Influence of iron, nickel and cobalt on biogas production during the anaerobic fermentation of fresh residual biomass

We have investigated the dependence of the rate of the production of biogas upon the concentration of nickel, cobalt and iron at sub-toxic concentration and monitored its composition as amount of hydrogen, methane and carbon dioxide. The distribution of the added metals between the liquid and solid phase has also been monitored.

The results of our investigations show that the addition of any of the listed metals to the sludge may cause the production of a higher amount of biogas and influence the methane or carbon dioxide percentage. Conversely, the effect on the hydrogen production depends upon the metal added, the age of the active sludge used, and its adaptation to the susbtrate. As a general feature, during the acidogenesis phase, nickel reduces, while iron increases, the percentage of dihydrogen in the biogas, while cobalt has no influence.     

Selective oxidation of benzyl alcohols to benzoic acid catalyzed by eco-friendly cobalt thioporphyrazine catalyst supported on silica-coated magnetic nanospheres

A novel magnetically recoverable thioporphyrazine catalyst (CoPz(S-Bu)8/SiO2@Fe3O4) was prepared by immobilization of the cobalt octkis(butylthio) porphyrazine complex (CoPz(S-Bu)8) on silica-coated magnetic nanospheres (SiO2@Fe3O4). The composite CoPz(S-Bu)8/SiO2@Fe3O4 appeared to be an active catalyst in the oxidation of benzyl alcohol in aqueous solution using hydrogen peroxide (H2O2) as oxidant under Xe-lamp irradiation, with 36.4% conversion of benzyl alcohol, about 99% selectivity for benzoic acid and turnover number (TON) of 61.7 at ambient temperature. The biomimetic catalyst CoPz(S-Bu)8 was supported on the magnetic carrier SiO2@Fe3O4 so as to suspend it in aqueous solution to react with substrates, utilizing its lipophilicity. Meanwhile the CoPz(S-Bu)8 can use its unique advantages to control the selectivity of photocatalytic oxidation without the substrate being subjected to deep oxidation. The influence of various reaction parameters on the conversion rate of benzyl alcohol and selectivity of benzoic acid was investigated in detail. Moreover, photocatalytic oxidation of substituted benzyl alcohols was obtained with high conversion and excellent selectivity, specifically conversion close to 70%, selectivity close to 100% and TON of 113.6 for para-position electron-donating groups. The selectivity and eco-friendliness of the biomimetic photocatalyst give it great potential for practical applications.     

石墨炉原子吸收光谱法测定土壤中痕量钻

建立了硝酸－氢氟酸－盐酸混酸体系微波消解土壤样品,石墨炉原子吸收分光光谱法测定土壤中痕量钴的方法。通过对标准土样的测定结果表明,该方法容易操作、准确、可靠。     

Characterisation of cobalt‐binding proteins in occupational cobalt exposuret†

In animal experimentations cobalt is found to be carcinogenic under conditions which are comparable with a possible exposure of human beings at the workplace.^1,2 Little is known about binding and distribution of incorporated cobalt in blood.

Blood, serum and plasma of workers occupationally exposed to cobalt were analyzed concerning cobalt‐binding. The samples were focused by preparative IEF in layers of granulated gels. The cobalt concentrations in the isolated fractions were measured with the aid of flameless atomic absorption spectrometry. The whole blood samples exhibit peaks with different sizes in the pH‐5‐ and ‐7‐range. The proportion of these peaks can change with individual samples. In serum and plasma cobalt is found only in the pH‐5‐range.

When separated by gelelectrophoresis under denaturating conditions the cobalt‐fractions in all blood, serum and plasma samples shows a similar protein pattern. Several proteins with different molecular weights are detected in the pH‐5‐fractions, whereas only hemoglobin is found in the pH‐7‐fractions. In agreement with these results is the refocusing in ultrathin‐layer of polyacrylamide. Heterogeneous protein patterns are demonstrated with the pH‐5‐fractions; the pH‐7‐fractions yield only the hemoglobin pattern.

In vivo cobalt is bound to plasma proteins‐perhaps‐albumin^3,4‐and hemoglobin. Till now the chemical structure of the binding is unknown.     

Cobalt and manganese stress in the microalga Pavlova viridis （Prymnesiophyceae）： Effects on lipid peroxidation and antioxidant enzymes

Pollution of marine environment has become an issue of major concern in recent years.Serious environmental pollution by heavy metals results from their increasing utilization in industrial processes and because most heavy metals are transported into the marine environment and accumulated without decomposition.The aim of the present study is to investigate the effects on growth,pigments, lipid peroxidation,and some antioxidant enzyme activities of marine microalga Pavlova viridis,in response to elevated concentrations of cobalt(Co)and manganese(Mn),especially with regard to the involvement of antioxidative defences against heavy metal-induced oxidative stress.In response to Co~(2 ),lipid peroxidation was enhanced compared to the control,as an indication of the oxidative damage caused by metal concentration assayed in the microalgal cells but not Mn~(2 ).Exposure of Pavlova viridis to the two metals caused changes in enzyme activities in a different manner,depending on the metal assayed:after Co~(2 )treatments,total superoxide dismutase(SOD)activity was irregular,although it was not significantly affected by Mn~(2 )exposure.Co~(2 )and Mn~(2 )stimulated the activities of catalase(CAT)and glutathione(GSH),whereas,ghitathione peroxidase(GPX)showed a remarkable increase in activity in response to Co~(2 )treatments and decreased gradually with Mn~(2 )concentration,up to 50μmol/L,and then rose very rapidly,reaching to about 38.98% at 200μmol/L Mn~(2 ).These results suggest that an activation of some antioxidant enzymes was enhanced,to counteract the oxidative stress induced by the two metals at higher concentration.     

Accident Due to Release of Hydrogen Sulphide in a Manufacturing Process of Cobalt Sulphide – Case Study

An accident occurs during the manufacture of cobalt sulphide unit due to liberation of hydrogen sulphide. Problems associated with the hydrogen sulphide and the recommended preventives measured have been discussed.     

Cobalt and zinc removal from aqueous solution by chemically treated bentonite

Natural bentonite was treated by hydrochloric, nitric, and phosphoric acids followed by washing with sodium hydroxide in order to enhance its adsorption capacity. The sample that treated with hydrochloric acid followed by further treatment with NaOH showed the highest cation exchange capacity with a value of 51.20 meq/100 g. The zero-point of charge for this sample was found to be 4.50. Adsorption isotherms for both cobalt and zinc were fitted using Langmuir, Freundlich, and Redlich-Peterson and showed an adsorption capacity of 138.1 mg Co²⁺ and 202.6 mg Zn²⁺ per gram of treated sample.     

Biosorption of Co(II) ions from aqueous solution using Chrysanthemum indicum: Kinetics,equilibrium and thermodynamics

The present study investigates the adsorption potential of Chrysanthemum indicum flower in its raw (CIF-R) and biochar (CIF-BC) form for the removal of cobalt ions from aqueous solution. The adsorbents were characterized for their surface area using BET analysis, surface morphology and elemental composition with SEM-EDAX and for the presence of functional groups by FTIR analysis. Batch adsorption experiments were carried out to evaluate the effect of process parameters, viz. pH, adsorbent dosage, initial metal ion concentration, contact time, stirring speed, presence of interfering ions and temperature on the adsorption of Co(II) ion using both the adsorbents. The optimum conditions for maximum removal of Co(II) ion was ascertained to be pH 5 for both adsorbents, adsorbent dose of 4 g/L and 3 g/L, equilibrium time of 60 min and 45 min, respectively, for CIF-R and CIF-BC. The maximum adsorption capacity of CIF-R and CIF-BC was found to be 14.84 mg/g and 45.44 mg/g, respectively, for the removal of Co(II) ion. The mechanism of adsorption was studied using different models of adsorption kinetics, isotherms and thermodynamics. It was inferred that Co(II) adsorption on both CIF-R and CIF-BC followed pseudo-second order kinetics and Langmuir isotherm model with the process being spontaneous and endothermic in nature.     

微波辐射合成酪氨酸席夫碱及其光度法测定蔬菜中钴的研究

在微波辐射下 ,合成酪氨酸与桑色素席夫碱 ,该方法有很多优点 .缩短反应时间 ,仅 1 0min完成反应 ,产率在 88.5 %～ 90 .1 % ,该席夫碱应用于光度法测定蔬菜中钴的含量 .实验表明 ,钴与酪氨酸席夫碱形成 1∶1络合物 ,最大吸收波长λmax =670nm ,摩尔吸光系数为 5 .2× 1 0 4L·mol- 1 ·cm- 1 ,方法对于测定蔬菜中的钴 ,结果较满意 .     

Multispecies transport of metal–EDTA complexes and chromate through undisturbed columns of weathered fractured saprolite

Laboratory-scale tracer experiments were conducted to investigate the geochemical and hydrological processes that govern the fate and transport of organically chelated radionuclides and toxic metals in undisturbed saturated columns of weathered, fractured shale saprolite. Three long-term, reactive contaminant injections were pulsed onto three separate soil columns, with the following influent mixtures: (1) ¹⁰⁹CdEDTA²⁻, (2) ¹⁰⁹CdEDTA²⁻ and ^57,58Co(II)EDTA²⁻, and (3) ¹⁰⁹CdEDTA²⁻, ⁵⁷Co(III)EDTA⁻, and H⁵¹CrO₄⁻. Both single and multiple species experiments were conducted to determine the importance of interaction between the contaminants and competition for surface sites. Flow interruption was used to identify physical and chemical non-equilibrium (PNE and CNE) which were caused by multiple pore-region flow and rate-limited chemical reactions, respectively. Reactive contaminant transport through the fractured, weathered shale was affected by sorption, redox, and dissociation reactions, which were mediated by soil organic matter and surficial oxides of Fe, Mn, and Al. The transport of CdEDTA²⁻ was significantly influenced by ligand-promoted dissolution of subsurface Fe and Al sources, resulting in the liberation of Cd²⁺, Al(III)EDTA⁻ and Fe(III)EDTA⁻. Flow interruption confirmed that the surface-mediated dissociation reaction was time-dependent, with the stability of the CdEDTA²⁻ complex dependent on its residence time within the soil. The migration of Co(II)EDTA²⁻ was dominated by oxidization to the highly stable Co(III)EDTA⁻ species, and elevated effluent Mn²⁺ suggested that surficial Mn(IV) oxides likely catalyzed the redox reaction, though Fe-oxides may have also contributed to the reaction. Dissociation (12%) of the Co(II)EDTA²⁻ complex was first observed during flow interruption, indicating that rate-limited dissociation of the complex by Fe-oxides may be significant under equilibrium conditions. The transport of HCrO₄⁻ was significantly altered by the reduction of mobile Cr(VI) to irreversibly bound Cr(III). The reduction reaction was catalyzed by surface-bound natural organic matter and flow interruption confirmed that the reaction was time-dependent. There was little evidence of competitive effects between the various contaminants in the multispecies experiments, since each was influenced by a different geochemical process during transport through the soil. The results of this study further support research findings that suggest anionic toxic metals and radionuclide–organic complexes can be significantly influenced by soil geochemical processes that can both enhance and impede the subsurface migration of these contaminants.