Sodium Hydroxide Concentration Research Articles

Impact of Alkali Concentration in Delignification Treatment for Cellulose Extraction from Rice Straw

Rice straw is an abundant agricultural byproduct with great potential as a sustainable source of cellulose. This study investigates the effect of sodium hydroxide concentration on the extraction of cellulose from rice straw through alkali delignification. Sodium hydroxide concentrations ranging from 3% to 11% were applied at a constant temperature of 60 °C for 60 minutes. The objective was to assess the impact of alkali concentration on cellulose yield and structural properties. Results showed that increasing alkali concentration led to a reduction in cellulose yield. Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) confirmed the effective removal of lignin, hemicellulose, and impurities across all concentrations. Additionally, the crystallinity index (CI) increased from 47.85% to 51.37% as alkali concentration rose, indicating successful delignification. However, a balance must be considered, as lower alkali concentrations, while environmentally friendlier and yielding more cellulose, resulted in lower purity, with FTIR, SEM, and XRD analyses revealing residual impurities in the extracted cellulose. This eco-friendly process offers a promising method for converting agricultural waste into valuable cellulose, contributing to sustainable industrial practices.

Development of filler-free and ambient-cured fly ash based geopolymer brick utilizing low molar concentration of activating solution

In this study, an effort has been undertaken to develop geopolymer bricks (GPB) using fly ash and an activating solution without the addition of any filler material. The primary objective is to establish the optimum mix ratio with the lowest possible concentration of sodium hydroxide (NaOH) in activating solution when mixed with fly ash, resulting in the GPB having compressive strength exceeding 10 MPa and water absorption below 20 % (Class-10 bricks). To achieve this objective, different activating solutions consisting of NaOH, a combination of NaOH and sodium silicate (Na2SiO3), and a combination of NaOH, Na2SiO3, and additional water were used. The samples underwent ambient curing until the age of testing. The X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) analyses examined the microstructural behavior of the GPB. Experimental results indicated that the compressive strength of 18 MPa and water absorption of 16.49 % was achieved when 2 M NaOH with Na2SiO3 and 5 % extra water were used to activate fly ash. Microstructural analysis revealed that the undissolved fly ash particles served as filler material, while the dissolved fly ash helped in the synthesis of cementitious material. The performance of these bricks was found to be equivalent to that of the traditionally available burnt clay bricks.

Bifunctional cationic modification of modal fabric for sustainable in textile dyeing with spent coffee grounds

In order to dye cellulose or regenerated cellulose with natural dyes, toxic metal mordants are generally employed. In response to this issue, the novel bifunctional cationic agent was pretreated to modify modal (regenerated cellulose) fabric prior to dyeing to enhance the fiber-dye affinity. The cationization reaction was carried out using a compound containing bicationic sites, N,N'-(oxybis (ethane-2,1-diyl))bis(3-chloro-2-hydroxy-N,N-dimethylpropan-1-aminium. This unique cationic agent is capable of producing nonvolatile amine and has no odor problem. The successful cationic modification was confirmed through FTIR spectroscopy and zeta potential measurement. The cationized process was optimized at a cationic and sodium hydroxide concentration of 90 and 20 g∙L‒1, respectively, with a duration of 5 h. The modified modal fabric significantly enhanced its dyeability with the extract from spent coffee grounds, resulting in deep brown colors. The cationized sample's color strength was noticeably improved. Cationized samples demonstrated better color fastness to washing than untreated samples. Crock fastness was comparable, except the light fastness at high dye concentrations was slightly lower. By utilizing cationization, it offers a promising and sustainable approach enhancing the dyeing with natural dye for green textile coloration.

Dynamic simulation-driven analysis of cadmium, nickel, cobalt, and iron adsorption mechanisms in zeolite LTA synthesized from Bentonite

A practical and cost-effective method was successfully developed for synthesizing high-performance zeolite LTA from bentonite clay by fine-tuning activation steps and crystallization parameters. The optimal synthesis conditions and crystallization mechanism were investigated. The synthesized zeolites were characterized using XRD, FTIR, and SEM-EDS techniques. The results highlight the significant influence of factors such as crystallization temperature, duration, and the effect of sodium hydroxide concentration on the formation of zeolites. Optimal conditions set at a crystallization temperature of 97°C, duration of 24 hours, and NaOH concentration of 4M yielded pure zeolite LTA, boasting high crystallinity levels. Achieving a peak crystallinity of 82%. The obtained zeolite LTA showed an exceptional Cd (II) ion exchange capacity. A mechanism involving adsorption of Cd2⁺, Ni2⁺, Co2⁺, and Fe2⁺ ions in zeolite LTA at the α and β-cages has been proposed using dynamic simulation. This mechanism supports all experimental results, in particular for LTA- Cd2⁺, Cd2⁺ ions are predominantly distributed in both α and β-cages, with a denser distribution in the α-cages, indicating a strong preference for these sites due to their geometric and electronic environment. The resulted zeolite LTA demonstrated ability for successful Cd (II) removal, affirming its utility as an efficient material in environmental remediation industries.

Environmentally sustainable color fading approaches of denim fabric using alternative garments dry process: An insight into chromatic parameters and physical properties

Denim has been elevated to the status of "classic" in the modern fashion cycle by numerous advancements and development efforts over the past few decades. Consumers today are interested in clothing comfort, environmental sustainability, and aesthetic appeals in addition to newborn designs and novel looks. Previous research works had only focused on evaluating the physical properties of denim samples after applying existing hazardous dry processes (whiskering, sandblasting, and PP {Potassium permanganate} spray), but those don’t portray scientific assessment regarding environmental impact assessment, chromatic values and vintage effects of denim. This research work explores sustainable alternative dry garment processes using sodium hydroxide and heat treatment with a view to achieving highly fashionable worn-out effects on sulfur-dyed denim, focusing on color fading. Process variables such as different sodium hydroxide concentrations (5 g/L, 10 g/L, 15 g/L, and 20 g/L) and heat treatment by stenter machine operating temperatures (140°C, 160°C, 180°C, and 200 °C) are used to conducting the research. Addressing a research gap, it evaluates Environmental Impact Measurement scores using EIM Software and chromatic parameters using Datacolor Spectrophotometer. Other examining factors such as color fastness (CF), and physical characteristics such as tensile and tear strength, shrinkage%, air permeability, and contact angle are evaluated. The alternative methods of dry process using are environmentally sustainable with scores of 7 and 1 (EIM software’s scoring system implies 0–33 for low impact, 34–66 for medium impact, and >66 for high impact) respectively. Evaluations indicate decreasing patterns in color strength and chromaticity with higher sodium hydroxide concentration like 20 g/L and heat treatment, leading to a light black or grayish hue at 200°C. Conversely, lower concentrations (5 g/L, 10 g/L) and temperatures (140°C and 160°C) show increased a* (red-green), b* (yellow-blue) values, and r% (reflectance %). Fabrics treated with lower sodium hydroxide concentrations and temperatures exhibit weaker resistance to color change and staining. The study provides a comprehensive assessment using metrics like EIM score, color strength, chromaticity, hue angle, CIELAB color space, reflectance%, and color fastness tests, including rubbing, washing, and light fastness.

Effect of Alkalization Time on the Toughness and Strength of Jute Sack Waste Lamina Composite as an Alternative Car Bumper Material

Alkaline conditions, such as the concentration of Sodium Hydroxide (NaOH) and the duration of soaking time, significantly affect the mechanical properties of natural fiber and its composites. The objective of this study is to investigate the effect of alkali treatment on the impact toughness and tensile strength of laminated composites made from jute sack (burlap) waste woven fibers, which can potentially be used as a substitute material for vehicle bumpers. The experimental group comprised specimens that were alkalized by manipulating the duration of soaking and the concentration of alkali in the woven fibers of jute sack waste, with a fiber orientation pattern of 0°/+90°/0°/+90°/0°. The fiber immersion time is 24 hours, 48 hours, and 72 hours when using a 5% NaOH concentration. Epoxy resin serves as a composite matrix, specifically epoxy resin and epoxy hardener. Two sets of specimens underwent tests to measure their tensile and impact strengths. The result of the study reveals that the jute sack laminated epoxy composite with a fiber orientation of 0°/+90°/0°/+90°/0° had the maximum tensile strength and impact strength after a 48-hour alkaline treatment at 14.99 MPa and 0.010 J/mm2, respectively. The alkali treatment has successfully enhanced the tensile strength of the jute fiber by approximately 42.49% and 39.66% when compared to the untreated jute fiber. The study concludes that the utilization of alkaline process with NaOH improves the surface area of the fiber, compatibility with polymer matrix and mechanical strength.

Machine learning prediction of mechanical properties of bamboo by hemicelluloses removal

The use of bamboo as a sustainable material is becoming increasingly prevalent; however, the optimisation of its mechanical properties remains a significant challenge. In this study, different concentrations of sodium hydroxide (NaOH) were used to remove the hemicellulose of bamboo and the effect of mechanical properties such as modulus of elasticity, flexural strength and elastic limit were evaluated. A total of 90 samples of data were collected and five machine learning algorithms including Principal Component Regression (PCR), Partial Least Squares Regression (PLSR), Ridge Regression (RR), Lasso Regression (LR) and Elastic Network Regression (ENR) were employed to build predictive models based on these properties. The models were trained and tested using 5-fold cross validation. The results showed that the mechanical properties of elastic modulus and elastic limit of bamboo medium were enhanced to 9.63 GPa and 66.44 MPa treated by 10 % NaOH, while the flexural strength of bamboo medium was up to 147.29 GPa with 5 % NaOH. The Ridge Regression algorithm was the best compared to other four algorithms. This methodological approach is not only offers an efficient way to optimize the mechanical properties of bamboo, but also enhances sustainable practices in the environmental sector.

Innovative In-House Sodium Silicate Derived from Coal Bottom Ash and Its Impact on Geopolymer Mortar

Aluminosilicate precursors and alkaline solutions are combined to produce geopolymers. However, the high cost and energy demand of conventional alkaline activators limit the widespread use of alkali-activated materials (AAMs). Alkaline activators extracted from industrial wastes and by-products can address these challenges by reducing environmental impacts to a certain extent. Researchers have investigated the process for extracting alkali activators from waste materials that are high in silica, such as Waste Glass (WG) and Rice Husk Ash (RHA). However, there were limited studies on the extraction of sodium silicate from materials containing a moderate amount of silica. This study presents detailed findings on the production of alternate sodium silicates from Coal Bottom Ash (CBA) containing 43.7% SiO2 using a hydrothermal process, demonstrating the potential of CBA as an affordable and eco-environmental source of alkaline activators for geopolymers. The derived sodium silicate (DSS) was prepared using various sodium hydroxide (SH) molarities (3, 6, and 9 M) and stirred for 5 hrs at 80 °C. The solubility of silica from CBA was also examined and compared with that of COM-SS and RHA, which served as the control. CBA-SS performance in AAM mortar, flowability, hardened density, compressive strength, and ultrasonic pulse velocity (UPV) tests were performed. The results revealed that the silica dissolution increased with increasing SH concentration. In addition, the specimens activated by commercial sodium silicate (COM-SS), RHA-9M, and CBA-9M exhibited an increase in their compressive strengths at 56 days, which were 62.9, 93.52, and 59.08 MPa, respectively. The specimens activated with Coal Bottom Ash Sodium Silicate (CBA-SS) performed similarly to COM-SS. Therefore, geopolymer mortars can utilize CBA as a source of silica to derive sodium silicate. XRD and FESEM-EDX results confirmed the production of aluminosilicate hydrate (C-A-S-H) and calcium sodium aluminosilicate hydrate (N-A-S-H) as the primary components of the geopolymer gel.

Maximization of Biodiesel production from oil that produced during salmon smoking process with high amount of omega-3 by using homogenous catalyst.

The escalating global demand for oil, coupled with declining fossil fuel production, prompts the urgent exploration of renewable alternatives. To address this challenge, researchers are actively seeking environmentally friendly fuels like biodiesel. Among potential feedstocks, oil that is produced from salmon smoking process during industry emerges as a promising option. Smoked salmon oil could be a challenge when producing biodiesel due to its high content of omega-3 compounds. Using homogenous commercial catalyst from alkali to achieve the highest yield from salmon smoking oil was the aim of the current study. A Box-Behnken design and response surface methodology in Design Expert software (version 13) was used to study the effect of four main factors on the biodiesel yield from salmon smoking oil. The optimum biodiesel values were 70°C, 90 min, 0.753 wt.%, and 20 wt.% for temperature, reaction time, sodium hydroxide concentration, and methanol concentration, respectively. At these optimum values, the highest biodiesel production was 92.0% with fatty acid methyl ester contents of 83.4% and conversion efficiency of 77%. Thin-layer chromatography and thermal gravimetric analysis confirmed the successful production of biodiesel at optimized conditions. Using Aspen Plus simulation software confirmed the cost-effectiveness of the homogenous catalyst used for enhancing biodiesel production from salmon smoking oil.

Niobium Metal–Organic Framework Is an Efficient Catalytic Support for the Green Hydrogen Evolution Process from Metal Hydride

Herein, the development of a niobium-based metal–organic framework (Nb-MOF) designed to serve as a catalytic support for the production of hydrogen (H2) from sodium borohydride (NaBH4) is reported. The Nb-MOF was synthesized via a solvothermal method using niobium ammoniacal oxalate (AmOxaNb) as the metal source and 1,4-benzenedicarboxylic acid (BDC) as the ligand. The resulting MOF was characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The characterization study confirmed the successful synthesis of Nb-MOF. The catalytic activity was optimized by examining five key factors: (i) platinum (Pt) and cobalt (Co) bimetallic compositions (ranging from 1:0 to 0:1 mmol), (ii) NaBH4 concentration (0.2, 0.3, 0.4, and 0.5 mol L−1), (iii) the Nb-MOF/Pt–Co catalyst dose (0.05, 0.10, 0.20, and 0.40 mmol), (iv) sodium hydroxide (NaOH) concentration (0.01, 0.05, 0.1, and 0.2 mol L−1), and (v) system temperature (293.15, 298.15, 303.15, 313.15, and 323.15 K). The optimal catalyst was identified as Nb-MOF supporting a Pt-Co bimetallic composition in a 0.4:0.6 mmol ratio, achieving a hydrogen generation rate (HGR) of 1473 mL min−1 gcat−1 and an activation energy of 19.2 kJ mol−1. Furthermore, this catalyst maintained its efficiency over 20 cycles, demonstrating significant potential as a sustainable solution for H2 evolution from NaBH4.

Pre-treated municipal solid waste bottom ash as alkali-activated mortar precursor

Pre-treated incinerator bottom ash was used as a precursor of alkali-activated mortars. Control mortars were produced using coal fly ash. Different combinations of alkaline activator were tested (sodium oxide/binder ratio (4%, 6%, 8%, 10% and 15%) and silicon dioxide/sodium oxide ratio (0, 0.5, 1.0, 1.5 and 2.0)) and the influence of these on the mortar's mechanical performance was evaluated. The mortars were tested in both fresh (for density and workability) and hardened states (for dry density, compressive and flexural strengths and modulus of elasticity) after 7, 28, 91 and 182 days. The first stage of work was precursor pre-treatment in a sodium hydroxide solution to prevent the expansion of fresh specimens due to the reaction of aluminium with the alkaline activator. The pre-treatment was effective in preventing excessive hydrogen gas generation during setting, leading to dimensional stability and improved strength. Different optimum sodium oxide contents were observed after 28 days (i.e. 15% for fly ash specimens and 8% for bottom ash specimens). The results of a simplified life-cycle assessment showed that such mixes exhibited lower overall carbon dioxide emissions when compared with cement-based counterparts. However, this trend was reversed with increasing contents of sodium hydroxide and sodium silicate.

Evaluating sisal fibers as an eco-friendly and cost-efficient alternative to cotton for the Moroccan absorbent hygiene and textile industries

The Moroccan textile and hygiene industries face challenges related to the cost and availability of imported cotton fibers, prompting the exploration of alternative and sustainable solutions. The goal was to replace cotton, which presented a significant challenge for the sector, while maintaining its quality properties. This study aimed to replace the imported cotton fibers in Morocco with sisal fibers, a locally available, cheaper, and durable product that exhibits satisfactory physicochemical properties. To achieve this, sisal fibers were treated with different concentrations of sodium hydroxide (NaOH), sodium chlorite (NaClO₂), and hydrogen peroxide (H₂O₂). Analytical techniques, including Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Optical Microscopy (OM), and X-ray Diffraction (XRD), were used to assess both sisal and commercial cotton fibers. Laboratory tests, such as pH measurements, water absorption, flammability, and degumming rate, were conducted to evaluate and compare their properties. Among the sisal samples analyzed, those treated with 10 % by weight (wt) NaOH and bleached with NaClO₂ showed satisfactory results. These fibers exhibited a compliant pH, a chemical structure similar to cotton, reduced fiber size, a type I crystal structure with a 0.36 crystallinity index, and improved thermal stability. Additionally, they presented a whitish appearance, softness similar to cotton, good fluid absorption capacity, and flame resistance. This study concluded that cotton fibers can be substituted with sisal fibers in the textile and hygiene industries. Further comprehensive analyses could expand the applicability of sisal fibers to additional sectors.

Effect of Mercerization on the Properties of Cellulose Fiber and Cellulose Hydrogel Extracted from Pineapple Leaf Fiber

AbstractThis study investigated the effects of alkaline treatment on the pineapple leaf fiber (PALF) cellulose extraction and the properties of cellulose hydrogel. PALF was treated with different concentrations of sodium hydroxide (NaOH) (2 to 10 wt %) and at room temperature (RT) and 80 °C. Then, extracted cellulose was then dissolved in N,N’‐dimethyl acetamide (DMAc)/lithium chloride (LiCl) solvent system and formed into hydrogel by phase inversion method. The Fourier transform infrared spectra shows the peak disappearance at 1606 cm−1 proves that lignin was removed starting from 6 and 4 wt % NaOH at RT and 80 °C, respectively. Higher NaOH concentrations treatment increased thermal stability and the crystallinity (71 to 79 %) of the fibers. Higher NaOH concentration and treatment temperature enhanced cellulose extraction from PALF, leading to more physical crosslinking during hydrogel formation. High amount of cellulose extracted decreased the hydrogel's swelling equilibrium and increased the gel fraction. The highest transmittance (87.8 %) and the lowest intensity of absorbance (at 280 nm corresponding to lignin) were obtained by the hydrogel prepared with PALF treated with 8 wt % NaOH at 80 °C. Clearly, this research findings provide new insights into optimizing cellulose extraction using alkaline treatment specifically for cellulose hydrogel formation.

Reflux extraction with saponification of crude wax from sugarcane filter cake for policosanol production

Abstract Filter cake, a by-product in the sugar industry, has significant amount of wax containing policosanol which can be extracted using proper method and solvent. Policosanol is a mixture of high molecular weight aliphatic primary alcohols and was reported to reduce cardiovascular diseases. This study explored the use of hot ethanol reflux extraction to recover the crude wax from the filter cake followed by saponification for policosanol purification. Crude wax yield of 84.5 mg crude wax/g filter cake was obtained using reflux extraction at 60° C, 500 rpm and 12 mL absolute ethanol/g filter cake. The maximum crude wax yield obtained from Soxhlet extraction was 121.88 ± 0.46 mg crude wax/g dry filter cake, which corresponds to 69.33% recovery. Using a two-level factorial design, the effects of sodium hydroxide (NaOH) concentration (0.1 M and 1 M), reaction time (30 minutes and 60 minutes)and reaction temperature (30 °C and 60 °C) on the policosanol yield during saponification were determined. Results showed that NaOH concentration and temperature have significant effects on policosanol yield while reaction time alone is insignificant. Increasing both the reaction time and NaOH concentration can lead to an increase in policosanol yield. The highest yield of 1.234 ± 0.322 mg policosanol/g crude wax after saponification was obtained at 60 °C for 60 minutes with 1 M NaOH. This is twice the amount of policosanol recovered as compared to 0.583 ± 0.026 mg policosanol/g crude wax without saponification.

On the applicability of the 06KHN28MDT steel to the production of pipes resistant to sodium hydroxide solutions

Sodium hydroxide is a very aggressive medium; therefore, the equipment for its production is subject to intense corrosion. Most of the process pipelines of the Bashkir Soda Company JSC are made of the Nickel 201 alloy, which has low abrasive resistance. As a result, there are cases of equipment failures due to corrosion-erosion destruction. Since this alloy is expensive, it is a relevant problem to replace it with cheaper materials that are not inferior in corrosion resistance. This paper presents the results of studying the possibility of replacing the nickel alloy with the 06KhN28MDT austenitic steel. It is shown that this steel is not inferior in its corrosion resistance and a number of other characteristics to the Nickel 201 alloy. Thus, at room temperature, at a sodium hydroxide concentration of 50%, the corrosion rate of the 06KhN28MDT steel is one-third as high as that of the Nickel 201 alloy. With the increasing concentration of caustic soda, the difference in corrosion resistance between these materials decreases and disappears when it reaches 80%. It has been found that the hardness of the 06KhN28MDT steel is four times as high as that of the Nickel 201 alloy. The studies have proved that the 06KhN28MDT steel can be recommended to replace the expensive nickel alloy in the production of pipes in contact with sodium hydroxide solutions.

An investigation of the mechanical strength, environmental impact and economic analysis of nano alkali-activated composite

The current study explores both the mechanical strength and life cycle assessments of fly ash (FA)-based alkali-activated concrete (AAC) with/without colloidal nano-silica (NS) addition at high and low molar concentrations of sodium hydroxide in the activator fluid (12 M and 3 M). The cradle-to-gate approach is used to establish the system boundaries for life cycle assessments (LCA). The environmental impact of AAC (with/without NS) and conventional cement concrete (CC) mixtures was determined using the ReCiPe midpoint and endpoint approaches across various impact categories. The AAC mixes with and without NS addition reduce greenhouse gas (GHG) emissions by 30 % and 25 % with respect to CC mix, respectively. Within the majority of impact categories, sodium silicate and sodium hydroxide production are the primary contributors, accounting for up to 91 %. However, in water depletion, global warming potential, and fuel depletion, the overall contribution is as high as 65 %. Also, the AAC mix with and without NS addition consumes 34 % and 14 % less electricity during its production with respect to the CC mixture. The CC mixes have almost 70 % more ecological damage and approximately 30 % more health risk than AAC with and without NS. However, the NS-modified AAC shows 20 % lower ecological and health risks than AAC without NS. The effect of resource scarcity on NS modified AAC is 50 % less than that of other mixes, including both AAC mix without NS and CC mix. In comparison to AAC without NS, the NS modified AAC demonstrates an 18 % reduced impact on resource scarcity. Finally, cost analysis demonstrates that AAC with NS is 16 % less expensive than CC, while AAC without NS is 26 % cheaper than CC. AAC containing 6 % NS inclusions exhibits environmental and economic benefits in addition to its enhanced mechanical performance, indicating its potential for widespread practical usage.

Evaluating Alkali Activation in Magnesium Slag Carbonization and Its Mechanism

In recent years, magnesium slag has been used as a raw material for solid waste treatment using the carbonization method and has proven to be promising in reducing carbon emissions. In this study, the alkali activation reaction was introduced to promote the carbonization of magnesium slag. The resulting mechanical properties, microstructural attributes, and carbonization mechanism were studied by varying the sodium hydroxide content, temperature, and carbon dioxide concentration during the reaction process. The results showed that the amounts of calcium hydroxide, C-S-H, and calcium carbonate in the reaction products increased with the sodium hydroxide content, which enhanced the compressive strength of the composite. However, it does not influence the carbonization mechanism with the increasing reaction temperature, which only elevates the reaction rate. With the increase in the carbon dioxide concentration during alkali activation, the carbonization reaction is dominated by the amount of CO2 dissolved in the reaction medium, and the carbonization mechanism is changed. Thus, a significant decrease in the calcium hydroxide content and a sharp increase in the calcium carbonate content in the products occurred, which significantly improved the compressive strength of the resulting magnesium slag composite. Among them, the maximum compressive strength is 6.83 MPa.

Pretreatment and dyeability analysis of cotton and novel Bauhinia vahlii fiber

The textile industry is witnessing a paradigm shift towards sustainable materials, prompting the exploration of novel natural fibers as alternatives to synthetic fibers to meet environmental standards and address the growing demand for eco-friendly and sustainable products. Different natural fibers possess varied properties and are suitable for numerous applications in conventional and technical textiles. The coloration of these textile materials is an important aspect of conventional textiles, which starts with the pretreatment of the material. This study introduces a novel blend of cotton and Bauhinia vahlii fiber, a lesser-known natural cellulosic fiber with promising textile properties, and evaluates its pretreatment outcomes and dyeability characteristics. The study employs a systematic approach to pretreat the cotton and Bauhinia vahlii fiber blend (cotton: Bauhinia vahlii fiber 70:30) in a single bath using a conventional combined scouring bleaching process. The pretreatment process is carried out two times with varied sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) concentrations for different processing times at 90 °C to assess the component fibers’ whiteness index, union bleaching balance, and weight loss percentage under diverse pretreatment conditions. Each time, 50% of the chemicals were used and continued for half of the processing time. The dyeability of the treated fibers is analyzed by dyeing the same in a single bath using amron bright red HF2R bifunctional reactive dye in varied shade depths (1%, 3%, and 5%) and fiber blend ratios (cotton: Bauhinia vahlii fiber 100:0, 90:10, 80:20, 70:30, and 0:100) to assess the color strength, union dyeing balance, and fastness properties. The maximum whiteness was achieved with 6 g per liter (gpl) of NaOH and H2O2 and at a processing time of 150 min with a whiteness index of 80.46 and 54.34 of cotton and Bauhinia vahlii fiber, respectively, with a union bleaching balance of 1.48. The dyed fibers’ colorimetric results confirm that Bauhinia vahlii fiber gives higher color strength than cotton fiber, irrespective of shade depth and blend ratio. The union dyeing balance of 1.2 was achieved at 5% shade depth with a 70:30 cotton Bauhinia vahlii fiber blend. This research contributes to the conventional textile field by introducing a sustainable fiber blend that reduces reliance on synthetic fiber and opens new avenues for utilizing Bauhinia vahlii fiber in conventional textile manufacturing.

Optimizing alkali-activated clay with rubber waste for sustainable earthen bricks: A comprehensive study

This study explores the potential of optimizing alkali-activated clay with rubber waste to create sustainable earthen bricks. The research addresses the environmental challenges associated with traditional cement-based construction materials by incorporating locally sourced calcined clay and recycled rubber tire waste. The experimental program involves testing different proportions of sand with calcined clay, varying sodium hydroxide (NaOH) concentrations, and integrating rubber content. The aim is to develop a material that balances environmental sustainability with improved mechanical and durability properties. The mechanical and microstructural properties of the resulting materials were evaluated through compressive and flexural strength tests, wetting and drying cycles, and advanced analysis techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that while the inclusion of rubber enhances certain properties such as reducing the unit weight and Structural Integrity During Wet-Dry Cycles, it adversely affects compressive and flexural strengths. This study highlights the importance of optimizing the balance between durability and mechanical strength to develop effective and sustainable construction materials.

Response Surface Design Models to Predict the Strength of Iron Tailings Stabilized with an Alkali-Activated Cement

Tailing storage facilities are very complex structures whose failure generally leads to catastrophic consequences in terms of casualties, serious environmental impacts on local biodiversity, and disruptions in the mineral supply. For this reason, structures at risk must be reinforced or decommissioned. One possible option is its reinforcement with compacted filtered tailings stabilized with binders. Alkali-activated binders provide a more sustainable solution than ordinary Portland cement but require an optimization of the tailing–binder mixture, which, in some cases, can lead to a substantial experimental effort. Statistical models have been used to reduce the number of those experiments, but a rational design methodology is still lacking. This methodology to define the right mixture for a required strength should consider both the mixture components and in situ conditions. In this paper, response surface methods were used to plan and interpret unconfined compression strength test results on an iron tailing stabilized with alkali-activated binders. It was concluded that the fly ash content was the most important parameter, followed by the liquid content and sodium hydroxide concentration. From the obtained results, several statistical models were defined and compared according to the definition of a strength prediction model based on a mixture index parameter. It was interesting to observe that models with the porosity cement index still provide reasonable adjustment even when different tailings’ water contents are considered.