Hydroxide Ratio Research Articles

Improving the Corrosion Resistance of Al anode and Specific Capacity in Al-air Batteries Using Mixed Electrolyte Solutions

This research aimed to investigate the corrosion improvement in Al-air batteries and their specific capacity, at various mixed ratios of sodium chloride and sodium hydroxide solutions 100:1, 99:1, 98:2, 90:10, 80:20, 70:30, and 0:100. The battery was discharged at different discharge current densities of 1, 5, 10, and 15 mA·cm-2. The self-corrosion of Al anodes and their electrochemical behavior was tested in the mixed electrolyte solutions at room temperature. Moreover, the chemical characterization of the electrode surface was analyzed using the EDS and XPS technique showing that mixed electrolyte solutions provide complex film on the aluminum surface, consisting of various atoms of Al, O, C, Na, and Cl which can reduce the self-corrosion of the aluminum anodes, and providing a higher energy capacity. Mixed electrolyte solutions with a sodium chloride to sodium hydroxide ratio of 80:20 by volume at a discharge current of 15 mA·cm-2 causes a maximum specific capacity of 1,508 mA·h·g-1. The mixed electrolyte solutions can increase the specific capacities of Al-air batteries by 1.4 and 25.6 times more than that of sodium chloride solution and sodium hydroxide solution alone, respectively.

Decarbonatization of Energy Sector by CO2 Sequestration in Waste Incineration Fly Ash and Its Utilization as Raw Material for Alkali Activation.

In this study, municipal solid waste incineration (MSWI) fly ash was subjected to mineral carbonation with the aim of investigating CO2 sequestration in waste material. The conducted study follows the trend of searching for alternatives to natural mineral materials with the ability to sequestrate CO2. The mineral carbonation of MSWI fly ash allowed for the storage of up to 0.25 mmol CO2 g-1. Next, both carbonated and uncarbonated MSWI fly ashes were activated using an alkaline activation method by means of two different activation agents, namely potassium hydroxide and potassium silicate or sodium hydroxide and sodium silicate. Mineral carbonation caused a drop in the compressive strength of alkali-activated materials, probably due to the formation of sodium and/or potassium carbonates. The maximum compressive strength obtained was 3.93 MPa after 28 days for uncarbonated fly ash activated using 8 mol dm-3 KOH and potassium hydroxide (ratio 3:1). The relative ratio of hydroxide:silicate also influenced the mechanical properties of the materials. Both carbonated and uncarbonated fly ashes, as well as their alkali-activated derivatives, were characterized in detail by means of XRD, XRF, and FTIR. Both uncarbonated and carbonated fly ashes were subjected to TG analysis. The obtained results have proved the importance of further research in terms of high-calcium fly ash (HCFA) utilization.

Artificial coarse aggregate from waste materials, fly ash and Msand dust through geopolymerization

Coarse aggregate is considered the most vital aspect, providing quantity and strength to the concrete. The aggregates are obtained mainly from natural resources by quarrying rocks or riverbeds. Each year, construction industries use large amounts of natural aggregates, resulting in the depletion of raw materials. Different methods, such as sintering, cold bombing, autoclaving, and geopolymerization, can prepare artificial coarse aggregates. Geopolymerization is a chemical reaction between an alkali solution and source materials containing alumina and silicate. The main objective of this study is to develop artificial aggregates with M sand dust and fly ash by geo polymerization. The ratio of Fly ash to M Sand Dust adopted is 40:60 by weight. Different molarities of sodium hydroxide was used for making the artificial aggregates with a solution-to-binder (S/B) ratio of 3.5 and a sodium silicate-to-sodium hydroxide ratio of 2.5. The mechanical properties of the developed lightweight aggregate are determined as per the specification requirement in IS 9142 (1979) for artificial lightweight aggregates for concrete masonry units. By comparison, these geopolymer aggregates are sustainable, and aggregates with 12 molarity NaOH showed better properties than other molarity NaOH aggregates based on its mechanical properties.

Synthesis and fluorescent property of carboxymethyl chitosan with different degrees of carboxymethylation and its application for fluorescence turn-on detection of Cd(II) ion

Recently, carboxymethyl chitosan (CMCS) has proved to be an intrinsically fluorescent material with aggregation-induced emission characteristic. In order to elucidate the influence of CMCS's chemical structure and solution behavior on its fluorescent intensity, two series of CMCS with different degrees of carboxymethylation (DCM) are synthesized by adjusting the mass ratio of monochloroacetic acid and sodium hydroxide to chitosan at various reaction temperature and time, and then characterized using Fourier-transform infrared spectroscopy and nuclear magnetic resonance. Their solution behaviors at different pH values are studied via zeta potential and ultraviolet-visible measurements. The data reveal that the isoelectronic point (IEP) of a CMCS decreases with increasing DCM, and all the CMCSs have good water solubility at pH range below their IEPs. Fluorescence spectra indicate that a CMCS shows the highest fluorescent intensity in a slightly acidic environment next to its IEP, and the photoluminescence of a CMCS solution increases significantly after heat treatment above T = 70 °C. Furthermore, we compare for the first time the use of heated CMCS solutions for the fluorescence turn-on detection of cadmium ion in pure and tap water, respectively. The limit of detection is found to be ca. 1 μM for the Cd2+ in pure water.

Effect of Sodium Silicate to Hydroxide Ratio and Sodium Hydroxide Concentration on the Physico-Mechanical Properties of Geopolymer Binders

Geopolymers are emerging materials in the construction industry that are yet to achieve uniform standards in their mode of synthesis. Several factors over the years are said to affect the performance of the binders which vary widely. This paper investigates the effect of silicate-to-hydroxide ratio and sodium hydroxide concentration on the mechanical properties of metakaolin-based geopolymer binders. Four SS/SH ratios of 0.5, 1.0, 1.5, and 2.0 and four SH concentrations of 8M, 10M, 12M, and 14M were studied with the kaolin calcined at 800oC. Physical and mechanical tests were conducted on sixteen (16) samples at testing ages of 7, 14, and 28 days. The mean density of the geopolymer binders was 1.86 g/cm3, and the samples increased with increasing SS/SH ratio and SH molarity with the 2MK14 having the maximum density of 1.95 g/cm3. The compressive strength and flexural strength of the samples generally increased with testing age (7-28 days). The compressive strength of the samples further showed a direct increase with SS/SH ratio, though, above SS/SH = 1, the compressive strength began to decrease gradually. The maximum compressive strength for these binders 14.6MPa which was recorded by the 1MK10 sample. The Pareto chart for the compressive strength of the samples showed that both the SS/SH ratio and SH concentration contributes significantly (95% significant level) to the compressive test results. However, the SS/SH ratio had a more standardised effect on the compressive strength of the binders. The maximum flexural strength (3.45MPa) was obtained from the 1MK8 geopolymer binder, and similar to the compressive test results, strength values were obtained at the SS/SH ratio of 1

Effect of GGBS on Fly Ash Based Geopolymer Mortar at Ambient and Heat Curing

AbstractThis study investigates and shows the effect of incorporation of ground granuated blast furnace slag (GGBS) content in fly ash (FA) based geopolymer mortar by assessing the strength properties of geopolymer mortar in both ambient (25 °C) and heat (60 °C) curing. The percentage of GGBS is varied from 0% to 50% with FA in geopolymer mortar. Sodium silicate (SS) and sodium hydroxide (SH) solutions are used to activate the main binders. For all the mixes the alkali/binder ratio, molarity (M), and sodium silicate (SS)/sodium hydroxide (SH) ratio are fixed to 0.45, 12 M, and 2, respectively. The fresh property in terms of slump flow and other properties like compressive strength, water absorption, and dry density of the geopolymer mortar are determined. The result of this study shows that the inclusion of GGBS content in FA‐based geopolymer mortar significantly increases the compressive in both the curing conditions. Maximum compressive strength of 44.33 MPa is obtained when 50% GGBS is added to the mixes at a curing temperature of 60 °C.

The effect of sodium hydroxide molarity on setting time, workability, and compressive strength of fly ash-slag-based geopolymer mortar

This research investigates the influence of sodium hydroxide (SH) molarity on fly ash-slag-based geopolymer mortar’s workability, setting time, and compressive strength. The molarity of SH varies between 1M, 2M, 4M, 6M, 8M, and 10M. The geopolymer mixture was proportioned to contain 30% slag as a substitution for fly ash, with the alkaline activator to binder (Al/Bi) ratio of 0.45 and the sodium silicate to sodium hydroxide ratio (SS/SH) of 1.5. The results showed that at a range of low molarity SH (1M, 2M, and 4M), the setting time was faster in a mixture containing higher molarities. In contrast, at a range of high molarity (6M, 8M, and 10M), the setting time is slower in a mixture with higher molarity SH. Based on the setting time, the concentration of SH that can be applied in the field is 1M, 2M, 8M, and 10M. Increasing the molarity of SH will decrease the workability but increase compressive strength. However, when SH molarity increased after optimal molarity was established, the compressive strength was reduced. The maximum compressive strength of mortar is 46.86 MPa, obtained at an SH molarity of 6M.

Hierarchical porous carbons with honeycomb-like macrostructure derived from steamed-rice for high performance supercapacitors

To promote the advancement of electrochemical energy storage systems and meet the demand for rationalization of resource utilization, sustainable biomass porous carbon is being widely explored as a promising material for supercapacitor applications. Here, rice grain was used as a biomass precursor and steamed. After the steaming process, the rice grains formed a fluffy material with a honeycomb-like structure. Not only this structure does contribute to the full infiltration of the activator to upgrade the activation efficiency, but also it helps to impede the tendency of crossing-linking between adjacent nanosheets during the subsequent activation so that thinner and higher-quality 2D carbon flakes could be obtained. Additionally, In the mild-activation route (the mass ratio of potassium hydroxide (KOH) and steamed rice is only 1:1), numerous and tunable micro/mesoporous structures emerged on the basis of a honeycomb-like macrostructure, creating a high specific surface area and an unobstructed pore channel for electrolyte ions. Experimentally, the electrode material from steamed rice at an activation temperature of 850 °C has the optimal micropore/mesopore proportion and achieves the highest specific capacitance (350.2 F/g) at 0.2 A/g in a 6 M KOH electrolyte. Meanwhile, it displays outstanding cycling stability (91.34% retention after 10,000 cycles) and excellent energy density (9.775 Wh/kg at 180 W/kg) when assembled into supercapacitors. This work shows that the “steaming effect” combined with chemical activation is beneficial for pore structure distribution in biomass materials, which contributes to the rapid fabrication of carbon electrodes for electrochemical energy storage equipment.

Evaluation of Photocatalytic, Antioxidant, and Antibacterial Efficacy of Almond Oil Capped Zinc Oxide Nanoparticles.

In this study, ZnO nanoparticles (NPs) were synthesized in the presence of almond oil at various molar ratios of zinc acetate and sodium hydroxide, including 0.5:1, 0.75:1, 1:1, 1.25:1, and 1.5:1, to obtain pH values of 11, 10, 9, 8, and 7, respectively. The XRD results revealed that ZnO NPs exhibit a hexagonal structure, with high crystallinity. SEM results showed that dense and large sized ZnO NPs were formed at pH 11, and relatively small (~30-40 nm) NPs were obtained at pH 9. The size distribution can be explained in terms of the presence of OH- ions at different pH levels. However, the larger size of the NPs at pH 7 compared to those at pH 8-11 were due to the coalescence of NPs suitable for antioxidant/antibacterial activities. ZnO NPs demonstrated a high degradation efficiency (~93%) in 90 min, with a high rate constant for Methyl Orange (MO), which is better than the previously reported rate. The larger sized almond oil capped ZnO NPs also showed excellent radical scavenging activity (94%) and are proven to be good carriers to resist Escherichia coli (E. coli) bacteria.

Hybrid geopolymer paste from high calcium fly ash and glass wool: Mechanical, microstructure, and sulfuric acid and magnesium sulfate resistance characteristics

Geopolymer is a sustainable binder composed of source materials containing aluminosilicates under strongly alkaline conditions promising for use in place of cement in building materials due to its low carbon footprint. Although high calcium fly ash can be used as a source material for geopolymer binder, it has rarely been studied with other wastes especially, glass wool waste. Therefore, this study presents the use of glass wool (GWF) from the insulating materials waste and high calcium fly ash (HCFA) as binary precursors to produce geopolymer paste. HCFA was replaced by GWF at a ratio of 10–40% by weight. The sodium silicate-to-sodium hydroxide (NS/NH) ratio of 1.0 and a liquid-to-binder ratio of 0.6 were used. The geopolymer pastes were cured at room temperature before mechanical, microstructural, and durability property analyses. The results showed that the setting time and slump flow increased with increasing GWF content. The incorporation of GWF had little effect on the early strength of the geopolymer paste, but the 28-day compressive strength was significantly enhanced up to ∼67% (30% replacement) higher than that of the HCFA geopolymer paste. Likewise, the flexural strength increased with increasing GWF replacement content. The total porosity of the hybrid geopolymer paste was lower than that of the HCFA one resulting from the reaction and filling effect of the geopolymer matrix. The XRD, FTIR, and SEM-EDX analyses showed the presence of geopolymerization products with calcium silicate hydrate regardless of the geopolymer mixture composition. This suggested that GWF could react with alkaline activators to form geopolymer products even though some unreactive GWF was observable when GWF replaced at 40% by weight. Furthermore, an increase in GWF content led to better resistance to sulfuric acid and magnesium sulfate attack, which was observed within 180 days. All of these results suggested that GWF was an effective secondary precursor for improving the fresh and hardened properties of HCFA-based geopolymer paste. In addition, the residue acts as a reinforcing material in the matrix paste. Consequently, improved resistance to acid corrosion and sulfate expansion were significant.

Preparation and inhibition performance of dry water materials for preventing spontaneous combustion of coal

This work aimed to effectively prevent the spontaneous combustion of coal in goafs by preparing a type of dry water material with a solid-in-liquid structure through the mechanical stirring method, with nano-aluminum hydroxide aqueous solution as the core material and hydrophobic nano-silicon dioxide as the wall material. The effects of solid-to-liquid ratio, stirring time, and mass concentration of nano-aluminum hydroxide on the particle size and microstructure of dry water were studied. Results showed that the prepared dry water powder was the most uniform and fine when nano-silica, nano-aluminum hydroxide, and water were mixed at a mass ratio of 5:0.75:49.25 and stirred at a speed of 23,000 r/min for 25 s. The samples were characterized by using a temperature-programmed oxidation device, a thermogravimetric analyzer, and a Fourier-transform infrared spectrometer, and the inhibition performance of dry water was evaluated. Results revealed that dry water effectively slowed the oxidation rate of coal and inhibited the release of CO in the low-temperature environment, and the cross-point temperature increased from 125.1 °C to 155.4 °C for raw coal. In a high-temperature environment, dry water delayed the process of spontaneous combustion of coal, the temperature leading to the maximum mass increased from 308.6 °C to 369.4 °C, and the ignition temperature rose from 458.2 °C to 484.7 °C. In addition, the dry water material can inhibit the oxidative decomposition of aliphatic hydrocarbons and the transformation of oxygen-containing functional groups in coal samples, thus indicating, from a microscopic level, that it has good inhibition performance.

A Novel Approach for the Synthesis of Eco-friendly Geopolymer Ternary Blended Mortar with GGBS, Sugarcane Bagasse Ash, and Sewage Sludge Ash under Ambient Curing Conditions

The Present work emphasizes preparing ternary blended geopolymer mortar by partial replacement of Ground Granulated Blast Furnace Slag (GGBS) with a precursor such as Sugarcane Bagasse Ash (SCBA) and Sewage Sludge Ash (SSA) with two different sodium silicate to sodium hydroxide (SS/SH) ratios to prepare an alkaline activating solution. The replacement of GGBS with SCBA and SSA varied from 0–30% by weight. Binary and ternary mortar mixes were tested for compressive strength and their morphological characters, it was found that 10% of SCBA and 20% of SSA incorporation in the binary mix resulted in a drop in strength which is less significant than other replacements for SS/SH ratio of 2.5. The ternary mix consisting of GGBS, SCBA, and SSA in the ratio of 70:10:20 respectively produced a compressive strength that is comparable with the control mortar having 100% GGBS after 28 days of ambient curing. X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), and Fourier-transform infrared spectroscopy (FTIR) studies showed the presence of C-A-S-H gel and participation of precursor in the geopolymer reaction which resulted in enhancement of strength. The Toxicity Characteristic Leaching Procedure (TCLP) results for SSA-incorporated mortar proved the leachability of heavy metals is within the limits. The application of geopolymer mortar proved to be vital in the sustainable production of building materials such as pre-cast elements, masonry units, etc.

Stabilization and solidification of arsenic contaminated silty sand using alkaline activated slag

Contamination of soils by arsenic represents a significant environmental and public health risk, making effective remediation strategies a pressing concern. One commonly employed technique is stabilization and solidification, which involves the addition of stabilizing binders such as cement to immobilize arsenic. This study investigates the potential of alkaline activated slag for stabilization and solidification of arsenic-contaminated soil, employing the toxic characteristic leaching procedure (TCLP) and unconfined compressive strength (UCS) tests. To assess the strength and leachability behavior, the research examines the effect of several factors, including binder content, curing time, curing conditions, alkaline activator solution to slag ratio, sodium silicate to sodium hydroxide ratio, and sodium hydroxide concentration. Additionally, field emission scanning electron microscopes (FE-SEM) in combination with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) tests are employed to analyze the stabilization and solidification mechanism. The study shows that increasing the slag content to 20% by weight after 28 days of curing at ambient temperature leads to a decrease of almost 92% in the concentration of leached arsenic and an increase in UCS from 80 kPa to approximately 19 MPa. The formation of albite and anorthite crystals, along with gels such as (N, C)-A-S-H and C–S–H, contributes to enhanced strength and reduced leachability. As a result, the use of alkaline activated slag is identified as an effective and environmentally friendly approach for the stabilization/solidification of arsenic-contaminated soils. This study highlights the use of alkaline activated slag as an effective solution for remediating arsenic-contaminated soils while simultaneously reducing waste, greenhouse gas emissions, and energy consumption. Slag, a byproduct of metal production, is often wasted due to a lack of value and landfill space. However, alkaline activated slag demonstrates the potential to stabilize soil, immobilize heavy metals, and provide efficient and sustainable soil remediation.

Performance Evaluation of M20 Grade Geopolymer Concrete using Fly Ash and GGBS with Super Plasticizer

Abstract: This study aimed to evaluate the strength properties of geopolymer concrete using fly ash and ground granulated blast furnace slag (GGBS) with the addition of a super plasticizer at a grade M20. The study used 70% fly ash and 30% GGBS to replace the cement content of the concrete mix, and sodium hydroxide and sodium silicate were used as Alkaline activators. The concentration of (NaOH) solution was maintained at 8 molarity and the dosage of activator ratio is 2.5 is a combination of sodium silicate and sodium hydroxide ratio. The compressive strength of the geopolymer concrete was tested at different ages (7, 14, and 28 days) to evaluate the strength properties. The results showed that the addition of fly ash and GGBS significantly improved the strength properties of the geopolymer concrete. Moreover, the optimized dosage of the super plasticizer was found to be 1% of the total weight of the mix. The study concludes that the use of fly ash and GGBS in geopolymer concrete can significantly improve its strength properties, and the addition of a super plasticizer can enhance its workability. This finding suggests that geopolymer concrete could be a viable alternative to conventional concrete in construction applications .The test result shows encouraging results of ordinary Portland cement concrete and geo polymer concrete so one can easily replace ordinary concrete with geopolymer concrete for precast applications.

Synthesis of alkali-activated mortar using phosphogypsum-neutralised bauxite residue

The present study was aimed at perspective utilisation of two wastes, bauxite residue (BR), an extremely alkaline material, and phosphogypsum (PG), a highly acidic substance, of entirely different natures. Development of alkali-activated mortar targeting pavement applications was explored. As BR and PG alone proved to be ineffectual in developing geopolymer/alkali-activated mortar because of undesirably low compressive strength, the challenge lies in synthesis of alkali-activated mortar with high strength using a combination of these wastes. PG proportions of 10, 20, 30, 40 and 50%; sodium hydroxide (NaOH) molarities of 8, 10, 12 and 14 M; and sodium silicate (Na2SiO3)/sodium hydroxide ratios of 0.5, 1.0, 1.5, 2.0 and 2.5 were chosen as variable parameters to develop the mortar. From the comprehensive experimental results, 30% PG, 12 M sodium hydroxide and sodium silicate/sodium hydroxide ratio of 1.5 were found as the optimum parameters for synthesising the mortar. It was demonstrated that the mortar made at a 70:30 combination of BR and PG had superior compressive strength of 31.24 MPa, minimum abrasion loss of 1.52 mm and water absorption of <7%, apart from constraining leaching of potentially toxic elements. On account of mechanical, durability and environmental performance, the present study recommends the aforementioned combination as ideally suitable material in pavement applications.

Comparison between the Compressive Strength of Binary and Ternary Alkaline-activated Pozzolanic Concrete

This research compared the compressive strength of binary and ternary alkaline-activated pozzolanic concrete. Rice husk ash (RHA) and Metakaolin (MK) combined partially with Ordinary Portland Cement (OPC) each are the binary concrete while the combination of rice husk ash and metakaolin (RHA/MK) combined partially with OPC is the ternary concrete. The OPC was replaced at 15% each with RHA, MK and RHA/MK in ratios 0.33 (X), 0.5 (Y) and 1.0 (Z) of sodium silicate (NS) to sodium hydroxide (NH) as activator. A mix design ratio of 1:2:4 and water-cement ratio of 0.65 with alkaline liquid to pozzolan of 0.30 was used in the process of the study. Physical properties of the constituent materials as well chemical analysis of pozzolans were determined. Slump and compacting factor tests were done on the freshly mixed concrete to determine their workability while compression test was performed on the hardened concrete cube samples of side 150mm to obtain the compressive strength. Curing was done for 7 and 28 days inside water tank. The result of the compression test showed that the compressive strength of the ternary concrete continuously increased as the sodium silicate to sodium hydroxide ratio increased. At the maturity age of 28days, the values of the compressive strength were 14.2 MPa, 17.5 MPa and 20.3 MPa for sodium silicate (NS) to sodium hydroxide (NH) ratios of 0.33, 0.5 and 1.0 respectively. These values are higher than the compressive strength for the binary concrete of RHA and MK taken separately for the same NS to NH ratios which at 28days curing age were 10.9 MPa, 14.8 MPa, 16.2 MPa for RHA and 14.0 MPa, 15.3 MPa, 18.2 MPa for MK. The result of the research can be used in the construction industry for normal concrete work as well as serve for effective waste disposal of agricultural waste products such as RHA and MK to reduce environmental pollution.

Effect of calcium hydroxide (Ca(OH)2) and magnesium sulfate (MgSO4) on vaname shrimp (Litopenaeus vannamei) cultivation in freshwater media

The purpose of this study was to determine the effect of giving the ratio of Calcium Hydroxide (Ca(OH)2) and Magnesium Sulfate (MgSO4) with different doses on the growth of white shrimp (Litopenaeus vannamei) production in freshwater media. This research was conducted by experimental method using Completely Randomized Design (CRD). The parameter studied was how the effect of the addition of Ca(OH)2 and Magnesium Sulfat (MgSO4) lime with different doses in the maintenance container with 5 treatments and 3 replications, so that 15 experiments were obtained. The treatments applied were: Treatment 1 (P1) Seawater without the addition of calcium and magnesium, P2 Freshwater + 80 ppm Ca(OH)2, P3 Freshwater + 80 ppm Ca(OH)2 and 40 ppm MgSO4, P4 Freshwater + 80 ppm Ca(OH)2 and 80 ppm MgSO4, and P5 Freshwater + 80 ppm Ca(OH)2 and 120 ppm MgSO4. The results showed that the highest survival rate using fresh water was at P4 which was 82%, the specific weight growth rate was 3.9%, and the specific length growth rate was 2.6%. the value of the feed conversion ratio is 0.8. For water quality parameters, the temperature ranges from 30.4-30.60C, water pH 7.2-8.2, DO 6.4-6.6 mg/L, Alkalinity 68-72 ppm, and Ammonia 0.1 mg /L.Keywords: Ca(OH)2; Freshwater; MgSO4; Vannamei Shrimp

Effect of calcium hydroxide (Ca(OH)2) and magnesium sulfate (MgSO4) on vaname shrimp (Litopenaeus vannamei) cultivation in freshwater media

The purpose of this study was to determine the effect of giving the ratio of Calcium Hydroxide (Ca(OH)2) and Magnesium Sulfate (MgSO4) with different doses on the growth of white shrimp (Litopenaeus vannamei) production in freshwater media. This research was conducted by experimental method using Completely Randomized Design (CRD). The parameter studied was how the effect of the addition of Ca(OH)2 and Magnesium Sulfat (MgSO4) lime with different doses in the maintenance container with 5 treatments and 3 replications, so that 15 experiments were obtained. The treatments applied were: Treatment 1 (P1) Seawater without the addition of calcium and magnesium, P2 Freshwater + 80 ppm Ca(OH)2, P3 Freshwater + 80 ppm Ca(OH)2 and 40 ppm MgSO4, P4 Freshwater + 80 ppm Ca(OH)2 and 80 ppm MgSO4, and P5 Freshwater + 80 ppm Ca(OH)2 and 120 ppm MgSO4. The results showed that the highest survival rate using fresh water was at P4 which was 82%, the specific weight growth rate was 3.9%, and the specific length growth rate was 2.6%. the value of the feed conversion ratio is 0.8. For water quality parameters, the temperature ranges from 30.4-30.60C, water pH 7.2-8.2, DO 6.4-6.6 mg/L, Alkalinity 68-72 ppm, and Ammonia 0.1 mg /L.Keywords: Ca(OH)2; Freshwater; MgSO4; Vannamei Shrimp

Mechanical and durability characteristics of GGBS-Dolomite geopolymer concrete using recycled coarse aggregates

Increased construction rate in recent times has led to many problems in the sector such as increased use of cement, exploitation of natural resources, and increased amount of demolition waste. To overcome these problems, using geopolymer binders in place of cement and replacing natural aggregates with recycled aggregates can be a good solution. In order to determine the impacts of adding recycled concrete particles to geopolymer concrete, this study examines the hardened and durability qualities ofthe material. In this study, Geopolymer concrete was made with GGBS and Dolomite as precursor material, and alkali solution made with sodium silicate to sodium hydroxide ratio of 2.5 and alkali to source material ratio of 0.6. In the geopolymer concrete, recycled coarse aggregates were used to replace traditional coarse aggregates by 50%. Results showed that compared to regular geopolymer concrete (NGPC), recycled aggregate geopolymer concrete (RAGPC) tends to have reduced compressive strength, split-tensile strength, and flexural strength by 14%, 13%, and 16%, respectively. For assessing the durability characteristics, tests on water absorption, acid attack, and sulphate attack were conducted. The water absorption of RAGPC was 1.14% more than NGPC. The acid resistance and sulphate resistance of RAGPC were found similar to NGPC after exposure to H2SO4 and MgSO4 solution for 90 days. The results indicate that RAGPC has similar durability characteristics to GPC. Since recycled coarse aggregates don't considerably diminish strength and have comparable durability qualities, the study indicates that it can be used to economically substitute natural coarse aggregates in geopolymer concrete.

Removal of endosulfan from water by municipal waste incineration fly ash-based geopolymers: Adsorption kinetics, isotherms, and thermodynamics

Alkali-activated municipal waste incineration fly ash (MWFA)-based geopolymers (GPA, GPB, and GPC) were synthesized under different sodium silicate to sodium hydroxide (SS/SH) ratios. The geopolymers were applied in the removal of endosulfan, a persistent and toxic chemical, from water. The adsorbents were characterized by XRD, SEM-EDX, and FTIR. Variation of SS/SH ratios resulted in morphologically distinguishable geopolymers with different compositions. The adsorption equilibrium data were best described by the Langmuir isotherm. The maximum adsorption capacities increased with an increase in SS/SH ratios in the order 1.87, 15.89, 16.97, and 20.01 mg/g for MWFA, GPA, GPB, and GPC, respectively. The kinetic data were best described by the pseudo-first-order model wherein the adsorption rate (k1) was independent of the SS/SH ratios and the geopolymer composition. The thermodynamic parameters, that is, enthalpy (∆H > 0), Gibbs free energy (∆G < 0), entropy (∆S > 0), and activation energy (Ea > 0), show that the processes were endothermic, spontaneous, physical (Ea and ∆H < 40 kJ/mol), and entropy-driven. Alkalination was beneficial since the geopolymers had a higher adsorption capacity (∼8–10 times) and affinity for endosulfan (∼30 times) than the precursor material (MWFA). The adsorption mechanism entailed electrostatic interactions and hydrogen bonding. The MWFA-based geopolymers are, therefore, potential alternative low-cost adsorbents for the removal of endosulfan from water and a strategy for the valorization of MWFA.