Dilute Acetic Acid Research Articles

The Sesquiterpenes from Cacalia tangutica

Cacalia tangutica belonged to the tribe Compositae have long been used as Chinese traditional folk herbs to treat headache, dizziness, hemiplegia, rheumatism, tussis and phlegm. Resently, our continuing studies on this plant revealed the presence of diversiform sesquiterpenes from a petrol extract of the aerial parts. The seven sesquiterpenes isolated were three eremophilane sesquiterpenes (1-3) including novel one (1), one known guaianetype sesquiterpeoid (4), one alloromadendrane sesquiterpene (5) and two eudesmane sesquiterpenes (6, 7) (Figure 1). Compound 1, a pink gum, +10 (c 1.30, CHCl3), has the molecular formula C15H22O4 (HR-ESIMS: m/z 267.1597 [M+1], calcd. for C15H23O4 267.1591). Its IR and UV spectra showed the presence of a hydroxyl (3323 cm−1) and α,β-unsaturated carbonyl systems a ketone (1660, 1613 cm−1 and λmax 244 nm, 203 nm). Analysis of the H NMR and C NMR (DEPT) spectrum of 1 along with HMQC experiment, the fifteen signals in C NMR and the signals of four methyl groups (δH: 1.17 s, δC: 18.5; δH: 1.27 d, J = 6.6 Hz, δC: 11.8; δH: 1.51 s, δC: 24.4; δH: 1.55 s, δC: 24.7) identified 1 as eremophlane sesquiterpene. The two olefinic signals (δH: 6.06 s, δC: 125.3 (CH); δH: 7.21 s, δC: 150.9 (CH)) combined with HMBC correlations (δH: 6.06 s/δC: 138.7 (C), 42.9 (C), and 30.2 (CH2); δH: 7.21 s/δC: 47.3 (CH), 42.9 (C), 138.7 (C), 165.7 (C), 185.7 (C), and 83.4 (C)) indicated the presence of characteristics of an 8-oneeremophila-6,9-diene derivative. An additional hydroxy and a peroxyl groups were required for the molecular formula C15H22O4. The signals appeared at δH 3.69 (ddd, 1H, J = 11.4, 11.1, 4.2 Hz) and δC 71.1 (CH) suggested the hydroxy group was equatorial stereochemistry at C-3, while the signals at δH 1.51 s, 1.55 s, 8.78 brs (H-peroxyl, D2O exchanged) and δC 24.4 (CH3), 24.7 (CH3), 83.4 (C) suggested the peroxyl group was at C-11. This was supported by the long range coupling of C-3 (71.1, CH) with the methyl proton (1.27 d, J = 6.6 Hz, H-15) and the long range coupling of C-11 (83.4, C) with the methyl protons (1.51 s, H-12; and 1.55 s, H-13) in the HMBC spectrum. In the HH COSY spectrum, H-4 (δ 1.42 d, J = 11.4 Hz) and H-2 (δ 2.27 m) were also correlated with H-3. To allow the assignments of structure 1 rigorously, a simple reductive reaction has been taken place as followed (see Figure 2). Compound 1 has been selectively reduced to compound 1-1 by potassium iodide in the solution of dilute acetic acid. The produce 1-1, a pale yellow oil, has the molecular α [ ]D 20

Efficacy of the ViziLite System in the Identification of Oral Lesions

Early detection of oral cancer is crucial in improving survival rate. To improve early detection, the use of a dilute acetic acid rinse and observation under a chemiluminescent light (ViziLite; Zila Pharmaceuticals, Phoenix, AZ) has been recommended. However, to date, the contributions of the individual components of the system have not been studied. The present study was done to investigate the efficacy of the individual components of the ViziLite system in providing improved visualization of early oral mucosal lesions. A total of 100 patients, 39 males and 61 females, age 18 to 93 years (mean age, 44 years), who presented to the Virginia Commonwealth University School of Dentistry for dental screening were examined. There were 58 Caucasians, 29 African-Americans, 5 Hispanics, 6 Asians, and 2 of mixed ethnicity. Thirty-five patients smoked, 53 used alcohol, and 25 both smoked and drank. After written consent, the oral cavity was examined under incandescent light for soft tissue abnormalities. After 1-minute rinse with 1% acetic acid, the mouth was re-examined for additional mucosal abnormalities. Then, the mouth was examined once again using the ViziLite system's chemiluminescent light. Any lesions detected by these 3 examinations that were clinically undiagnosable were brush biopsied (Oral CDx) for determination of cellular representation. In the original examination of the 100 patients, 57 clinically diagnosable benign lesions (eg, linea alba, leukoedema) and 29 clinically undiagnosable lesions were detected. After the rinse, 6 additional diagnosable lesions (linea alba) and 3 undiagnosable lesions were found. No additional lesions were detected with the chemiluminescent light. Of the 32 undiagnosable lesions that were brush biopsied, 2 were positive for atypical cellular characterization and warranted further investigation with a scalpel biopsy. Neither of these lesions was found to be premalignant or malignant. Although the acid rinse accentuated some lesions, the overall detection rate was not significantly improved. The chemiluminescent light produced reflections that made visualization more difficult and thus was not beneficial.

Heterogeneous Kinetics and Residue Curve Map (RCM) Determination for Synthesis of n-Hexyl Acetate Using Ion-Exchange Resins as Catalysts

Esterification of dilute acetic acid with n-hexanol was studied with cation-exchange resins (macroporous and gelular) in a jacketed stirred batch reactor to synthesize a value-added ester, namely, n-hexyl acetate. The effect of various parameters such as speed of agitation, catalyst particle size, molar ratio of n-hexanol to acetic acid, reaction temperature, catalyst loading, and reusability of catalysts was studied for optimization of the reaction condition. The nonideality of each component in the reacting mixture was accounted for by using the activity coefficient via use of the UNIFAC group contribution method. The kinetic data were correlated with both pseudo-homogeneous (PH) and adsorption-based reaction rate models, e.g., Eley−Rideal (ER), Langmuir−Hinshelwood−Hougen−Watson (LHHW), and the modified LHHW (ML). Residue curve maps (RCM) were experimentally generated under different conditions to elucidate the feasibility of n-hexyl acetate synthesis in a reactive distillation column (RDC).

Electroosmotic flow behaviour of metal contaminated expansive soil

It is important to study the flow behaviour through soil during electrokinetic extraction of contaminants to understand their removal mechanism. The flow through the expansive soil containing montmorillonite is monitored during laboratory electrokinetic extraction of heavy metal contaminants. The permeability of soil, which increases due to the presence of contaminants, is further enhanced during electrokinetic extraction of contaminants due to osmotic permeability. The variations in flow rates through the soil while the extracting fluid is changed to dilute acetic acid (used to control the increase of pH) and EDTA solution (used to desorb the metal ions from soil) are studied. The trends of removal of contaminants vis-a-vis the changes in the flow through the soil during different phases of electrokinetic extraction are established. Chromium ions are removed by flushing of water through the soil and increased osmotic flow is beneficial. Removal of iron ions is enhanced by induced osmotic flow and desorption of ions by electrokinetic processes.

Modification of chitosan by the Maillard reaction using cellulose model compounds

The Maillard reaction between chitosan and cellulose model compounds such as glucose and cellobiose was investigated. Chitosan and the compounds were dissolved in 1% acetic acid, and were dried at 50 °C. As the analysis of the film products, weight increase, color change, FT-IR, relative amounts of free amino groups, insolubility to dilute acetic acid and tensile properties were measured. When the compounds were added to chitosan, the film weight increased gradually and the color difference changed significantly. In addition, the relative amounts of free amino groups decreased rapidly, and the insoluble matter increased. The good tensile properties were obtained when the compounds were added at 20wt%. According to the results of FT-IR, the cleavages in sugar units of chitosan and the formation of heterocyclic compounds were observed. It was recognized that glucose reacts easily with chitosan compared to cellobiose. The progress of the Maillard reaction was dependent on the amount of the compound added.

Recovery of chitosan from aqueous acidic solutions by salting-out. Part 2: Use of salts of organic acids

We have previously reported that inorganic salts of the Hofmeister series could be used efficiently to recover chitosan from aqueous acidic solutions. Here, we extended these findings to food-compatible, naturally occurring, salts of tricarboxylic, dicarboxylic and monocarboxylic acids. Trisodium citrate was an efficient salting-out agent of 30 kiloDaltons (kDa) chitosan but was less potent in the case of a 240-kDa and a 70 cP form of the biopolymer dissolved in dilute aqueous HCl or acetic acid. Temperature (4 °C, room temperature or 50 °C) had no appreciable effect. We also showed that trisodium citrate was an efficient salting-out agent of chitosans for molecular sizes of 26,000 Da to ⩾139,000 Da. The sodium salt of dicarboxylic (malic, tartaric, succinic and malonic) acids salted-out 30 kDa chitosan but were generally less efficient in the case of the 240 kDa and 70 cP chitosans, independently of temperature. The sodium salt of monocarboxylic (acetic, lactic and propionic) acids were not efficient salting-out agents of any of the three types of chitosans used here, independently of temperature. The 30 kDa chitosan salted-out with the sodium salts of citric, tartaric, malic and malonic acids was in general soluble in dilute aqueous HCl or dilute aqueous acetic acid. Our data were consistent with the interpretation that some salts of food-compatible tricarboxylic and dicarboxylic acids could be used for salting-out chitosans, taking into account, (1) the efficiency of recovery and (2) the molecular size of the chitosans to be recovered.

Recovery of chitosan from aqueous acidic solutions by salting-out: Part 1. Use of inorganic salts

We describe a novel and easy-to-use approach based on salting-out to efficiently recover chitosan from aqueous acidic solutions. Inorganic salts of the Hofmeister series salted-out chitosans of 30 kiloDaltons (kDa), 240 kDa (35 cP) and a 70 cP form of the biopolymer dissolved in dilute HCl or acetic acid. The efficiency generally followed the ranking order of the Hofmeister’s salts ( SO 4 2 - > H 2 PO 4 - ≅ HPO 4 2 - > NO 3 - ) . Temperature (4 °C, room temperature, 50 °C) did not markedly affect the process. Ammonium sulfate was the most efficient salting-out agent of chitosans over a wide range of molecular sizes (2300 Da to >240,000 Da). The solubility (dilute HCl or acetic acid) of the salted-out chitosans varied from readily soluble to nearly insoluble. The choice of the Hofmeister’s salt(s) for salting-out chitosans must take into account, (1) the efficiency of recovery, and (2) the molecular size of the chitosans to be recovered.

Cu-accumulation at the interface between sputter-(Zn,Mg)O and Cu(In,Ga)(S,Se) 2 — A key to understanding the need for buffer layers?

Zn 0.85Mg 0.15O buffer layers can replace both i-ZnO and CdS in n-ZnO/i-ZnO/CdS/Cu(In x Ga 1 − x )(S y Se 1 − y ) 2/Mo/glass (CIGSSe) solar cells without significant loss of efficiency. We found that the efficiency of Zn 0.85Mg 0.15O buffered solar cells decreased with increasing sample temperature when we sputter-deposited Zn 0.85Mg 0.15O directly onto the CIGSSe absorber surface, e.g. from 9.5% without deliberate heating to 6.5% at 240 °C. To find an explanation for this behavior we sputter-coated bare, KCN-etched CIGSSe absorbers with about 420 nm of Zn 0.85Mg 0.15O at different sample temperatures and subsequently removed the Zn 0.85Mg 0.15O layers by wet-chemical etching with dilute acetic acid. The exposed CIGSSe surfaces were examined by surface-sensitive X-ray photoelectron spectroscopy (XPS) and X-ray excited Auger electron spectroscopy (XAES). We found a strong increase in the [Cu]/([In] + [Cu]) ratio compared to a bare, Acetic-acid-etched CIGSSe reference. The surface of samples that had been sputter-coated at 150 °C changed from being initially Cu-poor to Cu-rich. The chemical shift of Cu Auger peaks from the same surface confirmed this finding. The increased Cu/In ratio and the chemical shift were reversed after KCN etch. These findings are discussed in the context of the model of a Cu-depleted, wide-band gap surface region in CIGSSe solar cells as a prerequisite for high efficiency.

Synthesis, characterization and antibacterial activity of poly( N-vinylimidazole) grafted chitosan

Poly( N-vinylimidazole) has been grafted onto chitosan in dilute acetic acid solution via ceric ion initiation. The effect of the amounts of N-vinylimidazole monomer, cerium(IV) ammonium nitrate initiator, chitosan substrate, as well as chitosan molecular weight, temperature and reaction time on the grafting yield has been investigated. The maximum grafting yield achieved was 140% in 1.0% (w/V) chitosan solution at 0.2 M N-vinylimidazole, 70 °C within 3 h under nitrogen atmosphere. The grafted products were characterized by gravimetric methods, FTIR and DSC. Grafted chitosans with lower grafting yields less than 108% were completely soluble in neutral water. Products with higher % grafting values swell in aqueous solution. Grafted products have improved antibacterial activity.

Effect of Changes in Relative Humidity and Temperature on Ultrathin Chitosan Films

We have prepared uniform films of chitosan with thicknesses 20 nm < h < 200 nm by spincoating solutions of chitosan dissolved in dilute acetic acid onto silicon substrates while controlling the spin speed and the relative humidity inside the spincoater. After neutralizing the films, they readily absorbed water in the presence of high humidity. Heating of the films to elevated temperatures caused a large irreversible decrease in the film thickness, a small increase in the index of refraction, and a reduction in water absorption, as measured using ellipsometry. Comparisons of infrared absorption measurements of chitosan films collected before and after heating indicate an increase in the degree of acetylation with heating. Collectively, these observations are consistent with the release of bound water and a chemical change similar to acetylation at elevated temperatures.

Linking Adhesive and Structural Proteins in the Attachment Plaque of Mytilus californianus

The byssal attachment of California mussels Mytilus californianus provides secure adhesion in the presence of moisture, a feat that still eludes most synthetic polymers. Matrix-assisted laser desorption ionization mass spectrometry was used to probe the footprints of byssal attachment plaques on glass cover slips for adhesive proteins. Besides the abundant mcfp-3 protein family (Zhao, H., Robertson, N. B., Jewhurst, S. A., and Waite, J. H. (2006) J. Biol. Chem. 281, 11090-11096), two new proteins, mcfp-5 and mcfp-6, with masses of 8.9 kDa and 11.6 kDa, respectively, were identified in footprints, partially characterized and completely sequenced from a cDNA library. mcfp-5 resembles mcfp-3 in its basic pI and abundant 3,4-dihydroxyphenyl-L-alanine (Dopa; 30 mol %), but is distinct in two respects: it is more homogeneous in primary sequence and is polyphosphorylated. mcfp-6 is basic and contains a small amount of Dopa (<5 mol %). In contrast to mcfp-3 and -5, tyrosine prevails at 20 mol %, and cysteine is present at 11 mol %, one-third of which remains thiolate. Given the oxidative instability of Dopa and cysteine at pH 8.2 (seawater), we tested the hypothesis that thiols serve to scavenge dopaquinones by adduct formation. Plaque footprints were hydrolyzed and screened for cysteine dopaquinone adducts using phenylboronate affinity chromatography. 5-S-Cysteinyldopa was detected at nearly 1 mol %. The results suggest that mcfp-6 may provide a cohesive link between the surface-coupling Dopa-rich proteins and the bulk of the plaque proteins.

Structure of the O-antigen of Providencia stuartii O20, a new polysaccharide containing 5,7-diacetamido-3,5,7,9-tetradeoxy- l- glycero- d- galacto-non-2-ulosonic acid

The O-polysaccharide chain of the lipopolysaccharide (LPS) of Providencia stuartii O20 was found to contain d-glucuronic acid, N-acetyl- d-glucosamine, and a rarely occurring higher sugar 5,7-diacetamido-3,5,7,9-tetradeoxy- l- glycero- d- galacto-non-2-ulosonic acid (di- N-acetyl-8-epilegionaminic acid, 8eLeg5Ac7Ac). Degradation of the LPS with dilute acetic acid caused depolymerization of the polysaccharide chain by the ketosidic linkage to give a tetrasaccharide corresponding to the repeating unit of the polysaccharide. Based on sugar and methylation analyses of the tetrasaccharide and O-deacylated LPS as well as ESIMS, 1H and 13C NMR spectroscopy data, the structure of the O-polysaccharide of P. stuartii O20 was established.

Chitosan lactate as a nonviral gene delivery vector in COS-1 cells

The purpose of this research was to evaluate chitosan lactate (CL) of different molecular weights (MWs) as a DNA complexing agent for its efficiency in transfecting COS-1 cells (green monkey fibroblasts) and its effect on cell viability compared with polyethylenimine (PEI), a commercially available cationic polymer. CL and chitosan base dissolved in dilute acetic acid (chitosan acetate [CA]) of different MWs (20, 45, 200, 460 kDa) and N/P ratios (2:1, 4:1, 8:1, 12:1, 24:1) formed complexes with pSV beta-galactosidase plasmid DNA. The complexes were characterized by agarose gel electrophoresis and investigated for their ability to transfect COS-1 cells compared with PEI. Additionally, the effect of CL on the viability of COS-1 cells was investigated using 3-(4,5-dimethyliazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The binding of CL/DNA and CA/DNA was dependent on chitosan MWs. The N/P ratio of CL to completely form the complex with the DNA was higher than that of CA. Both CL and CA were comparable in transfection efficiencies at an N/P ratio of 12:1, but less efficient than PEI (P < .05). The cell viability in the presence of CL and CA at all MWs was over 90%, whereas that of PEI-treated cells was approximately 50%. These results suggest the advantage of CL for in vitro gene transfection, with the ease of preparation of polymer/DNA complexes and low cytotoxicity.

Beneficiation of Mardin-Mazıdaği (Turkey) calcareous phosphate rock using dilute acetic acid solutions

Abstract The dissolution process of the carbonate-rich phosphate rocks from the Kasrik area (Mardin-Mazidagi, Turkey) using dilute acetic acid has been investigated. The work involve to study the effect of the important variables such as reaction time, stirring speed, acetic acid concentration, temperature, particle size fraction, and stoichiometry. It has been found that the P 2 O 5 content of the phosphate rock increases from 12.7 to about 29 wt.% following the dissolution. A mathematical model in the following form was applied to express the dissolution of calcareous material in the rock; −log(1 − X ) = kt m . The dissolution of calcareous material in the phosphate rock has been observed to take place in two steps, the first being fast and the second being slow.

Chemical interactions and yellowing in chitosan-treated cellulose

The chemical interactions between cellulose and chitosan were studied in chitosan-treated celluloses using diffuse reflectance spectroscopic techniques (UV–Vis and FTIR) and fluorescence spectroscopy. The materials were obtained by treating pure cotton cellulose with chitosan in dilute acetic acid solutions of different concentration, and some samples were exposed to different thermal treatments in air. Other related materials, including cellulose treated with benzyl amine and chitosan-treated with acetaldehyde, were also prepared and studied as models for chitosan-treated celluloses. The spectra of the treated celluloses showed new absorption and emission bands that revealed the existence of chemical interactions. These bands were assigned to conjugated imines produced in the reaction of the chitosan amino groups with cellulose carbonyl groups. The reaction is strongly amplified at temperatures above 100 °C, causing the intense yellowing of chitosan-treated celluloses.

Effect of cyclooxygenase inhibitors on the micturition reflex in rats: correlation with inhibition of cyclooxygenase isozymes

To investigate the role of cyclooxygenase (COX) isozymes (COX-1 and -2) in the regulation of bladder volume capacity (BVC) in several rat urodynamic models, using a selection of nonsteroidal anti-inflammatory drugs (NSAIDs), some selective for COX-2, correlating the potency of the tested compounds in the urodynamic models and their in vitro potency as inhibitors of COX isozymes, to verify the relative importance of the different isozymes. The effects of an i.v. administration of several nonselective and selective COX-2 inhibitors (indomethacin, meloxicam, naproxen, aspirin, paracetamol, flurbiprofen, nimesulide, NS-398, celecoxib, rofecoxib and L 745337) on bladder filling and voiding were evaluated in conscious and anaesthetized rats by cystometry. The cystometry was done in conscious rats 1 day after catheter implantation, by filling the bladder with dilute acetic acid (0.2%) or saline, and again with saline 5 days after catheterization. Effects on isovolumic bladder contractions in anaesthetized rats were also evaluated. All the NSAIDs tested dose-dependently increased BVC; their potency at increasing BVC during infusion of the bladder with acetic acid was similar to that evaluated with saline on cystometry 1 day after catheterization. When a nonselective (naproxen) and a selective (nimesulide) COX-2 inhibitor were tested in rats with bladders infused with saline 5 days after catheterization, their effects on BVC were significantly lower than those evaluated at 1 day. All tested compounds dose-dependently inhibited isovolumic bladder contractions in anaesthetized rats. There was a good correlation between the potency in inhibiting the isovolumic bladder contractions in anaesthetized rats and in increasing BVC during cystometry in conscious rats with the bladder infused with acetic acid. The potency of the compounds in the cystometry model with bladders infused with acetic and in the isovolumic bladder voiding contractions correlated well with COX-2 inhibition, but not COX-1. Both nonselective and COX-2 selective inhibitors are more active in inhibiting the micturition reflex in rats with bladder overactivity caused by bladder irritation than in normal rats. The potency of the anti-inflammatory compounds in inhibiting bladder overactivity induced by chemical or surgical irritation, and their activity in a cystometrographic model practically independent of bladder irritation (isovolumic bladder contractions in anaesthetized rats), was related to the potency as inhibitors of COX-2 isozyme. This suggests that the involvement of prostaglandins in the micturition reflex in rats is mainly mediated by this isozyme.

Control of reactive distillation columns for amyl acetate production using dilute acetic acid

This work explores the feasibility of recovery of acetic acid from aqueous solutions with different acid concentrations. Instead of separating acid from water using azeotropic distillation, acetic acid is converted to acetate via esterification. A range of acetic acid concentrations is explored, varying from 100 wt%, to 75 wt%, to 50 wt%, and then to 30 wt%. The Total Annual Cost (TAC) analysis shows that a standalone reactive distillation is more economical than a flowsheet with a pre‐treatment unit. Process characteristics have been explored and the results show significant nonlinearity associated with reactive distillation columns for all four different acid concentrations. A systematic design procedure is devised to control reactive distillation columns by temperature control. Reasonable control performance can be achieved. A further improvement can be made by incorporating feedforward control for feed flow disturbance. Finally, one‐temperature‐one composition control structure is also examined. Acceptable control performance can be obtained while maintaining acetate composition.

Disulfide Proteome Analysis of Buckwheat Seeds to Screen Putative Allergens

ABSTRACTAccumulating evidence suggests a correlation between disulfide bonding and the allergenicity of proteins. Also, a significant characteristic of most food allergens is that they are stable to proteases. We sought to identify putative allergens of buckwheat seed comprehensively by combining a disulfide proteome technique with an in vitro digestibility test. First, a dilute acetic acid fraction of buckwheat seed was found to be rich in disulfide proteins. Internal amino acid sequence analyses of these proteins showed that most of them were known allergens or putative allergens sharing high amino acid sequence similarities to known allergens. Next, the fraction was subjected to in vitro protease digestion, which revealed relatively large fragments that were resistant to prolonged enzymatic digestion. These protease‐resistant fragments contained disulfide bonds that should have protected the potential enzyme cleavage sites by forming compact structures. These results confirm and extend our knowledge of the correlations among the disulfide bonding of proteins, their protease stability, and their allergenicity. Also, these observations suggest a new strategy to identify putative allergens by proteomic approaches as well as to mitigate them.

Process Chemistry and Design Alternatives for Converting Dilute Acetic Acid to Esters in Reactive Distillation

This work explores the recovery of acetic acid aqueous solution with different acid concentrations. Instead of separating acid from water using azeotropic distillation, acetic acid is converted to acetate via esterification. Two questions then arise. First, what is a better choice of alcohol (e.g., ranging from methanol to pentanol, C1−C5) for the esterification? This is a solvent selection problem. Second, what is the more economical process flowsheet (e.g., a stand-alone reactive distillation versus a pretreatment unit followed by a reactive distillation)? For the solvent selection problem, an earlier study [Tang et al., AIChE J. 2005, 51, 1683−1699] has indicated that the esterifications using methanol or pentanol is much more economical as compared to other choices (e.g., ethanol, 2-propanol, or butanol). Quantitative analysis reveals that the production of methyl acetate (from methanol and acetic acid) is not tolerant to acid concentration variation, and a very-high-purity acid feed is needed to achieve product specification. Thus, methanol is ruled out for esterification and pentanol is selected to convert acid to the ester. Next, a systematic design procedure is taken to design the process flowsheets and the total annual cost (TAC) is used to discriminate between different flowsheets, with and without pretreatment unit. A range of acetic acid concentration is explored, varying from 100 wt %, to 75 wt %, to 50 wt %, and then to 30 wt %. The TAC analysis shows that a stand-alone reactive distillation is more economical than the flowsheet with a pretreatment unit.

Suspension of Silver Oxide Nanoparticles in Chitosan Solution and its Antibacterial Activity in Cotton Fabrics

AbstractNew stable silver oxide suspension in chitosan solution was prepared from a mixture of silver nitrate and chitosan in dilute acetic acid as precursor, in which the complex interactions between silver ion and chitosan was also investigated through various instrumentation method seriously. The suspension was charactized through laser scan, infrared ray spectroscopy (IR), ultraviolet-visible spectroscopy (UV-vis) and X-ray diffraction (XRD), which indicated that the interactions between silver and chitosan in its precursor were destroyed partially. The measurements of the nanoparticles through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) disclosed the spherical profiles of these silver oxide nanoparticles of 10-20nm in average. Cotton fabrics treated by this emulsion were entitled remarkable antibacterial activity against S aureus and E. coli at pH 5 and 7 with sightless color effect and good washing fastness.