Concentration Of Sodium Silicate Solution Research Articles

Effect of sodium silicate concentration on the physico-chemical properties of dual-setting bone-like apatite cements

Calcium phosphate cements (CPCs) with their biocompatibility, osteoconductivity and injectability plays an important role in bone defects treatment. Dual-setting cement is a promising approach to improve the physicochemical and biological properties of CPCs in which the liquid phase contains dissolved monomers that polymerized during hardening process. In this study, a series of dual-setting cements were prepared by mixing dicalcium phosphate dihydrate (DCPD) as a solid phase and sodium silicate solution (SS) with different concentrations as hardening liquids. The idea was to evaluate the effect of SS concentration on the setting mechanism, physicochemical and mechanical properties of the formulated cements. The setting kinetics was attributed to the DCPD dissolution and calcium deficient hydroxyapatite (CDHA) precipitation in parallel to SS polymerization to form sodium silicate gel. This was responsible for the formation of an interpenetrating composite material in which the formed gel fills the micropores of the CPC cement. The results showed that the setting time can be modulated by varying the SS concentrates in the hardening liquid. It was shown, as the SS content in the cement liquid increased from 10 to 30 wt%, the setting time decreased from 56 to 5 min. Moreover, the DCPD dissolution and CDHA precipitation were accelerated by increasing the SS concentration. The bone-like apatite cement with the highest SS content exhibited an enhanced compressive strength and high resorption rates. Overall, the addition of sodium silicate gel is a promising approach to regulate the different properties of the apatite-forming cement to be used for bone fracture treatment.

Characterization of Silica Nanoparticles and Nanocolloid Synthesized in Acidic and Alkaline Media

Nanosilica in known as one of the most widely used components in various industries. In the current study, silica nanoparticle/colloid were synthesized in acidic and alkaline media using sodium silicate as a precursor. The effect of synthesis parameters on the morphology of the obtained nanoparticles and the rheological properties of silica colloid were studied. Microscopic observations revealed that size and morphology of the obtained silica nanoparticles can be changed by varying the ammonia to ethanol ratio, as well as the concentration of sodium silicate solution. The results revealed that the particles size is raised by increasing the ethanol to ammonia ratio and increasing the sodium silicate concentration leads to irregular and larger particles. the particles In fact, at (EtOH/NH3 :1 and Na2SiO3/H2O:0.07) a stable colloidal silica containing silica nanoparticles with average diameter of 65nm could be achieved. Additionaly, gelation time (tgel) of nanocolloid was measured using time sweep at constant frequencies of 0.1, 0.3 and 0.5 Hz. Applying the gelation point relations, the relaxation power (Δ) and fractal dimension (df) were measured as 0.22 and 2.39, respectively, indicating that the current system follows a non-stoichiometric equilibrium. Furthermore, the Fourier transform infrared spectroscopy (FTIR) test confirmed the formation of silica chemical bonding and the purity of the washed silica particles was increased from 84.18% to 87.33%, measured via X-ray fluorescence spectroscopy (XRF)

Synthesis of Nanosilica and its application as Water Based Mud Rheology Enhancer

This study synthesized nanosilica from sodium silicate solution using precipitation method for 3:1 ammonia/ethanol ratio, and examines the effectiveness of the nanosilica in formulating high-performance water based mud system. Sodium silicate solution (SSS) is a low-cost precursor than tetraethyl orthosilicate. Three (3) solutions of sodium silicate with concentrations 0.5 N, 1 N and 1.5 N were used to precipitate nanosilica. The use of sodium silicate solution in alkaline medium produces less agglomerated nanosilica. The results gave Similarly, three (3) different samples of silica nanoparticles (Sample A, Sample B, and Sample C) with each concentration respectively. The silica nanoparticles from the Sample A had the smallest in size and quantity, and also the most dispersed. For Sample B, the nanosilica produced was apparently bigger than that of sample A in size and quantity produced. Sample C was produced using two procedures: Sample C1 (with ultra Sonicator) and Sample C2. (ultra Sonicator). Samples C1 and C2 produced the biggest size and quantity of nanosilica with less the dispersion. But, there were aggregation problems, due to the higher concentration of sodium silicate solution. There was no much difference between samples C1 and C2; just that with the former, the nanosilica was better dispersed and the latter was little more aggregated. The precipitated nanosilica, Sample B with 1 N concentration of SSS gave the optimum size and quantity, and was used to formulate the examined high-performance water based mud system. The silica nanoparticles had a positive effect on the drilling fluid systems flow properties. This due to their ultrafine size and high surface area. Also, nanosilica production is cheap and feasible, so it could easily replace other expensive additives.

Design Mix Formulation and Optimization of Metakaolin Based Alkali Activated Geopolymer Concrete with the Taguchi Method

Concrete mix formulation is the science of deciding relative proportions of ingredients of concrete, to achieve desired properties in the most economical way. Formulation of concrete mix requires adequate knowledge of the properties of its constituents. Aluminosilicate materials have recently found applications in construction industry due to their unique and flexible properties. The metakaolin used for this study was the locally sourced kaolin calcined at 750oC. The alkali activating reagents include a fixed concentration of sodium silicate solution and sodium hydroxide solutions of three different concentrations. Strength development of metakaolin – based geopolymer concrete is quite different from that of ordinary Portland cement concrete due to differences in their constituents, hence, the need for special formulation, most especially when high strength is required. Taguchi method was adopted in this study to formulate mix proportion for high compressive strength of geopolymer concrete at ambient curing condition. Four parameters were selected that are more likely to influence the compressive strength of metakaolin – based geopolymer concrete, these include aggregate content, alkali – binder ratio, alkali reagent ratio and alkali reagent concentration. The effect of these parameters on the density, workability and compressive strength at 3, 7 and 28 days are determined. The result showed that an optimum mix obtained from a formulation formula (2.75SiO2 * Al2O3 * 0.55Na2O * 6.8H2O) produced a compressive strength of 62MPa at 28 days of open air curing. It was revealed that the molar concentration of the alkali reagent (sodium hydroxide) should be kept within 10M range for an open air curing, the alkali reagents to binder ratio should be kept at 0.7 or less with no addition of water to achieve reasonable workability. Also, it has been observed that the bulk density of metakaolin – based geopolymer concrete that yielded substantial strength fall within 2250kg/m3 and 2350 kg/m3.

In-situ synthesis of bi-modal hydrophobic silica nanoparticles for oil-water separation

We report the synthesis of hydrophobic silica nanoparticles of different mean sizes ranging in diameter from 48 to 260nm for the preparation of superhydrophobic composites. The nanoparticles were synthesized by adding methanol into aqueous solution of sodium silicate followed by the addition of trimethylchlorosilane. The different mean sizes of nanoparticles were achieved by varying the concentration of sodium silicate solution in methanol. It was found that nanoparticles with bi-modal distribution demonstrated superior hydrophobic properties owing to their hierarchical structure. The nanoparticles with bi-modal size distribution were deposited on cotton fabric and fibers to prepare superhydrophobic composites using an immersion technique. The prepared composites were used for the separation of four oil-water mixtures; the composites containing fabric separated oil-water mixtures via filtration while composites containing fibers separated oil-water mixture by absorption.

An Exploration of Factors Affecting the Preparation of SiO<sub>2</sub>-Coated α-Al<sub>2</sub>O<sub>3</sub> Pearlescent Pigment

The SiO2-coated α-Al2O3 pearlescent pigment was prepared by liquid phase deposition (LPD). The effects of concentration of sodium silicate solution, reaction temperature and pH value of the aluminum oxide suspending liquid were systemically studied in this paper. The obtained samples were characterized by scanning electron microscopy (SEM). The results showed that when the process parameters are the concentration of sodium silicate solution of 0.1 mol/L, the reaction temperature of 80 °C and the pH value of 9.0, the high quality of SiO2-coated α-Al2O3 pearlescent pigment could be obtained.

Systematic synthesis of high surface area silica nanoparticles in the sol–gel condition by using the central composite design (CCD) method

The sol–gel method is employed for producing high surface area silica nanoparticles from a cheap precursor, that is water glass (sodium silicate). To design the experiments systematically, the response surface method (RSM) combined with the central composite design (CCD) approach is used. Four major factors including the concentration of sodium silicate solution, solution pH, reaction temperature and reaction time are identified as the major controlling parameters and the particle surface area is considered as the response or the output parameter. A total of 31 experiments are designated by the CCD. The experiments are conducted at a centre point chosen based on experience and at its vicinity to investigate how the response changes as the factors change. Nanoparticles with a surface area as high as 630 m2/g and a particle size as low as 8 nm are produced at the optimum parameters of sodium silicate concentration of 1.5 × 10−4 g/L, pH of 4, a reaction temperature of 25°C and a reaction time of 1.5 h. A regression analysis is performed on the experimental data and a correlation is obtained that may be used to predict the particle surface area and investigate the effect of varying the factors on the response. Within the range of parameters studied here, it is found that the solution pH and then the process temperature have a profound effect on the surface area and concentration and reaction time have a moderate effect. An increase of the solution pH from 4 to higher values results in a rapid drop in the particle surface area.

The Effect of Activators on the Fly Ash-Based Geopolymers

This paper studies the influences of concentration and modulus of sodium silicate solution (Na activator) and sodium potassium silicate solution (Na-K activator) on the phase composition, microstructure and strength development in the geopolymers prepared using Class F fly ash. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and MAS NMR were utilized. It shows that the compressive strength increases while Na activator solution modulus increases, but when modulus exceeds 1.4, the compressive strength decreases, and it decreases markedly while modulus is greater than 2.0. The compressive strength improves with increase of sodium silicate solution concentration, and when concentration is 32%, compressive strength reaches the maximum, and then it reduces with concentration increment. It shows that the compressive strength increases while Na-K activator solution modulus increases, but when modulus exceeds 1.7, the compressive strength decreases, and it decreases markedly while modulus is greater than 2.0. The compressive strength improves with increase of Na-K activator solution concentration, and when concentration is 36%, compressive strength reaches the maximum. The main product of reaction in the geopolymeric material is amorphous alkali aluminosilicate gel.

Evaluation of n-Butane Gas Adsorption Performance of Composite Adsorbents Used for Carbon Canister

A novel adsorbent design technique was proposed to composite adsorbent used for carbon canister for improving the adsorption performance of n-butane gas. Two kinds of activated carbons were tested to produce composite adsorbents and evaluate the performance by measuring the adsorption isotherms of butane and pore structure characteristics. The volume-based amount of adsorption for the adsorbents prepared at sodium silicate solution concentration of 0.1wt% is 1.04 and 1.53 times that of the raw activated carbons (AC1 and AC2). The packing density of the composite adsorbent increased with the increase of sodium silicate solution concentration.

Mechanical and thermal properties of sodium silicate treated moso bamboo particles reinforced PVC composites

The main objective of this research was to study the potential of sodium silicate modification on moso bamboo particles as reinforcements for thermoplastic. Moso bamboo particles were modified with sodium silicate aqueous solutions (of 0.5%, 1%, 2%, 5% and 10% concentrations). The mechanical properties of sodium silicate treated moso bamboo particles reinforced PVC composites (BPPC) were calculated and compared with raw bamboo particles filled samples. The thermal characteristics of the BPPC were studied to investigate the feasibility of sodium silicate treatment on moso bamboo particles. The particle morphology and BPPC microstructure were investigated by scanning electron microscopy. Results showed that the tensile strength and modulus of elasticity of the BPPC increased before the concentration of sodium silicate solution reached 5% and got their maximum values of 15.72 MPa and 2956.80 MPa, respectively at 5% concentration. The modulus of rupture obtained the maximum value of 27.73 MPa at 2% concentration. The mechanical curve decreased as the concentration of solution went higher. Differential scanning calorimetric analysis illustrated that the sodium silicate solution treated BPPC possesses a better compatibility. More uniform dispersion of moso bamboo particles in PVC matrix was obtained after the sodium silicate treatment. Hence, the sodium silicate was a feasible and competitive agent of creating moso bamboo particles reinforced PVC composites.

Development research on composite adsorbents applied in adsorption heat pump

Abstract A novel adsorbent design technique base on the concept of Kelvin equation was proposed to develop hydrophilic adsorbent applicable to water vapor adsorption heat pump (AHP) for high performance. In the process, the composite adsorbent was prepared after silica gel was synthesized in the pores of activated carbons by impregnating activated carbons in sodium silicate solution. Two kinds of activated carbons were tested to produce composite adsorbent and to investigate the performance by measuring the adsorption isotherms of water vapor and pore structure characteristics. All adsorption isotherms of the silica impregnated activated carbons prepared shifted to a lower region of water vapor pressure compared to those of the raw activated carbons. The volume-based amount of adsorption in the AHP operation range ( φ = 0.1–0.4) for the adsorbents prepared at sodium silicate solution concentration of 10 wt.% and impregnating time of 48 h are 5.88 and 2.62 times that of the raw activated carbons (AC1 and AC2), respectively. Based on the Kelvin equation, it is clarified that the contact angle and the volume of pore radius greater than 1.2 nm decrease with the increase of sodium silicate solution concentration for the novel composite adsorbents, which contributes the isothermals shift to lower relative pressure range.

Effect of activator and curing mode on fly ash-based geopolymers

The influences of concentration and modulus of sodium silicate solution and curing mode on the phase composition, microstructure and strength development in the geopolymers prepared using Class F fly ash were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and MAS NMR were utilized. Results show that the compressive strength increases as sodium silicate solution modulus increases, but when modulus exceeds 1.4, the compressive strength decreases, and it decreases markedly while the modulus is greater than 2.0. The compressive strength was improved by the increase of sodium silicate solution concentration. When the concentration is 32%, the compressive strength reaches the maximum, then it reduces as concentration increasing. Elevated temperature can increase the strength of samples that synthesized from sodium silicate solution with 32% concentration and modulus 1.2. Compared to the strength of the sample cured at 50 °C, the strength of the samples cured at 65 °C and 80 °C are higher at 1 d and 3 d, but the same at 7 d. At high temperature, prolonged curing time will decrease the strength. Long precuring at room temperature before application of heat is beneficial for strength development, and there is about 50% increase in strength of the samples cured at 1 d precuring and 2 d elevated temperature as compared to the strengths of the samples cured for 3 d at elevated temperatures or cured for 28 d at room temperature. The main product of reaction in the geopolymeric material is amorphous alkali aluminosilicate gel.

Setting and strength characteristics of alkali-activated carbonatite cementitious materials with ground slag replacement

The effect of the ground granulated blast-furnace slag (GGBFS) addition, the modulus n (mole ratio of SiO2 to Na2 O) and the concentration of sodium silicate solution on the compressive strength of the material, i e alkali-activated carbonatite cementitious material (AACCM for short) was investigated. In addition, it is found that barium chloride has a satisfactory retarding effect on the setting of AACCM in which more than 20% (by mass) ground carbonatite was replaced by GGBFS. As a result, a cementitious material, in which ground carbonatite rock served as dominative starting material, with 3-day and 28-day compressive strength greater than 30 MPa and 60 MPa and with continuous strength gain beyond 90 days was obtained.

Synthesis of Nanosized Silica Powder by Ultrasonic Process

Nanosized silica powders were synthesized via w/o emulsion method using sodium silicate as SiO2 source under ultrasonic process. The powders were prepared under conventional process and ultrasonic process using the same reactants at ambient temperature for 1h varying the concentration of Na2SiO3 solution while fixing the concentration of surfactant in cyclohexane. The particle size of the silica powder decreased with decreasing the concentration of sodium silicate solution under both conditions, with and without ultrasounds. However, the particle size and size distribution of the silica powder with ultrasounds were smaller and narrower than those without ultrasounds, establishing that ultrasound treatments decrease the particle size and become narrow in particle size distribution.

Preparation of SiO2 nanoparticles by ion exchanging and study on their dispersion stability

By adopting sodium silicate as a major material, SiO2 nanoparticles (size in 8–15 nm waterdispersiod was prepared by ion exchanging. The effects of sodium silicate concentration, surfacemodifying time, temperature and technological conditions on their diameter, size distribution and dispersion stability were also studied. The result show that, the hydrophilic lipophlic and hydrophiliclipophilic SiO2 nanoparticles waterdispersoid can be prepared through different kinds of surfacemodifiers and the optimum reaction conditions have been determined as follows: sodium silicate solution concentration: 8 w%; silicone dosage: 3% of the total mass of nano SiO2 waterdispersoid; adding way and time of surfacemodifier: continual dropping for 2h; surfacemodifying temperature: 60–70°C.

Encapsulation of Water-Soluble Dye in Spherical Sol-Gel Silica Matrices

The water-soluble, Lithol rubine B, dye was encapsulated into silica microspheres matrices. Encapsulation has been carried out by sol-gel process of W/O microemulsions formed from sodium silicate and dye aqueous solution in cyclohexane medium. The average particle size could be tailored from 1–10 μm, depending on the processing parameter such as homogenizing speed in the formation of W/O emulsion, the weight ratio of water to oil, and concentration of sodium silicate solution, etc. The pore size of dye-doped silica microspheres was measured by nitrogen adsorption-desorption isotherms. The leaching behavior of dye entrapped in silica matrices was investigated by UV/VIS and UV diffuse reflectance spectroscopy for the extract and solid powders after immersion for 24 h in water. The doping of GPTS (3-glycidoxypropyltrimethoxysilane) in sodium silicate and dye mixture solution greatly enhanced the stability against leaching of the dye. It was ascribed that GPTS serves simultaneously as an intermediate for the chemical bonding between the dye and silica, and as an agent for the formation of hybrid sol responsible for the shrinkage of pore size.

Hydrophilication of Activated Carbon by Impregnating Silica into Pores.

A new hydrophilic method for achieving a high-performance adsorbent by impregnating silica into pores of activated carbon has been proposed. In the process, silica-gel was synthesized in the pores of activated carbon after inserting a sodium silicate solution into the pores. Three types of activated carbon were tested to produce hydrophilic activated carbon and to investigate the hydrophilicity by measuring the adsorption isotherms of water vapor and pore structure characteristics. The proposed method worked effectively for adding hydrophilicity to activated carbon, since all of adsorption isotherms of the material treated with this method shifted to a lower region of water vapor pressure than that of the raw material. The shift to a lower relative pressure of adsorption isotherm was maximum when the concentration of sodium silicate solution was 1 mass%.