Dilute Alkaline Solution Research Articles

Intrinsic CO2 nanobubbles in alkaline aqueous solutions

Nanobubbles (NBs) and their derivative, bulk nanobubbles (BNBs), have been widely studied due to their potential wide range of applications. However, the stable existence of intrinsic NBs and BNBs in solutions is still controversial. This study investigates the existence and behaviour of unknown nano-entities in dilute alkaline solutions using Field-Flow Fractionation Multi-Angle Light Scattering (FFF-MALS), resulting in the first report of the presence, size distribution, and size distribution changes under different treatments. The results suggest that neutral and acidic pure solutions of salts at concentrations below the solubility product do not contain detectable nano entities. Alkaline solutions, on the other hand, such as carbonate buffer and sodium hydroxide, do contain nano scatterers in the range of ∼100 nm diameter that cannot be removed by boiling or filtration. Reducing the pH of the solutions or freezing reduces their number densities. The freeze-thaw procedure strongly suggests that these nano entities are BNBs. Zeta Nanoparticle Tracking Analysis (ZNTA) shows the zeta potential and the concentration in agreement with previous literature. It can be concluded that intrinsic BNBs in alkaline solutions are an integral part of the total nano-entity population. This study highlights the importance of considering intrinsic BNBs when investigating nanoparticles in alkaline solutions with analytical methods such as Static Light Scattering (SLS), which can detect low number densities in the original liquid state that may not be plausible by other detection methods due to their detection thresholds or acquisition of sample preparation methods of drying or freezing that do not allow real-time observations.

Preparation and Characterization of Cellulose Derivatives from Agricultural Wastes

Background: Rice straw was pretreated with dilute alkaline and acid solutions to extract cellulose, which was then converted into cellulose acetate with acetic anhydride and phosphotungstic acid (H3PW12O40·6H2O). The concentration of KOH and the duration of immersion in acetic acid solution affected the removal of hemicellulose and lignin, and after pretreatment with 4% KOH and immersion in acetic acid for 5 hours, the treated rice straw contained 83wt.% cellulose. Phosphotungstic acid has been shown to be an excellent catalyst for the acetylation of rice straw cellulose. The degree of substitution (DS) values had a substantial effect on the solubility of cellulose acetate, and acetone-soluble cellulose acetate with DS values about 2.2 can be generated by varying the amount of phosphotungstic acid and acetylation duration. Objectives: The aim of the study was to evaluate the preparation and characterization of cellulose derivatives from agricultural wastes. Methods: This cross-sectional study was carried out in the Department of Communicable Diseases Control, Director General of Health Services, Dhaka, Bangladesh. For this investigation the rice plant straw was collected from Magura district region. The collected straws were then treated with 3 wt% nitric acid and 1.5 wt% NaOH solution separately. Statistical analyses of the results were be obtained by using window-based Microsoft Excel and Statistical Packages for Social Sciences (SPSS-24). Results: This study observed that the rice straw contained about 35.67% cellulose, 5.50% hemicellulose and 30.18 % α-cellulose. And the wheat straw contained about 43.99% cellulose, 7.30% hemicellulose and 36.70% α-cellulose. The degree of acetylation and degree of substitution of the synthesized cellulose acetate from rice straw were 39.046% and 2.413 respectively. On the other hand, the degree of acetylation and degree of substitution of the synthesized cellulose acetate from wheat straw were 40.79% and 2.59 respectively. ....

Riboflavin Crystals with Extremely High Water Solubility.

New insights into the unique biochemical properties of riboflavin (Rf), also known as vitamin B2, are leading to the development of its use not only as a vitamin supplement but also as a potential anti-inflammatory, immunomodulatory, antioxidant, anticancer, and antiviral agent, where it may play a role as an inhibitor of viral proteinases. At the same time, the comparison of the pharmacoactivity of Rf with its known metabolites, namely, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), is very complicated due to its poor water solubility: 0.1-0.3 g/L versus 67 g/L for FMN and 50 g/L for FAD, which is the limiting factor for its administration in clinical practice. In this study, we report the recrystallization procedure of the type A Rf crystals into the slightly hydrophobic type B/C and a new hydrophilic crystal form that has been termed the P type. Our method of Rf crystal modification based on recrystallization from dilute alkaline solution provides an unprecedented extremely high water solubility of Rf, reaching 23.5 g/L. A comprehensive study of the physicochemical properties of type P riboflavin showed increased photodynamic therapeutic activity compared to the known types A and B/C against clinical isolates of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhimurium. Importantly, our work not only demonstrates a simple and inexpensive method for the synthesis of riboflavin with high solubility, which should lead to increased bioactivity, but also opens up opportunities for improving both known and new therapeutic applications of vitamin B2.

Structural characterization and in vitro anti-colon cancer activity of a homogeneous polysaccharide from Agaricus bisporus

Colon cancer is the third most prevalent cancer and the second most deadly cancer in the world. Anti-colon cancer activity of Agaricus bisporus polysaccharides has not been studied. In this paper, Agaricus bisporus polysaccharides were sequentially extracted by room temperature water, hot water, high pressure hot water, dilute alkaline solution and concentrated alkaline solution. A homogeneous polysaccharide (WAAP-1) was obtained using DEAE Cellulose-52 column. Physicochemical properties, structural characterization and anti-colon cancer activity of WAAP-1 were investigated. The results showed that WAAP-1 was a neutral polysaccharide with molecular weight of 10.1 kDa. The monosaccharide composition was glucose, mannose and galactose with a molar ratio of 84.95:8.97:4.50. The main chain was mainly composed of (1,4)-α-D-Glcp and (1,6)-β-D-Manp. In vitro anti-colon cancer results showed that WAAP-1 could significantly inhibit proliferation of colon cancer cell HT-29. It promoted apoptosis and inhibited epithelial mesenchymal transition of HT-29 by up-regulating the expression of Caspase-3, Bax and E-cadherin proteins and down-regulating the expression of Bcl-2 and Vimentin proteins. The results provided new potential possibilities for the development of novel functional foods or antitumor drugs.

Perspective on pH adjustment in hydrometallurgical recycling of valuable metals from waste.

pH adjustment was considered a simple step in the hydrometallurgy process, but its complicated operation was ignored in the past. In some industrial applications, the leachate pH was slowly adjusted by a diluted alkaline solution, with the defects of doubling the leachate volume and causing droplet hydrolysis/coagulation. Up to date, promising routes have been developed for rapid pH adjustment, especially in sealed high-temperature/pressure vessels. New routes emerged in some redox/decomposition reactions of nitrate/urea and organics. Such reactions did not start and/or were slow at room temperature but started spontaneously at high temperatures to generate/consume free H+. This induced pH adjustment in a rapid and homogeneous way.

Multi-Techniques for Iodine Determination and Dose Uniformity Assays in Iodized Mineral Dietary Supplements

The determination of iodine in iodized mineral dietary supplements is considered a challenge, especially in view of the variety in the sample composition and the analyte concentration. Thus, in this work, microwave-induced combustion (MIC) was combined with ion chromatography (IC) and ion-selective electrode potentiometry (ISE) for iodine determination and dose uniformity assays in mineral dietary supplements. Sample masses up to 800 mg were efficiently digested and only a diluted alkaline solution (200 mmol L-1 NH4OH) was necessary to absorb the analyte for further determination step. The final digest was fully compatible with multi-technique detection usually available in routine analysis laboratories. Recoveries ranging from 94% to 106% was achieved and relative standard deviations for repeatability and intermediate precision were always lower than 8%. Limits of quantification were 4 µg g-1 and 10 µg g-1, respectively, by using IC and ISE. The analytical method was applied for iodine determination in mineral dietary supplements from four brands with different iodine dosages (from 100 to 1250 μg g-1, according to the manufacturers) and for uniformity assay evaluation using individual tablets/capsules of mineral dietary supplements. Non-compliance regarding label information for some samples was reported, drawing the attention of supervisory institutions. The analytical strategies presented in the present study can be successfully used in routine analysis of the quality control of mineral dietary supplements.

Effect of high volume tile ceramic wastes on resistance of geopolymer mortars to abrasion and freezing-thawing cycles: Experimental and deep learning modelling

Utilizing industrial and agriculture waste materials to produce a green and sustainable mortar have widely investigated and assessed based on the mechanical and durability properties. Herein, the abrasion and freezing-thawing resistance of fly ash (FA)-ground blast furnace slag (GBFS) based geopolymer mortars incorporating high content of tile ceramic wastes (TCWs) have been evaluated experimentally and mathematically using artificial neural network (ANN). A relatively dilute (4 M) alkaline solution was used to activate the ternary blend. The TCWs was maintained as a relatively large percentage of the total binder, i.e. 50%, 60% and 70%. Once the casting process was complete, curing of the samples was performed at 27 °C. These then underwent testing at day 1, day 3, day 7 and day 28 to provide durability data for various specimen ages. Tests encompassed exposure to abrasion, ability to withstand cyclic freeze-thawing and wet-drying, and permeability to water. Investigations to establish the impact of the high TCWs proportion on the generation of sodium aluminium, calcium aluminium and calcium silicate hydrate (N, C-A-S-H) gels, respectively, included X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy. The large percentage of TCWs (70%) generated GPMs that had a minimal effect on the environment and which, by day 28, evidenced a compressive strength above 35 MPa. Augmenting the GBFS and FA content promoted the capacity to withstand freeze-thawing cycles and enhanced durability. Improved performance was also observed in scenarios associated with abrasion resistance. In addition, the proposed models proved their accuracy in which MSE, MAPE, SI were less than 1.93, while R2 of greater than 0.9 confirmed the closeness between predicted and actual results. Substitution of TCWs and FA for GBFS additionally reduced landfill problems of ceramic wastes and achieved the sustainability aims.

The Influence of pH of Float on the Dyeability of Polyester Fabric

Disperse dyes are essentially non – ionic, exhibit poor solubility in water, and they can be used in the form of water dispersion. Polyester fibres are resistant to dilute aqueous acids and alkaline solutions and pH value does not provide a crucial impact on the dyeing mechanism; however, many disperse dyes undergo degradation if the pH is uncontrolled during aqueous dyeing. In order to minimize the possibility of dye hydrolysis, the dyeing is carried out in a slightly acidic medium, and pH is usually adjusted with acetic acid. In this work, the quantity of disperse dyes (Sinten Gelb P-5GL and Sinten Scharlach P-3GL) applied to polyester knitwear was investigated as a function of pH. The sorption capacity of polyester knitwear was monitored by using reflection curves and CIELab system, according to Swiss software Sandoz (based on spectrophotometry). The acetic acid was used for dyebath pH adjustment. The results showed that the maximum uptake of Sinten Gelb P-5GL and SintenScharlach P-3GL dyes by polyester knitwear occurred at pH 4.64 (0.2924%) and 6.20 (0.1860%), respectively. According to reflection curves in the range (max = 400-700 nm), the effect of pH on the sorption of Sinten Gelb P-5GL was more significant than one for Sinten Scharlach P-3GL, when concentration of dye is constant (0.4%). The CIELab values for three illuminants (daylight, light – bulb and incandescent) showed a significant dependence between pH float and hue and intensity of polyester knitwear dyeing with disperse dyes

Analytical profiling of Lentinan in hybrid nanostructures for intranasal Delivery: Method development and Validation

Lentinan (LNT) a polysaccharide obtained from mushroom Lentinus edodes, possesses potent anticancer and antitumor activity. To improve the bioavailability, encapsulation of LNT in polymer -lipid hybrid nanostructures (PLHNs) is done and administration via nasal pathway will bypass hepatic first-pass metabolism, which possibly will give high prospect for treatment of brain tumors. The estimation of entrapped LNT within Hybrid Nanostructures is one of the important parameters for the characterization of nanoparticles. Therefore, an analytical method was developed and validated for estimating plain LNT and LNT-PLHNs in Nasal Simulated Fluid (NSF) by conjugating with Congo Red (CR) in dilute alkaline solutions by employing high-performance liquid chromatography (HPLC). The developed method was validated for selectivity, linearity, precision, accuracy, robustness. The linearity was checked over the concertation range of 2–10 μg/mL the and limit of detection (LOD) and limit of quantification (LOQ) were 38.02 ± 0.21 ng/mL and 86.71 ± 0.82 ng/mL respectively. The mean percent recovery of LNT was 99.18 %; relative standard deviation (RSD) of 0.386 % and intra- and interday coefficient of variation was <2 %. The developed HPLC method was found suitable for assessing percent entrapment efficiency (%EE), in-vitro drug release, intracellular uptake study and stability profile of LNT-PLHNs obtained by solvent injection technique.

Mathematical Modelling of Alkaline and Ionic Liquid Pretreated Coconut Husk Enzymatic Hydrolysis

The problem of crude oil reserve shortage and air quality decline currently have led researches on renewable fuel such as bioethanol and biohydrogen. The attempt to provide such biofuel involves the utilization of enormously available wasted materials, lignocellulose. Coconut husk is one of such materials available in Indonesia. The previous work had reported the quantity of total reducing sugar produced after the enzymatic hydrolysis of pretreated coconut husk. The pretreatment methods used were dilute sodium hydroxide solution (1 and 4% w/v), 1,3-methylmethylimidazolium dimethyl phosphate ionic liquid and the combination of both methods. This work focused on constructing the mathematical model which describes the kinetic of those enzymatic hydrolysis reactions. Mathematical model expressions help describing as well as predicting the process behavior, which is commonly needed in the process design and control. The development of mathematical model in this work was done based on the total reducing sugar concentration resulted in batch hydrolysis reaction. The kinetic parameters including initial available substrate (S0), maximum reaction rate (rmax), and half-maximum rate constant (KM). According to the values of half-maximum rate constant (KM), the enzymatic hydrolysis performance of coconut husk treated using ionic liquid is better than that treated using dilute alkaline solution as the former had shown lower KM value and hence higher enzyme affinity to the substrate. The best hydrolysis result was performed using combination of 1% dilute sodium hydroxide solution and ionic liquid with kinetic model parameter of 0.5524 g/L.h of rmax, 0.0409 g/L of KM, and 4.1919 g/L of S0. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Purification and concentration of antioxidative dipeptides obtained from chicken extract and their application as functional food

In Japan, about 150,000 tons of egg-laying hens are discarded annually because quality of their meet is low. In order to add further value to carcasses of the spent egg-laying hens and utilize them, an efficient purification and concentration process for functional dipeptides in chicken extract obtained from these carcasses was developed in this study by combining ion-exchange chromatography and nanofiltration (NF) treatment. The functional dipeptides, Anserine and Carnosine, consisting of β-alanine and L-histidine (ACmix), showed a basic property and could be adsorbed directly onto a cation exchange resin. The ACmix were completely separated from other chicken extract elements when the chicken extract was passed through the column packed with cation exchanger and the dipeptides were eluted from the column by using diluted alkaline solution. Major contaminated substances in the ACmix after ion-exchange chromatography were Na+, K+ and creatinine. A NF membrane could remove these contaminants and concentrate ACmix without any heat treatment. Based on the results of pilot scale experiments, a mathematical model which could express efficiency of a NF process was newly proposed. By using the mathematical model, an industrial scale NF process which could process 3.6 tons of carcasses in a day were designed, where minimum purify and yield of ACmix in the final product were set at 90% and 95%, respectively. The ACmix had an antioxidant activity specifically to hypochlorite radicals and markedly reduced an oxidative stress in normal human volunteers in combination with vitamin C and ferulic acid.

Thermal characteristics of birch and its cellulose and hemicelluloses isolated by alkaline solution

AbstractCellulose and hemicelluloses were isolated from birch wood using a dilute alkaline solution and then consolidated into pellets as model compounds of cellulose and hemicelluloses in the wood cell wall. The purity of isolated cellulose and hemicelluloses was examined by Fourier-transform infrared spectroscopy and thermogravimetric analysis. The density, thermal diffusivity, heat capacity, and thermal conductivity were experimentally determined for consolidated birch powder, cellulose, and hemicelluloses in over-dry condition. The thermal degradation kinetic parameters of these materials were successfully calculated using a conversion rate step of 0.01, and the relationship with conversion rate was established. The results show that cellulose and hemicelluloses consolidated under 25 MPa had densities of 1362 kg/m3and 1464 kg/m3, respectively. The cell wall of birch powder in the oven-dry state was not collapsed under 25 MPa. The thermal diffusivity of consolidated birch powder, cellulose, and hemicelluloses linearly decreased with temperature, with values of 0.08, 0.15, and 0.20 mm2/s at room temperature, respectively. The specific heat capacity (1104, 1209, and 1305 J/(kg·K) at 22 °C, respectively) and thermal conductivity (0.09, 0.24, and 0.38 W/(m·K) at 22 °C, respectively) linearly increased with temperature, except for those for hemicelluloses which exhibited a nonlinear relationship with temperature above 120 °C, and their linear experimental prediction equations were given. Birch cellulose was more thermally stable than hemicelluloses. The thermal degradation kinetic parameters including activation energy and pre-exponential factor of birch powder, cellulose, and hemicelluloses varied with the conversion rate and calculation methods, with average activation energy in a conversion rate range of 0.02–0.15 of 123.2, 159.0, and 147.2 kJ/mol, respectively (using the Flynn–Wall–Ozawa method), for average natural logarithm pre-exponential factors of 25.0, 33.1, and 28.7 min−1, respectively. Linear and quadratic equations were fitted to describe the relationship between the kinetic parameters and conversion rates. These results give comprehensive thermal properties of the densified cellulose and hemicelluloses isolated from a specific wood.

Preparation and characterization of films from Chicken feathers for dye adsorption

Chicken feathers were partially hydrolyzed using dilute alkaline solutions in presence of thiourea, then dithiocarbamylated by treatment with carbon disulphide. Product was blended with polyvinyl alcohol to cast into environmentally friendly films. These films were characterized by FTIR spectroscopy, powder X-ray diffractometry, scanning electron and atomic force microscopies, and differential scanning calorimetry. Adsorption studies were carried out in 10–30 mg/L concentration range of dyes at 281, 291, and 301 K and pH 4, 7, and 9. The adsorption mechanism was analysed by applying various kinetic and isotherm models. Maximum adsorption capacity was found to be 714.3 mg/g at 281 K for methylene blue and 555.6 mg/g at 301 K for crystal violet from aqueous solutions.

Are there feasible strategies for determining bromine and iodine in human hair using interference-free plasma based-techniques?

An effective analytical method for bromine and iodine determination in human hair using interference-free inductively coupled plasma mass spectrometry (ICP-MS) was developed. Human hair was digested based on combustion reaction to obtain compatible solutions with ICP-MS analysis. Using microwave-induced combustion (MIC), masses of human hair ranging from 50 to 300 mg were efficiently digested. Only a diluted alkaline solution (100 mmol L−1 NH4OH) was used for the absorption of both analytes, which was fully compatible with ICP-MS analysis. Using these conditions low limits of detection were obtained (LOD of 0.01 μg g−1 for Br and 0.004 μg g−1 for I). Recovery tests at two levels (50% and 100%) using a standard solution or mixtures of the sample with certified reference materials (CRMs) were carried out to evaluate the suitability of proposed method and recoveries between 94% and 102% were always obtained. Accuracy was evaluated by analysis of a human hair CRM, and the Br and I concentrations obtained by the proposed method did not differ significantly from those described in the certificate. Repeatability (RSDs ≤ 4%) and reproducibility (RSDs ≤ 7%) of the results using proposed method were always very suitable. The digests obtained using the MIC method were fully compatible with ICP-MS and the interferences currently found using conventional digestion methods were completely eliminated. Ultra-trace concentrations of Br and I were determined in human hair, demonstrating that the proposed method is a suitable strategy, and it presents several advantages compared to others published in the literature.

Engineering of a Bacillus subtilis Strain Deficient in Cellulase: Application in Degumming of Ramie

Degumming is the most important step before ramie fibers are used in textile industry. Conventional chemical degumming technology with alkaline treatment at high temperature causes critical problems in environment. In addition to multiple degumming enzymes (e.g. pectinases and xylanases), Bacillus subtilis strain 168 can also produce cellulase which brings irreversible damage to ramie fibers. In this study, a strain deficient in cellulase was constructed by insertional inactivation of gene eglS to make it suitable for microbial degumming. Results showed that the cellulase activity was not detected in strain ΔeglS, after 25 h of incubation with strain ΔeglS, the weight loss of the ramie fibers was 20.20 %. Though the residual gum content of ramie fibers obtained in microbial degumming process was 19.67 %, microbial intervention followed by diluted alkaline solution treatment showed lower residual gum content (2.73 %) than chemical degumming (2.96 %). The single fiber breaking strength value of ramie fibers from bio-chemical degumming process reached 27.19 cN, which was the highest of three samples. Moreover, bio-chemical degumming process resulted in a 75 % decrease of alkali dosage as compared with chemical degumming process. This study provides a suggestion to genetically modify wild-type strain in order to protect ramie fibers from cellulase damage, and indicates a sustainable alternative for the traditional chemical degumming in the textile industry.

Easy preparation of nanoporous Ge/Cu3Ge composite and its high performances towards lithium storage

Nanoporous Ge/Cu3Ge composite is fabricated simply through selective dealloying of GeCuAl precursor alloy in dilute alkaline solution. The as-made Ge/Cu3Ge is characterized by three dimensional (3D) bicontinuous network nanostructure which comprises of substantial nanoscale pore voids and ligaments. Owing to the 3D porous architecture and the introduction of well-conductive Cu3Ge, the lithium storage performances of Ge are dramatically enhanced in terms of higher cycling stability and superior rate performance. Nanoporous Ge/Cu3Ge anode delivers steady capacities above 1000 mA h g−1 upon cycling for 70 loops at 400 mA g−1. In particular, after 300 cycles at the high rate of 3200 mA g−1 the capacity retention for Ge/Cu3Ge is able to reach a maximum of 99.3%. On the contrary, the pure nanoporous Ge encounters severe capacity decay. In view of the outstanding energy storage performances and easy preparation, nanoporous Ge/Cu3Ge exhibits great application potential as an advanced anode in lithium storage related technologies.

Bromine and iodine determination in human saliva: Challenges in the development of an accurate method

In this work, an analytical method for bromine and iodine determination in human saliva was proposed. A simple protocol based on centrifugation and direct analysis of supernatant by inductively coupled plasma mass spectrometry (ICP-MS) was investigated. Although this method was feasible for bromine determination, iodine was partially present in the supernatant and an agreement about 54% with reference value was obtained. In addition, microwave-induced combustion (MIC) and microwave-assisted dissolution were also evaluated. Using MIC, 0.2 mL of saliva added on 300 mg of microcrystalline cellulose were efficiently digested. A diluted solution (50 mmol L−1 NH4OH) was used for analytes absorption, and a reflux step of 5 min was applied to ensure quantitative recoveries of Br and I. Accuracy was evaluated by analyte recovery experiments, and recoveries between 94% and 98% were obtained. Microwave-assisted dissolution was evaluated for 2.0 mL of saliva using also a diluted alkaline solution (25 mmol L−1 NH4OH) and a microwave irradiation program of 35 min (including the cooling step). Results for this method agreed with those obtained using MIC. Although MIC has also been appropriated for further determination of Br and I in saliva, microwave-assisted dissolution can be considered a simpler sample preparation method and it was effective for high amount of sample (up to 2.0 mL). Moreover, final solutions were compatible with ICP-MS analysis, allowing the quantification of Br and I in human saliva at ultra-trace concentrations (limits of quantification were 0.052 μg mL−1 for Br and 0.022 μg mL−1 for I).

Thiol‐ene photofunctionalization of 1,4‐polymyrcene

Abstract1,4‐Polymyrcene was synthesized by anionic polymerization of β‐myrcene and was subjected to photochemical functionalization with various thiols (i.e. methyl thioglycolate, methyl 3‐mercaptopropionate, butyl 3‐mercaptopropionate, ethyl 2‐mercaptopropionate and 2‐methyl‐2‐propanethiol) using benzophenone/UV light as the radical source. The yield of thiol addition to the trisubstituted double bonds of 1,4‐polymyrcene decreased in the order 1° thiol (ca 95%) &gt; 2° thiol (ca 80%) &gt; 3° thiol (&lt;5%), due to the reversibility of the thiol‐ene reaction. Remarkably, thiol addition to the side‐chain double bonds was 8 − 10 times (1° thiol) or 24 times (2° thiol) faster than to the main‐chain double bonds, which can be explained by the different accessibility of the double bonds and steric hindrance. Despite the use of a 10‐fold excess of thiol with respect to myrcene units, the thiol‐ene addition was accompanied by chain coupling reactions, which in the extreme case of 3° thiol (or in the absence of thiol) resulted in the formation of insoluble crosslinked material. As an example, a methyl‐thioglycolate‐functionalized 1,4‐polymyrcene was saponified/crosslinked to give submicron polyelectrolyte particles in dilute alkaline solution. © 2018 Society of Chemical Industry

A simple and automated sample preparation system for subsequent halogens determination: Combustion followed by pyrohydrolysis

A simple and automated system based on combustion followed by a pyrohydrolysis reaction was proposed for further halogens determination. This system was applied for digestion of soils containing high (90%) and also low (10%) organic matter content for further halogens determination. The following parameters were evaluated: sample mass, use of microcrystalline cellulose and heating time. For analytes absorption, a diluted alkaline solution (6 mL of 25 mmol L−1 NH4OH) was used in all experiments. Up to 400 mg of soil with high organic matter content and 100 mg of soil with low organic matter content (mixed with 400 mg of cellulose) could be completely digested using the proposed system. Quantitative results for all halogens were obtained using less than 12 min of sample preparation step (about 1.8 min for sample combustion and 10 min for pyrohydrolysis). The accuracy was evaluated using a certified reference material of coal and spiked samples. No statistical difference was observed between the certified values and results obtained by the proposed method. Additionally, the recoveries obtained using spiked samples were in the range of 98–103% with relative standard deviation values lower than 5%. The limits of quantification obtained for F, Cl, Br and I for soil with high (400 mg of soil) and low (100 mg of soil) organic matter were in the range of 0.01–2 μg g−1 and 0.07–59 μg g−1, respectively. The proposed system was considered as a simple and suitable alternative for soils digestion for further halogens determination by ion chromatography and inductively coupled plasma mass spectrometry techniques.

Metam Sodium (MS) in Water and Cane Juice at Different Processing Conditions According to the Industrial Case. Part 1. Effects of Matrix, pH, Temperature, Processing Time, and Photolysis

The process for extracting sugarcane juice (Saccharum officinarum) represents the point of greatest contamination in sugarcane mills. Sodium dithiocarbamate also known as metam-sodium or MS is added to inhibit the growth of microorganisms especially Leuconostoc mesenteroides which is responsible for forming polysaccharides. Metam-sodium, upon decomposition, produces highly toxic byproducts. According to literature, under acidic conditions, MS is hydrolyzed resulting in methylamine (MA), CH3NH2, and carbon disulfide (CS2), and in dilute alkaline solutions, MS produces an oxidation reaction characterized by the formation of elemental sulfur (S) and methyl isothiocyanate (MITC). In this paper, it was studied how MS decomposes to MITC and/or MA considering the effects of the matrix (methanol and water); of temperature (4 and 25 °C); of processing time (0, 1, 2, 3, 4 days); and of pH (4.0, 4.5, 7.0). A second experimental design considering the effects of the matrix (water and sugarcane juice); of temperature (4, 25, 35, 45 °C); of processing time (30, 300 min); and of pH (4.0, 4.5, 7.0) was derived from the results obtained considering MITC and/or MA formation. According to the statistical analysis of these results (p matrix > pH > temperature. Results also indicated that the water matrix at pH = 4.5 and 45 °C had the lowest degradation rate (k), with a value of 8.82 day−1, while for the sugarcane juice matrix at the same pH and temperature conditions was larger, with a k value of 30.07 day−1. These results show that the matrix is also important for the degradation of dithiocarbamate to MITC and to MA.