Silicon Binding in Soil Humic Substances

In the present study, an attempt has been made to probe the nature of silicon-humus bonding as it occurs in nature ('untreated') as compared to the samples wherefrom the metalloid ions have been removed ('treated'). Infrared (IR) spectroscopy revealed the role of carboxylic acid groups of Humic acid (HA) in metal complexation. Si-O absorption reduced considerably in treatment to remove metalloid ions, but it remained quite strong in the treated samples indicating a strong Si-O linkage with humus. In XRD analysis, treated samples showed stronger γ-bands. DTA analysis indicated structural strain on the humic molecule induced by complexation with metalloid ions. Treated HAs had higher acidity values compared to the untreated samples. Treatment for removal of metal ions caused an increase in cation exchange capacity while a reduction of E4/E6 ratio. Treated HAs also showed higher molecular weights (Mv) compared to the untreated samples. Removal of metals renders certain groups free which form intermolecular bonds. On the basis of analytical data, it was observed that there is still some silicon bonds within humic acid molecule, even after removal of silicon by forcing conditions. Association of silicon with humus in soils are quantitatively and qualitatively different from other metal ions and it is clear that humic acid molecule possess silicon-humus bond like pure organo-metallic compounds.

Ferrate(VI) Synthesis Using Fe(OH)3 from Waste Iron Electrolysis and Its Application for the Removal of Metal Ions and Anions in Water

Ferrate(VI) salt is an effective oxidant and coagulant for water treatment and removal of metal ions. This study demonstrates a new approach to processing metal ions and anions in water by Fe(VI) through Fe(III) obtained from the electrolysis of waste iron transformer. The electrolysis was successfully carried out in the Na2SO4 electrolyte using waste iron and zinc plates as anode and cathode, respectively. Fe(III) electrolysis results through the characterization of FTIR and XRD indicate compliance with Fe(OH)3 standards. Synthesis of ferrate was carried out by adding Fe(III) from electrolysis with NaOCl in alkaline conditions. The formed ferrate solution shows a purple color with a typical maximum wavelength of 505 nm. Furthermore, the ferrate obtained is used to remove metal ions (Fe(III), Cu(II), Zn(II), Mg(II), Pb(II)) and anions (sulfate, nitrate, and carbonate) in water with pH variations. Ferrate treatment filtrate was analyzed using AAS for metal ions, while sulfate, nitrate, and carbonate anions used UV-Vis spectrophotometry, turbidimetry, and titration methods. The results showed that ferrate effectively eliminates metal ions and anions in water with optimum pH 6. The mechanism of heavy metal removal by ferrate(VI) can be explained by ionic bonding and adsorption.

Silicon Binding in Soil Humic Substances

In the present study, an attempt has been made to probe the nature of silicon-humus bonding as it occurs in nature ('untreated') as compared to the samples wherefrom the metalloid ions have been removed ('treated'). Infrared (IR) spectroscopy revealed the role of carboxylic acid groups of Humic acid (HA) in metal complexation. Si-O absorption reduced considerably in treatment to remove metalloid ions, but it remained quite strong in the treated samples indicating a strong Si-O linkage with humus. In XRD analysis, treated samples showed stronger γ-bands. DTA analysis indicated structural strain on the humic molecule induced by complexation with metalloid ions. Treated HAs had higher acidity values compared to the untreated samples. Treatment for removal of metal ions caused an increase in cation exchange capacity while a reduction of E4/E6 ratio. Treated HAs also showed higher molecular weights (Mv) compared to the untreated samples. Removal of metals renders certain groups free which form intermolecular bonds. On the basis of analytical data, it was observed that there is still some silicon bonds within humic acid molecule, even after removal of silicon by forcing conditions. Association of silicon with humus in soils are quantitatively and qualitatively different from other metal ions and it is clear that humic acid molecule possess silicon-humus bond like pure organo-metallic compounds.

Treatment of Textile Dye Wastewater using Cynobacteria Spirulina Sp

Along with toxic dyes textile dye wastewater contains various xenobiotic compounds therefore their treatment is necessary before discharging into the environment. Bioremediation was considered as one of the eco-friendly and self-sustainable treatment systems and amongst them cyanobacteria was considered as one of the best resources for the bioremediation of organic pollutants. Thus, in this present study, Spirulina sp. was evaluated for the treatment of real textile dye wastewater (RTDW) along with the removal of metal ions and other organic pollutants. The metabolic activities to Spirulina sp. leads to complete more than 98% decolorization of Reactive Brown GR11, Reactive Magenta HBB 26, Reactive Red Bs11 and Reactive Yellow 160 dye. However, to enhance the treatment efficiency of Spirulina sp. carbon and nitrogen sources were optimized. In the presence of 1% glucose and yeast extract Spirulina sp. showed 86% American Dye Manufacturers’ Institute (ADMI) removal and 83 % chemical oxygen demand (COD) reduction from the undiluted non-sterilize RTDW. The maximum treatment efficiency of Spirulina sp. was observed at pH-7 and 30 °C under optimized co-substrates. Degradation of RTDW and representative four azo dyes were further confirmed by using ultraviolet–visible spectrophotometry (UV–vis), High Performance Liquid Chromatography (HPLC), and Fourier- transform infrared spectroscopy (FTIR) analysis. Additionally, toxicity analysis was considered as the best method to evaluate the efficiency of treatment process. Phytotoxicity and cytotoxicity assay clearly show that Spirulina sp. treatment significantly reduces the toxic characteristics of RTDW.

Kinetic study of Heavy Metal ion removal through Hydrogels

The crosslinkers allyl mannitol (AM), allyl sorbitol (AS) and allyl pentaerythritol (AP) have been used for the synthesis of crosslinked polymeric gels of acrylic acid. These gels were used for the removal of heavy metal ions from water. The quantitative removal of metal ions was determined with the support of UV-visible absorption spectroscopy. The results show that the fully dried hydrogel samples have better adsorption potential for heavy metal ion removal. The kinetics of metal ion adsorption during the treatment of wastewater has also been studied. It was found that under certain conditions, the kinetics involved may be of pseudo first order while under different set of conditions, the kinetics involved is of pseudo second order.