G. Siva Reddy

Spectral Studies of Divalent Copper in Antlerite Mineral

Electron paramagnetic resonance (EPR) spectra on antlerite mineral are recorded both at RT & LNT. Optical absorption spectra are recorded from 200 - 2500 nm at RT. The chemical analysis of antlerite reveals that the concentration of CuO in the mineral is 67.30 wt%. Optical absorption spectrum of antlerite shows four bands, which are mainly due to Cu(II). EPR and optical results of the antlerite sample confirmed that Cu(II) is in rhombically distorted (D 2h ) octahedral symmetry with g 1 = 2.36, g 2 = 2.16 and g 3 = 2.07. The NIR spectra of antlerite are attributed to water fundamentals.

Characterisation of bhringaraj and guduchi herb by ICP-MS analysis, optical absorption, infrared and EPR spectroscopic methods.

Leaves of bhringaraj and guduchi herb of Kadapa district of Andhra Pradesh, India, are dried and powdered. ICP-MS analysis of samples indicates that copper is present in both the samples. An EPR study of guduchi sample also confirms the presence of Fe(III) whereas Eclipta alba confirms the presence of Fe(III), Mn(II) and Cu(II). Optical absorption spectrum of guduchi indicates that Cu(II) is present in rhombically distorted octahedral environment. NIR and IR results are due to carbonate fundamentals.

The Chemistry of Activation of Sphalerite—A Review

The collectorless flotation of sphalerite due to inadvertant activation is quite limited and the floatability of iron-bearing sphalerites with the aid of collector is due to the formation of diethyldixanthogen which forms a 5-membered ring complex with zinc(II). Hence activation of sphalerite by heavy metal ions, prefarably the softer species, is necessary in a majority of flotation circuits. Copper(II) ‘dopes’ ZnS phase and the surface compound slowly gets converted to covellite with simultaneous formation of sulphur, It has been reported that the formation of sulphur is also observed during activation by other metal ions; but lacks firm experimental support. However the standard redox potential of S2−/S0 indicates that the formation of sulphur is favourable, more so in acidic medium. But the sulphur formed is highly unstable and hence undergoes SN 2 reactions with the reductants. A majority of workers agree that rate of activation take place in two stages and slow stage of activation is due to diffusion...

Optical absorption near infrared and EPR studies of mottramite

Mottramite mineral from Tsumeb Corporation Mine, Tsumeb, Otavi, Namibia, is investigated in this present work. The mineral contains vanadium and copper contents of 22.73% and 16.84% by weight, respectively, as V2O5 and CuO. An electron paramagnetic resonance (EPR) study confirmed the presence of Cu(II) with g = 2.2. The optical absorption spectrum of mottramite indicates that Cu(II) is present in a rhombic environment. Near infrared results are due to water fundamentals.

EPR, UV-visible and near infrared spectroscopic characterization of dolomite

Dolomite mineral samples having white and light green colors of Indian origin have been characterized by EPR, optical, and NIR spectroscopy. The optical spectrum exhibits a number of electronic bands due to presence of Fe(III) ions in the mineral. From EPR studies, the parameters of for Fe(III) and , and for Mn(II) are evaluated and the data confirm that the ions are in distorted octahedron. Optical absorption studies reveal that Fe(III) is in distorted octahedron. The bands in NIR spectra are due to the overtones and combinations of water molecules. Thus EPR and optical absorption spectral studies have proven useful for the study of the solid state chemistry of dolomite.

Optical absorption and EPR studies on enargite

The behaviour of transition metal ions in enargite has been studied by electron paramagnetic resonance and absorption spectroscopy in the UV–VIS and near-IR regions. The ground state of Cu(II) ions in enargite is confirmed as 2B1g since g11>g⊥ (2.54>2.11). Three characteristic bands observed in the optical absorption spectra at 8275, 13105 and 18420 cm−1 are assigned to the transitions, 2B1g→2A1g, 2B1g→2B2 and 2B1g→2Eg, respectively, of Cu(II) ion in the tetragonal field. The presence of Fe(II) bands is an evidence for iron impurities in the mineral.

Optical absorption and EPR spectra of fuchsite.

Chromium containing mica is called fuchsite. Fuchsite originating from the Nellore district of India containing 3.37 wt.% of chromium is used in the present study. Optical absorption and EPR studies were carried out at room temperature (RT). The optical absorption spectrum gives energies at 14925, 15070, 15715, 16400, 17730 and 21740 cm(-1), which are attributed to spin-allowed transitions for Cr(3+) in an octahedral symmetry. EPR spectra show a strong resonance with g=1.98 along with two sets of weak resonances which are attributed to two sets of chromium in the sample. The zero field splitting parameter (D) is almost zero. These spectra are due to Cr(3+) in the mineral. The NIR spectrum is due to hydroxyl ions in the sample.

Characterization of Phyllanthus amarus herb by inductively coupled plasma mass spectrometric (ICP-MS) analysis, optical absorption and electron paramagnetic resonance (EPR) spectroscopic methods

A powdered sample of Phyllanthus amarus herb of Kadapa district of Andhra Pradesh, India, is used in the present study. ICP-MS analysis indicates that copper is present in higher concentration when compared to other elements. Although the Pb is toxic, it is within the permissible limit. The evaluated soil and herb physico-chemical parameters indicate that the sample is acidic in nature in comparison with the soil. An EPR study on powdered sample confirms the presence of Fe(III), Mn(II) and Cu(II). Optical absorption spectrum indicates that Fe(III) impurity is present in octahedral structure whereas Cu(II) is present in rhombically distorted octahedral environment. MIR results are due to carbonate fundamentals.

Effect of formaldehyde and nickel sulphate solutions on the activation of cyanide-depressed sphalerite

Abstract Cyanide-depressed sphalerite is treated with copper sulphate solution during the flotation of ZnS. The Cu 2+ ions not only displace Zn 2+ ions from the zinc cyanide complex, but also activate ZnS. The former process of preactivation consumes large amounts of Cu 2+ . An attempt has been made to replace copper sulphate solution by formalin or Ni 2+ solution for preactivation and then carry out the activation with Cu 2+ . The use of formalin improves the grade and recovery of sphalerite and is cheaper than copper sulphate. Just 80 ml of commercial formalin (35% w/v) per ton is found to be enough for effective preactivation. However the presence of a large excess of formalin is deleterious to activation and results in a lower grade with consequent loss of zinc in the tailings. Nickel sulphate solution is also found to be an effective preactivator. Both Ni 2+ and formalin also help to increase the silver content in the zinc concentrate. Both formalin and nickel sulphate solutions are also found to have a marginal effect on the depression of silica. Fe 3+ solution added between preactivation and activation helps to depress silica further. The higher grades and recoveries of iron-containing sphalerites is believed to be due to silica depression rather than formation of dixanthogen.

Intralesional Sclerotherapy - A Novel Approach for The Treatment of Intraoral Haemangiomas

In infancy and childhood haemangiomas are the most common neoplasms in head and neck region with an occurrence of about 60%. Approximately 40%-50% of all haemangiomas resolve incompletely, leaving permanent changes in the skin, such as telangiectases, epidermal atrophy, hypopigmentation or redundant skin with fibro-fatty residue but a few stubborn, problematic haemangiomas may result in serious disfigurement and dysfunction, and even become life-threatening. Most haemangiomas are managed by conservative methods that include corticosteroids (either systemic or local injection), sclerotherapy, interferon-alpha, laser therapy, embolization, cryotherapy, and radiation. Due to risk of haemorrhaging, surgical removal for small vascular lesions is not considered and it is more invasive than sclerotherapy. This case report presents the efficacy of intralesional sclerotherapy for the management of haemangiomas on dorsum and lateral border of tongue.In infancy and childhood haemangiomas are the most common neoplasms in head and neck region with an occurrence of about 60%. Approximately 40%-50% of all haemangiomas resolve incompletely, leaving permanent changes in the skin, such as telangiectases, epidermal atrophy, hypopigmentation or redundant skin with fibro-fatty residue but a few stubborn, problematic haemangiomas may result in serious disfigurement and dysfunction, and even become life-threatening. Most haemangiomas are managed by conservative methods that include corticosteroids (either systemic or local injection), sclerotherapy, interferon-alpha, laser therapy, embolization, cryotherapy, and radiation. Due to risk of haemorrhaging, surgical removal for small vascular lesions is not considered and it is more invasive than sclerotherapy. This case report presents the efficacy of intralesional sclerotherapy for the management of haemangiomas on dorsum and lateral border of tongue.