CaCl2 Concentration Research Articles

Enhanced contaminant retardation by novel modified calcium bentonite backfill in slurry trench cutoff walls

This study aimed at assessing containment properties of slurry wall backfill containing sodium hexametaphosphate (SHMP) modified calcium bentonite to contaminated groundwater. Free swell index and flexible-wall hydraulic conductivity (k) tests were conducted to investigate swelling and hydraulic performances of this novel backfill. The relative concentration (RC) and cumulative mass ratio (CMR) methods were adopted to assess transport parameters including hydrodynamic dispersion coefficient (D) and the retardation factor (Rd) of calcium ion (Ca2+) through the backfills. The results showed negligible to moderate decrease in the swell index of the modified bentonite and the modified backfill when exposed to 5 mM and 1 M calcium chloride (CaCl2) solution. Permeation with CaCl2 solutions increased the short-term k of the backfill by a factor of 0.9 to 1.1 as compared to the tap water permeation. The D values varied from 1.44 × 10–10 m2/s to 2.89 × 10–10 m2/s regardless of the CaCl2 concentration, whereas Rd was vulnerable to CaCl2 concentration. The CMR method yielded a higher coefficient of determination than the RC method, but it showed no particular advantage in evaluating the transport parameters. The SHMP-modification delayed the breakthrough time of Ca2+ by a factor of 15 to 199 in a model slurry trench wall.

Chemical route for synthesis of citric acid from orange and grape juices

Citrus fruits contain sufficient citric acid, which is the main tricarboxylic acid. The properties of citric acid make it an important additive in various process industries. This experimental study aims to produce citric acid from orange and grape juices. The chemical route for the synthesis of citric acid from citrus juices involves three steps: (i) neutralization to adjust pH (9-11) with a 2.8 M NaOH solution, (ii) addition of CaCl2 solution (40.3-41.1% w/v), and (iii) acidification with an H2SO4 solution (1.5-2.3 M) to produce citric acid. In this study, the fruits were peeled, crushed, filtered, neutralized, added CaCl2 solution, and acidified to obtain citric acid. The experiments were carried out by varying the final pH of the solution and the concentrations of CaCl2 and H2SO4 solutions, maintaining the total volume constant. A maximum citric acid yield of 91.1% and 79.8% were achieved from orange and grapefruits, respectively, at the optimum final pH of the solution and the concentrations of CaCl2 and H2SO4 solutions at 10, 40.7% w/v, and 1.9 M, respectively. Finally, the purified citric acid crystals were characterized using FTIR and XRD. Thus, it could be concluded that orange fruit would be a promising source for citric acid production than grape.

Utilization of Guazuma ulmifolia gum and sodium alginate to form protective beads of antioxidant peptides obtained from Phaseolus lunatus

Effect of peptides obtained from Phaseolus lunatus L. where biological properties such as antioxidant activity have been found. In addition to improve this beneficial effect, the microencapsulation could be a way to protect the peptides against the environment to which they are exposed. Gums extracted from plant seeds are a potential option such as Guazuma ulmifolia, and its seeds gum exhibits promising properties as coating materials in encapsulation. Two peptide fractions from P. lunatus L. were encapsulated (>10 and <10 kDa) by ionic gelation using mixtures of G. ulmifolia gum and sodium alginate (GUG:SA). A 23 experimental design was used: GUG:SA ratios (A) (70:30 or 30:70); CaCl2 concentrations (B) (0.05 or 0.15 M); and hardening time (C). (10 or 30 min). Multiple variable response analysis with a desirability coefficient identified optimum conditions for each peptide fraction. Better results were obtained for >10 kDa peptide fraction at optimal conditions of A: 70:30, B: 0.05 and C: 10, obtaining irregular beads with a diameter of 5.85 mm2, Bead Encapsulation efficiency 42% and 31 and 42 mM TEAC for ABTS and DPPH respectively. These results shown that GUG:SA mixture is a viable encapsulation system for preserving antioxidant peptide fractions.

EFFECT OF FOLIAR SPRAYING WITH SALICYLIC ACID AND CALCIUM CHLORIDE ON CHEMICAL CONTENT OF LEAVES FOR THREE CULTIVARS OF Gladiolus X hortulanus L.

This experiment was carried out in the Green net house at the College of Agriculture and Forestry for the period from April to September 2019, with the aim of assessing the response of three cultivars of Gladiolus X hortulanus L. for treatment with (SA) at a concentrations of zero and 250 mg.l-1 as well as treatment with (CaCl2) concentrations are zero, 500 and 1000 mg.l-1 sprayed on the vegetative growth twice. The results indicated the following: The red cultivar recorded the largest chlorophyll intensity in the leaves when picking flowers 54.958 (SPAD), the nitrogen percentage is 1.212%, the phosphorus is 0.383%, the potassium is 1.807% and the concentration calcium is 819.05 mg.l-1. The plants sprayed with salicylic acid at 250 mg.l-1 had a significant effect in recording the largest values of all studied traits. The treatment with calcium chloride with both concentrations of 500 and 1000 mg.l-1 resulted in a significant increase in the chlorophyll intensity in the leaves when picking flowers. The treatment with calcium chloride at 1000 mg.l-1 gave the largest values for the calcium concentration is 831.66 mg.l-1 . The treatment with calcium chloride at 500 mg.l-1 caused to increase the nitrogen percentage 1.232%, phosphorus 0.419% and potassium 1.851%.

Substrate- and Calcium-Dependent Differential Regulation of Mitochondrial Oxidative Phosphorylation and Energy Production in the Heart and Kidney.

Mitochondrial dehydrogenases are differentially stimulated by Ca2+. Ca2+ has also diverse regulatory effects on mitochondrial transporters and other enzymes. However, the consequences of these regulatory effects on mitochondrial oxidative phosphorylation (OxPhos) and ATP production, and the dependencies of these consequences on respiratory substrates, have not been investigated between the kidney and heart despite the fact that kidney energy requirements are second only to those of the heart. Our objective was, therefore, to elucidate these relationships in isolated mitochondria from the kidney outer medulla (OM) and heart. ADP-induced mitochondrial respiration was measured at different CaCl2 concentrations in the presence of various respiratory substrates, including pyruvate + malate (PM), glutamate + malate (GM), alpha-ketoglutarate + malate (AM), palmitoyl-carnitine + malate (PCM), and succinate + rotenone (SUC + ROT). The results showed that, in both heart and OM mitochondria, and for most complex I substrates, Ca2+ effects are biphasic: small increases in Ca2+ concentration stimulated, while large increases inhibited mitochondrial respiration. Furthermore, significant differences in substrate- and Ca2+-dependent O2 utilization towards ATP production between heart and OM mitochondria were observed. With PM and PCM substrates, Ca2+ showed more prominent stimulatory effects in OM than in heart mitochondria, while with GM and AM substrates, Ca2+ had similar biphasic regulatory effects in both OM and heart mitochondria. In contrast, with complex II substrate SUC + ROT, only inhibitory effects on mitochondrial respiration was observed in both the heart and the OM. We conclude that the regulatory effects of Ca2+ on mitochondrial OxPhos and ATP synthesis are biphasic, substrate-dependent, and tissue-specific.

Customization of liquid-core sodium alginate beads by molecular engineering

Detailed alginate molecular structural factors that modulated the texture of liquid core alginate beads were investigated. Under the same CaCl2 concentration and contacting time, a higher bursting force can be generated from both high Mw and low M/G alginate beads. G-block took part in faster dimerization, producing a compact gel network and long chains providing an elastic response generated by interchain interaction. Within same bursting force, high Mw beads were elastic than high G ones. Shorter chain length and higher M residue allowed more water to trap in the gel network, causing accretion in thickness and downed gel strength. The lowest shell thickness (0.11±0.01mm) was measured from the highest Mw and M/G sample, while the thickest (0.78±0.08mm) was from the lowest Mw and M/G alginate. The beads became brittle with a shortened chain length. Thus, alginate-based food products with a desired textural profile can be designed by varying alginate structures.

Droplet-Based Microfluidic Preparation of Shape-Variable Alginate Hydrogel Magnetic Micromotors.

This article introduces a facile droplet-based microfluidic method for the preparation of Fe3O4-incorporated alginate hydrogel magnetic micromotors with variable shapes. By using droplet-based microfluidics and water diffusion, monodisperse (quasi-)spherical microparticles of sodium alginate and Fe3O4 (Na-Alg/Fe3O4) are obtained. The diameter varies from 31.9 to 102.7 µm with the initial concentration of Na-Alginate in dispersed fluid ranging from 0.09 to 9 mg/mL. Calcium chloride (CaCl2) is used for gelation, immediately transforming Na-Alg/Fe3O4 microparticles into Ca-Alginate hydrogel microparticles incorporating Fe3O4 nanoparticles, i.e., Ca-Alg/Fe3O4 micromotors. Spherical, droplet-like, and worm-like shapes are yielded depending on the concentration of CaCl2, which is explained by crosslinking and anisotropic swelling during the gelation. The locomotion of Ca-Alg/Fe3O4 micromotors is activated by applying external magnetic fields. Under the rotating magnetic field (5 mT, 1–15 Hz), spherical Ca-Alg/Fe3O4 micromotors exhibit an average advancing velocity up to 158.2 ± 8.6 µm/s, whereas worm-like Ca-Alg/Fe3O4 micromotors could be rotated for potential advancing. Under the magnetic field gradient (3 T/m), droplet-like Ca-Alg/Fe3O4 micromotors are pulled forward with the average velocity of 70.7 ± 2.8 µm/s. This article provides an inspiring and timesaving approach for the preparation of shape-variable hydrogel micromotors without using complex patterns or sophisticated facilities, which holds potential for biomedical applications such as targeted drug delivery.

Growth Rate and Bone Hydroxyproline Concentration in Turkeys Fed with a Silage-Composed Diet Modified with Different Diet Cation-Anion Differences (DCADs).

Simple SummaryIn this study, we point to the possibility of using dietary cation–anion difference manipulation to improve growth rates and bone condition, especially in the last phase of poultry turkey husbandry, when birds have many bone abnormalities. Our goal was to determine the responses of body weight (BW) and bone hydroxyproline (Hyp) concentration in turkeys fed a corn silage (CS) diet with different values of dietary cation–anion differences (DCADs). The turkeys (n = 90) were divided into five groups and fed as follows: group A (control)—standard diet (SD) (60%) plus CS (40%); group B—SD (60%), CS (40%) plus 240 g of CaCl2 per 100 kg of diet; group C—SD (60%), CS (40%) plus 480 g of CaCl2 per 100 kg of diet; group D—SD (60%), CS (40%) plus 240 g of NaHCO3 per 100 kg of diet; group E—SD (60%), CS (40%) plus 480 g NaHCO3 per 100 kg of diet. The addition of a lesser amount of CaCl2 lowered the DCAD, which ranged between 52.5 ± 4.19 and 91.14 ± 3.14 mEq/kg DM. An increased content of CaCl2 led to high negative values of DCAD. NaHCO3 supplemented in both doses resulted in a significant elevation of DCAD. Compared to each experimental group, feeding birds with a diet supplemented only with CS resulted in a lower BW. Addition of CaCl2 or NaHCO3 to the diet improved BW, but only CaCl2 addition enhanced the bone Hyp amount. In conclusion, we suggest that an anionic diet with low DCAD can prevent bone abnormalities in large turkeys, especially in the final course of production.

A FT-NIR Process Analytical Technology Approach for Milk Renneting Control

The study proposes a process analytical technology (PAT) approach for the control of milk coagulation through near infrared spectroscopy (NIRS), computing multivariate statistical process control (MSPC) charts, based on principal component analysis (PCA). Reconstituted skimmed milk and commercial pasteurized skimmed milk were mixed at two different ratios (60:40 and 40:60). Each mix ratio was prepared in six replicates and used for coagulation trials, monitored by fundamental rheology, as a reference method, and NIRS by inserting a probe directly in the coagulation vat and collecting spectra at two different acquisition times, i.e., 60 s or 10 s. Furthermore, three failure coagulation trials were performed, deliberately changing temperature or rennet and CaCl2 concentration. The comparison with fundamental rheology results confirmed the effectiveness of NIRS to monitor milk renneting. The reduced spectral acquisition time (10 s) showed data highly correlated (r > 0.99) to those acquired with longer acquisition time. The developed decision trees, based on PC1 scores and T2 MSPC charts, confirmed the suitability of the proposed approach for the prediction of coagulation times and for the detection of possible failures. In conclusion, the work provides a robust but simple PAT approach to assist cheesemakers in monitoring the coagulation step in real-time.

Calcium Ion-Induced Structural Changes in Carboxymethylcellulose Solutions and Their Effects on Adsorption on Cellulose Surfaces.

The adsorption of carboxymethylcellulose (CMC) on cellulose surfaces is one of the most studied examples of the adsorption of an anionic polyelectrolyte on a like-charged surface. It has been suggested that divalent ions can act as a bridge between CMC chains and the surface of cellulose and enhance the CMC adsorption: they can, however, also alter the structure of CMCs in the solution. In previous investigations, the influence of cations on solution properties has been largely overlooked. This study investigates the effect of Ca2+ ions on the properties of CMC solutions as well as the influence on cellulose nanofibers (CNFs), which was studied by dynamic light scattering and correlated with the adsorption of CMC on a cellulose surface probed using QCM-D. The presence of Ca2+ facilitated the multichain association of CMC chains and increased the hydrodynamic diameter. This suggests that the adsorption of CMCs at high concentrations of CaCl2 is governed mainly by changes in solution properties rather than by changes in the cellulose surface. Furthermore, an entropy-driven mechanism has been suggested for the adsorption of CMC on cellulose. By comparing the adsorption of CMC from H2O and D2O, it was found that the release of water from the cellulose surface is driving the adsorption of CMC.

Influence of pulsed electric fields (PEF) with calcium addition on the texture profile of cooked black beans (Phaseolus vulgaris) and their particle breakdown during in vivo oral processing

This study investigated the use of pulsed electric fields/PEF (electric field strengths 1–2 kV/cm, specific energy 9–127 kJ/kg) to facilitate calcium uptake into black beans in preserving their hardness from thermal degradation during subsequent cooking (1 h, 70–90 °C). Increasing specific energy reduced CaCl2 concentration in PEF processing media to 100 ppm to improve the hardness of cooked black beans. Those pre-treated at lower energy required min. 300 ppm CaCl2. Cooked black beans with PEF-pretreatment shared similar hardness as without PEF but unexpectedly chewier (18–43% more energy to disintegrate the beans). In vivo mastication study showed particle size at 18 and 24 s of mastication was significantly different (p < 0.05) wherein “PEF without CaCl2” had the smallest particles compared to “No PEF with CaCl2” and “PEF with CaCl2”. The outer seed coats of PEF-pretreated beans were easily masticated to smaller and consistent particles. This implies that PEF improved particle breakdown during mastication.

Impact of calcium ions and degree of oxidation on the structural, physicochemical, and in-vitro release properties of resveratrol-loaded oxidized gellan gum hydrogel beads

Oxidized gellan gum (OGG) hydrogel beads as delivery systems for resveratrol were fabricated by ionic cross-linking with calcium chloride (CaCl2). The degree of oxidation (DO) and CaCl2 concentration had significant influences on the formation and functional properties of hydrogel beads. The resveratrol encapsulation efficiency (66.43%–79.84%) and loading capacity (4.15%–5.05%) of OGG hydrogel beads were enhanced as DO increased. The hydrogel beads exhibited a uniform spherical shape as observed by scanning electron microscope. Fourier transform infrared spectroscopy analysis confirmed that hydrogen bonds and ionic interaction participated in the formation of hydrogel beads. X-ray diffraction analysis revealed that the physical state of resveratrol was changed from crystalline to amorphous form after encapsulation. Furthermore, the physical stability and antioxidant capacity evaluation demonstrated that the hydrogel bead fabricated with DO80 OGG and CaCl2 concentration of 1.0 M could provide high protection for resveratrol against degradation by environmental stresses and maintain its antioxidant capacity. The DO and CaCl2 concentrations could modulate the in-vitro release behaviors of hydrogel beads and obtain a good small intestinal-targeted release of resveratrol at high DO and medium CaCl2 concentration. These findings suggested that a promising delivery system for encapsulating bioactive ingredients can be fabricated by rational design.

Encapsulation of Lemongrass Extract (Cymbopogon citratus) Coated Alginate/Chitosan Using Gelation Method

Lemongrass (Cymbopogon citratus) is a medicinal plant with various biological activities such as antibacterial, antifungal, antiprotozoal, anti-inflammatory, and antioxidant. This study aimed to encapsulate lemongrass bioactive in alginate/chitosan complex by enhancing the properties of CaCl2 crosslinked incorporated with tween 80 by ionic gelation method. The hydrogel was prepared by mixing alginate solution (2% w/v) and chitosan solution (1% w/v) with a ratio (1:1 v/v). Tween 80 (2% v/v) was added as a dissolution enhancer and CaCl2 as a crosslinker agent. The formulation varying by concentration of CaCl2 (0.1M to 0.3M) and lemongrass extract (2% to 12%). Encapsulation lemongrass with alginate-chitosan beads is characterized to determine encapsulation efficiency, swelling study, morphology, functional groups, and release study. The results showed that encapsulation efficiency ranged from 74.81% to 83.07%. Encapsulation efficiency increased with the addition of CaCl2 and lemongrass extract concentration. The swelling ratio ranged from 27.29 to 37.81, it will decrease with the addition of CaCl2 and lemongrass extract concentration. The Scanning Electron Microscopy (SEM) analysis of hydrogel beads shows a polyhedral shape, porous, and rough surface which indicates bioactive of lemongrass trapped on the beads. The Fourier Transform Infrared Spectroscopy (FTIR) results show new peaks at 1734 cm-1 as carbonyl stretch vibrations in ketones, aldehydes, and carboxylic acids, indicating the addition of lemongrass extract. Bioactive of lemongrass extract loaded alginate-chitosan beads was successfully released as much as 87.12% at pH 6.8. This study suggested the strong potential alginate-chitosan beads as an encapsulating agent for lemongrass extract using the ionic gelation method, and it has potential as a drug delivery system.Keywords: encapsulation; lemongrass; alginate; chitosan; CaCl2

Construction and Application of Flocculation and Destability System of Biodrill-A Drilling Fluid in Bohai Oilfield

To protect the marine ecological environment of Bohai Bay, the waste drilling fluid in Bohai oilfield have to be treated. In the light of the composition characteristics of Biodrill-A drilling fluid, the compounding method of the inorganic–organic flocculants was adopted to assist the flocculation and solid–fluid separation of Biodrill-A drilling fluid. Through the orthogonal test design, the main factors impacting the flocculation effect on Biodrill-A drilling fluid were found to the concentration of inorganic flocculant CaCl2 and the flocculation pH value. The optimal flocculation treatment was further obtained through single-factor optimization. Specifically, when the inorganic flocculant CaCl2 concentration was 0.9 w/v%, the organic flocculant concentration was 0.01 w/v%, the flocculation pH was 8, and the flocculation time was 7 min. Eventually, the final dewatering rate could reach 84.02%. In the optimized compound flocculants, the inorganic flocculant CaCl2 reduced the zeta potential of clay particles by electric neutralization to decrease the repulsion among particles, and the organic one could absorb and wrap the clay particles through bridging curling and electric neutralization after flocculation destabilization. Both inorganic and organic flocculants facilitated the large flocs and particles of clay particles. The field test showed that the inorganic–organic flocculants were suitable for the on-line flocculation treatment process based on centrifugal machine. The waste drilling fluid was reduced by 82%, and the water content of the separated solid phase was as low as 25.7%.

Geotechnical properties of yellow silty sand soil modified by bio-stimulation with presence of NiCl2

Microbiologically induced calcite precipitation (MICP) is now widely tried to improve the quality of mostly sandy soil due to its application prospect to sustainability, environment-friendly and cost-efficiency. The present study is aiming to evaluate the feasibility of bio-stimulation, one of MICP techniques, for strengthening the engineering quality of Shanghai silty sand soil, a special type of soil located in low hillside of west Shanghai, as well as the influence of two factors: CaCl2 as a cementing material and NiCl2 as a co-factor, which was rarely researched before and can be viewed as the influence of urease activity on bio-stimulation result. The direct shear test, unconfined compressive test, supersonic wave test and calcite mass test have been carried out to evaluate engineering performance of yellow silty sand soil enhanced by bio-stimulation method as well as their relationship with concentration of CaCl2 and NiCl2 solutions. The result shows that bio-stimulation method can significantly promote the characteristics of Shanghai yellow silty sand soil and there seems to be extreme point for concentration of CaCl2 and NiCl2 solution in improving the quality of Shanghai yellow silty sand. Microstructure and composition of treated soil by bio-stimulation method have also been analyzed by Scanning Electron Microscope (SEM) and Energy dispersive Spectrometer (EDS), with giving the corresponding micro-mechanism of bio-cementation among soil particles.

Effect of Harvesting Stages and Calcium Chloride Application on Postharvest Quality of Tomato Fruits

Tomatoes are a good source of vitamins, minerals, antioxidants, and enzymes, which are beneficial to human health. They are one of the most commercially high-value vegetable crops that experience a huge postharvest loss after harvest. The present experiment is conducted to investigate the effect of different maturity stages (mature green, breaker, and half-ripe stage), pre- and post-harvest treatment with different concentrations (0.0%, 1.0%, 1.5%, and 2.0%, w/v) of calcium chloride (CaCl2) on the postharvest performance, antioxidant and enzymatic activity of lowland tomato fruits, stored at ambient temperature (28 ± 2 °C and 75 ± 5% RH). Tomato fruit of mature green stage treated with 2% CaCl2 significantly (p = 0.05) declined the ethylene production (15.53%), weight loss (16.43%), and delayed color development by slowly synthesizes the lycopene content as well as extended the shelf life. The maximum amount of total phenolic content (TPC) was demonstrated at the highest level of CaCl2 (2%) after 20 days of storage life at ambient conditions. The concentration of CaCl2 influenced the activity of different plant defense enzymes, and the higher doses of CaCl2 (2%) accelerated the activity of peroxidase (POD) (13%), polyphenol oxidase (POP) (7.3%), and phenylalanine ammonia-lyase (PAL) (8.5%) relative to that of the control samples. Therefore, the tomato producers and traders could extend the storage duration of tomato fruits by harvesting at the mature green stage and applying 2% CaCl2 in both pre-and postharvest at ambient storage conditions.

Revealing the Enhancement and Degradation Mechanisms Affecting the Performance of Carbonate Precipitation in EICP Process

Given that acid-rich rainfall can cause serious damage to heritage buildings in NW China and subsequently accelerate their aging problem, countermeasures to protect their integrity and also to preserve the continuity of Chinese culture are in pressing need. Enzyme-induced carbonate precipitation (EICP) that modifies the mechanical properties of the soil through enhancing the interparticle bonds by the precipitated crystals and the formation of other carbonate minerals is under a spotlight in recent years. EICP is considered as an alternative to the microbial-induced carbonate precipitation (MICP) because cultivating soil microbes are considered to be challenging in field applications. This study conducts a series of test tube experiments to reproduce the ordinary EICP process, and the produced carbonate precipitation is compared with that of the modified EICP process subjected to the effect of higher MgCl2, NH4Cl, and CaCl2 concentrations, respectively. The modified EICP, subjected to the effect of higher MgCl2 concentrations, performs the best with the highest carbonate precipitation. The enhancement mechanism of carbonate precipitation is well interpreted through elevating the activity of urease enzyme by introducing the magnesium ions. Furthermore, the degradation of carbonate precipitation presents when subjected to the effect of higher NH4Cl concentration. The decreasing activity of urease enzyme and the reverse EICP process play a leading role in degrading the carbonate precipitation. Moreover, when subjected to the effect of higher CaCl2 concentrations, the slower rate of urea hydrolysis and the decreasing activity of urease enzyme are primarily responsible for forming the “hijacking” phenomenon of carbonate precipitation. The findings of this study explore the potential use of the EICP technology for the protection of heritage buildings in NW China.

Carboxymethyl Cellulose Hydrogel from Biomass Waste of Oil Palm Empty Fruit Bunch Using Calcium Chloride as Crosslinking Agent.

Carboxymethyl cellulose (CMC) is modified cellulose extracted from oil palm empty fruit bunch (OPEFB) biomass waste that has been prepared through etherification using sodium monochloroacetate (SMCA) in the presence of sodium hydroxide. In this research, CMC hydrogel was prepared using calcium chloride (CaCl2) as the chemical crosslinker. Throughout the optimization process, four important parameters were studied, which were: (1) CMC concentration, (2) CaCl2 concentration, (3) reaction time, and (4) reaction temperature. From the results, the best gel content obtained was 28.11% at 20% (w/v) of CMC with 1% (w/v) of CaCl2 in 24 h reaction at room temperature. Meanwhile, the degree of swelling for CMC hydrogel was 47.34 g/g. All samples were characterized using FT-IR, XRD, TGA, and FESEM to study and compare modification on the OPEFB cellulose. The FT-IR spectrum of CMC hydrogel showed a shift of COO− peaks at 1585 cm−1 and 1413 cm−1, indicating the substitution of Ca2+ into the CMC molecular chains. The XRD diffractogram of CMC hydrogel showed no observation of sharp peaks, which signified an amorphous hydrogel phase. The CrI value also proved the decrement of the crystalline nature of CMC hydrogel. TGA–DTG thermograms showed that the Tmax of CMC hydrogel at 293.33 °C is slightly better in thermal stability compared to CMC. Meanwhile, the FESEM micrograph of CMC hydrogel showed interconnected pores indicating the crosslinkages in CMC hydrogel. CMC hydrogel was successfully synthesized using CaCl2 as a crosslinking agent, and its swelling ability can be used in various applications such as drug delivery systems, industrial effluent, food additives, heavy metal removal, and many more.

Effects of calcium, magnesium, and strontium chlorides in determining the total acid number using potentiometric titration

The most widely used method for determining the total acid number (TAN) in crude oils is American Society for Testing and Materials (ASTM) D664, which is subject to interference from hydrolyzable salts. This study investigated and determined at which salt concentration NaCl, CaCl2, MgCl2, and SrCl2 significantly interfere with the determination of the TAN in crude oil using the ASTM D664 method. To evaluate the influence of salts on the titration solvent of ASTM D664 and crude oil, pure chloride salts, and two mixtures of these salts, were added to the titration solvents (at 1500–8000 mg kg−1) and water-in-oil emulsions (alpha and gamma). Precipitation was observed during the titrations of these solvents. Analysis of the precipitates via gravimetric analysis, X-ray diffraction, and attenuated total reflection Fourier transform infrared spectroscopy demonstrated that they were composed of Ca(OH)2, Mg(OH)2, and Sr(OH)2. The alpha oil exhibited an increase in acidity from 0.28 up to 2.47 mg KOH g−1 with the chloride salt mixtures, whereas gamma oil exhibited an increase in acidity from 2.26 up to 4.17 mg KOH g−1 with the chloride salt mixtures. One hundred milligrams of CaCl2, MgCl2, or SrCl2 remaining in the oil was sufficient to interfere with the in TAN determination using the ASTM D664 method.

Effect of NaCl and CaCl2 concentration on the rheological and structural characteristics of thermally-induced quinoa protein gels

The effect of ionic strength on the heat-induced gelation of quinoa protein isolates (QPI) at pH 7 was investigated. The gelation behaviour and gel strength were characterised by oscillatory rheology. The microstructural characteristics of QPI solutions and gels were probed by ultra-small angle neutron scattering (USANS), small-angle X-ray and neutron scattering (SAXS, SANS), and confocal laser scanning microscopy (CLSM). This suite of techniques provided structural details covering a wide range of length scales from tens of micron to nanometre. It was found that the gelation temperature decreased from 73 °C to 40 °C and the G* (1 Hz) increased from ∼67 Pa to ∼1285 Pa with increasing concentration of NaCl from 0 to 200 mM. A particle size of ∼32 Å and ∼57 Å was identified within the QPI gel containing 0–200 mM NaCl from SAXS and SANS, respectively and whose size decreased upon addition of CaCl2. For all QPI samples, heat treatment promoted protein aggregation on the micron scale, while a larger structural unit (Rg∼ 170 nm) was kept intact as revealed by USANS. A similar mass fractal structure (df = 2) was observed in the QPI gels containing 0–200 mM NaCl, while CaCl2 addition caused the formation of large protein agglomerates (Rg∼2.5–4.0 μm) with a more compact and denser structural organisation (df = 2.5) inside the protein blobs. CLSM showed that the QPI gels containing CaCl2 are prone to phase separation. Overall, this finding shows the thermal gelation behaviour of QPI can be modulated by the ion type and concentration, which is similarly observed in other globular protein systems. These results provide useful information for the design and preparation of quinoa gels for food applications.