Soaking In Water Research Articles

Hydronium-Crosslinked Inorganic Hydrogel Comprised of 1D Lepidocrocite Titanate Nanofilaments.

When a few drops of acid (hydrochloric, acrylic, propionic, acetic, or formic) are added to a colloid comprised of 1D lepidocrocite titanate nanofilaments (1DLs)-2 × 2 TiO6 octahedra in cross-section-a hydrogel forms, in many cases, within seconds. The 1DL synthesis process requires the reaction between titanium diboride with tetramethylammonium (TMA+), hydroxide. Using quantitative nuclear magnetic resonance (qNMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), the mass percent of TMA+ after synthesis is determined to be ≈ 13.1±0.1%. The TMA+ is completely removed from the gels after 2 water soak cycles, resulting in the first completely inorganic, TiO2-based hydrogels. Ion exchanging the TMA+ with hydronium results in gels with relatively strong hydrogen bonds. The hydrogels' compression strengths increased linearly with 1DL colloid concentration. At a 1DL concentration of 45gL-1, the compressive strength, at 80% deformation when acrylic acid is used, is ≈325kPa. The strengths are ≈ 50% greater after the TMA+ is removed. The removal of all residual organic components in the hydrogels, including TMA+, is confirmed by qNMR, Fourier-transformed infrared spectroscopy (FTIR), and TGA/DSC. The 1DL phase is retained after gelation, TMA+ removal, and 80% compression.

Facile fabrication of a starch-based wood adhesive showcasing water resistance, flame retardancy, and antibacterial properties via a dual crosslinking strategy

The demand for non-toxic, environmentally friendly, easily processable, water-resistant, flame-retardant and antimicrobial adhesives in the wood processing industry is becoming increasingly urgent. Few adhesives can both simultaneously possess these functions and synthesis easily. This paper presents a one-pot process utilizing corn starch, sodium hypochlorite, itaconic acid, and borax to synthesize a starch-based adhesive with dual crosslinking. Initial crosslinking takes place between the carboxyl groups of itaconic acid and hydroxyl groups on oxidized starch due to the formation of ester bonds. Secondary crosslinking occurs borate ester bonds between starch hydroxyl groups and boric acid. The entire reaction process is environmentally benign, generating no waste, with all reactants converted into final products, aligning with “green” chemistry principles. When used to bond wooden boards, this adhesive achieved a dry shear strength of 5.34 ± 0.24 MPa, and a wet shear strength of 1.22 ± 0.06 MPa after soaking in water. Additionally, this starch-based adhesive exhibited antibacterial properties against Escherichia coli (ATCC 8739) and Staphylococcus aureus. Moreover, with borax incorporated, the adhesive demonstrated flame-retardancy. The limiting oxygen index for bonded wooden boards was 30.9 %, qualifying it as a flame-retardant material. These multiple functions render it promising for applications in the wood processing industry.

Preparation and characteristics of zein/ethyl cellulose composite coating applied in aqueous system

Zein and ethyl cellulose (EC) were used as raw materials to prepare a composite coating applied in aqueous systems with mechanical properties, water stability, water solubility (including room-temperature (RT)/high-temperature and neutral/acidic conditions), and oil resistance as evaluation index. Results showed the most suitable conditions were mass ratio of zein/EC at 1:9, 93 % (v/v) aqueous ethanol, oleic acid as the plasticizer with the amount of 0.3 g/g, and curing temperature at 70 °C. Under these conditions, the tensile strength of composite coating was 4.61 MPa and elongation at break was 21.60 % after 4 weeks of soaking in water. Oil seepage was not observed within 1 week. The water solubility of coating in neutral water was 5.13 % at RT for 24 h, and 3.79 % at 80 °C for 2 min; in acidic water (pH = 4) was 4.54 % at RT for 24 h, and 5.44 % at 80 °C for 2 min. SEM results showed swelling occurred in zein coating after soaking, presenting micropores in soaked zein coating; zein microparticles in composite coating partially broke down and fell off after soaking. Water contact angle results revealed surface hydrophobicity by the following order: EC coating > composite coating > zein coating. FTIR results showed composite coating was physically compounding by hydrophobic interactions and hydrogen bonds.

Multiplication and development in the nursery of Pterocarpus erinaceus, an endangered agroforestry species in Cote d'Ivoire

Pterocarpus erinaceus is a multi-purpose species threatened with extinction. The present study aims to contribute to the improvement of multiplication and nursery growth of Pterocarpus erinaceus hulled seeds. To this end, four pre-treatments were applied to Pterocarpus erinaceus hulled seeds to lift their dormancy in order to facilitate germination of the species. These were: untreated seeds as Control (To), soaking in ordinary water for 24 h (T1), soaking in hot water at 60°C (T2) and soaking in sulfuric acid (H2SO4) for 20 min (T3). Germination parameters such as germination rate, germination time and average germination time were evaluated. Growth in height, diameter, number of leaves and root length were determined. Germination data and growth parameters were collected. Analyses showed that soaking shelled seeds in ordinary water for 24 h was the best treatment, with a germination rate of 43%. Pre-treatment of the seeds with sulfuric acid for 20 min showed the lowest germination rate (1%), due to the sensitivity of the seeds. Furthermore, these pre-treatments had no effect on seedling growth in the nursery. Those interested in producing Pterocarpus erinaceus seedlings are advised to soak shelled seeds in ordinary water for 24 hours to ensure better germination in the nursery.

Effect of Treating Alfalfa Seeds with Gibberellin and Nano-fertilizer on Productive Characteristics and Protein Content in Hydroponic Cultures

This study was carried out in an experiment in an incubator designed for hydroponic seed germination with tight thermal insulation in the laboratories of the Department of Plant Production Technologies at the Technical College of Agriculture in Mosul, which is affiliated with the Northern Technical University in Iraq, where the seeds of the Dutch variety alfalfa (Medicago sativa. L) were germinated commercially and four times between 2022 and 2024. The experiment was carried out in a completely randomized design (CRD) with two factors and three replicates in perforated dishes with dimensions of 28 cm in length and 19 cm in width (area 532 cm2) at a seed rate of kg / m2, resulting in an average seed weight of 53 g in one dish. The first experimental factor was the germination periods, while the second factor was soaking the seeds in solutions of varying amounts made from gibberellin and nano-compound fertilizer with the comparison treatment, which is soaking in water alone, as follows: Gibberellin 100 ppm and given the symbol GA 100ppm- Gibberellin 200 ppm and given the symbol 200ppm GA- --Nano fertilizer 20:20:20 NPK at a concentration of 2000 ppm and given the symbol NPK2000ppm. -Nano fertilizer 20:20:20 NPK at a concentration of 4000 ppm and given the symbol NPK4000ppm. This study showed that the Gibberellin 200ppm GA treatment was significantly superior to the rest of the other soaking treatments in the characteristics of the height of the incubator (3.66 cm), as well as the wet weight of both seedlings and roots and their dry weight, which were (497.88, 56.97g/dish-1), respectively, The fresh and dried root weights were considerably greater in the same treatment, at (400.86 and 43.86 g/dish-1), respectively. while the comparison treatment was superior. Morally, it was significantly superior to the rest of the other soaking treatments in the characteristic of protein in the medium was (18.29%). As for the times of hydroponic seed germination, there were no significant differences between the times in all the studied characteristics, which enhances the high degree of incubator isolation, the accuracy of implementing the experiment, and the accuracy of taking the results.

Effect Of Giving Warm Water Immersion Therapy For Oedema Of The Legs Of Pregnant Women Third Trimester At Pratama Clinic Cahaya Lubuk Pakam

During pregnancy there are changes in pregnant women, both physical and psychological, which often make pregnant women feel uncomfortable, Swelling in the legs is one of the pregnancy discomforts that pregnant women often complain about and 80% are found in pregnant women in the third trimester. Oedema causes discomfort in pregnant women and can even hinder some activities (1). This study aims to determine the effect of warm water soaking therapy on leg oedema in pregnant women in the third trimester. This study uses a quantitative research design with a one-group pretest-posttest design model, namely observations are made on samples before being given warm water therapy and observations are made again after being given warm water therapy. Samples were taken by purposive sampling. Based on the probability of the test results listed in the table, it can be known that the resulting probability is 0.01. This means that the probability < level of significance (? = 0.05), so that Ha is accepted and H0 is rejected. This means that there is a significant difference between lower limb oedema in pregnant women in the third trimester before giving warm water soaking (Pretest) and oedema of the lower limbs in pregnant women in the third trimester after giving warm water soaking (Postest). Therefore, it can be concluded that there is an Effect of Warm Water Soaking on the Increase of Leg Oedema in Pregnant Women in the Third Trimester at the Pratama Cahaya Lubuk Pakam Clinic in 2024.

Influence of Pre-sowing Seed Treatments and Growing Media on Performance of Consecutive Sowing for Constant Production of Fenugreek Microgreens (Trigonella foenum-graecum L.) under Shade Net

The present investigation was conducted at the College of Horticulture, Dr. Balasaheb Sawant Konkan Krishi Vidyapeeth Dapoli, Dist. Ratnagiri, State-Maharashtra, India in 2023-24. The experiment was laid out in a split-plot design with factorial arrangement having eight treatment combinations and three replications. Factor A comprised two pre-sowing seed treatments: W1: Water soaking of seed and W2: without soaking, while, Factor B included four growing media: M1: Soil + FYM (3:1), M2: Coarse Sand, M3: Cocopeat and M4: Soil + Cocopeat (1:1). The data recorded during investigation revealed that the pre-sowing seed treatments and media influenced the growth and yield parameters of fenugreek microgreens. Among two pre-sowing seed treatments, W1 (Water soaking) had superior effect on all growth and yield parameters compared to W2 (Without soaking). Among various growing media M4-Soil + Cocopeat (1:1) found superior in some growth parameters like, days for germination (avg. 3.39), yield (avg. 678.20 g/m2) and maximum number of cycles (avg.13.46). The treatment combination W1M4-[ Water soaking of seed + Soil + Cocopeat (1:1)] performed better in terms of days to germination (avg. 2.88), days required for harvest (8.33), yield (avg. 1505.57 g/m2), number of cycles (avg. 15) in 6 months.

Comparative examination of leaching kinetics of soluble solids and effluent characteristics in different soaking processes of paddy parboiling

ABSTRACT Paddy was soaked with up to 30% moisture, and hot water soaking (35, 40, 45, 50, 55, 60 °C) was compared to cold soaking (CS) and submerged aerated soaking (SAS) in terms of the parameters of the paddy grain and the effluent. The investigation demonstrated that hot water soaking yielded the highest total solids (TS) (1.946 ± 0.045 g/L), total dissolved solids (TDS) (1.724 ± 0.013 g/L), and electrical conductivity (EC) (2.651 ± 0.039 mS/cm) values. Elevated dissolved oxygen (DO) (3.72 ± 0.04 mg/L) was observed in the hot water soaking (60 °C) due to the reduction of soaking duration of up to 2 h. By contrast, the SAS maintained a nearly neutral pH (7.35 ± 0.01) and lower turbidity (510.0 ± 1.4 NTU) level compared to the hot water soaking process. The leaching rates and moisture absorption were computed using pseudo-second-order leaching kinetics and Peleg model absorption kinetics, and a higher leaching rate (0.081 g/L min) was detected at 60 °C. The SAS produced higher efficiency with less resource consumption and an environmentally advantageous approach by reducing effluent strength and maintaining total solids in paddy grains. The new knowledge created by the comprehensive evaluation CS, SAS, and hot water soaking of paddy parboiling using leaching models and paddy hydration adds new insights to the development of efficient paddy parboiling methods.

EFFECTS OF USING VARIOUSLY PROCESSED CULBAN GRAINS AS A PARTIAL SUBSTITUTE FOR SOYBEAN MEAL ON GROWTH OF CYPRINUS CARPIO L.

The objective of this study is to improve the nutritional value of Culban Vicia peregrina using four different methods: soaking in water for 12 hours, cooking for 40 minutes, roasting for 15 minutes, and germination for 7 days to reduce the effects of anti-nutritional. For 56 days, soybean meal was utilized to replace the grains treated by the abovementioned procedures by 40% ( T3, T5 T7 and T9) and 20% (T4, T6 and T8) in the diets for common carp Cyprinus carpio L., as well as a control diet comprising 30% of soybean meal (T1). The results of the statistical analysis showed the superiority of the fed fish the T7 significantly (P≤ 0.05) in the criteria of TLW,TG and DWG. The fed fish outperformed the T4, T5 and T6 significantly in the criteria of RGR and SGR compared to the control diet(T1). The best FCR and FER were obtained in the T6 and T7, which differed significantly from the T1. With the exception of treatments T2, T7, and T9, the fed fish performed significantly better than all other treatments in the PPV criterion. It can be concluded in present study the substituting culban seeds heated or biologically(germination technique) processed could replace up to 40% of the soybean meal.

Thermal modification of Lantana camara stalks and its characterization

Abstract This paper deals with value addition and utilization of Lantana camara, an invasive species with unprecedented rate of growth, by thermal modification. Lantana camara stalks were thermally modified using vacuum heat treatment (VHT), oil heat treatment (OHT), and steam heat treatment (SHT) at 180 °C and 200 °C and subsequently changes in physical, chemical and mechanical properties were studied. Weight loss was observed in vacuum and steam heat treated samples due to thermal degradation while oil heat treated samples showed weight gain due to oil uptake. SHT exhibited the highest (19 %) weight loss at 200 °C. The color of the modified lantana attained uniform dark colour, OHT exhibited the most intense effect on colour changes. Fourier transform infrared (FTIR) and Fourier transform near infrared (FTNIR) spectroscopic analyses indicated degradation of hemicellulose and change in cellulose crystallinity due to heat treatment. Dimensional stability of thermally modified Lantana stalks improved across treatments, with SHT achieving the highest anti-swelling efficiency of 67.3 % at 200 °C and lowest water absorption (43 %) after 72 h of water soaking. The dynamic modulus of elasticity of thermally modified Lantana remained constant in all the treatment processes. Overall, the results indicate that thermal modification can increase utilization potential of L. camara.

Fabrication of Green Composite Materials Using the Weight Sum Method (WSM) Method

The quest for sustainable materials the investigation into natural fibers for composite materials has been prompted by this development., aiming to reduce the environmental impact of traditional synthetic composites. In this study, we investigate the potential of flax, hemp, jute, kenaf, and ramie fibers as reinforcements in green composites fabricated using the Water Soaking Method (WSM). The evaluation parameters considered include density (g/cm3), fiber diameter (μm), tensile strength (MPa), Young’s modulus (GPa), and elongation at break (%). Through meticulous experimentation and analysis, it is revealed that jute emerges as the frontrunner among the alternatives, exhibiting superior performance across multiple evaluation parameters. Jute-based green composites demonstrate commendable strength and stiffness properties, coupled with a moderate density, making them promising candidates for various structural applications. Conversely, kenaf fiber-based composites exhibit the lowest performance in terms of evaluated parameters, indicating potential limitations in its suitability for high-performance applications. The comparative assessment underscores the significance of material selection in composite fabrication, emphasizing the diverse mechanical properties exhibited by different natural fibers. Furthermore, the utilization of the WSM method showcases its effectiveness in producing green composites with desirable characteristics, signifying its potential as a viable manufacturing technique for sustainable materials. eco-friendly composites, highlighting the importance of considering multiple factors such as fiber type and fabrication method in achieving optimal performance and environmental sustainability in composite materials. Further research may delve into refining fabrication techniques and exploring novel fiber combinations applications.

Influence of Green Synthesized Silver and Zinc Nanoparticle on Seed Quality Attributes in Red Sander (Pterocarpus santalinus Linn.)

Red Sanders (Pterocarpus santalinus), or Rakta chandana, is an endangered tree native to the Southern Indian Peninsula, valued for its medicinal and dye properties. However, its germination is hindered by a hard seed coat, phenolic compounds and hormonal imbalances. Nanotechnology in forestry enhances product innovation, paper processes and sustainability through plant-based nanoparticle biosynthesis. The experiment used a completely randomized design (CRD) with three replications and evaluated seven presowing treatments: T1 (AgNPs at 1000 ppm for 24 hours), T2 (ZnNPs at 2000 ppm for 24 hours), T3 (Conc. H2SO4 for 12 minutes), T4 (NaDC 500 ppm), T5 (Dewinging), T6 (soaking in hot water at 100°C for 5 minutes) and T7 (control). The results indicated that seeds treated with ZnNPs at 2000 ppm (T2) exhibited highest germination rate (56%), germination speed (1.04), root length (17.05 cm), shoot length (16.33cm) and highest dry weight (6.22 g) and highest seedling vigour Index-I (1869). In comparison H2SO4 treatment (T3) delivered 51.67 per cent germination and a speed of germination (0.95), with root length (15.28 cm), shoot length (16.22 cm), dry weight (5.24 g) and seedling vigour Index (1628) slightly lower but still significant. The control (T7) had the lowest performance with 31 per cent germination, a speed of 0.36, root length (15.28 cm), shoot length (16.22 cm), lower dry weight (1.63 g) and the lowest Seedling Vigour Index (649). Overall, ZnNPs at 2000 ppm (T2) were the most effective in enhancing germination, seedling growth and overall vigour in Red sanders.

Environmental and economic impacts of processing rice straw with water for energy and coproducts

Incorporating supplementary cementitious materials (SCM) such as rice straw ash (RSA) as cement replacement in concrete is a key path toward mitigating the contributions of cement to global climate change. A cost-benefit study and an environmental life cycle assessment (LCA) were performed to compute the impacts of water soaking, drying, and reverse osmosis (RO) of the leachate to factor in the use of rice straw as feedstock at biomass energy plants, RSA for concrete, and the RO-treated leachate as fertilizer and water for farms. The cost-benefit analysis showed that the sale of electrical energy from biomass, RSA, and fertilizer required further optimization of the processes to become profitable for the involved parties. The LCA showed a global warming avoidance equivalent to net -15kgCO2-eq per tonne of rice straw that could be achieved by substituting fossil fuel energy resources and cement avoidance in concrete.

Rapid and highly sensitive detection of trace chromium and copper in tea infusion using laser-induced breakdown spectroscopy combined with electrospinning technology

Tea infusion, as one of the most popular beverages, is favored by people around the world. However, tea plants accumulate heavy metals from the soil during growth, which are gradually transferred to the leaves and subsequently decomposed into the tea infusion after soaking in hot water. Long-term consumption of tea infusion containing heavy metals may lead to severe health issues, such as liver dysfunction and cancer. Therefore, rapid, precise, and highly sensitive detection of heavy metals in tea infusion becomes crucial for human health. Traditional methods, such as atomic absorption spectroscopy (AAS), suffer from long detection cycles, high costs, and the risk of secondary pollution from chemical extraction reagents. Thus, this paper presents a method, using laser-induced breakdown spectroscopy combined with electrospinning technology (LIBS-ES), to detect trace amounts of Cr and Cu in tea infusion. The electrospun nanofiber membranes (ENM) were modified with gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs), achieving ultra-sensitive detection of Cr and Cu. The experiment results show that the limits of detection for Cr and Cu are 5 μg/L and 10 μg/L, respectively. Moreover, this method was successfully applied to the detection of Cr and Cu in seven different types of tea infusion, achieving recovery rates of 99 %-106 % and 99 %-108 %, respectively. The method demonstrated good performance even under the interference of other ions at various concentrations, providing a reference for the rapid and highly sensitive detection of heavy metals in tea infusion.

Optimizing multi-recycled concrete for sustainability: Aggregate gradation, surface treatment methods and life cycle impact assessment

Utilizing demolished waste as recycled aggregate in concrete is a sustainable practice, however, the concerns over inconsistent quality, such as hardened mortar content and water absorption, hinder global adoption. This study evaluates the physical, microstructural properties and gives insights into Life Cycle Impact Assessment of three generations of recycled aggregate concrete. The microstructure analysis yielded compelling insights into the role of Interfacial Transition Zone (ITZ) of reclaimed aggregate on concrete. The study demonstrated that the effective proportioning of coarse and fine aggregate particles using Compressible Packing Model (CPM), resulted in a reduction of dosage of cement in concrete volume, reducing the Binder Intensity Index (BII), and an improvement in the strength and stability of concrete. Additionally, surface treatment methods, including water soaking, mechanical, and thermo-mechanical treatments, were explored. The thermo-mechanical treatment method proved to be effective in reducing 40–60 % of residual mortar. Life cycle assessment of treated and untreated recycled aggregate concrete was performed, considering five environmental impact indicators viz., Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Abiotic Depletion Potential (ADP) and Human Toxicity (HT). These indicators illustrated that CPM method of mix proportioning accompanied with thermo-mechanical treatment of repurposed aggregate resulted in lowering environmental impact. These findings underscore the potential for sustainable concrete construction through the use of treated recycled aggregate, offering valuable insights into methods for augmenting its quality and performance.

Four-Ingredient Blends of Poly(lactic acid) with Cottonseed Oil and Meal for Biocomposite Utilization

The development and characterization of agricultural byproduct-based biocomposites are an important part of green chemistry. In this work, four-ingredient blends were formulated with the melt blending method. The set of composites (named as CSO series) was made with poly(lactic acid) (PLA) as the major matrix, washed cottonseed meal (WCSM) as a filler, cottonseed oil (CSO) as a compatibilizer, and glycerol (GLY) as a plasticizer. The morphological analysis showed the homogenous dispersion of the cottonseed byproducts into the PLA matrix to some extent. The thermogravimetric analysis revealed that thermal stability was impacted by the ingredient’s addition. The functional group analysis of the sample and simulation by Fourier transform infrared spectra confirmed the chemical interactions of PLA with WCSM in the blend products. CSO was most likely subjected to physical blending into the products. The mechanical strengths of those composites were affected by the ratios of PLA-CSO. Generally, the tensile strengths were in the range of 0.74–2.1 MPa, which indicate its suitability for low-strength biodegradable plant container development. The blend products had a lower water absorption during the water soaking test. This work shows the feasibility of incorporating cottonseed WCSM and CSO into a PLA composite for sustainable agricultural applications.

Effect of pre-sowing treatments on seed germination and postgerminative seedling growth of acacia angustissima (mill.)

Seeds of Acacia angustissima were subjected to a control and five pre-sowing (soaking in cold water for 24 hours, soaking in hot water (100° C) for 5 minutes, immersion in 60 % H2SO4 for 30 seconds, immersion in 60 % H2SO4 for 5 minutes, and immersion in 60 % H2SO4 for 15 minutes) treatments. The number of seeds that sprouted was recorded daily for calculation of germination indices. When there had been no further germination in any of the treatments for four weeks, the height, number of leaves, number of leaflets, and root length of seedlings were determined. One-way analysis of variance was used to test the effects of the pre-sowing treatments on seed germination and seedling growth. Final Germination Percentage, Germination Rate Index, and Seedling Vigour Index were significantly higher in the warm water than other five treatments which displayed similar responses of the traits. Similar, the warm water pre-treatment resulted in the longest seedlings, when shoot height and / or root length was considered. There was no significant effect of treatment on Mean Germination Time, number of leaves, and number of leaflets. The findings suggest that hot water pre-sowing treatment is the most suitable for seed germination and initial seedling height attainment of Acacia angustissima.

Effect of pre-sowing treatments on seed germination and postgerminative seedling growth of acacia angustissima (mill.)

Seeds of Acacia angustissima were subjected to a control and five pre-sowing (soaking in cold water for 24 hours, soaking in hot water (100° C) for 5 minutes, immersion in 60 % H2SO4 for 30 seconds, immersion in 60 % H2SO4 for 5 minutes, and immersion in 60 % H2SO4 for 15 minutes) treatments. The number of seeds that sprouted was recorded daily for calculation of germination indices. When there had been no further germination in any of the treatments for four weeks, the height, number of leaves, number of leaflets, and root length of seedlings were determined. One-way analysis of variance was used to test the effects of the pre-sowing treatments on seed germination and seedling growth. Final Germination Percentage, Germination Rate Index, and Seedling Vigour Index were significantly higher in the warm water than other five treatments which displayed similar responses of the traits. Similar, the warm water pre-treatment resulted in the longest seedlings, when shoot height and / or root length was considered. There was no significant effect of treatment on Mean Germination Time, number of leaves, and number of leaflets. The findings suggest that hot water pre-sowing treatment is the most suitable for seed germination and initial seedling height attainment of Acacia angustissima.

Tannin removal from Persian gum and investigation of physicochemical properties: Comparing different methods

Persian gum (PG) is a novel natural exudate gum and the main challenge regarding PG is tannin content of gum which limits its application in food and pharmaceutical industries. In fact, tannins are known as anti-nutrient compounds because they limit bioavailability of proteins and minerals. Hence, in this study, the effect of microwave radiation (180, 450, 600 W for 5 min), autoclaving (121 °C for 20 min), boiling (5, 10 and 15 min) and soaking either in water or saline solutions (mono- and divalent salts) was evaluated to remove tannins from Persian gum. Moreover, the effect of tannin removal on the physicochemical properties was investigated by evaluation of rheological properties (flow behavior and viscoelastic tests), zeta potential and Fourier transform infrared spectroscopy (FTIR) data. Our outcomes demonstrated that the highest tannin removal efficiency found to be 75.67 ± 0.25, 74.32 ± 0.54 and 67.08 ± 0.19 % which belonged to soaking in water (180 min), soaking in CaCl2 solution (1% w/v, 90 min) and boiling (15 min) treatments of brownish PG granules, respectively (p < 0.05). Interestingly, removal of tannin increased apparent viscosity of PG dispersion. Based on oscillatory tests, boiling treatment caused exhibition of solid-like behavior, in contrast to control sample. Tannin removal reduced zeta potential and the lowest reduction belonged to the gums soaked in water (from -32.3 to -28.7 mV); however, formation of ion-bridging in the presence of CaCl2 caused a remarkable decrease. FTIR analysis declared that in the boiled sample, a decrease was detected in vibration intensity within the range of 3200–3500 cm−1 (-OH groups) which can be due to heat degradation. Findings of the present research confirmed that soaking in water is a low-cost and practical method for tannin removal of PG, which almost had no negative effect on physiochemical properties of gum.

Preparation and characterization of polymeric cellulose wood adhesive with excellent bonding properties and water resistance

Developing the most abundant cellulose resources in nature as wood adhesives is a challenging but significant work. In this study, an oxidized cellulose-hexamethylene diamine-urea (OCHU) resin adhesive, of high bonding performance, and excellent water resistance has been prepared. The cellulose was firstly enzymatically hydrolyzed to increase its solubility and expose more hydroxyl groups, then oxidized by sodium periodate (NaIO4) to generate a biological compound being rich of aldehyde groups. The OCHU adhesive was prepared by crosslinking oxidized cellulose (OC) with a synthetic reactive polyurea (HU) polymer, which was formed through the deamidation reaction between hexamethylenediamine (H) and urea (U). This adhesive exhibited a 24 h cold water soaking strength of 1.61 MPa, 3 h hot water (63 °C) strength of 1.05 MPa and a dry strength of 1.71 MPa. Compared to oxidized cellulose-hexamethylenediamine (OCH) adhesive, a significant increase of 60 % in this adhesive's wet strength. The Schiff base and addition reactions in the preparation were confirmed by XPS, solid-state NMR, and FTIR. This cellulose-based wood adhesive has great market competitiveness for mass production and application in the plywood industry, due to its excellent bonding properties.