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111.
Peanut skin, when treated with formaldehyde to polymerize tannins, is a highly efficient substrate for removal of many heavy metal ions from aqueous waste solutions. The ions Ag1+, Cd2+, Cr6+, Cu2+, Hg2+, Ni2+, Pb2+, Zn2+, as well as Ca2+ and Mg2+, were contacted with formaldehyde-treated peanut skin. Quantitative removal could be achieved with Ag1+, Cd2+, Cu2+, Hg2+, Pb2+, and Zn2+. Capacity of the substrate for ions was promising for Pb2+ (2.1 meq/g substrate), Cu2+ (3.0 meq/g), and Cd2+ (1.3 meq/g). Sorption from a solution containing Cd2+, Cu2+, Hg2+, Ni2+, Pb2+, Zn2+, on a packed column of formaldehyde-treated peanut skin indicated that Hg2+, Pb2+, and Cu2+ were rapidly and completely bound to the packing, while Cd2+, Ni2+, and Zn2+ were poorly bound until the preferred ions had been removed from solution. 相似文献
112.
Potential catalysts for the partial oxidation of methane to methanol have been synthesised and tested in high pressure annular reactors. Uranium oxide and molybdenum oxide catalysts and iron sodalite catalyst have been tested under the conditions reported in the patents and under conditions which allow comparison with reactions carried out in the gas phase. None of the catalysts tested showed an improvement on the gas phase results. It was found that the oxidative nature of the metal oxide catalysts is an inherent feature which reduces the selectivity to methanol. 相似文献
113.
Control and operability characteristics of an adiabatic spouted bed reactor with a first order reaction are investigated. The reactor transient response to changing operating conditions is analyzed and the generic control problems are formulated. Reduced-order state space models suitable for process control studies are constructed by utilizing the methods of orthogonal collocation and singular perturbation.Based on modern control and estimation techniques a hierarchy of different control systems is systematically generated. The assessment of alternative d 相似文献
114.
The white pine cone beetle, Conophthorus coniperda, exhibited dose and enantiospecific responses to -pinene in stands of mature eastern white pine, Pinus strobus, in a seed orchard near Murphy, North Carolina, USA. (–)--Pinene significantly increased catches of cone beetles to traps baited with (± )-trans-pityol. (+)--Pinene did not increase catches of beetles to pityol-baited traps and interrupted the response of beetles to traps baited with (±)-trans-pityol and (–)--pinene. Maximal attraction of cone beetles to pityol-baited traps was obtained with lures releasing (–)--pinene at a rate of 103 mg/day at 23°C. Lures releasing (–)--pinene at rates lower or higher than 103 mg/day resulted in reduced catches to traps baited with (±)-trans-pityol. The sex ratio in all catches was heavily male biased. Attraction of the clerid predator, Thanasimus dubius, to traps baited with (±)-trans-pityol increased significantly with the presence of -pinene, irrespective of enantiomeric composition. Maximal attraction of T. dubius to pityol-baited traps occurred with devices releasing (–)--pinene at the highest rate tested, 579 mg/d at 23°C, a sub optimal rate for cone beetles. 相似文献
115.
F.H. Scholes S.A. Furman A.E. Hughes T. Nikpour N. Wright P.R. Curtis C.M. Macrae S. Intem A.J. Hill 《Progress in Organic Coatings》2006
Leaching and characterisation studies have been undertaken on two chromate-inhibited epoxy polyamide primers. Leaching was carried out in 5% (w/v) NaCl solutions at different pH values (1, 3, 5 and 7) and the amount of Cr released into solution was monitored over time. Cr release was initially high, but as the immersion time increased the leaching from the primers slowed. Prior to and after immersion, the primers were characterised by a number of techniques including electron microprobe analysis, X-ray microdiffraction, Raman spectroscopy, and positron annihilation lifetime spectroscopy. The unexposed primers were found to contain the inorganic phases SrCrO4, BaSO4 and TiO2 (anatase or rutile). Upon immersion, water uptake by the primers was observed, together with a decrease in the amount of SrCrO4 in the primers. These studies provide insights into the mechanism of chromate leaching from inhibited primers. 相似文献
116.
Separation of sterol esters from wax esters in the lipids of vernix caseosa and adult human skin surface was accomplished
by column chromatography on MgO. The fatty acids of the sterol esters and wax esters of both samples were separated into saturates
and monoenes, and examined in detail by gas liquid chromatography (GLC). The saturated fatty acids of the wax esters of vernix
caseosa and of adult human skin surface were remarkably similar. They ranged in chain length from at least C11 to C30, six skeletal types being present: straight even, straight odd, iso, anteiso, other monomethyl branched and dimethyl branched.
A large number of patterns of monoenes were observed, each pattern consisting of desaturation of a specific chain at Δ6 or
Δ9 plus its extension or degradation products. The mole per cent of the total Δ6 and Δ9 patterns of wax ester fatty acid monoenes
of vernix caseosa were 87% and 12%, respectively, and 98% and 1%, respectively, for adult human skin surface lipid. The sterol
ester fatty acids of vernix caseosa were much different from those of adult human skin surface: vernix caseosa saturates were
largely branched and of lengths greater than C18, whereas the saturates of adult human surface lipid resembled the wax ester fatty acids. Of the vernix caseosa monoene patterns,
the mole per cent was 30% Δ6 and 70% Δ9, whereas of the adult human skin surface sterol ester fatty acids 89% were Δ6 and
11% Δ9. Chain extension was particularly pronounced in the sterol ester fatty acid monoenes of vernix caseosa amounting to
7–8 C2 units in some cases. The fatty acids of the sterol esters of both vernix caseosa and adult human skin surface appear to be
derived from the sebaceous gland and from the keratinizing epidermis, but those of the wax esters are from the sebaceous glands
only. 相似文献
117.
The loss in activity of Pt-promoted and unpromoted 25 wt% Co–Al2O3 catalysts has been compared under identical conditions except for adjustment of the space velocity to give the same initial CO-conversion. Both catalysts underwent a 200 h period of rapid, initial decline in CO conversion and then a slower, linear decline during the next 1000 h. Pt-promotion did not alter the cobalt dispersion (or average particle size) from that of the unpromoted catalyst but did increase the amount of cobalt that was reduced. When compared not by time-on-stream, but by the moles of Co converted per unit weight of catalyst, both the Pt-promoted and unpromoted catalysts decline in activity at the same rate. 相似文献
118.
I. S. Purwaningsih I. S. Purwaningsih G. A. Hill J. V. Headley 《Chemical Engineering Communications》2002,189(2):268-283
The design of bioremediation reactors for destroying toxic organic compounds requires an understanding of the mass transfer behavior of these chemicals into and out of the vessel. The dissolution rates and air stripping of three aromatic hydrocarbon particles were measured and theoretically modeled in a well mixed bioreactor with varying agitation speed, temperature, slurry concentration and air flow rate. It was confirmed that the dissolution rate of particles is influenced by both solubility and molecular structure. The volumetric mass transfer coeffcient of dissolution increased with higher agitation speeds and higher temperatures. This studyindicates that stripping from the liquid phase to the gas phase was controlled by physical properties: that is high Henry's law constant and relatively low solubility. The mechanistic model successfully predicted the disappearance of particles and the dissolved concentration of aromatic compounds due to simultaneous dissolution and air stripping. 相似文献
119.
The incorporation of inorganic phosphate (as NaH2PO4) into the phospholipids of sheep red blood cells was studied in vitro in blood samples from five highpotassium (HK) and five
low-potassium (LK) sheep. The erythrocytes from HK sheep incorporated more activity in 4 hr than those from the LK sheep.
However no activity was incorporated into the major phospholipids of the cells (phosphatidyl ethanolamine, phosphatidyl serine,
and sphingomyelin) of either group. The phosphatidic acid fraction was labeled in both groups and to a significantly greater
extent in the HK samples. However the highest activity in the phospholipid of sheep red-cells was located in three unknown
compounds not previously detected. Their specific activities were the same in the HK and the LK samples although they were
present in slightly larger amounts in the HK samples. In general, incorporation was at a rather low level, and from stoichiometric
considerations it was concluded that the metabolism in the red-cell phospholipids could not be directly involved in the active
transport of ions across the cell membrane. This work also confirmed a previous report that no quantitative differences exist
among the major phospholipid classes in the two types of cells. 相似文献
120.
Gary C. Stevens 《应用聚合物科学杂志》1981,26(12):4259-4278
An infrared absorption spectroscopy study of the curing kinetics of a low (1.12) epoxide/hydroxyl-group ratio bisphenol A epoxy resin—phthalic anhydride system is reported. A full infrared peak assignment to molecular vibrational modes is given for the range 400 to 4000 cm?1, and the optical density behavior of all peaks during reaction is discussed in detail. Proposed rival reaction mechanisms are considered and their respective kinetic behavior discussed. The reaction was found to follow consecutive-step addition esterification and simultaneous addition etherification, and epoxide—hydroxyl group and carboxylic acid dimer hydrogen bonding was found to occur. The reaction behavior supports a proposed hydroxyl group-limited inhomogeneous bulk reaction mechanism of a colloid type. 相似文献