Sulfides increase with temperature

Figure 4 shows the variation with temperature of the equilibrium mole fractions for a few feed gas compositions. The curves in Sections A and B represent the equilibrium state for mixtures initially composed of 3.4% hydrogen sulfide and 5.9% carbon monoxide in the absence and presence of 15% water vapor, respectively. Helium made up the balance in each gas mixture. Species present at less than the micromolar fraction level were ignored. To conduct the same computer program on each gas mixture, an extremely low concentration of water vapor (4.5 X 10"5% ) was assumed in cases A and C of Figure 4. Sections C and D in this figure illustrate the effect of 7% water vapor for a sulfur dioxide-carbon monoxide mixture at the low concentration level. As expected, both hydrogen sulfide and hydrogen were present with the water vapor, and the concentrations of hydrogen sulfide and carbonyl sulfide increased with temperature up to 700 °C.

In finely divided form, hafnium is pyrophoric, igniting in air spontaneously. However, bulk metal reacts slowly in oxygen or air above 400°C. The rate of oxidation increases with temperature. The product is hafnium dioxide, Hf02. It combines with nitrogen, carbon, boron, sulfur and silicon at very high temperatures to form hafnium nitride HfN, hafnium boride HfB, hafnium sulfide HfSi2, respectively. Nitride formation occurs at 900°C. 

Given the inherently competitive nature of emission and photocurrent, it should not be surprising that photocurrent was generally observed to increase with temperature. Figure 2 is a photocurrent-temperature profile obtained at +0.7 V vs. Ag (PRE) in sulfide electrolyte the light intensity and sulfide concentration employed ensured that photocurrents were limited by excitation rate and not by mass transport, i.e., photocurrents... 

A number of researchers have studied the effects of treating asphalts with sulfur. The solubility of sulfur in asphalt increases with temperature but is quite low at temperatures below 149°C (the maximum safe temperature for practical mix handling operations to avoid hydrogen sulfide formation). Attempts have been made to form homogeneous dispersions of sulfur in asphalt by mixing, emulsification, and pumping action. The... 

Pa s as compared to about 93 Pa s for untreated sulfur [4]. The dependence of the viscosity on the H2S content of the melt at temperatures of between 170 and 300 °C has been determined [72]. The H2S reacts with sulfur in a reversible reaction to polysulfanes H2S which have been detected by infrared [73] and NMR [74] spectroscopy in such melts. For this reason the solubility of H2S in liquid sulfur increases with temperature up to 385 °C [72, 73, 75] while usually gases are less soluble if the temperature is increased. Polysulfanes therefore lower the viscosity of liquid sulfur as efficiently as hydrogen sulfide does [4]. The freezing point of sulfur is also lowered by H2S... 

Double-Bed Catalysts. Because the temperature of the colder section in the nonisothermal catalyst bed could not be readily controlled, an apparatus was constructed that contained two separate furnaces, each containing 20 g of Surinam red mud. The temperature of the first bed was varied to determine the optimum operating conditions with an inlet gas of 0.57% sulfur dioxide, 0.89% carbon monoxide, and 3% water vapor in helium. The exhaust gas analyses from the first furnace are shown in Figure 6. These results indicate that the hydrogen sulfide and sulfur dioxide removal efficiency increases with temperature up to about 400 °C. Beyond this temperature there is little improvement. 

In general, it was found that the selectivity of the reaction towards hydrogen sulfide increases with increasing reaction temperatures and water concentrations. The relationship between hydrogen sulfide selectivity and the amount of water in the system is shown in Figure 5. 

Sulfur exchange between sulfided CoMoOx/AbOa catalyst and gas phase radioactivity of H2S has been studied by Qian et al. (1997) at high (1-5 MPa) pressure in a pressurised fixed bed flow reactor. The H2S sulfided catalyst was treated with H2/H2 S pulses (0.1% of H2 S). The differences in the flow rates did not affect practically the measured Sexc/Scat ratios. These increased with temperature from 15 to 44% of the total sulfur in the 503-673 K region. 

In petroleum processing, sulfur compounds originate with crude oils and include polysulfides, hydrogen sulfide, mercaptans, aliphatic sulfides, disulfides, and thiophenes [32]. Corrosion by these sulfur compounds occurs between 260 C (500°F) and 538°C (1000°F). The corrosion rate increases with temperature to 454°C (850°F) and then decreases. Corrosion rate curves as a function of temperature for various steels with different chromium levels for a specific amount of sulfur in the processing streams are called McConomy curves [33] or modified McConomy curves [32], If the sulfur content in the system is different, a corrosion multiplier is then applied for varying stdfur amounts. In addition, Copper-Gormen curves have been developed for various alloys that predict corrosion rate with respect to temperature for a range of H2S composition [34]. 

Pattabi et al. reported obtaining self-standing flexible nanocomposite films based on PVP capped CdS NPs embedded in a PVA matrix with photoluminescence properties (Pattabi et al. 2007) and electrical conductivity (Amma et al. 2014). CdS NPs were obtained from cadmium nitrate and hydrogen sulfide by a nonaqueous method and then were dispersed in a PVA matrix. With an average particle size of approximately 3-5 nm, they contributed to the obtaining of photoluminescence emission spectra with two peaks, at 502 and 636 mn (Pattabi et al. 2007). The electrical conductivity of the (PVP-CdS) PVA films was seen to increase with temperature (Amma et al. 2014). 

Cotton yam is dyed in package machines and the dye exhausted by increasing the temperature and adding salt. The dye must be completely dissolved when preparing the dyebaths to avoid contamination with undissolved dye in the yam package. The increased avaUabUity of the prereduced Hquid dyes and the improved quaHty of sodium sulfide have reduced this problem. Incorrectly dissolved dye was previously the cause of most faulty dyeings. 

Thiepin, as a seven-membered conjugated system with sulfur as heteroatom, is a member of the 8 7t-electron heteroannulenes which are antiaroinatic according to Hiickel s rule. In contrast to oxepin, thiepin is not stable at room temperature and no valence isomerism with an arene sulfide has been observed. Stable thiepins are obtained only when two bulky substituents, e.g. /ert-butyl, are introduced into positions 2 and 7. In benzothiepins the annellation effect of the aromatic rings contributes decisively to the stability of these compounds stability increases with an increasing number of fused benzene rings. 

This mechanism can explain the formation of Te-bearing Au-Ag veins in which sulfides are poor in amounts. The deposition of sulfides is generally difficult by this mechanism because solubilities of sulfides generally increase with decreasing of pH. However, if temperature of mixed fluid decreases considerably by this mechanism, the deposition of sulfides may be possible, because solubilities of sulfides due to chloro complexes decrease with decreasing of temperature. 

The ratio ki km =5 x 10-4 at 300K increases with increasing temperature, since E >Em. The rate constants of the sulfide reaction with hydroperoxide are collected in Table 17.4. 

Geochemical results show that the degree of sulfide oxidation is dependent upon the temperature of the piles and the rock sulfide content. In the basal drain effluent of the Type III pile, a decrease in pH was observed throughout the summer as the pile warmed. Sulfate concentrations also increase with the warming of the pile and decrease as the pile cools. The decrease in pH is correlated with an increase in the concentrations of dissolved metals. 

The temperature dependency of the sulfate reduction rate for single sulfate-reducing bacteria is high, corresponding to a temperature coefficient, a, of about 1.13, i.e., a change in the rate with a factor Q10 = 3.4 per 10°C of temperature increase. Because diffusion of substrate into biofilms or sediments is typically limiting sulfide formation, the temperature coefficient is reduced to about... 

Measurements of the optical properties in this range of wavelengths can probe the fundamental electronic transitions in these nanostructures. Some of the aforementioned effects have in fact been experimentally revealed in this series of experiments (90). As mentioned above, the IF nanoparticles in this study were prepared by a careful sulfidization of oxide nanoparticles. Briefly, the reaction starts on the surface of the oxide nanoparticle and proceeds inward, and hence the number of closed (fullerene-like) sulfide layers can be controlled quite accurately during the reaction. Also, the deeper the sulfide layer in the nanoparticle, the smaller is its radius and the larger is the strain in the nanostructure. Once available in sufficient quantities, the absorption spectra of thin films of the fullerene-like particles and nanotubes were measured at various temperatures (4-300 K). The excitonic nature of the absorption of the nanoparticles was established, which is a manifestation of the semiconducting nature of the material. Furthermore, a clear red shift in the ex-citon energy, which increased with the number of sulfide layers of the nanoparticles, was also observed (see Fig. 21). The temperature dependence of the exciton... 

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