Doped oxides of cerium as inorganic colorants

The colour of inorganic colorants is based on metal ions such as cadmium, lead, chromium or cobalt, the majority of which are unfortunately potentially toxic. Thus, there is in a need to introduce alternative metal or metal oxides, which would be environmentally friendly and economically viable as a replacement for potentially toxic inorganic colorants. Rare earth-based colorants offer an additional opportunity for the development of optically pure colours. In this study, a replacement for potentially toxic colorants has been sought through the use of a rare earth metal ion, cerium. Appropriate doping of cerium oxides with molybdenum and iron gives an orange–red colorant. The conditions ideal for optimal colour have been standardised and the resultant colorant characterised through powder X-ray diffraction techniques, particle size measurement, etc. The colorants exhibit good hiding power and tinting strength.     

An eco‐efficient rationalized leather process

BACKGROUND: The leather industry is under pressure to develop environmentally efficient leather‐making processes to comply with modern pollution and discharge legislation. Conventional leather‐processing methods are known to contribute significant pollution loads in tannery wastewaters. The rationalized process described here involves a salt‐free curing, lime and sulfide‐free beamhouse process and post‐tanning followed by tanning employing a reverse leather‐processing technique. RESULTS: Scanning electron microscopy (SEM) analysis substantiated that the grain surface, fibre separation and tight packing of fibres are similar for leathers from conventional and rationalized processes. The functional performance of the leathers is found to be on par with that of conventionally processed leathers. The rationalized leather process reduces the usage and discharge of chemicals by 68% and 82%, respectively. It also enjoys the reduction in biochemical oxygen demand (BOD), chemical oxygen demand, Cl^?, SO₄^2? and total solids loads by 58%, 62%, 95%, 66% and 85%, respectively. The rationalized process also results in reduction of water consumption and discharge and energy by 37%, 37% and 38%, respectively. CONCLUSION: The rationalized process utilizes resources efficiently with reduced environmental impact without compromising leather qualities and can be seen as being eco‐efficient compared to the conventional leather process. Copyright © 2007 Society of Chemical Industry     

Colored cool colorants based on rare earth metal ions

Colored pigments with high near infrared reflectance and not based on toxic metal ions like cadmium, lead and cobalt are being sought as cool colorants. Through appropriate doping two pigments Ce-Pr-Mo and Ce-Pr-Fe have been developed to offer a reddish brown and reddish orange color, respectively. These pigments have been characterized and found to be highly crystalline with an average size of 300 nm. A shift in band gap energy from 2.21 to 2.18 eV has been observed when Li₂CO₃ was used as a mineralizer. Scanning electron microscope-energy dispersive X-ray analysis (SEM-EDAX) measurement indicate a uniform grind shape and distribution of metal ion, with over 65% reflectance in the NIR region, these pigments can well serve as cool colorants.     

铁鞣新方法(续)

将铁鞣与铬鞣进行了优化结合,这种鞣制技术不仅可以加工出质量上乘的皮革制品,同时又可以满足废液中铬与铁的含量低于100mg/kg的标准。此工艺制造的皮革可耐沸水试验,阐述了其鞣制技术和鞣制机理。对铁鞣法在加工山羊绒面革和绵羊全粒面服装革中出现的问题进行了研究。用扫描电镜对鞣革的结构特性进行了研究,对成革的物理机械性能及染色特性也做了分析和阐述。     

A wideband radar for high-resolution mapping of near-surface internal layers in glacial ice

Snow accumulation rate is an important parameter in determining the mass balance of polar ice sheets. Accumulation rate is currently determined by analyzing ice cores and snow pits. Inadequate sampling of the spatial variations in the ice sheet accumulation has resulted in accumulation rate uncertainties as large as 24%. We designed and developed a 600-900-MHz airborne radar system for high-resolution mapping of the near-surface internal layers for estimating the accumulation rate of polar ice sheets. Our radar system can provide improved spatial and temporal coverage by mapping a continuous profile of the isochronous layers in the ice sheet. During the 2002 field season in Greenland, we successfully mapped the near-surface layers to a depth of 200 m in the dry-snow zone, 120 m in the percolation zone, and 20 m in the melt zone. We determined the water equivalent accumulation rate at the NASA-U/spl I.bar/1 site to be 34.9/spl plusmn/5.1 cm/year from 1964 to 1992. This is in close agreement with the ice-core derived accumulation rate of 34.6 cm/year for the same period.     

Solar dryer for leather and a comparative study on the characteristics of open-, solar- and electrical-dried leathers

Solar energy is a cost effective, eco-friendly and pollution-free concept. It can prove to be a major energy saver for tannery application such as hot water production and leather drying. For achieving leather of good quality, controlled processing techniques are to be adopted. In order to achieve faster drying rates for higher productivity and economy in drying, a forced type of solar dryer set-up with an electrical back-up was developed. This paper illustrates the data on three different drying processes namely the open, solar and electrical drying. The data includes physical properties, surface texture, thickness variation and area reduction of leather. By controlling the drying temperature and relative humidity in solar drying, it is possible to achieve physical characteristics closer to open drying for higher productivity and cost-effective results.     

Ga2Te3 and Ga3Te2 clusters: understanding their structures, vibrational and energetic features using DFT and ab initio methods

A study of the Ga₂Te₃ and Ga₃Te₂ clusters is presented using three different levels of theory, namely; DFT, MP2 and CCSD(T). We used the 6-311G(d) basis set for gallium atom and the LANL2DZdp ECP basis set for tellurium atom. The results include geometrical parameters, vibrational frequencies and energies of the low-lying structures. We report the vertical electron detachment energy (VEDE) and adiabatic electron detachment energy (AEDE) for the anionic species. The neutral Ga₂Te₃ cluster adopts a V-shape configuration with ¹A₁ ground state whilst its anion is kite shaped with ²A₁ ground state. On the other hand, the Ga₃Te₂ and Ga₃Te₂ ˉ species prefer a three dimensional 6-D_3h geometry with ²A₂^″ and ¹A₁^′ electronic states, respectively. The adiabatic electron affinity (AEA) for Ga₂Te₃ is 2.78 eV and that of Ga₃Te₂ is 2.86 eV at the CCSD(T)//B3LYP level. We analyse, discuss and compare the findings of our research with the analogous gallium chalcogenides.     

铁鞣新方法

将铁鞣与铬鞣进行了优化结合,这种鞣制技术不仅可以加工出质量上呈的皮革制品,同时又可以满足废液中铬与铁的含量低于100mg/kg的标准。此工艺制造的皮革可耐沸水试验,阐述了其鞣制技术和鞣制机理。对铁鞣法在加工山羊绒面革和绵羊全粒面服装革中出现的问题进行了研究。用扫描电镜对鞣革的结构特性进行了研究,对成革的物理机械性能及染色特性也做了分析和阐述。