A New Approach to Explaining the Oscillatory Oxidation of Arsenites, Stibnites and Vismutinites Using Magnetic Method

Magnetic and relativistic effects in uranium catalysts, the movement of charged particles under the effect of a uniform electric field and uniform magnetic field were studied in the paper. We have considered various mechanisms oscillating reactions （Models Jabotinsky-Korzukhina, Brusselator, Oregonator and Advanced Oregonator）. The mechanisms of the motion of charged particles under the influence of an electric field and a uniform magnetic field were proposed.

Effect of sodium arsenite on spermatogenesis, plasma gonadotrophins and testosterone in rats

To investigate the effect of arsenic on spermatogenesis. Methods: Mature (4 months old) Wistar rats were intraperitoneally administered sodium arsenite at doses of 4, 5 or 6 mg-kg^-day1 for 26 days. Different varieties of germ cells at stage VII seminiferous epithelium cycle, namely, type A spermatogonia (ASg), preleptotene spermatocytes (pLSc), midpachytene spermatocytes (mPSc) and step 7 spermatids (7Sd) were quantitatively evaluated, along with radioimmunoassay of plasma follicle-stimulating hormone (FSH), lutuneizing hormone (LH), testosterone and assessment of the epididymal sperm count. Results: In the 5 and 6 mg/kg groups, there were significant dose-dependent decreases in the accessory sex organ weights, epididymal sperm count and plasma concentrations of LH, FSH and testosterone with massive degeneration of all the germ cells at stage VII. The changes were insignificant in the 4 mg/kg group. Conclusion: Arsenite has a suppressive influence on spermatogenesis and gonadotrophin and testosterone release in rats.

Oxidation of As(Ⅲ) by potassium permanganate

The oxidation of As（Ⅲ） with potassium permanganate was studied under conditions including pH, initial As（Ⅲ） concentration and dosage of Mn（Ⅶ）. The results have shown that potassium permanganate was an effective agent for oxidation of As（Ⅲ） in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As（Ⅲ） by Mn（Ⅲ）. Although theoretical redox analyses suggest that Mn（Ⅶ） should have better performance in oxidization of As（Ⅲ） within lower pH ranges, the experimental results show that the oxidation efficiencies of As（Ⅲ） under basic and acidic conditions were similar, which may be due to the adsorption of As（Ⅲ） on the Mn（OH）2 and MnO2 resulting from the oxidation of As（Ⅲ）.

Arsenic uptake and transport of Pteris vittata L.as influenced by phosphate and inorganic arsenic species under sand culture

In order to understand the similarity or difference of inorganic As species uptake and transport related to phosphorus in Ashyperaccumulator, uptake and transport of arsenate （As（V）） and arsenite （As（Ⅲ）） were studied using Pteris vittata L. under sand culture. Higher concentrations of phosphate were found to inhibit accumulation of arsenate and arsenite in the fronds of P. vittata. The reduction in As accumulation was greater in old fronds than in young fronds, and relatively weak in root and rhizome. Moderate increases, from 0.05 to 0.3 mmol/L, in phosphate reduced uptake of As（Ⅲ） more than As（Ⅴ）, while the reverse was observed at high concentrations of phosphate （≥1.0 mmol/L）. Phosphate apparently reduced As transport and the proportion of As accumulated in fronds of P. vittata when As was supplied as As（Ⅴ）. It may in part be due to competition between phosphorus and As（Ⅴ） during transport. In contrast, phosphate had a much smaller effect on As transport when the As was supplied as As（Ⅲ）. Therefore, the results from present experiments indicates that a higher concentration of phosphate suppressed As accumulation and transport in P. vittata, especially in the fronds, when exposed to As（Ⅴ）, but the suppression of phosphate to As transport may be insignificant when P. vittata exposed to As（Ⅲ） under sand culture conditions. The finding will help to understand the interaction of P and As during their uptake process in P. vittata.

Recovery of copper sulfate after treating As-containing wastewater by precipitation method

The solid sodium hydroxide neutralized acidic As-containing wastewater till pH value was 6. Green copper arsenite was prepared after copper sulfate was added into the neutralized wastewater when the molar ratio of Cu to As was 2：1 and pH value of the neutralized wastewater was adjusted to 8.0 by sodium hydroxide. The arsenious acid solution and red residue were produced after copper arsenite mixed with water according to the ratio of liquid to solid of 4：1 and copper arsenite was reduced by SO2 at 60℃ for 1 h. The white powder was gained after the arsenious acid solution was evaporated and cooled. Copper sulfate solution was obtained after the red residue was leached by H2SO4 solution under the action of air. The results show that red residue is Cu3（SO3）2·2H2O and the white powder is As2O3. The leaching rate of Cu reaches 99.00% when the leaching time is 1.5 h, molar ratio of H2SO4 to Cu is 1.70, H2SO4 concentration is 24% and the leaching temperature is 80 ℃. The direct recovery rate of copper sulfate is 79.11% and the content of CuSOa·5H2O is up to 98.33% in the product after evaporating and cooling the copper sulfate solution.

Industrial experiment of copper electrolyte purification by copper arsenite

Copper electrolyte was purified by copper arsenite that was prepared with As2O3.And electrolysis experiments of purified electrolyte were carried out at 235 and 305 A/m2,respectively.The results show that the yield of copper arsenite is up to 98.64% when the molar ratio of Cu to As is 1.5 in the preparation of copper arsenite.The removal rates of Sb and Bi reach 74.11% and 65.60% respectively after copper arsenite is added in electrolyte.The concentrations of As,Sb and Bi in electrolyte nearly remain constant during electrolysis of 13 d.The appearances of cathode copper obtained at 235 and 305 A/m2 are slippery and even,and the qualification rate is 100% according to the Chinese standard of high-pure cathode copper(GB/T467-97).

Sodium arsenite reduces severity of dextran sulfate sodium-induced ulcerative colitis in rats

The histopathological features and the associated clinical findings of ulcerative colitis (UC) are due to persistent inflammatory response in the colon mucosa. Interventions that suppress this response benefit UC patients. We tested whether sodium arsenite (SA) benefits rats with dextran sulfate sodium (DSS)-colitis. The DSS-colitis was induced by 5% DSS in drinking water. SA (10 mg/kg; intraperitoneally) was given 8 h before DSS treatment and then every 48 h for 3 cycles of 7, 14 or 21 d. At the end of each cycle rats were sacrificed and colon sections processed for histological examination. DSS induced diarrhea, loose stools, hemoccult positive stools, gross bleeding, loss of body weight, loss of epithelium, crypt damage, depletion of goblet cells and infiltration of inflammatory cells. The severity of these changes increased in the order of Cycles 1, 2 and 3. Treatment of rats with SA significantly reduced this severity and improved the weight gain.

Modeling transport of arsenic through modified granular natural siderite filters for arsenic removal

Groundwater arsenic (As) contamination is a hot issue,which is severe health concern worldwide.Recently,many Fe-based adsorbents have been used for As removal from solutions.Modified granular natural siderite (MGNS),a special hybrid Fe(II)/Fe(III) system,had higher adsorption capacity for As(III) than As(V),but the feasibility of its application in treating high-As groundwater is still unclear.In combination with transport modeling,laboratory column studies and field pilot tests were performed to reveal both mechanisms and factors controlling As removal by MGNS-filled filters.Results show that weakly acid pH and discontinuous treatment enhanced As(III) removal,with a throughput of 8700 bed volumes (BV) of 1.0 mg/L As(III) water at breakthrough of 10 mg/L As at pH 6.Influent HCO3^- inhibited As removal by the filters.Iron mineral species,SEM and XRD patterns of As-loading MGNS show that the important process contributing to high As(III) removal was the mineral transformation from siderite to goethite in the filter.The homogeneous surface diffusion modeling (HSDM) shows that competition between As(III) and HCO3^- with adsorption sites on MGNS was negligible.The inhibition of HCO3^- on As(III) removal was connected to inhibition of siderite dissolution and mineral transformation.Arsenic loadings were lower in field pilot tests than those in the laboratory experiments,showing that high concentrations of coexisting anions (especially HCO3^-- and SiO4^4-),high pH,low EBCT,and low groundwater temperature decreased As removal.It was suggested that acidification and aeration of high- As groundwater and discontinuous treatment would improve the MGNS filter performance of As removal from real high-As groundwater.

Effect of In Vivo and in Vitro Treatment with Arsenite on Rat Hepatic Mitochondrial and Microsomal Enzymes

The effects of arsenite on activities of several enzymes including mitochondrial pyruvate dehydrogenase(PDH) and succinate dehydrogenase(SDH) ,microsomal cytochrome P450 and b5 , NAD(P)H cytochrome C reductase and glutathione S-transferase were studied. The effects of arsenite on the mitochondrial membrane lipid peroxidation(LPO), the content of hepatic cytosol reduced glutathione and the activity of glutathione peroxidase was also investigated in rats.The results indicated that the activities of mitochondrial PDH and SDH were inhibited to 59% and 57% of the control activities respectively after arsenite was administered by intraperitoneal injection(i. p.) for 7 consecutive days at a dose of 20 mg/kg. Administration of arsenite led to a potential decrease of GSH content.The increase in lipid peroxidation of liver mitochondrial membrane prepared from rats treated with arsenite was also observed(P<0. 05) . Arsenite did not appear to affect the liver cytosolic glutathione peroxidase and microsomal enzyme activities in vivo. In in vitro test, liver mitochondria and cytosol were treated with arsenite , which led to a decreased SDH activity and GSH content and increase of mitochondrial LPO in a dose-dependent pattern that was similar to the results obtained in in vitro experiments. Selenite played a significant antagonistic role in effects of arsenite either in vivo or in vitro on the activities of mitochondrial PDH and SDH, and the content of mitochondrial LPO and cytosolic GSH. This results suggested that the toxic effects of arsenite on rat were associated with increased levels of LPO and the injured SH group in body caused by arsenite.

Fabrication of A Folic Acid-Modified Arsenic Trioxide Prodrug Liposome and Assessment of its Anti-Hepatocellular Carcinoma Activity

Objective To reduce the toxicity and side effects of arsenic trioxide(ATO)and provide a new approach for the treatment of primary liver cancer,a folic acid-modified calcium arsenite liposomal“target-controlled”drug delivery system(FA-LP-CaAs)was fabricated using the reverse microemulsion method.Methods A Malvern particle size analyzer and a transmission electron microscope were employed to determine the particle size,distribution,zeta potential and morphology of FA-LP-CaAs.Further,inductively coupled plasma emission spectrometry was employed to determine the drug loading capacity,entrapment efficiency,and in vitro release behavior of FA-LP-CaAs.To determine its toxicity in human hepatoma cells(HepG2)and human normal hepatocytes(LO2)and its effect on HepG2 cell cycle and apoptosis,the MTT method was used.Laser confocal and flow cytometry were also employed to determine the uptake of FA-LP-CaAs by cells.After establishing a mouse liver cancer model,the in vivo distribution of the drug included in the formulation was investigated using in vivo fluorescence.To evaluate the liver cancer targeting and anti-tumor effects of FALP-CaAs in vivo,the distribution of ATO in tissues and changes in tumor volume and body weight after liposomal administration were investigated using hematoxylin-eosin(HE)-stained tumor sections.Results The particle size,zeta potential and PDI of FA-LP-CaAs were(122.67±2.18)nm,(12.81±0.75)mV and 0.22±0.01,respectively,while its drug loading capacity was 18.49%±1.14%.In vitro experimental results revealed that FA-LP-CaAs had a strong killing effect on HepG2 cells.Further,the cell uptake capacity of this formulation was found to improve.Based on in vivo assessments,FA-LP-CaAs could significantly increase the distribution of ATO in tumor sites and inhibit tumor growth.Conclusions Herein,an FA-LP-CaAs formulation was successfully fabricated.This liposomal drug delivery system had a round appearance,uniform particle size,good polydispersity coefficient,evident“core-shell”structure,high drug loading capacity and pH response,tumor targeted drug delivery and sustained drug release.These findings support further research and the application of ATO as an anti-liver cancer prodrug and provide a new method for the treatment of liver cancer.

Laterite, Sandstone and Shale as Adsorbents for the Removal of Arsenic from Water

This study aims at exploring arsenite (As (III)) removal from water using naturally available rocks (laterite, sandstone and shale) in C?te d’Ivoire. The study focused on the adsorbent dose, operating pH, contact time, initial arsenite concentration, and modelisation on the removal of arsenite by performing batch adsorption experiment with well water. The optimal dosage related to an initial As (III) concentration of 5 mg/L was about 50, 75 and 145 g/L for laterite, sandstone and shale respectively. Laterite has a better adsorption capacity in comparison to sandstone and shale. On the other hand, kinetic study reveals that the equilibrium times are 5 h for laterite, 3 h for sandstone and 8 h for shale. Results showed that laterite, sandstone and shale could remove the arsenic in groundwater at initial arsenic concentrations below 5 mg/L, satisfying the World Health Organization (WHO) standard for drinking water. Moreover, kinetics study showed that the overall adsorption rate of arsenite was described by the pseudo-second-order kinetic model.

Arsenic exposure and glutamate-induced gliotransmitter release from astrocytes

The present study used cultures of primary astrocytes, isolated from neonatal rats, to verify the hypothesis that arsenite-induced neurotoxicity can influence neuronal function by altering glutamate-induced gliotransmitter release. Primary astrocytes were exposed to 0, 2.5, 5, 10, 20 or 30 μM arsenite for 24 hours. Cell viability and morphological observations revealed that 5 μM arsenic exposure could induce cytotoxicity. Cells were then cultured in the presence of 0, 2.5, 5, or 10 μM arsenite for 24 hours and stimulated with 25 μM glutamate for 10 minutes. Results showed that [Ca2＋]i in astrocytes exposed to 5 and 10 μM arsenite was significantly increased and levels of D-serine, γ-aminobutyric acid and glycine in cultures exposed to 2.5-10 μM arsenite were also increased. However, glutamate levels in the media were significantly increased only after treatment with 10 μM arsenite. In conclusion, our findings suggest that arsenic exposure may affect glutamate-induced gliotransmitter release from astrocytes and further disturb neuronal function.

Ameliorating effects of Raphanus sativus leaves on sodium arsenite-induced perturbation of blood indices in Swiss albino mice

Objective: To evaluate the ameliorating effects of Raphanus sativus leaves(RSL)against sodium arsenite(Sa)-induced adverse effects through mice experiments.Methods: Swiss albino mice were divided into four equal groups: control, Sa, RSL,RSL + Sa. Sa(10 mg/kg body weight/day), and powder form of RSL(50 mg/kg body weight/day) were provided as food supplement orallty. Blood indices were measured using commercially available kits through colorimetric methods.Results: It was observed that lactate dehydrogenase, alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase activities were significantly(P < 0.05)higher in Sa-treated mice than those in the control group. RSL significantly reduced Sainduced elevation of the activities of these enzymes in serum significantly(P < 0.05).Serum butyrylcholinesterase activity and high density lipoproteins cholesterol levels in Satreated mice were significantly(P < 0.05) lower than the control group, and the food supplementation of RSL could significantly(P < 0.05) prevent the reduction of Sa-mediated serum butyryl cholinesterase activity and high density lipoproteins cholesterol levels. RSL could also reduce the Sa-induced elevation of serum urea level significantly(P < 0.05).Conclusions: Results of this study suggest the protective or ameliorating effects of RSL on Sa-induced perturbation of blood indices are related to the hepatic, cardiovascular and kidney dysfunction. Therefore, RSL may be useful to reduce arsenic toxicity in human in the future.

Effect of aqueous seed extract of Mucuna pruriens on arsenic-induced testicular toxicity in mice

Objective:To investigate the protective effects of Mucuna(M.)pruriens against arsenic-induced testicular impairment in albino mice.Methods:Thirty-six male albino mice were divided into six groups,with 6 mice in each group.Group 1 received drinking water as the normal control.Groups 2 to 6 received sodium arsenite(40 mg/L)in drinking water.Group 3 received sodium arsenite(40 mg/L)and 300 mg/kg body weight(b.w.)of N-acetylcysteine.Group 4 received sodium arsenite(40 mg/L)and 500 mg/kg b.w.of M.pruriens.Group 5 received sodium arsenite(40 mg/L)and 1000 mg/kg b.w.of M.pruriens.Group 6 received sodium arsenite(40 mg/L)and 2000 mg/kg b.w.of M.pruriens.N-acetylcysteine and M.pruriens were administered orally once a day.Animals were subjected to the above treatments for 45 days.Animals were sacrificed with overdose of ketamine 24 h following drug administration.The testis was used for biochemical estimations(lipid peroxidation and glutathione),and the epididymis was used to determine the sperm count and morphology.Results:Sodium arsenite significantly decreased(P<0.01)the sperm count and glutathione levels of the testis.It significantly increased(P<0.01)the abnormal architecture of the spermatozoa and lipid peroxidation levels.Treatment with M.pruriens significantly increased the sperm count and the glutathione levels[500 mg/kg b.w.and 1000 mg/kg b.w.(P<0.01)].A significant decrease in sperm abnormality and lipid peroxidation levels[500 mg/kg b.w.and 1000 mg/kg b.w.(P<0.01)]was also observed.Conclusions:The perturbed sperm parameters and antioxidant levels of the arsenic insulted testis are attenuated by 500 mg/kg b.w.and 1000 mg/kg b.w.M.pruriens.

Absorption of Arsenite on Several Iron (Hydro-)Oxides and Impact from Pre-processing Methods

The absorption reactions of arsenite on Fe （hydro-）oxides are studied. The three absorbent types are Fe（OH）3 gel and two Fe （hydro-）oxides, in which the Fe（OH）3 gel was dried in a microwave oven under vacuum at 80℃. It is found that pH changes from 9.71 to 10.36 in 6 minutes after the Fe （OH）3 gel was mixed with NaAsO2 solution, as the arsenite replaces the OH- in goethite and Fe（OH）3. At the 40th minute after the start of the reaction, pH decreases, which is most probably because that the monodentate surface complex of absorbed arsenite has changed into mononuclear-bidentate complex and released proton. The decline in pH values indicates not the end of the absorption but a change in the reaction type. Temperature and dissolved gas has little effect on these two types of reactions. The total absorption of arsenite increases after the absorbent is irradiated with ultrasound, which also lead to difficulty in separating the solids from solution. The absorption capacity for arsenite of Fe（OH）3 gel dried in a microwave oven under vacuum is 53.18% and 17.22% respectively better than that of Fe （OH）3 gel and gel dried at 80℃. The possible reasons are that the water molecules in the gel vibrates with high frequency under the effect of microwave irradiation, thereby producing higher porosity and improved surface activity.

Enhanced Arsenite Removal Using Bifunctional Electroactive Filter Hybridized with La(OH)_(3)

A bifunctional electroactive filter was rationally fabricated for simultaneous oxidation and sequestration of toxic trivalent arsentic As(Ⅲ).A novel nanoscale La(OH)_(3) modified electrochemical carbon nanotube(CNT)network filter was prepared by a facile electrodeposition strategy.The As(Ⅲ)decontamination kinetics and adsorption capacity were both found to increase with the flow rate(1.5-6.0 mL/min)and the applied voltage(0-2.5 V).The CNT filter hybridized with La(OH)_(3)(CNT-La(OH)_(3))has demonstrated the ultra-high adsorption capacity of 750.2 mg/g for As(Ⅲ),which is ascribed to the combined role of sufficient adsorption sites,flow-through filtration and electric field.XPS analysis revealed that the As(Ⅲ)decontamination mechanism involved a two-step adsorption-oxidation process.The formation of inner-sphere La-O-As complexes,ligand exchange and electro-adsorption are all parts of the As(Ⅲ)adsorption process.The adsorbed neutrally-charged As(Ⅲ)was further oxidized to negatively-charged As(V)when aided by an electric field,which could be effectively sequestrated by La(OH)_(3).The CNT-La(OH)_(3) filter shows high stability under alkaline conditions and can be regenerated with dilute NaOH solution.In this study,all experiment results have demonstrated a promising and effective CNT-La(OH)_(3) electrochemical filter for As(Ⅲ)pollution minimization.

Trace Level Arsenic Quantification through Methyl Red Bromination

A simple protocol has been developed for the quantification of trace level arsenic through methyl red bromination. The proposed method is based on the oxidation of arsenic(III) to arsenic(V) by the bromine and the residual bromine’s reaction with methyl red to form colorless bromo methyl red. As the concentration of arsenic increases, the bleaching of the dye decreases due to bromine consumption. Measuring the intensity of the unreacted methyl red at 515 nm forms the basis of arsenic quantification. The molar absorptivity of this method has been found to be 2.25 × 103 L/mol/cm. The method obeys Beer’s law in the concentration range 0 - 0.25 μg/mL. The Sandell sensitivity and the limit of detection (LOD) were found to be 0.03 μg/mL/cm2 and 0.03 μg/mL respectively. The relative standard deviation has been found to be 0.35% at 1.0 μg/mL. The reaction conditions have been optimized and the interference due to various common cations and anions were studied. The proposed method has been successfully applied to the determination of trace level arsenic in various environmental samples like water, soil and vegetable samples.

Abatement of Arsenite from Water by Glow Discharge Electrolysis

Glow discharge electrolysis provides an alternative method for the removal of arsenite from water. Glow discharge electrolysis of aqueous solution containing arsenite is studied under altemating current altemating current （50 Hz） discharge. It is found that arsenite [As（III）] get converted to arsenate [As（V）]. The yield is studied with various parameters such as discharge current, duration of discharge and pH （2-10）. The results are interpreted on the basis of interaction of the OH and eaq （produced consequent to the interaction of H2O＋ and e with water at the surface of the solution） with arsenite [As（III）] through the intermediate oxidation state, namely [As（IV）].

Indirect photocatalytic reduction of arsenate to arsenite in aqueous solution with TiO_2 in the presence of hole scavengers

The indirect photocatalytic reduction of arsenate to arsenite in aqueous solution with titanium dioxide(TiO_2)was investigated with various hole scavengers such as methanol, ethanol, 2-propanol, formaldehyde, acetone,formic acid and acetic acid. Although the direct photocatalytic reduction of arsenate to arsenite with TiO_2 was impossible, an indirect reduction of As(V) was possible in the presence of sacrificial electron donors to form strongly reductive radicals. The addition of ethanol was very effective for indirect photocatalytic reduction of As(V) in aqueous solution with TiO_2 photocatalyst. The indirect photocatalytic reduction rate of As(V) may be related with both the reaction rate constants of reaction of hydroxyl radicals with hole scavenger and the reactivities for the radicals M· which are produced by the reaction of ·OH with hole scavenger.

Enhanced Removal of Arsenite from Ground Water by Adsorption onto Heat-Treated Rice Husk

The effect of heat treatment for rice husk was investigated on the removal of arsenite in ground water by the adsorption onto the rice husk surface. The heat treatment was performed at the temperature from 80oC to 300oC in the closed system under anoxic environment. The continuous adsorption column method was applied for the removal of arsenite. The removal efficiency (75%) with rice husk treated at 150oC was better compared to those (54%) obtained with untreated rice husk. Therefore, the heat treatment of rice husk at relatively low temperature was effective for the enhancement of arsenic removal from water. The treatment conditions of As removal from aqueous solution were optimized. The developed treatment technique was applied into the real ground water sample in Bangladesh. The As concentration in sample water after treatment was approximately 18 and 8 μg/L, which was below the WHO guideline value of maximum admissible level of arsenic in ground water for Bangladesh (50 μg/L). The developed technique might become a potential avenue for simple and low cost arsenic removal methods.