The comparison of phenol sorption on phenyltrimethylammonium (PTMA)- and benzyltrimethylammonium (BTMA)-bentonite shows a clear difference as far as phenol sorption isotherms are concerned. For PTMA-bentonite the sorption isotherm is of a straight-line character which results from simple partitioning of phenol between the aqueous and organic phases sorbed on the bentonite surface. For BTMA-bentonite the isotherm has a convex shape, characteristic of physicochemical sorption.For the first time a three-parametric model, including the dissociation constant of phenol pKa, distribution constant of phenol Kdphen and phenolate anion Kdphen− between the aqueous phase and the bentonite phases is used for the evaluation of phenol sorption on organoclays with pH change. The model shows that the values of Kdphen are higher than those of Kdphen− for all investigated initial phenol concentrations.The inspection of the FTIR spectrum of BTMA-bentonite loaded with phenol in the regions 1300–1600 and 1620–1680 cm−1 shows the features of π–π electron interaction between the benzene rings of phenol and the BTMA cation together with the phenol–water hydrogen bond strengthened by this interaction. 相似文献
Reaction-rate parameters are given for the detailed chemistry of gas-phase hydrogen combustion, involving 21 reversible elementary steps. It is indicated that, when attention is restricted to specific combustion processes and particular conditions of interest, fewer elementary steps are needed. In particular, for calculating autoignition times over a wide range of pressures for temperatures between about 1000 and 2000 K, five irreversible elementary steps suffice, yielding a remarkable reduction in complexity. It is explained that, from a mathematical viewpoint, in terms of global reaction-kinetic mechanisms, the hydrogen–oxygen system in principle comprises only six overall steps. Rational reduced chemical mechanisms for hydrogen combustion therefore necessarily must have fewer than six overall steps. For autoignition over the range of conditions specified above, ignition times can be determined accurately by considering, in addition to an elementary initiation step and an elementary termination step, at most three overall steps for reaction intermediaries, which reduce to two for very fuel-lean conditions and to one for stoichiometric or fuel-rich conditions. The resulting reductions can simplify computations that need to be performed in risk analyses for hydrogen storage and utilization. 相似文献
This on-site survey study was performed to determine the concentrations and emissions of aerial contaminants in the different
types of swine houses in Korea and then to present beneficial information available for Korean pig producers to manage optimal
air quality in swine house. The swine houses investigated in this research were selected based on three criteria; manure removal
system, ventilation mode and growth stage of swine. Mean concentrations of aerial pollutants in swine houses were 8 ppm for
ammonia, 300 ppb for hydrogen sulfide, 2 mg m−3 for total dust, 0.6 mg m−3 for respirable dust, 4 log(cfu m−3) for total airborne bacteria and 3 log(cfu m−3) for total airborne fungi, respectively. Mean emissions based on pig (liveweight; 75 kg) and area (m2) were 250 and 340 mg h−1 for ammonia, 40 and 50 mg h−1 for hydrogen sulfide, 40 and 50 mg h−1 for total dust, 10 and 15 mg h−1 for respirable dust, 1.0 and 1.3 log(cfu) h−1 for total airborne bacteria and 0.7 and 1.0 log(cfu) h−1 for total airborne fungi, respectively. In general concentrations and emissions of gases were relatively higher in the swine
houses managed with deep-pit manure system with slats and mechanical ventilation mode than the different swine housing types
whereas those of particulates and bioaerosol were highest in the naturally ventilated swine houses with deep-litter bed system. 相似文献
This paper is devoted to the numerical and experimental investigation of hydrogen self-ignition as a result of the formation of a primary shock wave in front of a cold expanding hydrogen gas jet. Temperature increase, as a result of this shock wave, leads to the ignition of the hydrogen–air mixture formed on the contact surface. The required condition for hydrogen self-ignition is to maintain the high temperature in the area for a time long enough for hydrogen and air to mix and inflammation to take place.
Calculations of the self-ignition of a hydrogen jet are based on a physicochemical model involving the gas-dynamic transport of a viscous gas, the kinetics of hydrogen oxidation, the multi-component diffusion, and the heat exchange. We found that the reservoir pressure range, when a shock wave formed in the air during depressurization, has sufficient intensity to produce self-ignition of the hydrogen–air mixture formed at the front of a jet of compressed hydrogen. We present an analysis of the initial conditions (the hydrogen pressure inside the vessel, the temperature of the compressed hydrogen and the surrounding air, and the diameter of the hole through which the jet was emitted), which leads to combustion. 相似文献