Calcium Benzoate Research Articles

Analysis of aromatic carboxylic acid and calcium salt couples with gas chromatography-mass spectrometry: Implications and comparison with in situ measurements at Mars' surface

Aromatic organic salts such as benzoates or phthalates may be widespread degradation products of organic molecules at the surface of Mars. The low volatility of these aromatic carboxylic salts could have compromised their detection through thermal extraction in situ analyses such as those performed by the Viking landers. However, over the years, analytical chemistry laboratories on board current and future Martian surface missions, such as the Sample Analysis at Mars (SAM) instrument suite on board the Curiosity rover and the Mars Organic Molecule Analyzer (MOMA) instrument of the Rosalind Franklin ExoMars rover, respectively, have evolved. These instruments have improved in efficiency to detect refractory and polar organic compounds, which could influence the detection of aromatic organic salts. To evaluate the capability of detecting aromatic organic salts on Mars with in situ instruments, we performed laboratory experiments under Viking, SAM, and MOMA-like Gas Chromatography-Mass Spectrometry (GC–MS) conditions with two carboxylic acid/salt couples: phthalic acid/calcium phthalate and benzoic acid/calcium benzoate. We studied the behavior and signatures of both molecular forms when using pyrolysis and derivatization experiments and the implications of these results in the search for organic molecules on Mars. This study showed that the Viking experiments could not have detected the presence of aromatic carboxylic salts in Martian samples because its maximum pyrolysis temperature was too low (500 °C). However, we showed that calcium benzoate and calcium phthalate, despite their refractory nature, could be identified indirectly through the detection of thermal and derivatized degradation products, both with SAM and MOMA. No conclusive proof of the presence of these aromatic organic salt species have been found in the SAM in situ data but given the right instrumental set-up they could be detected if present. The conclusions of this work raise essential questions on the detectability of refractory molecules, the analytical efficiency of flight instruments, and the interpretation of in situ data.

Nematicidal Activity of Organic Food Additives

Organic food additives are popular in various spheres of human activity: the food industry, agriculture, veterinary and human medicine, the chemical industry, and other sectors. Due to the relatively short time of their breakdown in the environment, their non-toxicity to various organisms in certain concentrations, and their large annual amounts of production, application, and influx into the environment, it is an important task to study their influence on ecology. To help reduce toxic pressure on the environment, we studied the influence of 32 organic food additives on larvae of the nematodes Strongyloides papillosus, Haemonchus contortus, Muellerius capillaris, which are parasites of the digestive tracts of ruminants. This article presents the results of in vitro studies of organic food additives (acetic, propionic, lactic, sorbic, adipic, fumaric, malic, citric, ascorbic, and dehydroacetic acids, sodium formate, calcium formate, potassium acetate, calcium acetate, sodium diacetate, calcium propanoate, sodium lactate, potassium sorbate, sodium sorbate, calcium sorbate, trisodium citrate, monosodium glutamate, sodium dehydroacetate, sodium benzoate, potassium benzoate, calcium benzoate, biphenyl, dibutylhydroxytoluene, hexamethylenetetramine, 2-phenylphenol, natamycin, and nisin) on nematode larvae at various stages of their development. Propionic acid and 2-phenylphenol, used in the food industry, exerted notable nematicidal effects on larvae of S. papillosus, M. capillaris, and H. contortus: 1% concentrations of the substances killed 85% of these larvae, except H. contortus, which were tolerant to 2-phenylphenol in 52% of cases. Other tested food additives at 1% concentrations could not kill more than 70% of invasive nematode larvae in 24 h. The research determined various degrees of toxicity of the studied substances to invasive (third age) and non-invasive (first and second age) larvae, which are related to a decrease in the feeding intensity of parasitic nematodes on the stage of third age larvae. Thus, some organic food additives, introduced into the environment with food wastes, are able to affect the vitality of certain nematode species to a varying extent.

Conversion of Benzimidazoles, Imidazothiazoles and Imidazoles into more Potent Central Nervous System Acting Drugs.

Benzimidazole (albendazole), imidazothiazole (levamisole) and imidazole (euconazole) are used in chemotherapy of helminthosis and mycosis respectively, with central nervous system (CNS) side effects. But only a limited number of azole groups are used clinically in the treatment of CNS diseases, which are on increase and could not be cured permanently. Due to increased incidence of more challenging new CNS diseases, there is a need for the synthesis of more potent CNS drugs. Hence, literature studies were carried out for the identification of common pathways for the synthesis of the three groups of compounds, their CNS properties and the possibility of modifying them to potent CNS drugs. Findings have shown that gloxal with formaldehyde in the presence of ammonia can be converted into imidazole, imidazothiazole and benzimidazole via distillation, condensation, alkylation, acylation, oxidation, cyclization, sulphation and amidation. However, agents such as phosphorus pentoxide, ethanolic potassium hydroxide, sodium hypochlorite, sodium hexafluroaluminate, aniline, calcium acetate, calcium benzoate, sodium hydroxide, aromatic aldehydes, bromoketones, alpha dicarbonyl compounds among others are used as reagents. The furan ring(s) may have a strong capability of penetrating CNS for the treatment of neurological disorders. The products from the three groups have agonistic, antagonistic, mixed agonistic and mixed antagonistic depressant and stimulant activities due to the presence of heteroatoms such as nitrogen, oxygen and sulphur. Imidazole may be the most potent with best characteristics of CNS penetrability and activity followed by imidazothiazole and benzimidazole. Azole group is common to all the three classes and may be responsible for some of their CNS effects. The resultant compounds could act via all neurotransmitters, voltage and ligand-gated ion channels and may be chiral.

Indoor Fungal Growth on Variable Antifungal at Different Wall Finishing on Plasterboard

Various health complaints often been attributed to pollution and the poor quality of the indoor air. If there is good practice in building design, construction, and maintenance, the structures should remain dry. However, when there is moisture damage, the materials may be in contact with water for prolonged times, which inevitably leads to microbial growth or even total deterioration of the building material. Antimicrobial coating is designed to generate a surface that is easy to clean and can also incorporate active agents, commonly called antifungal, that prevent microbial colonization, the subsequent growth and bio-deterioration of the substrate. This paper presents the sustainable treatment for indoor environment quality in buildings by examining the application of potassium sorbate, zinc salicylate, and calcium benzoate that used as food industry preservatives as indoor antimicrobial agents. Four types of wall finishing used on plasterboard substrate: acrylic paint, glycerol based-paint, thin wallpaper, and thick wallpaper. The result indicated that potassium sorbate is the best bio compound to react as antifungal agent to prohibit the growth of indoor fungi. All the antifungal shows difference level of their effectiveness from each other. Only 40% of fungi were able to grow on thin wallpaper by using potassium sorbate as antifungal agent.

The Effectiveness of Antifungal Controlling Aspergillus Niger Growth on Plasterboard

Good indoor environmental quality is desired for a healthy indoor environment. The microbial growth under indoor environments contribute to the poor indoor environmental quality that can cause various of health problems. In this study, the applications of three types of antifungals to prevent microbial migration, subsequent growth and bio-deterioration of the substrates. The aim of this research was to evaluate the coating-bio resistance in remediation of indoor fungal using three types of antifungals with different types of wall finishing materials. The treatment was exposed to optimum temperature and relative humidity at 30°C and 90% respectively. The potassium sorbate, zinc salicylate and calcium benzoate are tested against Aspergillus niger which is collected from indoor rooms. This study has revealed the growth of A. niger are more affected by the potassium sorbate on thick wallpaper, which is the percentage growth are 47%.

The Aspergillus niger growth on the treated concrete substrate using variable antifungals

The aim of this study was to evaluate the Aspergillus niger (A. niger) growth on substrates after incorporates with different compounds of antifungals which is normally used in food industry. The antifungals named as potassium sorbate (PS), calcium benzoate (CB) and zinc salicylate (ZS) were applied on concrete substrate covered with different wall finishing such as acrylic paint (AP), glycerol based paint (GBP), thin wallpaper (THIN) and thick wallpaper (THICK). The concrete substrate were inoculated with spore suspension, incubated at selected temperature (30oC) and relative humidity (90%)in plant growth chamber. The observations were done from the Day 3 until Day 27. The results showed that the growth of the A. niger for concrete treated by PS for AP, GBP, THIN, and THICK were 64%, 32%, 11% and 100%, respectively. Meanwhile for CB, the growth of A. niger on AP, GBP, THIN, and THICK were 100%, 12%, 41%, and 13%, respectively. Similarly, treated concrete by ZS revealed that the growth of A. niger on the same substrate cover were 33%, 47%, 40%, and 39%, respectively. The results obtained in this study provide a valuable knowledge on the abilities of antifungals to remediate A. niger that inoculated on the concrete substrate. Consequently, this study proved that the PS covering with THIN more efficiency compares CB and ZS to prevent A. niger growth.

The application of bioactive compounds from the food industry to control mold growth in indoor waterborne coatings

Microbial growth in indoor environments creates health problems, especially in people with asthma; approximately 80% of these patients are allergic to mold. Antimicrobial coatings are formulated to generate surfaces that are easy to clean and may also incorporate active agents, commonly called biocides, which inhibit microbial colonization, subsequent growth and bio-deterioration of the substrates.Some research lines seek to replace traditional organometallic and organochlorines biocides with environmentally acceptable ones. The aim of this research was, primarily, to explore the possible application of different compounds used in food industry like preservatives to be used as antimicrobial additives for antimicrobial coatings. Four biocides were tested against two different ambient molds isolated from an interior painted wall (Chaetomium globosum and Alternaria alternate). The selected biocides were zinc salicylate, zinc benzoate, calcium benzoate and potassium sorbate. The resulting paints were subjected to biological and physical tests (viscosity, hiding power, humidity absorption and biocides leaching rate). Bioassays revealed that zinc benzoate and zinc salicylate resulted active against both fungi.

Coordination ability of alkali metal or alkaline earth metal ions with aromatic dicarboxylate, sulfonate, or disulfonate ions in acetonitrile

In a poor solvating solvent, acetonitrile, the coordination ability of alkali metal (Li+, Na+) and alkaline earth metal (Mg2+, Ca2+, Ba2+) ions with carboxylate and sulfonate ions has been thoroughly examined, based on the precipitation of non-charged species and the successive re-dissolution of charged species. At first, the formation of [C6H5CO2Ca]+ (the calcium benzoate cation) in acetonitrile was evidenced by ESI-MS. Tetraethylammonium 3-nitrophthalate (3-nitro-1,2-benzenedicarboxylate, L2−) of 2.0×10−3moldm−3 was precipitated completely by the addition of 2.0×10−3moldm−3 Ca(ClO4)2, although the absorption spectrum of L2− was only slightly changed by 1.0×10−3moldm−3 Ca(ClO4)2. In the presence of 5.0×10−3moldm−3 Ca(ClO4)2, however, the precipitates re-dissolved drastically. The successively formed species between Ca2+ and L2− were proposed to be CaL22−, CaL0, and Ca2L2+. The lithium ion also caused the precipitation of non-charged species (Li2L0) as well as the re-dissolution of charged species (tentatively assigned to be Li3L+ or Li4L2+), however, the re-dissolution with Na+ took place just hardly. We were able to observe the re-dissolution of precipitates for 4-nitrophthalate through the formation of positively charged species in the presence of excess amounts of the alkaline earth metal ions, but not of the alkali metal ions. Tetraethylammonium p-toluenesulfonate, and 1,5-, 2,6-, and 2,7-naphtalenesulfonates were also examined. The “reverse” coordination constants have been successfully evaluated for some of all the systems, e.g., K2=3×107 (2 Mg2++L2− ⇆ Mg2L2+) and K3=2×108 (3 Li++L2− ⇆ M3L+), where L2−=2,7-naphthalenedisulfonate.

Implementation of High Resolution 43Ca Solid State NMR Spectroscopy: Toward the Elucidation of Calcium Sites in Biological Materials

Calcium is one of the most abundant cations in living organisms. It is found in the mineral phase of bone and in proteins like calmodulin. However, its exact environment beyond the first coordination sphere is often unknown, thus hampering the understanding of many biological processes. Here, calcium benzoate trihydrate (Ca(C(6)H(5)COO)(2) x 3 H(2)O) was used as a model for the NMR analysis of calcium sites in biological materials, because of the similarity of its calcium coordination, to water and carboxylate ligands, to that in several calcium-proteins. First, calcium-43 magic angle spinning (MAS) and static NMR spectra of a (43)Ca enriched sample were recorded at different magnetic fields, to investigate the electronic environment of calcium. Complex static lineshapes were obtained because of the presence of anisotropic NMR interactions of similar magnitude (chemical shift anisotropy and quadrupolar interaction), and the full interpretation of the spectra required simulations and gauge-including projector augmented wave (GIPAW) DFT calculations. An NMR investigation of the coordination environment of Ca(2+) was carried out, using high resolution (13)C-(43)Ca MAS NMR experiments such as TRAPDOR (transfer of population double resonance) and heteronuclear J-spin-echoes. It was shown that despite the weakness of (13)C-(43)Ca interactions, it is possible to discriminate carbon atoms according to their calcium environment. Long-range calcium-carbon correlations were even evidenced by TRAPDOR, reaching distances >5.6 A. This work demonstrates that by combining solid state NMR experiments, DFT calculations, and simulations, it will be possible to elucidate the electronic and coordination environment of calcium in many important and complex materials.

Advanced Solid State NMR Techniques for the Investigation of the Organic-Mineral Interfaces in Biomaterials

AbstractHigh resolution solid state NMR experiments were carried out on several compounds, to see how this technique can now be used to investigate in detail the surface structure of different biomaterials. First, because the surface of titanium implants can be functionalized by phosphonic acids, for instance to prevent bacterial adhesion,17O NMR experiments were performed on model TiO2 surfaces functionalized by 17O enriched phosphonic acids, to look at the mode of grafting of these coupling agents. Results bring clear evidence of the formation of Ti-O-P bridges and of the presence of residual P=O and P-OH groups. Second, given that calcium phosphates are widely present in biological hard tissues and synthetic biomaterials, 43Ca correlation experiments were performed on 43Ca enriched materials (hydroxyapatite and calcium benzoate), to see how the proximities between this nucleus and neighbouring atoms can be analyzed. Results show that both Ca…C and Ca…H proximities can be evidenced, and could thus help elucidate interface structures. All in all, these studies should pave the way to future investigations of biomaterials, and in particular of the structure of organic-inorganic interfaces.

Structure and Physical Stability of Hydrates and Thermotropic Mesophase of Calcium Benzoate

The aim of this study is to investigate the hydration and the dehydration processes of calcium benzoate hydrates (trihydrate and monohydrate), thermotropic mesophases (dehydrated mesophase and lyophilized mesophase) and amorphous state, and the influence of their molecular order on those processes. X-ray analysis revealed that trihydrate has a planar structure composed of two types of planes-one from benzoic acid, water, and calcium ion and another from benzoic acid and water-and that both planes are linked by three water molecules. It was found that calcium benzoate was able to exist as thermotropic mesophases by dehydration of trihydrate and lyophilization. These mesophases were characterized by polarizing-light microscopy (PLM), X-ray powder diffraction (XRPD), differential thermal analysis (DTA), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Both mesophases prepared by two procedures showed some similar physical properties, but lyophilized mesophase seemed to have molecular structure with higher order than dehydrated mesophase. The mesophases exhibited different hydration behavior. The dehydrated mesophase showed a stepwise rehydration process where it became monohydrate first and then trihydrate. The lyophilized mesophase became trihydrate without appearance of monohydrate. An amorphous form could also be prepared and it rehydrated first to the monohydrate and then trihydrate. The results suggest that the more disordered dehydrated mesophase and amorphous state change to monohydrate whereas the more ordered lyophilized mesophase cannot change to monohydrate but only to trihydrate.

Characterization of a Process for the In-Furnace Reduction of NOx, SO2, and HCl by Carboxylic Salts of Calcium

Calcium magnesium acetate has been assessed as an agent for the reduction of NOx, SO2, and HCl, at the pilot scale, in a down-fired combustor operating at 80 kWth. In addition to this, the chemical and physical processes that occur during heating have been investigated. Benchmarking of calcium magnesium acetate with a suite of five other carboxylic salts (calcium magnesium acetate, calcium propionate, calcium acetate, calcium benzoate, magnesium acetate, and calcium formate) has been performed. NOx reduction involves the volatile organic content of the carboxylic salt being released at temperatures of >1000 °C, where the reaction of CHi radicals with NO under fuel-rich conditions can result in some of the NO forming N2 in a “reburning” process. Thermogravimetry−Fourier transform infrared (TG−FTIR) studies identified the nature of the decomposition products from the low- and high-temperature decompositions. In addition, the rate of weight losses were studied to investigate the influence of the organic deco...

Thermal stability of food additives of glutamate and benzoate type

Many years ago, thermal analysis earned its place as a current instrumentation technique in assisting/solving the analytical problems of pharmaceuticals. A relative new trend is the study of the thermal stability of food additives in connection with the molecular structure. The studied compounds were: natrium and potassium glutamate, respectively natrium, potassium and calcium benzoate. The thermogravimetric data (TG) were obtained in dynamic nitrogen atmosphere, with open Pt crucible and heating rates of 5, 7, 10 and 12 K min-1, using a Perkin-Elmer TGA7 equipment. In order to estimate the non-isothermal kinetic parameters, the Friedman's differential-isoconversional method and the method suggested by Budrugeac and Segal (based on the compensation effect) were used. A variation of the activation energy vs. conversion was observed by using Friedman's method. The discrimination between the different reaction steps was performed by the non-parametric kinetic method, suggested by Sempere, Nomen and Serra. This is due to a complex process. The thermal stability data are very important for avoiding a possible misuse by processing of the studied food additives.

Calcium-based sorbents for simultaneous NO x/SO x reduction in a down-fired furnace

The performance of a suite of different carboxylic salts of calcium, have been assessed as dual NO x /SO x reducing agents. The salts studied include, calcium magnesium acetate (CMA), calcium acetate (CA), calcium formate (CF), calcium benzoate (CB), calcium propionate (CP) and magnesium acetate (MA). The primary fuel was propane operating with a primary zone stoichiometry fixed at λ 1=1.05 and the reburn zone stoichiometry, λ 2, was varied between 1.03 and 0.86. Overall stoichiometry, λ 3, was 1.15. CMA was also tested using a US Blend coal as the primary fuel. Experiments were performed in a down-fired pulverised coal furnace operating at an output of 80 kWth. Results showed that CMA and CP were the best dual NO x /SO 2 performers followed by CB, CA, MA and CF. Also, the co-injection of urea with the carboxylic salts as an advanced reburning agent was studied. The results showed that real improvements in NO reduction over basic reburning of greater than 70% could be obtained depending to a large extent on the initial effectiveness of the reburn fuel as well as nitrogen stoichiometric ratio within the reburn zone. Decomposition of the carboxylic salts was studied by thermo-gravimetric analysis (TGA) yielding information on the release of organic fractions important as precursors for CH i radical formation. Examination of structural and thermo-chemical properties of the carboxylic salts identified a correlation of NO reduction under reburning conditions with volatile organic content. Calcium magnesium acetate and calcium propionate showed superior SO 2 capture ability with reductions greater than 70% at Ca/S above 2, around 20% higher than calcium acetate and calcium formate. Magnesium acetate achieved reductions of less than 10% at Mg/S ratios up to 2.5. There is a clear difference in the potential effectiveness of the sorbents as dual NO x /SO 2 reductants, since the organic input for a given Ca input varies according to the composition of the sorbent. Some compromise may have to be made when choosing the correct operating conditions since good reductions in SO 2 may not give acceptable NO x reductions. However, the application of advanced reburning under these conditions has been shown here to compensate for low initial NO x reductions by basic reburning.

Pyrolysis of Aromatic Carboxylic Acid Salts: Does Decarboxylation Play a Role in Cross-Linking Reactions?

The pyrolysis of sodium benzoate, potassium benzoate, and calcium benzoate has been investigated between 435 and 500 °C as models for carboxylic acid salts in low-rank coals to determine if the decarboxylation of benzoate salts can contribute to cross-linking reactions during the thermal processing of low-rank coals. Decarboxylation was the dominant reaction pathway for all three salts. However, char formation (leading to poor mass balance) was also observed in all cases. The reaction proceeds via an anionic pathway, where the initial decarboxylation of benzoate salt leads to the formation of a phenyl anion as the key intermediate. Proton abstraction by the phenyl anion from another molecule of benzoate leads to the formation of benzene and benzoate dianion, which can react with CO2 to form a di-salt of phthalic acid (i.e., the Henkel reaction). Both benzene and phthalate account for >95% of the total products in the pyrolysis of sodium and potassium benzoates. The minor products diphenylmethane, benzophenone, triphenylmethane, and 9-phenylfluorene can form by a mechanism involving the reaction of phenyl anion with alkali benzoate to generate benzophenone, which reacts further to form the other products. Contrary to previous reports, calcium benzoate pyrolysis proceeds via an anionic mechanism to form benzene and benzophenone as the major products. No evidence of any calcium phthalate formation is observed in the pyrolysis of calcium benzoate. Furthermore, the reaction of benzophenone with the phenyl anion to form diphenylmethane, triphenylmethane, and 9-phenylfluorene seems to be slowed considerably (compared to sodium and potassium benzoates), based on the observed yield of these minor products. The rate constant for the pyrolysis of these benzoate salts, which decarboxylate slower than corresponding acids, decreases in the following order: potassium benzoate > sodium benzoate ≫ calcium benzoate. The pyrolysis rate is increased by at least a factor of 3 in the presence of water. Water traps the intermediate phenyl anion very efficiently to form benzene almost exclusively. Based on these findings, it can be concluded that the presence of water can drastically reduce cross-linking reactions and significantly improve liquefaction.

Inhibition of steel corrosion by calcium benzoate adsorption in nitrate solutions

The inhibitive properties of calcium benzoate for steel corrosion were studied in sodium nitrate solutions at room temperature. Corrosion parameters of the steel/nitrate and steel/benzoate + nitrate interfaces were obtained from polarisation curves. Adsorption parameters of benzoate on steel in sodium nitrate solutions were determined through changes in the degree of surface coverage by the inhibitor, as a function of concentration, time and adsorption potential. The effect of chloride on the corrosion inhibition of benzoate was analysed exposing the metal in different chloride solution concentrations.

Inhibition of steel corrosion by calcium benzoate adsorption in nitrate solutions: theoretical and experimental approaches.

The inhibitive effects of calcium benzoate on steel corrosion were studied in sodium nitrate solutions at room temperature. Corrosion parameters of the steel/nitrate and steel/benzoate + nitrate interfaces were obtained from polarization curves. Adsorption parameters of benzoate on steel in sodium nitrate solutions were determined through changes in the degree of surface coverage by the inhibitor, as a function of concentration, time, and adsorption potential. The most likely adsorption configuration of benzoate on iron was envisaged with the help of semiempirical calculations such as extended Hückel calculations. A two-dimensional flat configuration was involving at least two metal atoms, one interacting with the phenolic group and the other with the carboxylate moiety. The effect of chloride on the corrosion inhibition of benzoate was analyzed by exposing the metal to different chloride solution concentrations, from which corrosion parameters were calculated and compared with those in nitrate solutions.

The effects of calcium benzoate in diets with or without organic acids on dietary buffering capacity, apparent digestibility, retention of nutrients, and manure characteristics in swine.

Eight barrows (Yorkshire x [Finnish Landrace x Dutch Landrace]), initially 30 kg BW, were fitted with ileal cannulas to evaluate the effects of supplementing Ca benzoate (2.4%) and organic acids (OA) in the amount of 300 mEq acid/kg feed on dietary buffering capacity (BC), apparent digestibility and retention of nutrients, and manure characteristics. Swine were allotted in a 2 x 4 factorial arrangement of treatments according to a cyclic (8 x 5) changeover design. Two tapioca-corn-soybean meal-based diets were formulated without and with acidogenic Ca benzoate. Each diet was fed in combination with OA (none, formic, fumaric, or n-butyric acid). Daily rations were equal to 2.8 x maintenance requirement (418 kJ ME/BW(.75)) and were given in two portions. Chromic oxide (.25 g/kg) was used as a marker. On average, Ca benzoate lowered BC by 54 mEq/kg feed. This salt enhanced (P < .05) the ileal digestibility (ID) of DM, OM, arginine, isoleucine, leucine, phenylalanine, alanine, aspartic acid, and tyrosine (by up to 2.4 percentage units). Also, the total tract digestibility (TD) of DM, ash, Ca and GE, and Ca retention (percentage of intake) was greater (P < .05) in swine fed Ca benzoate, whereas N retention remained unaffected. Addition of all OA (formic and n-butyric acid, in particular) exerted a positive effect (P < .05) on the ID of amino acids (except for arginine, methionine, and cysteine). A similar effect (P < .05) was found for the TD of DM, OM, CP, Ca and total P and for the retention of N and Ca. In swine fed Ca benzoate, urinary pH decreased by 1.6 units (P < .001). In conclusion, dietary OA have a beneficial effect on the apparent ileal/total tract nutrient digestibilities, and Ca benzoate increased urine acidity, which could be effective against a rapid ammonia emission from manure of swine.

Control of the HCl Emissions from the Combustion of PVC by In-Furnace Injection of Calcium-Magnesium-Based Sorbents

This is a laboratory study on the reduction of hydrochloric acid (HCl) emissions from the combustion of poly(vinyl chloride) (PVC), by in-furnace injection of calcium- and magnesium-based sorbents. Experiments were conducted in a nearly isothermal, electrically heated, drop-tube furnace, at gas temperatures of 850 and 1050°C. PVC and the sorbents were premixed in powder form and injected in the furnace, where combustion of the fuel, release of HCl, and chlorination of the sorbents took place. Combustion was globally fuel-lean, with bulk equivalence ratios in the range of 0.2–0.5; particle heating rates were 104–105 K/sec; gas residence times were ≈1 sec. Experiments burned pure pulverized PVC (to serve as a baseline) or PVC mixed with pulverized Ca(OH)2, Mg(OH)2, calcium acetate (CA), magnesium acetate (MA), calcium-magnesium acetate (CMA), calcium formate (CF), calcium propionate (CP), and calcium benzoate (CB). The particle size of PVC was in the range of 125–150 μm, the size of the sorbents varied but it was typically <100 μm. The Ca/Cl or Mg/Cl molar ratios were set to 1:2, reflecting a stoichiometric composition, except for CMA where the Ca/Cl ratio was set to either 1:6 or 1:3. The HCl reduction efficiency of the sorbents in these runs ranged from 3% to 98%. The calcium-based sorbents exhibited high HCl capture efficiencies (72–98%), especially the organic salts (89–-98%). The latter compounds, upon de volatilization of their organic components, formed high-porosity cenospheric particles, which imposed minimal mass diffusion limitations. The magnesium-based sorbents did not react significantly (3–5%) with HCl in this temperature range. However, a considerable fraction of the magnesium in CMA appears to have taken part in the chlorination reaction. Varying the gas temperature between 850°C and 1050°C did not significantly affect the HCl capture efficiency of the sorbents. Key words: HCl emissions; PVC combustion; clacium-based sorbents for HCl capture; calcium-magnesium-acetate (CMA)

Dual SO 2 -NO x Concentration Reduction by Calcium Salts of Carboxylic Acids

The simultaneous removal of SO 2 and NO x by calcium salts of carboxylic acids was evaluated in a laboratory-scale furnace in atmospheres containing 2,000 ppm SO 2 , 1,000 ppm NO, 3% O 2 , and 12% CO 2 at gas temperatures between 550 and 1,250°C (825 and 1,425 K) with a residence times of 4 s in an isothermal zone. The salts studied included calcium formate (CF, Ca(COOH) 2 ), calcium acetate (CA, Ca(CH 2 COOH) 2 ), calcium propionate CP, (Ca(CH 2 CH 2 COOH) 2 ) and calcium benzoate (CB, Ca(C 6 H 4 COOH) 2 ). Maximum reductions in SO 2 concentration due to the formation of CaSO 4 were recorded as follows: 60% for CP, 55% for CF, 35% for CA, and 18% for CB at gas temperatures in the neighborhood of 950°C and at a Ca/S molar ratio near 2.8. With the organic portion of the injected salts acting as secondary fuel for NO x control, maximum NO x concentration reductions were 88% for CP, 65% for CB, 22% for CA and less than 10% for CF at gas temperatures near 950°C at bulk equivalence ratios (actual to stoichiometric organic fuel-to-air ratio) that varied between 0.5 for CF and 2.1 for CB. A recently constructed, narrower furnace increased the gas flow velocities and the particle dispersion in the gas. Therein, at residence times as low as 1 s, CP achieved simultaneous SO 2 and NO x removal of over 80% at gas temperatures ≥950°C. The addition of an oxidizing zone following the carboxylic acid sorbent injection zone affected the overall SO 2 -NO x removal according to the stoichiometry of the sorbent injection zone. When this zone was: (1) fuel-lean, the overall SO 2 removal improved; (2) stoichiometric, the overall SO 2 removal was not affected; and (3) significantly fuel-rich, the overall SO 2 removal worsened. Under most conditions, the overall reduction of NO x was not affected by the oxidizing zone. At temperatures below 800°C, Ca either was retained as CaCO 3 or remained bound to the organic compounds in the sorbents. At temperatures between 950 and 1,150°C, increasing amounts of CaO were found. The composition of the calcined sorbent and the availability of Ca was used to interpret the results of a cenosphere sulfation model. The sorbent sulfation kinetics were found to be bounded by those of pure CaO and pure CaCO 3 .