Determination of the Acidic Degradation Products, Acetic, Propionic, Butyric, and Phthalic Acid in Aqueous Pseudolatexes of Cellulosic Esters by High Performance Liquid Chromatography

An isocratic, reversed-phase HPLC method was developed to quantify the organic acids, acetic, propionic, butyric, and phthalic acid, formed as a result of ester hydrolysis, in pseudolatexes of cellulosic esters. Colloidal dispersions of cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate were prepared by a microfluidization-solvent evaporation method. Dispersions of cellulose acetate phthalate were prepared by redispersion of a spraydried commercial pseudolatex. The acids were detected at 210 nm, the mobile phase being 0.025 M phosphate buffer: methanol (80:20 v/v%, pH 3.0). The peak height response was linear over the studied concentration range of 2 - 10 mM/L for the aliphatic acids and 20-100 μM/L for phthalic acid. The minimum detectable quantities for acetic, propionic, butyric, and phthalic acid were 0.02 mM/L, 0.05 mM/L, 0.1 mM/L, and 0.0005 mM/L, corresponding to a % change in acetyl, propionyl, butyryl, and phthalyl content of 4.0 × 10⁴, 1.2 × 10³, 2.9 × 10³, and 2.8 × 10^-5 for a 30% w/v pseudolatex. The colloidal polymer particles were separated by ultracentrifugation, filtration, or flocculation with aluminum chloride solution before analysis of the aqueous phase. Similar acid concentrations were obtained for the three separation methods. The recovery from spiked samples was almost complete for acetic, approximately 90% for propionic acid, and less than 80% for butyric acid.     

Preparation of extrapure zinc oxide and zinc acetate from diethylzinc

We have developed a process for the preparation of extrapure zinc oxide and zinc acetate from diethylzinc, which includes ultrapurification of this compound through low-pressure fractional distillation, oxygen oxidation of the purified diethylzinc in combustion mode, and heat treatment of the resultant zinc oxide. Zinc acetate was obtained by dissolving the zinc oxide in acetic acid. The content of regulated metallic impurities (iron, copper, aluminum, silicon, cadmium, nickel, cobalt, tin, lead, chromium, molybdenum, and magnesium) in the zinc oxide and zinc acetate was 10^?5 to 10^?6 wt %, and their net content was <5 × 10^?4 wt %.     

Prepation and Stability of Aqueous-Based Enteric Polymer Dispersions

Abstract

Aqueous, colloidal dispersions of the enteric polymers, cellulose acetate phthalate (CAP), hydroxypropyl methylcellulose phthalate (HP-551, and polyvinyl acetate phthalate (PVAP) have been developed; and their application in tablet film coating demonstrated. The formation of free phthalic acid as a result of phthalate ester hydrolysis was monitored during storage of the dispersions. Increased free phthalic acid concentrations were found to adversely affect physical stability in dispersions of the cellulose polymers. Storage temperature and pH effects on phthalate ester stability were also considered     

Spectrophotometric Determination of Simultaneously Present Neptunium,Americium, and Plutonium in Aqueous Solutions

A spectrophotometric method was developed for determining simultaneously present Np, Am, and Pu in sulfuric and perchloric acid solutions. The molar extinction coefficients ε were determined. In the concentration ranges 1.0 × 10^?4?2.0 × 10^?3 M for Pu and Am and 5.0 × 10^?4?1.0 × 10^?2 M for Np, the overall error does not exceed 5%. The detection limits are 3.0 × 10^?5 M for Pu and Am and 1.0 × 10^?4 M for Np.

     

Quartz crystal microbalance and spectroscopy measurements for acid doping in polyaniline films

Abstract

We investigated the doping of thin polyaniline (PANI) films, prepared by the chemical oxidation of aniline, with different acids. The initial step in the investigation is the preparation of PANI films from aqueous hydrochloric acid solution. This is followed by dedoping with ammonia to obtain a PANI base, which is subsequently doped with strong acids (e.g. hydrochloric, sulfuric, phosphoric and trichloroacetic acids) and with a weak acid (acetic acid). The dopant weight fraction (w), which is connected with the gain of mass during the doping of PANI, was determined in situ using a quartz crystal microbalance (QCM). The behavior of PANI upon doping with different anions derived from strong acids indicates that both proton and the anion uptake into the polymer chains occur sharply, rapidly, completely, and reversibly. However the uptake in the case in acetic acid is characterized by slow diffusion. The doping was studied at different concentrations of acetic acid. A second cycle of dedoping–redoping was also performed. The kinetics of the doping reaction is dominated by Fickian diffusion kinetics. The diffusion coefficients (D) of the dopant ions into the PANI chains were determined using the QCM and by UV–Vis absorption spectroscopy in the range of (0.076–1.64)× 10^?15 cm² s^?1. It was found that D in the second cycle of doping is larger than that evaluated from the first cycle of doping for high concentrations of acetic acid. D for the diffusion and for the dopant ion expulsion from the PANI chains was also determined during the redoping process. It was found that D for acetic acid ions in the doping process is larger than that calculated for the dedoping process.     

Dechlorination of polychlorinated biphenyls using magnesium and acidified alcohols

Polychlorinated biphenyls (PCBs) were widely used in industry until their regulation in the 1970s. However, due to their inherent stability, they are still a widespread environmental contaminant. A novel method of degradation of PCBs (via hydrodehalogenation) has been observed using magnesium powder, a carboxylic acid, and alcohol solvents and is described in this paper. The rates of degradation were determined while varying the type of acid (formic, acetic, propionic, butyric, valeric, benzoic, ascorbic, and phosphoric), the amount of magnesium from 0.05 to 0.25 g, the amount of acetic acid from 0.5 to 50 μL and the concentration of PCB-151 from 0.1 to 50 μg/mL, as well as the alcohol solvent (methanol, ethanol, propanol, butanol, octanol, and decanol). The results of these studies indicate that the most rapid PCB dechlorination is achieved using a matrix consisting of at least 0.02 g Mg/mL ethanol, and 10 μL acetic acid/mL ethanol in which case 50 ng/μL of PCB-151 is dechlorinated in approximately 40 min.     

Comparing End-Use Potential for Industrial Food-Waste Sources

Approximately one quarter of the global edible food supply is wasted. The drivers of food waste can occur at any level between production, harvest, distribution, processing, and the consumer. While the drivers vary globally, the industrialized regions of North America, Europe, and Asia share similar situations; in each of these regions the largest loss of food waste occurs with the consumer, at approximately 51% of total waste generated. As a consequence, handling waste falls on municipal solid waste operations. In the United States, food waste constitutes 15% of the solid waste stream by weight, contributes 3.4 × 10⁷ t of carbon dioxide (CO₂) equivalent emissions, and costs 1.9 billion USD in disposal fees. The levels of carbon, nutrients, and moisture in food waste make bioprocessing into higher value products an attractive method for mitigation. Opportunities include extraction of nutraceuticals and bioactive compounds, or conversion to a variety of volatile acids—including lactic, acetic, and propionic acids—that can be recovered and sold at a profit. The conversion of waste into volatile acids can be paired with bioenergy production, including hydrogen or biogas. This present review compares the potential for upgrading industrial food waste to either specialty products or methane. Higher value uses of industrial food waste could alleviate approximately 1.9 × 10⁸ t of CO₂ equivalent emissions. As an example, potato peel could be upgraded to lactic acid via fermentation to recover 5600 million USD per year, or could be converted to methane via anaerobic digestion, resulting in a revenue of 900 million USD per year. The potential value to be recovered is significant, and food-waste valorization will help to close the loop for various food industries.     

A comparative study on copper corrosion originated by formic and acetic acid vapours

The copper corrosion rate and products originated by the action of formic and acetic acid vapours at a 100% relative humidity were studied. Copper specimens were exposed to formic and acetic acid vapours for a period of 21 days. Five formic and acetic acid vapour concentrations (10, 50, 100, 200 and 300 ppm) were tested. Copper corrosion rates of up to 1300 mg m^–2 d^–1 (mmd) for formic acid and up to 2300 mmd for acetic acid were measured using a gravimetric method. The corrosion-product layers were characterised using electrochemical, X-ray powder diffraction and scanning electron microscopy techniques. Some of the compounds identified were: cuprite (Cu₂O), for both acids; cupric hydroxide monohydrate (Cu(OH)₂ · H₂O) and copper formate tetrahydrate (Cu(HCOO)₂ · 4H₂O), for formic acid; and copper acetate dihydrate (Cu(CH₃COO)₂ · 2H₂O) and copper hydroxide acetate dihydrate (Cu₄(OH)(CH₃COO)₇ · 2H₂O), for acetic acid.     

Effect of acetic acid and water content in the spray solution on structural,morphological, optical and electrical properties of Al and In co-doped zinc oxide thin films

Aluminium and indium co-doped zinc oxide (AIZO) thin films were deposited using ultrasonic spray pyrolysis. Depositions were performed by varying the acetic acid and water content in the spraying solution which resulted in the formation of different nanostructures like hexagons, flowers, chisels, curved nanostructures, hexagonal pyramids, super grown hexagons, and inter-connected nanostructures. Further, the physical properties such as structural, optical, electrical, and surface texture parameters were examined. The structural studies showed that films were of crystalline nature, with different crystallite sizes and grown with a preferential orientation along (002) plane. The optical transmittance assessments proved that films were highly transparent (>?80%) in the visible region. The electrical sheet resistance was found to be in the range 29–1K Ω/□. Surface parameters like average roughness, root mean square roughness, and peak-valley height values helped to understand the homogeneity of the thin films. Finally, the suitability of AIZO films for transparent conductive oxide applications were tested by estimating the figure of merit (FOM). Among the different solution conditions, films fabricated using a starting solution containing 25 ml of acetic acid and 25 ml of water exhibited the lowest resistivity (2.47?±?0.03?×?10^?3 Ω-cm) along with the highest FOM (5.83?±?0.42?×?10^?3/Ω).     

Sorption of phenolics and carboxylic acids on polybenzimidazole

The sorption of phenolics and carboxylic acids on the new ion-exchange resin polybenzimidazole (PBI) has been measured using aqueous solutions of the sorbates and compared with the sorption on another weak-base resin, poly(4-vinyl pyridine) (PVP). The phenolics used include phenol, p-cresol, p-chlorophenol and m-aminophenol, while the carboxylic acids chosen are formic, acetic, propionic and butyric acids. For aminophenol and phenol, the equilibrium sorption capacities of PBI and PVP are comparable, while for more acidic p-cresol and p-chlorophenol, PVP has significantly higher equilibrium sorption than PBI. On the other hand, for carboxylic acids at low concentrations, PBI exhibits considerably higher sorption capacity than PVP, the difference being more pronounced for acids with smaller acidity. At low concentrations, formic acid has several-fold higher sorption than phenol on PBI, which thus offers a simple method for separation of formic acid from phenol in dilute solutions. PBI has fast sorption kinetics for both phenols and carboxylic acids and a fast rate of stripping and regeneration with dilute NaOH, being much superior to PVP in both these respects.     

Hydrolysis of Cellulose Acetate and Cellulose Acetate Butyrate Pseudolatexes Prepared by a Solvent Evaporation-Microfluidization Method

Aqueous colloidal Cellulose acetate dispersions have recently been introduced as an alternative to organic polymer solutions for the coating of osmotically active cores with a semipermeable membrane. Cellulose esters are known to hydrolytically degrade in an aqueous environment. This study followed the chemical degradation of pseudolatexes of the cellulose esters, cellulose acetate and cellulose acetate butyrate, over time and as a function of temperature. The pseudolatexes were prepared by a microfluidization-solvent evaporation method. The hydrolysis of the cellulose esters was followed by determining the pH and the amount of the acidic degradation products, acetic and butyric acid, in the aqueous phase of the polymer dispersions with an HPLC assay. The degradation followed a pseudo first-order equation and rate constants and activation energies were calculated. In addition to chemical instability, agglomeration and gelling of the colloidal particles occurred. The pseudolatexes were stable at 4°C, however, if stored at higher temperatures, the preparation of a redispersible polymer powder is recommended.     

Prepation and Stability of Aqueous-Based Enteric Polymer Dispersions

Aqueous, colloidal dispersions of the enteric polymers, cellulose acetate phthalate (CAP), hydroxypropyl methylcellulose phthalate (HP-551, and polyvinyl acetate phthalate (PVAP) have been developed; and their application in tablet film coating demonstrated. The formation of free phthalic acid as a result of phthalate ester hydrolysis was monitored during storage of the dispersions. Increased free phthalic acid concentrations were found to adversely affect physical stability in dispersions of the cellulose polymers. Storage temperature and pH effects on phthalate ester stability were also considered     

Comparison of a SiO2–CaO–ZnO–SrO glass polyalkenoate cement to commercial dental materials: ion release, biocompatibility and antibacterial properties

Ion Release and biocompatibility of a CaO–SrO–ZnO–SiO₂ (BT 101) based glass polyalkenoate cement (GPC) was compared against commercial GPCs, Fuji IX and Ketac Molar. The radiopacity (R) was similar for each material, 2.0–2.8. Ion release was evaluated on each material over 1, 7, 30 and 90 days. BT 101 release included Ca (23 mg/L), Sr (23 mg/L) Zn (13 mg/L), Si (203 mg/L). Fuji IX release includes Ca (0.7 mg/L), Al (3 mg/L) Si (26 mg/L), Na (60 mg/L) and P (0.5 mg/L) while Ketac Molar release includes Ca (1 mg/L), Al (0.6 mg/L) Si (23 mg/L), Na (76 mg/L) and P (0.7 mg/L). Simulated body fluid trials revealed CaP surface precipitation on BT 101. No evidence of precipitation was found on Fuji IX or Ketac Molar. Cytotoxicity testing found similar cell viability values for each material (~60 %, P = 1.000). Antibacterial testing determined a reduced CFU count with BT 101 (2.5 × 10³) when compared to the control bacteria (2.4 × 10⁴), Fuji IX (1.5 × 10⁴) and Ketac Molar (1.2 × 10⁴).     

Effect of carboxylic acid on sintering of inkjet-printed copper nanoparticulate films

The reduction effect of various carboxylic acids on inkjet-printed copper film was investigated. Carboxylic acids were exposed to the film by nitrogen gas that was bubbled through the liquid acids during the annealing process. It was observed that in the case of saturated monocarboxylic acid (formic, acetic, propionic, butyric), the acids with shorter hydrocarbon chains perform better in reducing the surface copper oxides in the printed copper conductive film. The printed films exposed to formic acid vapor exhibited the lowest resistivity (3.10 and 2.30 μΩ cm when annealed at 200 and 250 °C, respectively). In addition, the oxalic acid more effectively reduces copper oxide than formic acid and its usage can shorten the annealing time for highly conductive printed copper film. This reductive annealing process allows fabrication of copper patterns with low resistivity, (3.82 μΩ cm annealed at 250 °C) comparable to the resistivity of bulk copper.     

Stability of Neptunium(V) in Concentrated Acetic Acid Solutions

Np(V) acetate in glacial acetic acid and aqueous acetic acid solutions is resistant to disproportiona-tion and occurs in equilibrium with the NpO₂(Ac)·H₂O precipitate. Within the time of dehydration with excess acetic anhydride, Np(V) disproportionates. The inverse reproportionation process occurs after adding excess water to anhydrous acetic acid containing acetic anhydride, Np(IV), and Np(VI). Addition of HClO₄ causes rapid disproportionation of Np(V) in anhydrous acetic acid and in concentrated acetic acid solutions. The spectra of suspensions containing Np(V) and potassium acetate in concentrated acetic acid contain absorption bands with maxima at 990 and 1020 nm, assigned to NpO₂(Ac)₃^2- anions and K₂NpO₂(Ac)₃ particles, respectively.

     

Characterisation of bacterial cellulose partly acetylated by dimethylacetamide/lithium chloride

Cellulose is a water-insoluble polysaccharide used at an industrial scale for the manufacture of paper and films or in the dust form, natural, hydrolysed or derivatised. The cellulose produced by G. hansenii (former A. xylinum) has a structure identical to that of plants, but is free of lignin and hemicellulose, with several unique physical–chemical properties. The main barrier to the use of cellulose is its insolubility in water and most organic solvents, but soluble derivatives can be obtained with the use of ionic solvents. Bacterial cellulose, produced in a static, 4% glucose medium, was dissolved in hot DMAc/LiCl (120, 150 or 170 °C). The solution was analysed by ¹³C NMR, and the effect of the dissolution on the crystalline state was shown by X-ray crystallography. The crystalline structure was lost upon dissolution, becoming amorphous; this was also observed for Avicel^® plant cellulose. The soluble cellulose was partly acetylated in acetic anhydride with acetic anhydride-cellulose ratios of 1:50, 1:6 and 1:12 (w/v). The resulting cellulose acetates were examined by infrared spectroscopy, and the best result was 43% (w/v). The degree of acetylation was determined via ¹H NMR spectroscopy by comparing the area of the glucose ring at 2.60–5.20 ppm and that of the methyl proton of the acetate group at 1.80–2.20 ppm. The ¹³C NMR spectra showed acetylation at C6 ? C2 > C3 at 60–80 ppm, with C1 signals at ~ 100–104 ppm. The derivatisation of bacterial cellulose in DMAc/LiCl/acetic anhydride (1:4:50, v/v/v) gave rise to 87% substitution. The process of dissolution of the bacterial cellulose is essential for the analysis of the insoluble polymer in water, facilitating analysis and characterisation of these composites by ¹³C NMR spectroscopy, size exclusion chromatography and light scattering techniques.     

Attack of cement pastes exposed to organic acids in manure

Manure such as silage effluents and liquid manure contains organic acids which constitute a severe chemical threat toward the concrete of agricultural structures. The purposes of this study were to identify the chemical composition parameters that influence durability by analysing the behaviour of the chemical elements of the cement paste (Ca, Si, Al, Fe and Mg) in organic acid solutions and to compare the intensity of the chemical attack by the different acids found in liquid manure. This study was carried out on cement pastes made from four binders (ordinary Portland cement, slag cement, OPC blended with silica fume and OPC blended with fly ash). The hardened cement pastes were first crushed, then immersed in solutions made of five organic acids with an initial pH of 4 and constantly stirred. The pH and the concentrations of major elements were monitored over time.

The results show that Si, Al, and Fe appear to be favourable elements for the chemical resistance of binders whereas the amount of Ca should be limited. Moreover, it is shown that the four acids found in liquid manure (acetic, propionic, butyric, iso-butyric) are equally aggressive. Lactic acid, present with acetic acid in silage effluent, is more aggressive according to the value of its pK_a.     

Removal of bacteria and viruses from waters using layered double hydroxide nanocomposites

We have identified synthetic layered double hydroxides (LDH) nanocomposites as an effective group of material for removing bacteria and viruses from water. In this study, LDH nanocomposites were synthesized and tested for removing biological contaminants. LDH was used to remove MS2 and øX174 (indicator viruses), and Escherichia coli (an indicator bacterium) from synthetic groundwater and to remove mixed communities of heterotrophic bacteria from raw river water. Our results indicate that LDH composed of magnesium–aluminium or zinc–aluminium has a viral and bacterial adsorption efficiency ≥99% at viral concentrations between 5.9 × 10⁶ and 9.1 × 10⁶ plaque forming units (pfu)/L and bacterial concentrations between 1.6 × 10¹⁰ and 2.6 × 10¹⁰ colony forming units (cfu)/L when exposed to LDH in a slurry suspension system. Adsorption densities of viruses and bacteria to LDH in suspension ranged from 1.4 10¹⁰ to 2.1 10¹⁰ pfu/kg LDH and 3.2 × 10¹³–5.2 × 10¹³ cfu/kg LDH, respectively. We also tested the efficiency of LDH in removing heterotrophic bacteria from raw river water. While removal efficiencies were still high (87–99%), the adsorption capacities of the two kinds of LDH were 4–5 orders of magnitude lower than when exposed to synthetic groundwater, depending on if the LDH was in suspension or a packed column, respectively.     

Effect of Vitamin E Dialyzer Membrane on Anemia in Hemodialysis Patients

Red blood cell (RBC) survival in patients on chronic maintenance hemodialysis (HD) has been reported to be shortened due to the oxidative damage of RBC membrane. The use of antioxidants might help in the control of anemia and reduce the erythropoietin (EPO) dose needed. Objective: The objective was to determine the effects of vitamin E‐bonded dialyzer membrane (VEM) on anemia and EPO requirements in chronic HD patients. Patients and methods: We prospectively studied 19 stable patients on HD (8 males, age 58.47, range 31–76 years) who were shifted from other dialyzer membranes to VEM for 6 months. At baseline they were given a mean dose of EPO of 90.6 ± 51 U kg^–1 BW^–1 week^–1. Clinical data, dry body weight corrected pre‐dialysis RBC, hemoglobin, reticulocytes, serum iron and ferritin, complete biochemistry, iPTH, and CRP were studied at 3 and 6 months, while therapy scheme was reevaluated monthly. Results: A significant rise, compared to the baseline, was found in hemoglobin and in RBC at 3 months of treatment (12.44 ± 1.16 g/dL vs. 11.2 ± 1.2 g/dL, p = 0.002; and 4.01 ± 0.53 × 10⁶/μL vs. 3.64 ± 0.5 × 10⁶/μL, p < 0.05) and at the end of follow‐up (12.17 ± 1.33 g/dL vs. 11.2 ± 1.2 g/dL, p < 0.05; and 4.03 ± 0.53 × 10⁶/μL vs. 3.64 ± 0.5 × 106/μL, p < 0.05). No significant change in serum iron and ferritin, reticulocytes, EPO dose used, iPTH, Kt/V, or CRP was found at the end of follow‐up compared to the baseline (68.8 ± 17 mg/dL vs. 67.9 ± 18 mg/dL, p = NS; 421 ± 296 mg/dL vs. 478 ± 359 mg/dL, p = NS; 3.76 ± 0.89 × 10⁴/μL vs. 3.82 ± 0.78 × 10⁴/μL, p = NS; 90.2 ± 53 U kg^–1 BW^–1 week^–1 vs. 90.6 ± 51 U kg^–1 BW^–1 week^–1, p = NS; 157 ± 43 pg/dL vs. 148 ± 56 pg/dL, p = NS; 1.21 ± 0.22 vs. 1.2 ± 0.17, p = NS; 7.15 ± 5.42 mg/L vs. 15.38 ± 29.8 mg/L, p = NS, respectively). Conclusions: Despite the small number of patients and the short time interval of treatment, an antioxidant effect of VEM apparently achieved early a better control of anemia in HD patients.     

Stability of Mixtoxantrone Hydrochloride in Solution

Abstract

A stability-indicating reversed-phase high performance liquid chromatographic method was developed for the detection of mitoxantrone HC1 and its degradation products under accelerated degradation conditions. The degradation kinetics of mitoxantrone HC1 in aqueous solution over a pH range of 1.18 to 7.20 and its stability in propylene glycol-or polyethylene glycol 400-based solutions were investigated. The observed rate constants were shown to follow apparent first-order kinetics in all cases. The pH-rate profile shows that maximum stability of mitoxantrone HC1 was obtained at pH 4.01. No general acid or base catalysis from acetate or phosphate buffer species was observed. The catalysis rate constants on the protonated mitoxantrone imposed by hydrogen ion water and hydroxy ion were determined to be 3.72 × 10 min^?1 5.64 × 10-min^?1 and 1.108 × 10^?2min^?1, respectively. The degradation rate constants of mitoxantrone affected by different ionic strength systems. Irradiation with 254 nm UV light at 25±0.5°C was found when canpared with the light-protected controls. Incorporation of nonaqueous propylene glycol or polyethylene glycol in the pH 4.01 mitoxantrone solution shows an increase in its stability at 502±0.5°C.