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- Author or Editor: M. Ashraf x
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Studies on thermal characterization of lignin
Substituted phenol formaldehyde resin as wood adhesives
Abstract
Thermal properties of control phenol formaldehyde (cpf) adhesive and lignin substituted phenol formaldehyde (lpf) adhesives have been investigated in detail. The effect of varying lignin mass percent of phenol and source of lignin like bagasse, eucalyptus bark, coconut coirpith and coffee bean shell on the thermal stability have been studied using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). 50 mass% of lignin loading in cpf adhesive shows better bond strength, whereas lignin incorporation up to 25 mass% yields a resin of thermal stability comparable to cpf. Loading of lignin in cpf delays the first thermal transition event. The mass loss in this event was found to increase with increasing lignin content. Lignin source has significant effect on the thermal stability of lpf resins. Rate of curing is enhanced by incorporation of lignin into cpf.
Salinity reduces plant growth and yield by affecting morphological and physiological processes. To alleviate the harmful effects of salt stress various approaches involving plant hormones are used. In this study several parameters involving the measurement of cell membrane injury were used to observe whether stress tolerance could be enhanced in Chinese cabbage (B. oleracea capitata L. Chinensis group) by soaking the seeds for 10 h in distilled water (control), or in 100, 150 or 200 mg l−1 gibberellic acid (GA3). The NaCl concentrations were 0 (control), 50, 100 and 150 mM. Seed treated with GA3 showed increased water uptake and decreased electrolyte leakage as compared to that of distilled water-primed seeds even 24 h after soaking under control conditions. Seed priming with GA3 increased the final germination and the germination rate (1/t50, where t50 is the time to 50% germination) under salt stress conditions. Seed priming also alleviated the harmful effect of salt stress on cabbage in terms of fresh and dry weights. Leaf area was higher in plants raised from seeds primed with the higher GA3 concentrations as compared with those raised from seeds treated with distilled water under control conditions (without NaCl) or at 50 mM NaCl stress. The chlorophyll content increased with the NaCl concentration, especially in plants grown from seeds primed with GA3. Plants grown from GA3-primed seeds also suffered lower cellular injury both under control conditions and under NaCl stress.
A pot culture experiment was conducted to study the influence of NH 4 Cl (AnalaR grade or commercial fertilizer) on soil pH and on the growth, yield and nutrient uptake of cotton (cv. NIAB-Karishma) grown in alkaline soil. The experiment was carried out in a net-house under natural conditions. The soil used was clayey loam with pH 8.61, and ammonium chloride either from commercial fertilizer or of AnalaR grade (both containing up to 25% N) was applied in three split doses, after germination (10 days), at the vegetative stage (40 days) and at the flowering stage (80 days) @ 6, 12 and 18 kg ha −1 . The application of NH 4 Cl decreased the soil pH and increased the plant height and cotton yield plant −1 . Plants treated with NH 4 Cl AnalaR grade produced higher yields as compared to NH 4 Cl commercial fertilizer. The uptake of micronutrients such as Fe, Cu, Zn and B was enhanced by NH 4 Cl application in both the stem and leaves of cotton. However, AnalaR grade NH 4 Cl proved more effective than NH 4 Cl commercial fertilizer in all cases.
Summary
Many studies have shown that water hyacinth (Eichhornia crassipes) roots can be used to accumulate high concentrations of organic as well as inorganic pollutants. They are currently used to remediate aquatic environments and aqueous solutions. In the present study, sorption of uranium from aqueous solutions by using dried roots of water hyacinth has been investigated. The sorption of uranium was examined as a function of initial concentration, pH, weight of roots and contact time. Five different concentrations 20, 40, 60, 80, and 100 μg . ml-1 were used. Sorption proves to be very rapid and depend on pH, weight of roots and concentration of uranium. Maximum sorption capacity of water hyacinth roots was 64,000 U6+ μg/g. The sorption of uranium by water hyacinth roots follows a Langmuir isotherm.
Abstract
Study of the extraction of W(VI) ions using supported liquid membrane has been carried out. The carrier used for this metal ion transport, is tri-n-octylamine (TOA) dissolved in xylene. The liquid was supported in microporous polypropylene film. The parameters studied are effect of carrier concentration in the membrane, acid concentrations in the feed solution, concentration of stripping agent on transport of W(VI) ions and of temperature on the transport properties of these supported liquid membranes. The optimum conditions of transport for these metal ions determined are, TOA concentration, 0.66 mol·dm–3 (TOA); HF concentration in the feed solution, 0.01 mol·dm–3 and concentration of NaOH used as stripping agent 2.5 mol·dm–3. The maximum flux and permeability determined under optimum conditions are 3.06·10–5 mol·m–2·s–1 and 8.44·10–11 mol· ·m2·s–1 at 25±2°C and 4.21·10–5 mol·m–2·s–1 and 11.55·10–11 mol·m2·s–1 at 65°C, respectively. The diffusion coefficients for the metal ion carrier complex in the membrane have also been determined. Under the optimum conditions the value for the metal ion carrier complex is 0.14·10–11 mol·m2·s–1. Mechanism of transport and the complex formed in the presence of HF have also been discussed. The transport process involves two carrier amine molecules and two protons.
Abstract
The nuclear properties of99mTc radionuclide are ideal for organ imaging. Study of the technetium transport across supported liquid membranes has been performed to get data for its separation from other elements. Tri-n-octylamine diluted in xylene was used to constitute the liquid membranes, supported in polypropylene microporous films. Stripping on the product solution side was performed with dilute NaOH solutions. The effect of sulphuric acid, nitric acid and hydrochloric acid in the feed on transport of99mTc as TcO 4 – ions has been studied. The permeability of the given ions determined from kinetic activity data has been found to be in the order of PH2SO4>PHCl>PHNO3. The flux values have been calculated based on this permeability data. The increase in carrier concentration has shown an increase in flux and permeability values to a given optimum concentration. The increase in temperature has been found to reduce the transport of Tc ions. The optimum conditions for transport of99mTc for the given acid concentration have been determined. Mechanism of Tc ion transport has also been provided based on chemical reactions involved at the membrane interfaces and uptake of Tc ions by the membrane. MoO 4 2– ions do not permeate through membrane under optimum conditions of transport for TcO 4 2– ions from H2SO4 solution.
Abstract
Extraction behaviour of the chelates of group VB–VIIB and VIII elements using 1-(2-pyridylazo)-2-naphthol (PAN) has been studied as a function of pH. Studies have been made to back-extract the metal ions from the organic phase into the aqueous solution containing the optimum concentration of KCN and HClO4 and buffers of appropriate pH. The masking agents such as citrate, cyanide, thiosulphate, fluoride and thiourea were used to achieve more specific separations. The studies indicate the potentiality of PAN as a useful solvent extracting reagent in devising group chemical separation procedures for activation analysis.
Abstract
Water hyacinth (Eichhornia crassipes) is known to accumulate elements from rivers and a good tool for water monitoring. To test the usefulness of such an aquatic plant as a bioindicator, we have determined the levels of Na, Ca, Cr, Fe, Co, Zn, As, Rb, Zr, Sb, Cs, La, Ce, Nd, Sm, Eu, Tb, Yb, Hf, Ta, Th, and U in water hyacinth around industrial facilities and along the studied area by instrumental neutron activation analysis. The concentrations of Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, and Pb were determined in upstream river water and effluent factories. Contamination factor, and pollution load index was calculated. The results show that higher concentrations as well as bioaccumulation factors of these elements were observed in water hyacinth samples around the industrial facilities. On the other hand a decrease in calcium concentration was observed as a result of the thermal pollution of Nile river water. The pollution load index for the studied area was estimated to be 4.2.
Abstract
Potassium iron(III)hexacyanoferrate(II) supported on poly metylmethacrylate has been synthesized and investigated for the strontium(II) removal from HNO3 and HCl solutions. The ion exchange material characterized by different techniques and found to be stable in 1.0–4.0 M HNO3 solutions, has been used to elaborate different parameters related to ion exchange and sorption processes involved. The data collected suggested its use to undertake removal of Sr(II) from more acidic active waste solutions. Thus the material synthesized had been adjudged to present better chances of application for Sr(II) removal as compared to other such materials.
