instantly oxidize the chromogenic substrate ABTS for the color development under acidic conditions without the requirement of H2O2. During the detection step, cyanide in the sample was converted into gaseous hydrogen cyanide (HCN) using sulfuric acid. The HCN species then reacted with the generated Ag+ species via coordinate covalent bonding to form silver cyanide complex ions [Ag (CN2)]-. The amount of Ag+ species used for oxidizing ABTS subsequently decreased and so did the color intensity on the paper-based test kit. Specifically, the color intensity decreased with increasing cyanide concentrations in the range of 2.50–20.0 mg L−1. The limit of detection (LOD) and limit of quantification (LOQ) were 0.48 mg L−1 and 1.59 mg L−1, respectively. The developed test kit showed relatively high selectivity towards cyanide and high tolerance towards other cations and anions present in real samples. When applied to real samples including fruit juices and food products, the performance of the rapid and low-cost test kit was well validated by a conventional precipitation titration method.

Groundwater quality assessments around acassava processing mill on the sedimentary terrain of Ilaro, South-western Nigeria

Groundwater quality assessments were carried out around a cassava processing mill within the Ilaro metropolis, South-western Nigeria using a hydro-chemical approach. Nineteen samples were obtained from proximate water wells which serve as sources of water for drinking, domestic, and irrigation activities. Twenty physicochemical parameters were analyzed, and the results were compared with the permissible limits of the world health organization (WHO) for drinking water. The pH values of the groundwater samples range between 4.60 and 7.65 which were not within the permissible limit and suggest the presence of contaminants in the water samples. The concentrations of electrical conductivity (EC), total dissolved solids (TDS), and total hardness (TH) in the groundwater samples were 100% compliance, while Hydrogen cyanide (HCN) concentrations in the groundwater samples were 0% compliance with standard permissible limit by WHO. All the Anions (Cl−, HCO3−, NO3−, SO42−) in the groundwater samples were 100% compliance except CO32-which is 79% compliance, and cations (Ca2+, Mg2+, Na+ and K+) concentrations were 100% compliance with the standard permissible limits. The concentrations of Fe, Cd, Mn, Pb, Zn, Cu in the samples were 0%, 0%, 31%, 36%, 100%, 100% in compliance respectively with standard permissible limits. The groundwater quality index (GWQI) and contamination index (CI) of the groundwater samples ranges from 527.24 to 699.16 and 24.03 to 38.80 respectively. The values of GWQI and CI of the groundwater samples were 0% compliance with recommended standard permissible limit for drinking and domestic purposes. The samples also showed moderate to high tendencies of aggressively corroding metals. The samples were unsuitable for irrigation and the concentrations of HCO3− and CO32− influenced the suitability of the samples. Strong direct relations exist between carbonate and electrical conductivity indicating freshwater status.

Isolation and Assessment of Cyanide Biodegradation Potential of Indigenous Bacteria from Contaminated Soil

Eight effective bacterial strains were isolated from cyanide-contaminated soil, from which, two (S11 and S13) were tested to determine their minimum inhibitory concentration using potassium cyanide (KCN) and potassium tetracyano nickelate (K2Ni(CN) 4). The isolates were tested for their KCN biodegradation potential (by measuring ammonia production) at neutral and alkaline pHs (7.0 and 9.0). Furthermore, the effect of the initial KCN concentration on biodegradation was evaluated at the optimal pH using nitrogen free M9 medium, supplemented with KCN as nitrogen source. The results showed that both strains tolerated cyanide concentrations of up to 10 × 10-3 mol⋅l-1 (0.651 g⋅l-1 KCN; 2.409 g⋅l-1 K2Ni(CN)4) which makes them good candidates for cyanide bioremediation. For both strains, a change of initial pH from 7.0 to 9.0 significantly enhanced KCN degradation. S13 grown at pH 9.0 and S11 cultivated at pH 7.0 released the highest and lowest amounts of ammonia, respectively. For both strains, the release of ammonia increased when the initial KCN concentration increased from 10-3 to 5 × 10-3 mol⋅l-1. These findings open prospects for the application of these bacteria for remediation of cyanide-contaminated soils and wastewater at alkaline pH, alkaline pH being conditions that prevent cyanide volatilization.