Twenty-eight two-, three-, four-, and five-component amine mixtures have been evaluated as possible activators of CO2 absorption into aqueous carbonate/bicarbonate solutions. Measurements were per- formed using a pressure autoclave with a sparger at conditions close to industrial ones. On the basis of these results, a formula for a new, more efficient amine activator named INS13 was developed. The activator was tested both in a pilot plant and on an industrial scale in an ammonia plant producing 300 tons/day of ammonia. Activator INS13 was applied in a number of ammonia plants in Poland and abroad.
Results of an extensive research program, aimed at finding new, more efficient activators of carbon dioxide absorption into aqueous carbonate/bicarbonate solutions are presented. Both single amines (2-ethyl-aminoethanol, 2-isopropyl aminoethanol, piperazine, tetraethylenepentamine, N-ethyl-piperazine and glicyne) and amine mixtures have been investigated. Absorption rate measurements were conducted in a laminar-jet absorber. Reaction rate constants for the particular activators were determined. Mixtures of aliphatic amines with cyclic amines, as well as mixtures of cyclic amines with cyclic amines were found to exhibit synergetic effect. Such amine mixtures might be used as new promoters for CO2 absorption in carbonate solutions in the modified Benfield process.
In the paper the results of measurements of CO2 absorption rate in aqueous potassium carbonate solutions containing cyclohexylamine, diethanolamine, 2-methylaminoethanol and triethylenetetramine as activators have been presented. Enhnancement mass transfer factors as well as reaction rate constants have been determined. Results show that among the tested activators triethylenetetramine and 2-methyl-aminoethanol may be used (instead of diethanolamine) as new promotors in a modified BENFLIELD process.
The paper presents the technology and basic properties of three compositions of lead-free ceramics: (i) (K0.44Na0.52Li0.04)NbO3, (ii) (K0.44Na0.52Li0.04)NbO3+0.5%mol Nd2O3 and (iii) (K0.44Na0.52Li0.04)NbO3+0.5%mol Pr2O3. Powders of the designed compositions based on KNLN were obtained with the classic ceramic technology, as a result of solid phase synthesis, from a mixture of simple oxides and carbonates. The synthesis of ceramic powders was carried out at Ts = 900°C for ts = 4 h, while compaction by free sintering at Tsint = 1100°C for tsint = 2 h.
XRD studies have shown that doping with praseodymium and neodymium promotes the formation of the tetragonal phase in the base composition (K0.44Na0.52Li0.04)NbO3 at lower temperatures. On the other hand, microstructural tests have shown that the admixture of neodymium and praseodymium improves the sinterability of ceramic samples during the technological process; however, the ceramic samples still exhibit high porosity.
The study of the possibility of removing organic compounds from wastewater originating from the biodiesel purification stage by two catalytic processes, HSO5-/transition metal and Fenton method has been presented. The source of the ion HSO5- is potassium monopersulphate (2KHSO5·KHSO4·K2SO4) (Oxone) that may be decomposed into radicals (OH., SO4-., SO5-.) by means of transition metal as Co(II). Different concentrations were used for both compounds and the combination ([Co2+] = 1.00μM/[HSO5-] = 5.00·10-2 M) achieved the highest COD removal (60%) and complete decomposition of the oxidant was verified for contact times of 45 min. This process has some advantages comparing to the conventional Fenton method such as the absence of the costly pH adjustment and the Fe(III) hydroxide sludge which characterize this treatment process. The Fenton process showed that the combination of [H2O2] = 2.00M/[Fe2+] = 0.70 M was the best and archived COD removal of 80%. The treatments studied in this research have achieved high COD removal, but the wastewater from the biodiesel purification stage presents very high parametric values of Chemical Oxygen Demand (667,000 mgO2/L), so the final COD concentration reached is still above the emission limit of discharge in surface water, according the Portuguese Law (Decree-Law 236/98). However, both treatments have proved to be feasible techniques for the pre-oxidation of the wastewater under study and can be considered as a suitable pre-treatment for this type of wastewaters. A rough economic analysis of both processes was, also, made.
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