Potentiometric back titration as a robust and simple method for specific surface area estimation of lignocellulosic fibers

The specific surface area (SSA) of cellulosic or lignocellulosic fibers is seldom reported in the recent literature on papermaking, despite its close relation with the degree of refining and other key pulp properties. Amidst outdated assays (Pulmac permeability test) and methods that, while accurate, are of doubtful usefulness for papermaking purposes (N2 adsorption–desorption), we suggest a methodology based on the cationic demand. A commonly used cationic polyelectrolyte, poly(diallyldimethylammonium chloride) (PDADMAC), became adsorbed onto thermomechanical pulp samples. Then, a potentiometric back titration with an anionic polyelectrolyte measured the cationic demand, expressed as microequivalents of PDADMAC per gram of pulp. Multiplying this value by the surface area of a microequivalent of polymer, considering rod-like conformation in the case of minimum ionic strength, yielded the SSA of the lignocellulosic pulp. Our system assumes that the quaternary ammonium groups were anchored through electrostatic and ion–dipole interactions. Measuring the carboxyl content allowed for discriminating between both kinds of forces. Finally, the model could be validated by plotting the estimated SSA values against the Schopper-Riegler degree, attaining high correlation coefficients (R2 ~ 0.98). Owing to the high molecular weight of the polyelectrolyte of choice (107 kDa), and more particularly in the case of fine-free pulps, SSA values estimated from the cationic demand were consistently lower than those from dye (Congo red) sorption. Instead of being a drawback, the limited diffusion of PDADMAC through fibers can enable papermakers to attain a more helpful quantification of the available surfaces in operations with low residence times.

Volumetric Analysis

Volumetric Analysis describes the general process of quantifying acid-base reactions by titration in which the known concentration of one solution (often a standard solution) is used to determine the unknown concentration of another. Common terms are defined, and calculations involving acid-base titration based on the concept of reaction stoichiometry, number of moles, mole ratio and molarity are discussed. The treatment is then broadened to include calculations involving mass and percentage of substance titrated. Back (or indirect) titration, a method to determine the concentration of a volatile substance or an unknown solid that is insoluble or only partly soluble in water, is described. The Kjeldahl method of determining the nitrogen content in organic and inorganic samples is used to illustrate back titration.

Titration of chelating fibrous sorbent in the presence of complex-forming divalent cations

Titration curves of H-forms of the fibrous chelating sorbent with iminodiacetic groups based on industrial polyacrylonitrile fiber Nitron with potassium hydroxide in 1M KCl solution in the presence of Ni2+, Co2+, Cu2+ and Ca2+ chlorides were obtained. The method used made it possible to simultaneously measure the pH of the solution and the concentration of the divalent cation at each point of the titration curve. From these data, the dependences of their sorption values on the pH of the equilibrium solution were calculated. The curves of direct and back titration practically coincided in all cases. As the pH changed during titration, precipitation was observed at pH values of precipitation of the corresponding hydroxides. In this case, the increase in pH was suspended or greatly slowed down by adding alkali to the titration cell. The formation of a precipitate occurred mainly in a solution for Co2+ and Ni2+ (pH 8), when the ion exchanger was saturated with a metal ion. In the case of Cu2+ (precipitate formation pH 4), Cu2+ sorption occurs at both lower and higher pH due to ionization of carboxyl groups and partial dissolution of the precipitate. In all cases, the maximum sorption of Ni2+, Co2+, Cu2+, Ca2+ corresponded to the formation of sorption complexes of the R–N(CH2COO-)2Me2+ type.

Comparison of Acid-neutralizing capacity of antacids in Erbil City

Background and objective: Antacids are basic substances that can neutralize hydrochloric acid and reduce gastric acidity. They are over the counter drugs used to treat dyspepsia. The most commonly used antacids are sodium bicarbonate, magnesium hydroxide, aluminum hydroxide, and calcium carbonate. This study aimed to evaluate the effectiveness of antacids that are commonly used in Erbil city by finding their acid-neutralizing capacity. Methods: The method for acid-neutralizing capacity was adapted from pharmacopeia. The samples were prepared by dissolving the antacid in an excess amount of hydrochloric acid, then neutralizing the excess acid with sodium hydroxide solution by doing back titration. The number of milliequivalents that are neutralized by the antacid is the acid-neutralizing capacity of the antacid. Results: Rennie® chewable tablet showed the highest acid-neutralizing capacity, followed by AntacidAwa and Maalux® plus. The lowest acid-neutralizing capacity was for the suspensions Gaviscon® and Enoxon®. Conclusion: Acid-neutralizing capacity is an easy and quick method to evaluate the efficacy of antacids. Different combinations of salts and concentrations can affect the acid-neutralizing capacity of the antacid. The higher the neutralizing effect of the antacid, the more effective the antacid is. Keywords: Acid-neutralizing capacity; Antacid; pH; Dyspepsia; Erbil.

New Thermal Latent Catalyst Using Titanium and Organic Ligand for Urethane Polymerization

New thermal-latent metal catalyst such as tetrakis (lauorate) titanium (LPTi) was designed and synthesized based on a lauroyl peroxide and titanium. The synthetic method is simple with one step reaction. LPTi structure was confirmed by FT-IR analysis, also nano-sized structure of LPTi confirmed using SEM-EDX. LPTi is thermal-latent metal catalyst including titanium that not only promotes urethane synthesis reaction but also increases the dissociation rate of blocked isocyanate. As a result of quantitative analysis of NCO (%) through back titration, when LPTi was added, NCO (%) increased from 2.34% to 3.24%. LPTi can be used as an excellent catalyst for urethane reaction by reducing the polymerization time by about 30% compared to no catalyst. LPTi can be applied to the electronic polymer synthesis.

A study on highly concentrated lactic acid and the synthesis of lactide from its solution

Lactic acid is an important platform compound used as raw material for the production of lactide and polylactic acid. However, its concentration and composition distribution are not as simple as those of common compounds. In this work, the mass concentration distribution of highly concentrated lactic acid is determined by back titration. The components of highly concentrated lactic acid, crude lactide, and polymer after the reaction are analyzed by HPLC. Different concentrations of lactic acid solution were prepared for the synthesis of lactide and its content in the product was determined by 1H NMR analysis. We found that lactide is more easily produced from high-concentration lactic acid solution with which the condensed water is easier to release. Hence, the removal of condensed water is crucial to the formation of lactide, although it is not directly formed by esterification of two molecules of lactic acid.

Carboxymethyl Glucomannan from Amorphophallus oncophyllus as an Alternative Heavy Metal Removal from Wastewater: Adsorption of Cadmium and Zinc

Carboxymethyl glucomannan (CMGM) was successfully synthesized through the reaction of glucomannan from Amorphophallus oncophyllus and monochloroacetic acid, using NaOH as a catalyst. Two types of glucomannan were used in this study, low viscosity glucomannan (LGM) and high viscosity glucomannan (HGM). The produced CMGM were differentiated into LCMGM (synthesized from LGM) and HCMGM (synthesized from HGM). The CMGM structure was characterized by FTIR, and the degree of substitution (DS) was determined using back titration method. The DS value were 0.484 and 0.412 for LCMGM and HCMGM, respectively. Both CMGMs were then evaluated for its adsorption capacity towards Zn and Cd at the optimum pH of 6, with 60 minutes adsorption time for each sample. The maximum adsorption capacity of Zn was 13.61 mg/g and 13.04 mg/g for LCMGM and HCMGM, respectively. While for Cd, the maximum adsorption capacity of LCMGM and HCMGM was 17.70 mg/g and 15.90 mg/g. The adsorption capacity of the sample follows the Langmuir isotherm adsorption. In conclusion, CMGM from A. oncophyllus has demonstrated its potential as a reusable adsorbent for efficient removal of Cd and Zn.

Degradation of Nonylphenol Ethoxylate-10 (NPE-10) by Mediated Electrochemical Oxidation (MEO) Technology

Nonylphenol ethoxylate (NPE-10) is a non-ionic surfactant that is synthesized from alkylphenol ethoxylate. The accumulation of NPE-10 in wastewater will endanger the ecosystem as well as the human being. Nowadays, NPE-10 can be degraded indirectly by using an electrochemical treatment by the advancement of technology. Thus, this study is aimed to evaluate the electro-degradation potential of NPE-10 by MEO using Ce(IV) ionic mediator. In addition, the influence of Ag(I) ionic catalyst in the performance of MEO for the degradation of NPE-10 was also observed. The potency of MEO technology in the NPE-10 degradation was evaluated by voltammetry technique and confirmed by titrimetry and LC-MS analysis. The results showed that in the absence of Ag(I) ionic catalyst, the degradation of NPE-10 by MEO was 85.93%. Furthermore, when the Ag(I) ionic catalyst was applied, the performance of MEO in degradation of NPE-10 was improved to 95.12%. The back titration using Ba(OH)2 confirmed the formation of CO2 by 46.79%, whereas the redox titration shows the total of degradation organic compounds by 42.50%. It was emphasized by the formation of two new peaks in the LC-MS chromatogram. In summary, our results confirmed the potential of MEO technology for the NPE-10 degradation.

Comparison of the Effects of the Cationization of Raw, Bio- and Alkali-Scoured Cotton Knitted Fabric with Different Surface Charge Density

Modification of cotton with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) has been studied extensively and can be operated by means of exhaustion, cold pad-batch, and continuous and pad-steam methods. Most of the research addresses the cationization of cotton fabric after bleaching or mercerization, or during the mercerization process. In our studies, we performed a comparison of the cationization effects on raw, enzymatic, and alkali-scoured cotton knitted fabrics applying CHPTAC according to the exhaustion method. The charge density of the cotton surface was measured using a Muetek Particle Charge Detector and a “back titration” method with polyelectrolytes. These results were compared with the nitrogen content in the samples, K/S measurements of tested samples after dyeing with anionic dye (Acid Yellow 194), and other physicochemical parameters such as weight loss, whiteness, and wettability.

Titrimetric Analysis of Chloride Concentration in Beers using Synthetic Mercury(II) Compound

The monothiocyanato-mercuric(II) nitrate [Hg(SCN)NO3] reagent has been prepared synthetically in an aqueous medium and subjected for studies of titrimetric analysis of chloride concentration in beers. In this studies, a measured volume of beer sample was added into known and an excess amount of Hg(SCN)NO3 reagent and the surplus Hg(SCN)NO3 was determined by back titration against standard potassium thiocyanate (KSCN) solution using ferric nitrate [Fe(NO3)3] indicator. The chloride ion and Hg(SCN)NO3 were found to be reacting in the 1:1 stoichiometric ratio. The amount of chloride in beer was determined with the amount of Hg(SCN)NO3 utilized in the titration reaction. The presence of organic and inorganic materials had no effect on the titrimetric assay of chloride concentration in beers as proved by the chloride recovery experiment. The statistical analysis of results showed average standard deviation of 0.01034 and average relative error 1.12%, which indicates the accuracy of the procedure.