Concentration Of Sodium Hydroxide Solution Research Articles

Corrosion assessment of ferrocement element with nanogeopolymer for marine application

AbstractCorrosion is the major reason which limits the practical application of ferrocement structures in the marine environment. To protect the thin and strong wire mesh reinforcement, preventive methods are required to be employed. One of such methods implemented in this paper is novel application of geopolymer mortar on the surface of the wire mesh. The microstructural pores present in the highly durable fly ash based geopolymer mortar are further enhanced by using nanomodified fly ash particles to achieve the impermeable surfaces. Effect of alkaline solution concentration on the chloride ion penetration and corrosion has been investigated by using the different concentration of sodium hydroxide solution from 8 to 14 M. From the results, it is noted that for the geopolymer specimens, the chloride ions penetration values of 542.70 Coulombs is observed at 28 days which comes under the category of very low as per ASTM C1202‐10. The chloride ion penetration observed in geopolymer specimen is 17% lesser than ferrocement panel with conventional cement mortar. The time taken for cracking is delayed in the case of ferrocement panel with geopolymer mortar of 10 M concentrated sodium hydroxide solution by thrice the times of specimen with conventional cement mortar. This indicates that the incorporation of nanogeopolymer in ferrocement element not only increased the strength but also its serviceability against cracking and corrosion resulted in the extensive application of ferrocement construction in marine environment.

Effect on Combustion Properties of Coal Treated by Microwave Irradiation Combined with Sodium Hydroxide Solution

A Kentucky coal sample treated by microwave irradiation (MI) combined with sodium hydroxide solution was performed using a thermo-gravimetric analyzer (TGA) coupled to a Fourier transform infrared spectrometer (FTIR). The combustion properties and structural changes of coal under different conditions were investigated and compared. The results show that the desulfurization efficiency of coal samples increases with the increase of sodium hydroxide solution concentration. Microwave irradiation can significantly improve the desulfurization efficiency. The whole combustion process of the treated coal sample becomes longer; the combustion performance becomes worse. The total mass loss of coal treated samples is significantly reduced, and the temperature corresponding to the maximum weight loss rate decreases with the increase of sodium hydroxide concentration. The infrared spectra of the coal samples treated with microwave and 5% sodium hydroxide solution were basically unchanged, while the O containing groups and aromatic C-H groups increased in the coal samples treated with 20% sodium hydroxide solution.

Protective structures on carbon steel in aqueous-salt solutions containing catholyte

The process fluid of oil fields, with a huge amount of dissolved gases, mechanical impurities, salt ions, mineral acids and bases present in them, has a destructive effect on the internal surface of oil collection equipment. The simultaneous presence of carbon dioxide and hydrogen sulfide pose the greatest danger, since they are catalysts for the cathode reaction of hydrogen depolarization of low-alloy steel, and lead to the formation of soluble corrosion products - iron hydrogencarbonate. One common way to prevent electrochemical corrosion of oil equipment is to neutralize acidic components of process media. Sodium hydroxide is often used as a neutralizer, however, the content of sodium salts contaminates the obtained oil products and catalysts and leads to disruption of the technological process of its further processing. Accordingly, there is provided a process for the non-reactive neutralization of acidic components by introducing a solution of a hydroxide-saturated catholyte. In the scientific and technical literature, the problem of forming protective films on the surface of carbon steel by introducing catholyte into the process liquid remains insufficiently studied. In scientific research work, a method of forming surface structures by selecting the concentration of a catholyte solution has been developed. The thickness of the obtained protective structures obtained in the model of produced water formed on the surface of low-alloy steel A516-55 in solutions of sodium hydroxide and catholyte was calculated. The study revealed the dependence of the corrosion rate of steel on the concentration of sodium hydroxide solution and catholyte solution at various pH values.

Effect of sodium hydroxide solution concentration on liquid entrainment in a steam boiler

Liquid entrainment or carryover is a phenomenon that liquid droplets are carried out from a boiler or steam drum during steam generation. The droplets may convey some dissolved solids and cause damage to steam equipment such as scaling deposits in valves and steam piping and erosion of turbine blades. The appearance of dissolved solids in boiler water mainly comes from the internal water treatment process by dosing some chemical substances into the boiler in order to prevent corrosion and scale formation. Trisodium phosphate (Na3PO4) is one of chemical substances commonly added during boiler operation to control the pH of boiler water. However, it can cause the occurrence of sodium hydroxide (NaOH) solution which results in the increase of total dissolved solid (TDS) concentration in boiler water. Therefore, this study is aimed to develop a test section in order to investigate the parameters affected by liquid entrainment in the boiler. The experiment is performed in ambient conditions under an air-water system. Three variable factors are taken into consideration, including the concentration of NaOH solution, the height of the water level in the test tank, and the gas superficial velocity which represents the flow velocity of steam during steam generation. The results show that the increase of the gas superficial velocity and the water level height in the tank resulted in the enhancement of the entrainment rate. The increase of the water level height played an important role on the liquid entrainment. The increase of NaOH concentration directly impacted the existing film bubbles and the longer stability of foam bubbles at the water surface which resulted in a higher entrainment rate. Therefore, TDS control was one of the most important factors which could be incorporated with the appropriate height of the water level and the consistency rate of steam generation in order to minimize the liquid entrainment.

Ba3[Rh(OH)6]2 ⋅ H2O – a Precursor to Barium Oxorhodates with One‐dimensional Hydrogen Bonding Systems

AbstractOrange‐colored single‐crystals of barium hexahydroxo‐rhodate(III) monohydrate, Ba3[Rh(OH)6]2 ⋅ H2O, were synthesized in a PTFE‐lined autoclave at 200 °C starting from Ba(NO3)2, RhI3 and concentrated sodium hydroxide solution (water‐base ratio 4 : 1). Single‐crystal X‐ray diffraction revealed the triclinic space group (no. 2) with lattice parameters a=824.60(6) pm, b=852.78(5) pm, c=885.34(6) pm, α=94.294(3)°, β=92.422(3)°, γ=91.673(3)° at 100(1) K. The crystal structure consists of [Rh(OH)6]3− octahedra surrounded by barium cations and water molecules. Hydrogen bonds with a wide range of donor‐acceptor distances are located between hydroxide groups and water molecules to form one‐dimensional hydrogen bonding networks in c direction. Upon heating in air, Ba3[Rh(OH)6]2 ⋅ H2O decomposes first to “BaRhO3” with a superstructure of the hexagonal perovskite type, which undergoes a phase transition to the 2H hexagonal perovskite Ba9Rh8O24 above 900 °C.

Effect of alkali activator dosage on compressive and tensile strength of ground granulated blast furnace slag based geopolymer concrete

Use of ordinary portland cement contributes to environmental deterioration by releasing enormous quantities of CO2. To reduce use of cement, this research focuses on preparation of solely ground granulated blast-furnace-slag-based geopolymer binder, activated by a combination of sodium hydroxide and sodium metasilicate cured under ambient temperature at 27 °C. Engineering properties of geopolymer binder are evaluated and compared with conventional cement to assess its suitability as a binder for making geopolymer concrete. Compressive strength, flexure strength, and split tensile strength are determined for geopolymer concrete. Microstructural analysis of geopolymer is performed by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) with energy dispersive X-ray analysis (EDAX), and Fourier-transform infrared spectroscopy (FTIR) tests. The concentration of alkali activators is optimized by laboratory trials and maximum compressive, flexural, and split tensile strengths of 44.07, 5.60, and 4.39 MPa, respectively, are obtained for geopolymer concrete at 2 mol/L concentration of sodium hydroxide solution with the ratio of sodium metasilicate to sodium hydroxide taken as 2.0.

Characterization of Ultrafine Silica Prepared from Rice Husk Ash by Sol-Gel Method

Rice husk ash that is removed from the combustion process in a furnace has a potential for silica source through the sol-gel process. The experiment was conducted in different concentrations of sodium hydroxide solution of 5.0, 7.5, and 10.0 % w/v in the preparation of the sodium silicate solution. For further observation, different pH values of the gel solution were also examined with values of 1 to 7. Particle Size Analyzer (PSA) has been used for size characterization of samples, while Energy Dispersive X-Ray Spectrophotometer (EDS) was used to determine the composition of the powder. The result shows that for all cases the silica products still contain carbon materials. The different pH values of the silica gel solution exhibit a different physical appearance of the gel. At pH values of 5 to neutral 7, the silica gel is completely formed, while in more acidic conditions there are only precipitates or none of both. Mostly, silica particles were in the size of micrometers with more than 90% in the range of 2-128 µm. The composition characterization showed different percentages of silica and the good result was found at 5.0% of sodium hydroxide solution with a gel solution pH of 7.

Highly efficient sorption of molybdenum from tungstate solution with modified D301 resin.

The separation of molybdenum (Mo) from tungstate solution is a bottleneck problem in tungsten (W) metallurgy, and it hinders the development of high-purity tungsten materials. In this research, a modified D301 resin was used to adsorb and separate molybdenum from tungstate solution. The maximum sorption capacity (Qe) of modified D301 for MoS42− was found to be 428 mg g−1 and the separation coefficient (β) was 108.9 when the contact time was 4 h and the reaction temperature was 25 °C and the pH value of the tungstate solution was 7.2. The sorption process conforms to Langmuir isotherm models and the quasi-second-order kinetic model. The sorption mechanism was also discussed, which was a single layered spontaneous sorption process. Theoretical calculations infer bonding behavior between the N atom on the resin and the S atom on the MoS42− molecule. The sorption energy is −7.67 eV, which indicated that the sorption process is stable chemical sorption. The desorption experiment showed that more than 90% molybdenum could be desorbed from the loaded resin when the concentration of sodium hydroxide solution was 5 w%. Finally, after three-stage sorption–desorption, almost all molybdenum in the solution was adsorbed, achieving better separation of tungsten and molybdenum.

Effect of Alkali-Washing at Different Concentration on the Chemical Compositions of the Steam Treated Bamboo Strands

The objective of this study was to investigate the effect of alkali-washing with different sodium hydroxide concentrations on the chemical compositions of steam-treated Betung bamboo strand. Strands were subjected to steam treatment at 126 °C for 1 h under 0.14 MPa pressure and followed by washing with 1-5% sodium hydroxide solution for 30 sec. The alteration of structural and non-structural chemical components content of bamboo strands was evaluated. Steam and washing treatments with various concentrations of sodium hydroxide solution considerably reduced the extractive content of bamboo strands, and the cell wall chemical components of the strand in the small degree. FTIR analysis showed noticeable changes in peaks related to hemicellulose and lignin. The relative crystallinity increased significantly after steam and washing treatment with sodium hydroxide up to 3% concentration. SEM Images showed smooth and clean strands surface after washing with 3% sodium hydroxide.

Studies on the corrosion resistance of Al7075 / SiC metal matrix composites in an alkaline environment

Metal matrix composites are of interest every day due to their lightweight, improved mechanical properties, and increased corrosion resistance. They are used in the aeronautical, aerospace, marine, and automotive industries. A variety of methods can estimate Their corrosion properties. The open-circuit potential studies are also a tool for evaluating the corrosion of composite materials. This research paper focuses on studying open circuit potential determination of the aluminium 7075 alloys reinforced with silicon carbide particulate in differently concentrated sodium hydroxide solutions. The composite materials were prepared by adding 2, 4, 6, 8 and 10 weight percentages of silicon carbide to the aluminium base metal liquid melt metallurgy technique (Vortex method). The silicon carbide used as reinforcement in size range of 50 – 80 µm, which is commercially available. The SiC particulates material is had been preheated to 400°C and introduced into the liquid melt of Al7075 at a rate of 100 g/m, under constant agitating condition using a mechanical stirrer system for 3 to 4 minutes. Rectangular specimens of 2 cm length, 1cm width and 1 mm thickness were used for the experiments. 1sq.cm area of the specimens was exposed to sodium hydroxide medium. Open circuit potential experiments test was conducted using a multimeter and calomel electrode system. The potential observed for 2, 4, 6, 8 and 10% silicon carbide composites were less than the potential of matrix alloy for a range of 30 hours.

Optimization of Alkali Treatment Process Parameters for Kenaf Fiber: Experiments Design

ABSTRACT Alkali treatment of natural fibers will improve the mechanical, chemical, and thermal characteristics of natural fiber reinforced epoxy composites. The influence of alkali treatment on the improvement of mechanical strength of natural fiber reinforced epoxy composites depends on the selection of process parameters of the treatment. In this work, the optimization of four key process parameters for alkali treatment of kenaf fiber has been studied using orthogonal array-oriented fractional factorial experimental design. The concentration of sodium hydroxide solution, process temperature, time, and fiber to solution weight ratio were the four chosen parameters and the tensile strength of the composite sample fabricated with treated kenaf fiber and epoxy resin was taken as output response. The hand layup method was used to fabricate the composite materials, and specimens were prepared for the tensile test. All samples were fabricated by ensuring the fiber weight ratio of 40%. Five samples were prepared at each experiment category, and mean values were taken for analysis. The results revealed that 6% NaOH solution, 30°C process temperature, 8 hours process time, and 1:15 fiber to solution weight ratio are identified as optimum process parameters for a tensile strength of 58.16 MPa.

Production of geoploymer mortar reinforced with sustainable fibers

Abstract Geopolymer has been presented as new evolution in the concrete technology world, where cementitious materials such as ceramic powder and Slag have been replaced by high percentages of cement used in construction. Thus, the activation of such materials was performed by highly alkaline solutions in order to be acted as a binder in the mix. Therefore, the selection of suitable ingredients proportion of geopolymer mortar to achieve desired strength at required workability has been intended in this study. The experimental Program has been implemented for the preparation of geopolymer mortar mixes. The concentration of sodium hydroxide solution was kept constant in the order of 12 M throughout the experiment. The ratio of Water to geopolymer binder ratio was 0.35, alkaline solution-to- cementitiuos materials ratio was 0.30 and sodium silicate-to-sodium hydroxide ratio was 1.85 by mass. Workability of geopolymer mortar was measured by flow table apparatus and cubes of 50 mm side were cast and tested for compressive strength after 28 days of normal water curing. The study concludes that the combination of ceramic powder and Slag up to 40% (by weight), in the total binder material, can be used for developing the geopolymer mortar. Continuously, the use of 1% steel fibers or 1% steel fiber with 0.5% sisal fibers promotes the level of cement replacement by such cementitous materials (slag and ceramic powder) up to 60%.

Effects of Compositional and Physico – Chemical Mix Design Parameters on Properties of Fly Ash Geopolymer Mortars

The present experimental study investigated the effects of mix design parameters on workability and compressive strength of fly ash geopolymer (FA – GPC) mortars. Observed effects of the compositional parameters comprising SiO2/FA, Na2O/FA and H2O/FA mass ratios, were inter – linked with those of the physico – chemical mix parameters namely:– the concentration of sodium hydroxide solution, ratio of sodium silicate to sodium hydroxide, and the alkali activator to raw material ratio. In the preparation of mortars, low calcium (Class F) FA was activated using a combined solution of sodium hydroxide and sodium silicate, and mixed with fine aggregate at the aggregate to FA ratio of 2.25. Altogether, seventy – two (72) mortar mixtures were prepared by varying the values of compositional parameters. It was found that the SiO2/FA ratio of 0.08 to 0.11, Na2O/FA ratio of 0.05 to 0.08, and H2O/FA ratio of 0.32 to 0.37, are the optimum ranges that gave the best workability values and compressive strength results, depending on the H2O/FA ratio. In mix design, the various values of compositional parameters are obtained by appropriately combining the aforementioned physico – chemical parameters.

Electrolytic Iron Production from Alkaline Bauxite Residue Slurries at Low Temperatures

Primary iron metallurgy is characterised by significant direct carbon dioxide emissions, due to the carbothermic reduction of the iron ore. This paper deals with the electrification of primary iron production by developing a new and innovative process for the carbon-free production of metallic iron from bauxite residue which is a byproduct of the alumina industry. It is based on the electroreduction of iron oxides from bauxite residue suspensions in concentrated sodium hydroxide solutions, at low temperature and normal pressure. The iron oxide source used in the present study is bauxite residue provided by MYTILINEOS SA, Metallurgy Business Unit-Aluminium of Greece. The research study is a preliminary screening of bauxite residue as a potential raw material for iron production by performing experiments in a small-scale electrolysis cell. The first results presented here show that iron can be produced by the reduction of iron oxides in bauxite residue with high Faradaic efficiency (>70%). Although significant optimisation is needed, the novel process shows great promise.

Determination of Anions in High Concentration of Sodium Hydroxide Solutions by Ion Chromatography with Inline Neutralization Method

Determination of Anions in High Concentration of Sodium Hydroxide Solutions by Ion Chromatography with Inline Neutralization Method

Dissolution of quartz sand in sodium hydroxide solution for producing amorphous precipitated silica

This research studied the dissolution of quartz sand in sodium hydroxide solution as an effort to form silica precipitate. The dissolution process was carried out using the leaching method directly at atmospheric pressure. The process variables in this study included the concentration of sodium hydroxide solution, temperature, dissolution time, and stirring rate. The four process variables had a positive influence to enhance silica precipitate formation, The result showed that the extraction rate was still low even though the SiO2 concentration in the starting material was very high. Temperature provided the most significant influence among other process variables. The result exhibited that silica precipitate content was 13.6% obtained in the optimum condition at a temperature of 90 °C with a stirring speed of 800 rpm using a 7.5 M of sodium hydroxide solution.

Compressive Strength of Fly Ash Geopolymer Concrete by Varying Sodium Hydroxide Molarity and Aggregate to Binder Ratio

The concentration of sodium hydroxide solution increased the reaction rate during geopolymerisation process and thus enhanced the development of early strength of concrete. While the percentage volume of aggregates played a vital role in the strength development due to the better durability then paste alone and also filling and packing ability. The aim of the study is to determine the optimum molarity of sodium hydroxide and aggregate to binder ratio of geopolymer concrete towards high strength performance concrete based on compressive strength. The variable samples investigated include the sodium hydroxide (NaOH) concentration and aggregate to binder ratio at room temperature curing; the ratio of alkali activator solution and solid to liquid ratio remained constant. This resulted the presents work on the development of fly ash based geopolymer concrete having increment on the rate of compressive strength development from 7 to 28 days was found between 61 MPa and 82 MPa, respectively.

Exploration of mechanical and durability characteristics of fly ash-GGBFS based green geopolymer concrete

In this paper, the use and effect of Ground Granulated Blast Furnace Slag (GGBFS) addition to fly ash (FA) on the performance of Geopolymer Concrete was presented. A reference of Ordinary Portland cement concrete (OPC) mix was used to compare with geopolymer concrete. The effect of different proportions of GGBFS addition, ambient curing, and curing age on the properties of geopolymer concrete was reported. The concentration of sodium hydroxide solution with 8 M and solution to binder ratio as 0.4 were taken for all the mixes of geopolymer concrete. This paper reported an investigation data on the mechanical and durability characteristics of fly ash-GGBFS based geopolymer concrete and that data was compared with the control mix (OPC). SEM analysis was done on selected samples to estimate the microstructural characteristics. The results concluded that a geopolymer concrete mix containing 60% GGBFS and 40% fly ash at 28 days of ambient temperature achieved maximum compressive strength (55.63 MPa) and further performed durable under severe environmental conditions.

Mild sodium hydroxide pretreatment of tobacco product waste to enable efficient bioethanol production by separate hydrolysis and fermentation

Tobacco product waste (TPW) was considered as a novel and sustainable feedstock for second-generation ethanol production. TPW with over ~ 44% cellulose content was efficiently pretreated using concentrated (10% W/V) sodium hydroxide (SH) solution at different temperatures (0, 25, and 80 °C) and retention times (3 and 6 h). Subsequently, the pretreated biomass was subjected to separate enzymatic hydrolysis and fermentation by the filamentous fungus Mucor hiemalis. Promising results were achieved following 3 h pretreatment of TPW at 80 °C, whereas the hydrolysis yield was substantially increased up to 91.3%. Besides, comprehensive tacking of key features of biomass (e.g., composition, crystalline structure, surface hydrophilicity and morphology, and accessible surface area) by semi-quantitative methods together with FTIR and SEM observations revealed major improvements occurred after mild SH pretreatment. Consequently, the maximum ethanol production as high as ~ 97% of theoretical ethanol yield was obtained, while it was only 44.4% from the untreated TPW. The implication of the work could possibly support TPW utilization for large-scale ethanol production in a tobacco-based biorefinery framework.

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.