Remediation technologies for heavy metal contaminated groundwater.

Efficient and durable electrocatalysts from earth-abundant elements play a vital role in the key renewable energy technologies including overall water splitting and hydrogen fuel cells. Here, generally used CoFe based layered double hydroxides (LDHs) were first delaminated and exfoliated in the DMF-ethanol solvent (CoFe LDH-F), with enhancement both in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The exfoliation process creates more coordinatively unsaturated metals and improves the intrinsic electronic conductivity, which is important in water electrolyzer reactions. In the basic solution, the CoFe LDH-F catalyst outperforms the commercial iridium dioxide (IrO2) electrocatalyst in activity and stability for OER and approaches the performance of platinum (Pt) for HER. The bifunctional electrocatalysts can be further used for overall water splitting, with a current density of ∼10 mA/cm2 at the applied voltage of 1.63 V for long-term electrolysis test, rivalling the performance of Pt and IrO2 combination as benchmarks. Our findings demonstrate the promising catalytic activity of LDHs for scale-up alkaline water splitting.

Defect-Rich Ultrathin Cobalt–Iron Layered Double Hydroxide for Electrochemical Overall Water Splitting

Adsorption of heavy metals on functionalized-mesoporous silica: A review

Presence of toxic and recalcitrant heavy metal ions in industrial effluents is a major environmental concern. These fatal metal ions are not only hazardous in exceeding concentrations but due to the property of biomagnification it is urgent to look for the plausible solutions. This review article is an attempt to gather the research findings attempted in yester years for the removal of such metals from aqueous solutions by using waste materials from industries, such as blast furnace sludge, slag and flue dust, fly ash, black liquor lignin, and red mud. Studies have been complied keeping various efficiency influencing parameters such as optimum dose, contact time, initial concentration of metal ions, and many more in consideration. This article also tries to summarize the various problems and shortcoming of the work carried so far and attempts to explore the feasible suggestions.

A review on potential usage of industrial waste materials for binding heavy metal ions from aqueous solutions

Water pollution is one of the global challenges that society must address in the 21st century aiming to improve water quality and reduce human and ecosystem health impacts. Industrialization, climate change, and expansion of urban areas produce a variety of water pollutants. In this work, we discuss some of the most recent and relevant findings related to the release of heavy metals, the possible risks for the environment and human health, the materials and technologies available for their removal. Anthropogenic activities are identified as the main source of the increasing amounts of heavy metals found in aquatic environments. Some of the health hazards derived from repeated exposure to traces of heavy metals, including lead, cadmium, mercury, and arsenic, are outlined. We also give some perspectives about several techniques used to detect heavy metals, as well as about the factors that could affect the contaminant removal. The advantages and drawbacks of conventional and non-conventional heavy metal removal methods are critically discussed, given particular attention to those related to adsorption, nanostructured materials and plant-mediated remediation. Some of the commercial products currently used to eliminate heavy metals from water are also listed. Finally, we point out some the requirements and opportunities linked to developing efficient methods for heavy metal removal, such as the ones that exploit nanotechnologies.

Heavy metal water pollution: A fresh look about hazards, novel and conventional remediation methods

Removal of copper from aqueous solution using red mud

A New Method for the Purification of Carbonic Anhydrase Isozymes by Affinity Chromatography

The antioxidant activity of aqueous and ethanol extracts of iris (Iris germanica L., family Iridaceae) has been evaluated in vitro using various antioxidant assays, including reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities. Both aqueous and ethanol extracts exhibit strong total antioxidant activity, showing 95.9, 88.4, 79.9% and 90.5, 78.0, 65.3% inhibition on peroxidation of linoleic acid emulsion in concentrations of 10, 30, and 50 µg-ml, respectively. Both extracts also possess effective reducing power and exhibit free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities in concentrations of 20, 40, and 60 µg-ml. The antioxidant properties were compared to those of reference antioxidants (BHA, BHT, and α-tocopherol). In addition, the total content of phenolic compounds in both aqueous and ethanol iris extracts has been determined as gallic acid equivalent. The results indicate that iris has in vitro antioxidant properties, which can be the major factor responsible for the inhibition of lipid peroxidation.

Antioxidant and radical scavenging properties of Iris germanica

Carbonic anhydrase (CA) was purified from bovine erythrocyte plasma membrane and characterized in this study. For this purpose, the blood taken from young animals was hemolysed, the membrane fraction was separated, and this fraction was repeatedly washed. The enzyme (CA) was removed from the membrane with buffered TritonX-100 (1%); it could be purified at a factor of 22.8 by affinity chromatography. The CA obtained from erythrocyte membrane has an esterase activity as well as hydratase activity. The Vmax and Km of the enzyme for the substrate (p-nitrophenyl acetate) are 1.948x10(-3) mM/L x dak, and 3.596 mM, respectively. The purification degree of the enzyme was controlled by SDS-PAGE (3-10), which showed two distinct bands. It was determined that the enzyme had activity within the pH range of 4.5-9.5 and that the optimal pH was 7.5. The temperature at which it showed activity was 20-60 degrees C and optimal temperature was 37 degrees C. Molecular weight of CA was found to be 29844 and 61706 Dalton by gel filtration. On the other hand, sulfanilamide and acetazolamide affected the enzyme.

Purification and characterization of carbonic anhydrase from bovine erythrocyte plasma membrane.

Extracellular pectin lyase (EC 4.2.2.10) was produced by Bacillus pumilus (P9) in solid state fermentation. Pectin lyase enzyme was purified 36.36 fold by using DEAE-cellulose anion exchange column chromatography and characterized. Molecular weight of the enzyme was determined as 25 kDa by using Sephadex G-100 gel filtration chromatography. Purification of enzyme was controlled by SDS-PAGE. The optimum pH and temperature of enzyme was determined as pH 6.0 and 60C, respectively. Pectin lyase was mostly stable at 40C. Its’ activity deceased in 50% for 1h at 60C and 40% for 4 h at 50C. Vmax and KM were calculated respectively as 0.298 mg/mL and 132.6 mol/L*min. The presence of 10 mM concentration of Ca, Cu, Mn, Mg, Zn, Hg, Fe and EDTA, L-cystein, ascorbic acid and -mercaptoethanol significantly enhanced the pectin lyase of the purified enzyme. The purified pectin lyase enzyme was used for getting fruits juices. It was determined that yields of fruits juices significantly improved when it was compared with control.

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Nazan Demir

Papers

Removal of copper from aqueous solution using red mud

A New Method for the Purification of Carbonic Anhydrase Isozymes by Affinity Chromatography

Antioxidant and radical scavenging properties of Iris germanica

Purification and characterization of carbonic anhydrase from bovine erythrocyte plasma membrane.

Production of a Novel Pectin Lyase From Bacillus pumilus (P9), Purification and Characterisation and Fruit Juice Application