The acidity function, H_o, of Hammett and Deyrup for a neutral basic indicator has been shown to correlate with the specific reaction rate constant, k, for a number of acid-catalyzed reactions with an A-1 mechanism. Correlations of this type have been reported for many of the strong mineral acids and certain weak acids over a wide temperature range and in aqueous, nonaqueous, or mixed solvent systems. The acid-catalyzed depolymerization of trioxane is one specific reaction which has shown relationships between rate constants and H_o in aqueous media and has been studied in the present investigation for the purpose of providing a suitable background for a study of acidity in non-aqueous media. The approach was to study the rate of depolymerization in solutions of hydrochloric acid at several temperatures and in mixtures of hydrochloric acid and various chloride salts at one particular temperature. The reaction mixtures of these solutions were prepared by mixing and diluting stock solutions of hydrochloric and trioxane (with weighed amounts of salt for salt mixtures) with water. After removal of the dissolved air, the dilatometric technique was used to determine the rate of reaction by the Guggenheim method. A set of readings, r_t, taken at times, t, and a set of readings, r_t+G, taken after allowing a fixed amount of time, G, to elapse after the first set, are related by the equation ln (r_t+G - r<sub>t</sub = - kt + constant and the slope of a plot of ln (r_t+G - r_t) against t gave the specific reaction rate constant, k, when multiplied by 2.303. The results obtained in this investigation ruay be summarized by the following statements: 1. The specific reaction rate constants (sec.⁻¹) for the decomposition of trioxane in aqueous solutions of hydrochloric acid over the temperature range of 25-60° C. can be summarized by the equation k = 3.6 x 10¹³ (h_o)^1.17_e - 28,600/RT where h_o is the value of the acidity function for hydrochloric acid. 2. The addition of a chloride salt to a reaction mixture results in an increase in the rate of reaction by an amount which is roughly in inverse proportion to the size of the cation of the salt. More exactly, the specific reaction rate constants (min⁻¹) for the decomposition of trioxane in aqueous solutions of hydrochloric acid and lithium chloride at 40° C. can be summarized by the equation log k = -1.16 H_o + 0.326 C_S 4.603 where H_o refers to the measured value of the acidity function for hydrochloric acid and C_S refers to the LiCl concentration. / Master of Science

Leaching is the most widely used process for extraction of nickel metal from lateritic ores. In this study, nickel extraction from Manisa-G&ouml / rdes region laterites by hydrochloric acid leaching is aimed. The mineralogical analysis of sample showed that hematite, goethite, dolomite, quartz and smectite are the main minerals in the ore. Attrition scrubbing, cycloning and magnetic separation with permroll were used as preconcentration processes but results were unsatisfactory. HCl leaching experiments were conducted both at room temperature and at elevated temperatures. The effects of various parameters such as leaching duration, particle size, concentration of HCl, pulp density, Cl- concentration and temperature on nickel recovery were examined. The results showed that under the optimised leaching conditions (particle size: 100 % -1 mm, HCl concentration: 3 N, leaching duration: 3 hours, leaching temperature: 100 oC, pulp density: 1/30 solid to liquid ratio by volume) it was possible to extract 87.26 % of nickel in the ore.

Given the volatile, generally high price of crude oil, as well as environmental concerns associated with its use as a fuel, development of alternative energy sources is currently of considerable interest. Lignocellulose-derived energy has the potential to supplant traditional fossil fuels in the future because of its economic and environmental advantages. Lignocellulosic biomass is abundant and renewable. Lignocellulose is primarily composed of cellulose, hemicellulose and lignin, which can be converted by acid hydrolysis to simple sugars used in fermentation to produce biofuels. In this study, hemicellulose was hydrolyzed with different concentrations of hydrochloric acid at different temperatures. The resulting components were analyzed by high performance liquid chromatography (HPLC). The hydrolysis of cellulose was similarly characterized, with two additional parameters, the degree of polymerization (DP) and the crystallinity index (CrI), which were analyzed by Ubbelohde viscometer and X-ray diffraction respectively. The experimental results indicate that the hydrolysis rate of hemicellulose and the generation rate of furfural and 5-hydroxymethylfurfural (HMF) increased with increasing hydrochloric acid concentrations and reaction temperatures. In the selected five monosaccharides, xylose, glucose, mannose, arabinose and galactose, xylose has the highest hydrolysis rate and the accumulation of furfural during xylose hydrolysis is also the highest. Moreover, the hydrolysis rate of cellulose and the generation rate of glucose also increased with increasing hydrochloric acid concentrations and reaction temperatures. DP and CrI, both decreased when the cellulose was treated in concentrated hydrochloric acid. The rate of change of DP increased with the concentrations of acid and the reaction temperatures. The change rate of CrI increases by increasing concentration of acid and the temperature when it is above 0℃, while the CrI index decrease sharply when the reaction temperature was kept below 0℃. Experimental results also show that the hydrolysis rate of cellulose is much lower than that of hemicellulose.

Thesis (Ph. D.)--University of Michigan, 1954. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 127-130).

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 188-192). Available also in a digital version from Dissertation Abstracts.

The main object of the present investigation has been to establish a titration curve for mohair keratin and to compare it with similar data for wool, to determine whether the differences in physical and chemical properties could be attributed in any way to the acidic and basic character of these fibres. As shown in subsequent discussion such measurements provide extremely useful information regarding the chemical structure of proteins in general, and in the technical fields involving processes such as wool scouring, carbonizing and dyeing. The study has been extended to include certain modified wools, i.e. photochemically damaged, and oxidized keratin. The most successful contribution to the titration data of wool keratin is the work of Steinhardt and Harris and subsequent authors have tended to adopt their procedures without modification. In the present study attempts have been made to obtain a clearer understanding of the fundamental processes. New techniques and analytical methods have been introduced to improve the accuracy of the measurements.

Given the volatile, generally high price of crude oil, as well as environmental concerns associated with its use as a fuel, development of alternative energy sources is currently of considerable interest. Lignocellulose-derived energy has the potential to supplant traditional fossil fuels in the future because of its economic and environmental advantages. Lignocellulosic biomass is abundant and renewable. Lignocellulose is primarily composed of cellulose, hemicellulose and lignin, which can be converted by acid hydrolysis to simple sugars used in fermentation to produce biofuels. In this study, hemicellulose was hydrolyzed with different concentrations of hydrochloric acid at different temperatures. The resulting components were analyzed by high performance liquid chromatography (HPLC). The hydrolysis of cellulose was similarly characterized, with two additional parameters, the degree of polymerization (DP) and the crystallinity index (CrI), which were analyzed by Ubbelohde viscometer and X-ray diffraction respectively. The experimental results indicate that the hydrolysis rate of hemicellulose and the generation rate of furfural and 5-hydroxymethylfurfural (HMF) increased with increasing hydrochloric acid concentrations and reaction temperatures. In the selected five monosaccharides, xylose, glucose, mannose, arabinose and galactose, xylose has the highest hydrolysis rate and the accumulation of furfural during xylose hydrolysis is also the highest. Moreover, the hydrolysis rate of cellulose and the generation rate of glucose also increased with increasing hydrochloric acid concentrations and reaction temperatures. DP and CrI, both decreased when the cellulose was treated in concentrated hydrochloric acid. The rate of change of DP increased with the concentrations of acid and the reaction temperatures. The change rate of CrI increases by increasing concentration of acid and the temperature when it is above 0℃, while the CrI index decrease sharply when the reaction temperature was kept below 0℃. Experimental results also show that the hydrolysis rate of cellulose is much lower than that of hemicellulose.

Aluminum has high resistance to attack in many environments but corrodes rapidly in most inorganic acids. The purpose of this investigation was to attempt to determine the rates and mechanism of the surface reactions for the corrosion of aluminum in hydrochloric acid vapors as a function of the vapor concentration, vapor composition, and temperature. Corrosion tests were made by suspending aluminum foil samples, five centimeters by two centimeters, by a glass thread. The samples were located in the vapor over hydrochloric acid solutions. The glass thread with the sample was attached to the center of a glass rod. One end of the rod was fixed; the other was suspended from one end of the arm of an analytical balance, permitting periodic weighing of the corroding samples without removal from the flask. The tests were conducted above hydrochloric acid solutions whose concentration varied from 2 to 32 weight percent. Ten temperature levels, from zero to 48°C, were employed so that the vapor pressures of the various acid concentrations overlapped. Weighings were made at 10 minute intervals for 200 minutes. The corrosion products were analyzed by standard x-ray diffraction techniques. The rate of weight gain was found to be a linear function with a respect to time and exponential with respect to hydrochloric acid concentration. The rate passed through a maximum at a hydrogen chloride partial pressure of 1.77 mm Hg. The decrease in rate above the maximum is due to the formation of a protective aluminum trichloride six hydrate (Al Cl₃ • 6 H₂O) film. Temperature increased the rate of weight gain at all hydrogen chloride partial pressure. Based on the analysis of the corrosion products the following mechanism is proposed for the corrosion of aluminum. For hydrogen chloride partial pressures below 1.77 mm Hg, the hydrogen chloride acts at the electrolyte for the following electrochemical reaction. 2 Al + (3 ÷ X)H₂O = Al₂O₃ • X H₂O ÷ 3 Hg For hydrogen chloride partial pressures above 1.77 mm Hg., the hydrogen chloride enters into the ration as follows 2 Al + 6 H Cl + 12 H₂O = 12 Al Cl₃ • 6H₂O + 3 Hg The energy of activation is approximately constant over the entire experimental range indicating that the same mechanism is controlling both proposed corrosion reactions. The controlling reactions would be the primary electrode reactions which are identical for both regions. / Master of Science

In this thesis, corrosion data were subjected to statistical analysis for the purpose of obtaining meaningful estimates of the specific rate of reaction and the energy of activation and obtaining a response equation for prediction of weight gain. A two-stage analysis was used in the estimation of specific rate and activation energy. First, an estimate of the reaction rate for each test run was obtained from linear regression analyses of weight gain on time. A weighted linear regression was then performed with reciprocals of estimated variances of rates as weights; the estimated order of reaction was obtained. It was shown that the mechanisms of the two possible reactions, i.e., formation of aluminum oxide or AlC13x6H20, are different. At the lower HCl partial pressures (Al2O₃ the product}, the specific rates and the activation energy were estimated in two ways: (1) the method of weighted linear regression when stoichiometric first order is assumed; (2} the method 0f weighted covariance analysis when empirical order is assumed. The data in the A1c13x6H20 portion were inconclusive. The prediction equation was obtained by an analysis of covariance; the model was that of a two-way classification with time as a covariate. Main effects ( temperature and pressure) were estimated. Finally, a response equation, tor prediction of the weight of corrosion product (A12O₃ ), was found. This equation is valid for HCl partial pressures o,QO) to 2.90 mm Mg; temperatures 17 °C to 44 °C, time of exposure $0 to 130 minutes. / Master of Science

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