Concentration Of Sodium Hydroxide Solution Research Articles

Analyzing the compressive strength of green fly ash based geopolymer concrete using experiment and machine learning approaches

In this research, two different machine learning approaches are proposed for predicting the compressive strength of fly ash based geopolymer concrete. Experimental work with a total of 335 mix proportions were conducted to produce the data for training and validating processes. In the proposed models, the amount of fly ash, water glass solution, sodium hydroxide solution, coarse aggregate, fine aggregate, water, concentration of sodium hydroxide solution, curing time, and curing temperature were considered as nine input variables, while compressive strength was the output feature. The performance of the machine learning approaches was evaluated using a set of three metrics, including correlation coefficient (R), mean absolute error (MAE) and root mean square error (RMSE). Good correlation between machine learning models and experimental results was obtained. The proposed models can be employed to build a standard mix, and for designing the mix proportions of fly ash based geopolymer concrete.

Extractive Separation of Scandium from Strongly Alkaline Solution by Quaternary Ammonium Salt

ABSTRACTExtraction and separation of scandium(III) from concentrated sodium hydroxide solution using quaternary ammonium salt (Aliquat 336, CH3R3NOH) in kerosene as a diluent with 10% (v/v) octanol as a modifier were investigated. The parameters that affect the extraction process were separately studied. On the basis of the slope analysis method, the composition of the extracted species was proposed to be [CH3R3NSc(OH)4]. The structure of the extracted metal species was supported by FT-IR investigations. Furthermore, the thermodynamic parameters related to the extraction process were estimated and the extraction process was found to be exothermic and spontaneous. The loading capacity of Aliquat 336 towards Sc(III) and stripping of loaded Sc(III) from the organic phase were also examined. Based on the acquired results, the method developed was applied for the recovery and separation of Sc(III) and other metal ions from a synthetic solution similar in composition to that expected from the leaching solution of red mud in strongly alkaline medium.

EVALUATION OF THE ENGINEERING PROPERTIES OF FLY ASH-BASED GEOPOLYMER BRICKS

This paper is aimed to evaluate the engineering properties of fly ash-based geopolymer bricks. Four geopolymer brick mixtures were designed with a constant solution-to-binder ratio of 0.40 and various concentrations of sodium hydroxide solution. The engineering properties of fly ash-based geopolymer bricks consisting of compressive strength, unit weight, water absorption, water permeability, and ultrasonic pulse velocity were investigated. The microstructure of fly ash-based geopolymer bricks was also investigated by using the scanning electron microscope (SEM). Test results indicated that the compressive strength, unit weight, and ultrasonic pulse velocity (UPV) of geopolymer bricks increased, while the water absorption and water permeability of geopolymer bricks reduced with increasing NaOH concentration. Moreover, brick samples with high NaOH concentration showed a higher geopolymeric reaction of fly ash than brick samples with low NaOH concentration. All geopolymer brick samples produced in this study showed a good quality with compressive strength of above 10.1 MPa, water absorption of below 9.4%, water permeability of below 1.84 L/m2 .h, and UPV of above 2500 m/s.

Effects of High-Concentration Alkali Treatment on Surface Bioactivity of Porous Titanium

Various surface treatment methods have been used to modify the surface activation of dense titanium. In this study, a high concentration of sodium hydroxide solution was used to treat porous titanium prepared by adding porous agent at different times. The results of the study showed that after alkali treatment, porous titanium was implanted into the back muscle of the dog and the implanted sample was taken out for bone formation protein-2 enzymatic immunoassay after 6 months. The porous titanium inner wall has been covered. The microstructures vary with the treatment time. The treated surface can induce the formation of hydroxyapatite deposition and promote the expression of BMP-2, which shows good bone induction. High concentration alkali treatment of porous titanium, the method is simple, can shorten the HA formation time, can effectively activate porous titanium inner and outer surfaces, is an effective method to prepare bioactive porous titanium.

Volume Change Characteristics of Eco-Friendly Mortar Mixes Produced with Geopolymeric Binder and Recycled Fine Aggregate

Abstract The production of geopolymer mortar using recycled fine aggregate (RFA) generated from concrete waste has significant potential to be a sustainable construction material. In this article, the volume change properties of the produced geopolymer mortar mixes are studied in terms of drying shrinkage up to the age of 180 days and reported as the percentage increase with respect to the shrinkage value of 3 days. The influence of RFA content, alkaline liquid (AL) in terms of the concentration of sodium hydroxide (SH) solution, the ratio of sodium silicate (SS) solution to SH solution, and the ratio of AL to fly ash (FA) were investigated on the drying shrinkage properties of the geopolymer mortar mixes. All the cast specimens were cured at 80°C for 24 hours. Higher drying shrinkage values were observed for the mortar mixes produced with higher RFA content, AL/FA, SS/SH ratio, and lower concentration of SH solution. Scanning electron microscope images were studied for the samples taken from the geopolymer mixes showing lower drying shrinkage values to understand the microstructure.

Influence of Fiber content and screw speed on the Mechanical characterization of Jute fiber reinforced Polypropylene composite using Taguchi Method

Utilizations of natural fiber-reinforced composites are increasing day by day due to many environmental advantages and replacement of petroleum-based products. Now a day’s researchers also focused on the replacement of thermoplastics in place of thermoset plastics due to many of the advantages. Out of many potentialities, low-cost productions with lower cycle time and high reparability are important parameters. This paper focused on the mechanical characterization of chemically treated jute fiber reinforced thermoplastic polypropylene (PP) composite processed using a twin-screw extruder. Jute fibers were chopped into smaller lengths and treated 4% concentrated Sodium hydroxide solution for 2 hours with the stirring speed of 50 rpm. These fibers were mixed with thermoplastic matrix and prepared composites using twin screw extruder by varying jute fiber mass faction 10, 20 and 30% and screw speed 100, 200 and 300 rpm. The influences of mechanical properties like tensile, flexural, and impacts (Both notched and unnotched) are discussed for varying screw speeds of the extruder and percentages of the jute fiber. Further, water absorption was studied for various temperatures to understand the influence of fiber adding in polypropylene. In polymers head deflection strength were very important, so further heat deflection temperature were studied. The results show mechanical properties varies significantly by varying screw speed and mass percentages

PEMBUATAN KERTAS RAMAH LINGKUNGAN KOMBINASI LIMBAH AMPAS TAHU DAN LIMBAH KULIT PISANG KEPOK DENGAN METODE PEMISAHAN ALKALISASI

Tofu dregs waste contains 30.4% cellulose content, while kepok banana peel has high cellulose content (60-65%), hemicellulose 6-8%, and lignin 5-10%. The purpose of this study was to determine the process of making natural paper from tofu dregs waste and kepok banana peel waste as an alternative raw material for wood substitutes and to find out the characteristics of natural paper produced from tofu waste fiber and kepok banana peel waste based on SNI 287:2010 (including test water content) and SNI 6588-1:2010 (including pH acidity test). Based on the results of research that has been carried out, the optimum composition in making paper from tofu dregs and kepok banana peels is 50:50% variation. The temperature and time of heating and the optimum concentration of sodium hydroxide solution was 120 oC for 90 minutes with sodium hydroxide solution concentration of 10.0%, pulp content of 46.45%, cellulose content of 53.3%, and lignin content of 46.67%. All levels obtained have met the requirements of SNI. Based on the FT-IR spectrum analysis, tofu dregs and kepok banana peels are suitable for use as raw materials for making paper because they contain cellulose. Based on the SEM analysis, the morphological surface structure, the tighter the fiber bonds, this proves that the diameter of the resulting fiber is very small, because the smaller the fiber diameter, the better the mechanical properties.

Study on Biochemical Degumming Process of Mulberry Fiber, Part 2: Orthogonal Optimization Analysis

ABSTRACT The mulberry fiber is extracted from the mulberry bast by biochemical degumming method. Based on the single factor experiment, the orthogonal experiment is further designed. The optimal process parameters for biochemical combined degumming are as follows: pretreatment stage, sulfuric acid solution concentration 2.5g/L, time 1h, temperature 60°C, bath ratio 1:20; alkaline pectinase treatment stage, alkaline pectinase solution concentration 46g/L, time 8h, temperature 50°C, bath ratio 1:20, solution pH = 9; alkali boiling stage, sodium hydroxide solution concentration 10g/L, alkali boiling time 3h, sodium silicate 30g/L, temperature 100°C, bath ratio 1:20; xylanase treatment stage, the concentration of xylanase solution 9g/L, the time 4h, the temperature 50°C, the bath ratio 1:20, and the solution pH = 4.8. By comparing the properties of mulberry fiber obtained by biochemical degumming and chemical degumming, it is found that the biochemical degumming process has less damage to fibers and more effective removal of lignin and hemicellulose.

Design and Fabrication of a Wet Mechanical Brushing Unit for Lye Pre-treated Cassava Root

The design and fabrication of a wet mechanical brushing unit for lye pre-treated cassava root was described in this paper. The objective of this work was to determine the time of reaction, the temperature and the concentration of sodium hydroxide solution that will effectively digest the peel and also the speed of the machine, output size, efficiency of peeling and tuber loss. It was determined that using lye solution to digest cassava root peel depends on the severity of the concentration of the solution and the time of root immersion. From the preliminary labouratory tests carried out, the optimal combination of process parameters in terms of concentration, temperature and time of root immersion for UMUCASS44 in lye are 20%, 60°C and 15 minutes, respectively. These values are sufficient to digest the peels of the root for enhanced brushing.

Carbon-Mineral Adsorbent from Petroleum Pitch and Precipitated Colloidal Silica

The carbon-mineral adsorbent was prepared according to a two-stage scheme, which, despite the hydrophilic nature of the surface of colloidal silica, made it possible to prepare pellets with a high specific surface area and compressive strength of up to 70 m2/g and 8 MPa, respectively. The proposed method consists in mixing petroleum pitch and colloidal silica in the first stage, followed by granulation and carbonization (at 1000 °C); the resulting carbon-mineral material is crushed and mixed with petroleum pitch in the second stage, after which it is also granulated and carbonized (at 700 °C). Based on the obtained carbon-mineral sorbent, a highly porous carbon adsorbent is produced by etching the silicate base in a concentrated solution of sodium hydroxide during boiling. The total pore volume of the obtained samples reached 3.5 cm3/g.

Study of mechanical properties of fly ash-based geopolymer concrete

The world is facing the challenges of climate changes due to the increase in CO2 emissions. Cement production is one of the biggest contributors to CO2 emissions due to combustion processes that require high temperatures. The new development in building construction showed that fly ash based Geopolymer concrete can be as structure materials to reduce or even eliminate ordinary Portland cement concrete. This paper presented the research results of fly ash based geopolymer concrete mechanical properties, like the compressive strength, flexural strength, and Elastic Modulus. The data were collected from the test results of geopolymer concrete specimens made from 2 sources of Fly Ash with varying concentration of sodium hydroxide solution from 4 M up to 12 M. The range of achieved compressive strength was from normal to high strength concrete. The correlation between the compressive strength and flexural strength and the Elastic Modulus of geopolymer concrete will be the highlight of this paper. The mathematical formulation of compressive strength and its flexural strength and Elastic modulus will be determined and compared with normal Portland Cement Concrete.

Effect of combined dilute-alkaline and green pretreatments on corncob fractionation: Pretreated biomass characterization and regenerated cellulose film production

Pretreatment is an essential step prior to the effective valorization of lignocellulosic biomass. However, depending on the pretreatment method, it can be costly and originate potential environmental threats. In this study, green pretreatments, namely Liquid Hot Water (LHW) and 1-butyl-3-methylimidazolium chloride (BmimCl), as well as low concentrated sodium hydroxide solution (NaOH), were applied individually and in combination to pretreat corncob, and their effects on physicochemical properties of fibers were analyzed. The pretreated samples were dissolved in ionic liquid and attempts to prepare regenerated cellulose films have been made. While NaOH was efficient to removal lignin, LHW presented higher solubilization hemicellulose. By combining these treatments, the biomass was fractionated in a complementary way, and a solid enrich-cellulose fraction with high thermal stability and crystallinity was obtained. The BmimCl did not significantly change the chemical composition of biomass and, independent of the treatment applied in combination, samples were regenerated as amorphous cellulose coexisting with lesser amount of cellulose crystalline I. This structural conversion was also confirmed through thermogravimetric analysis, from which a decrease in thermal stability was verified. This latter property was markedly affected by the presence of hemicellulose remained after some pretreatments. The obtained results indicate that each pretreatment performed can meet different application requirements. The LHW-NaOH pretreated sample was the only one suitable to produce regenerated films, which exhibited good mechanical properties to be used in value-added applications, such as packaging.

Recovery of rare earths from waste cathode ray tube (CRT) phosphor powder with organic and inorganic ligands

Cathode ray tubes (CRTs) have an appreciable amount of rare earth elements (REEs). In this document, the leaching and recovery of the REEs from CRTs, with different organic and inorganic ligands is presented. Among the complexing agents tested, the pyrophosphate ion was found to be the most advantageous for the extraction of REEs from CRTs, as an alternative to the traditional methods that use highly acidic solutions (pH < 1) and elevated temperatures. Thermodynamic analyses predict the formation of soluble REE-pyrophosphate complexes in a pH range of 2–8. Leaching solutions of 0.1 M Na4P2O7 at pH 6 and room temperature were employed. REE dissolution from the untreated CRT powder under these conditions was extremely low, due to the encapsulation by other components in the powders, such as ZnS (26%), and the high content of phosphates (6%), that severely limited the solubility of the REEs. To increase extraction, pretreatments were employed to alter and remove the passivating species: roasting at 800 °C or contact with concentrated solutions of sodium hydroxide at 95 °C. The combination of these pretreatments completely eliminated the Zn and 79% of the phosphate ion, as well as other base metals, resulting in an improved exposure of REEs for subsequent leaching. Extractions for Y, Eu, Sm, and Ce of 58, 90, 90 and 87%, respectively, were achieved with the pyrophosphate solution at ambient temperature. The REEs were later recovered as oxides by adjusting the solution pH to 11. Subsequently, once the pyrophosphate solution pH is reestablished, it may be reused for leaching.

Confining Photoacidity

Confining Photoacidity

Optimization of the design parameters of fly ash-based geopolymer using the dynamic approach of the Taguchi method

The dynamic approach of the Taguchi method is applied to optimize the mixture proportions and manufacturing conditions of fly ash-based geopolymer (FAGP) mortar using fly ash produced at two different thermal power plants in the Kyushu region, Japan. Ground granulated blast-furnace slag (GGBS) is also used as an activation powder. The design parameters of a system, with the volume ratio of powder to alkaline activating solution as the input value and the flow value as well as the flexural and compressive strengths as the output values, are optimized based on the calculation of the signal-to-noise ratio. As a result, optimum values for the mass ratio of sodium silicate solution to sodium hydroxide solution, concentration of sodium hydroxide solution, GGBS replacement ratio, mixing time, curing temperature, and cumulative temperature in heat curing are obtained. The values of the optimized design parameters are almost the same, regardless of the type of fly ash. The compressive strength of the optimized FAGP mortar ranged from 28.8 N/mm2 to 47.1 N/mm2 at 2 days, corresponding to the input values. Furthermore, it is confirmed that the optimized FAGP mortar has strength stability and sulfuric acid resistance up to 91 days sufficient for practical purposes.

Influence of Glass and Limestone Powders in High Calcium Fly Ash Geopolymer Paste on Compressive Strength and Microstructure

The effects of replacing high calcium fly ash with containment glass powder and limestone powder in the geopolymer are investigated in this paper. The high calcium fly ash was replaced by either glass powder or limestone powder at 20% and 40% by weight. The geopolymer paste was tested for setting time and compressive strength and evaluated of its microstructure on SEM, XRD, FTIR, and MIP. The results indicated that the setting time of geopolymer paste was increased with the replacement of glass powder and reduced by replacement of limestone powder. The compressive strengths were generally higher than those of controls. The maximum increase of compressive strength was 33% when replaced fly ash with 20% of glass powder at 8 molar NaOH concentration of sodium hydroxide solution. The microstructure evaluations show the remaining particles of raw materials and the compatible of hydration reaction and polymerization when having limestone powder in the mix proportion. Furthermore, the powder acts as a filler in the gels.

Engineering properties of clayey soil stabilised with alkali-activated slag

The effects of alkali-activated slag on the engineering properties of clayey soil were investigated. The mix proportion parameters were chosen by using Taguchi's experimental design methodology. Four factors (ground-granulated blast-furnace slag content, concentration of sodium hydroxide solution, sodium hydroxide-to-sodium silicate weight ratio and alkaline solution-to-slag weight ratio) were assessed in order to obtain the greatest compaction properties, uniaxial compressive strength and California bearing ratio (CBR). Significant improvements were observed in the mechanical properties (unconfined compressive strength (UCS) and CBR) of the clayey soil with addition of the stabilisers. Optimal values (15% slag content, sodium hydroxide concentration of 6 M, sodium hydroxide-to-sodium silicate ratio of 0·5 and alkaline solution-to-slag ratio of 2·5) increased the UCS of the compound from 8 to 100 kg/cm2 at 7 d. The excessive addition of alkaline solutions weakened the strength parameters of the soil. The results showed that the most influential factor was the alkaline solution-to-slag weight ratio. The Taguchi method is an effective and suitable experimental method for optimising alkali-activated slag parameters.

Leaching behavior and kinetics of vanadium extraction from vanadium-bearing steel slag

The vanadium-bearing steel slag as solid waste is also one of valuable vanadium-containing resource. Recovering vanadium from the refractory steel slag is a great challenge in the world. A leaching process study using high concentration sodium hydroxide solution was proposed in this laboratory work. The effects of sodium hydroxide concentration, particle size, leaching temperature and the ratio of alkali to slag on the rate of vanadium leaching were determined and the leaching kinetics was presented. It indicates that the leaching rate is highly sensitive to the sodium hydroxide concentration and leaching temperature and increases with increasing temperature and sodium hydroxide concentration. By studying the reaction mechanisms, it was found that the dicalcium silicate, tricalcium silicate and calcium ferrited which co-exist with calcium vanadate in the vanadium-bearing steel slag were gradually exposed and reacted with NaOH media to form Na3VO4. The leaching kinetics was analyzed which indicated that the leaching rate is controlled by the chemical reaction with the apparent activation energy of 51.34 kJ/mol. On the basis of this process, the vanadium can be effectively extracted with a leaching rate of more than 80%. The leaching medium can be recycled. It is an effective and cleaner process for leaching vanadium.

Bond strength of alkali-activated slag based tunnel fireproof coating material

Abstract The influence of the concentration of sodium hydroxide solution on the tensile bond strength of alkali-activated slags (AAS) used as a tunnel fireproof coating material was studied under t...

The effect of calcination temperature on metakaolin structure for the synthesis of zeolites

ABSTRACTThe aim of this research was to determine the temperature of kaolin calcination in order to obtain an intermediate product (metakaolin) for the synthesis of geopolymers with potential application as self-supporting zeolitic membranes. The products obtained were analysed with X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The structural analysis of the metakaolins obtained suggested that the optimal temperature for the proposed application is 700°C. After alkali activation of metakaolin, it is possible to obtain zeolite A and hydroxysodalite. The factors analysed, determining the type and quantity of crystalline phases, were activation temperature and concentration of sodium hydroxide solution (activator). The largest amounts of zeolites were obtained by alkali activation with 9 mol/dm3 NaOH solution at 70°C.