Molar NaOH Research Articles

The Effect of Sodium Hydroxide Molarity on The Compressive and Splitting Tensile Strength of Ferronickel Slag-Based Alkali-Activated Mortar

The use of cement as the main binding agent in construction contributes approximately 7-10% in total of carbon dioxide gas emissions worldwide. In this study, the replacement of Portland cement using ground granulated ferronickel slag (GFNS) activated by the combination of sodium hydroxide (NaOH) dan sodium silicate (Na2SiO3) was utilized for producing alkali-activated mortar (AAM) as construction material. Four different mortar mixtures were prepared in this experimental work. There were three mixtures of ferronickel slag-based alkali activated mortar (FAM) with the variations of NaOH molarity of 6, 8, and 10M and cement-based mortar mixture (PCM) with water-to-cement ratio (w/c) of 0.5 was used as the control specimens. Overall, the flow and workability of the FAM specimen was lower than the PCM specimen due to the presence of silicate caused a sticky characteristic on the paste. On the other hand, the unit weight of FAM mortar was higher than the PCM specimen. Among all FAM mixtures, the most effective compressive strength and splitting tensile strength results were achieved by the FAM8 mixture, with a compressive strength at 28 days of 33.72 MPa and the splitting tensile strength at 28 days of 2.65 MPa, which had both good workability and chemical reaction of the material.

Low-energy impact behavior of ambient cured engineered geopolymer composites

Engineered geopolymer composite (EGC) is a new kind of fiber reinforced geopolymer composite with tensile strain-hardening behaviors. This paper was intended to investigate the low-energy impact behaviors of EGC. To further reduce the carbon footprint and material cost of EGC, the feasibility of developing ambient cured EGC with cheap local PVA fiber was discussed according to the micromechanics-based analytical models. The compressive, tensile and impact tests of EGC, engineered cementitious composites (ECC), pure geopolymeric matrix and cementitious matrix were conducted and compared. It was found that the EGC specimens have similar tensile behaviors with ECC and the ultimate tensile strain of EGC can be as high as 7.5%. Under impact load, it was found that the PVA fibers could effectively restrict the crushing and spalling of geopolymeric matrix. Also, the dissipated energy of pure geopolymeric matrix is 3.8 times higher than that of cementitious matrix, indicating that it is recommendable to develop impact-resistant material based on geopolymeric matrix. The influences of NaOH molarity on the impact behaviors of EGC and geopolymeric matrix were discussed. It was found that the impact-resistance of EGC improved with the increase of NaOH molarity, while the threshold of NaOH molarity for geopolymeric matrix was recommended as 12 mol/L. Even though the compressive strength of EGC is lower than ECC, it can be concluded that EGC could have comparable or even higher impact-resistance than ECC under different low-velocity impact conditions.

Synthesis of Fly-ash and Slag Based Geopolymer Concrete for Rigid Pavement

This research work describes the synthesis of fly-ash and granulated blast furnace slag (GGBS) based Geopolymer concrete (FSGC) for paving applications. The study looked at a total of 12 combinations comprising GGBS in proportions of 25%, 50%, 75%, and 100% as a fly-ash substitute, sodium hydroxide (NaOH) solutions of 8, 10, and 12 molars(M), and a fixed sodium hydroxide solution to sodium silicate (S/S) ratio of 2.5. The specimens were all cured outside in the open air. The investigation found that when the GGBS content and NaOH molar concentration increase, the mix's consistency stiffens, resulting in zero slumps and making it harder to work with. At the same time, as the GGBS content and NaOH molarity increased, the mechanical strengths of SFGC mixes improved. Maximum mechanical strengths were achieved using a mixture of 100 percent GGBS and 12 M NaOH solution. According to the findings of the study, the SFGC mix with GGBS content ranging from 25% to 30% and NaOH molarity ranging from 8 M to 10 M is adequate for meeting the criteria of paving grade concrete standards.

The Use of Recycled Aggregate Sludge for the Preparation of GGBFS and Fly Ash Based Geopolymer

Aggregate sludge is a waste product produced from crushing, screening, and washing processes at aggregate plants. Because of the large quantity and high treatment cost of this sludge, it cannot be disposed of as landfill, and thus, has caused environmental concern over the years in Taiwan. In this preliminary study, the recycled aggregate sludge was reutilized for construction applications through the geopolymerization process. The ground granulated blast furnace slag (GGBFS) and fly ash (FA) were selected as alkaline activated materials for the fabrication of sludge geopolymer. Several process parameters that may affect the mechanical and physical properties of geopolymer were investigated. These parameters are sludge/GGBFS/FA ratios, solid/liquid (alkali solution) ratio, the molarity of NaOH, and curing time. According to the test results, the compressive strength of geopolymer specimens (70/30 sludge/GGBFS ratios) made with 4 M and 6 M NaOH can reach 39.17 MPa and 43.6 MPa after 28 days of curing. The specimen made with 60/40 sludge/GGBFS ratios has a strength of 61.3 MPa. After replacing GGBFS with 10% fly ash (70/20/10 sludge/GGBFS/FA), the strength of the specimen can also reach 43 MPa. According to the test results obtained in this study, it was found that the higher the NaOH concentration, the higher the strength of the geopolymer, and the GGBFS also can contribute more to the mechanical properties of geopolymer than fly ash. This preliminary study suggests that it is possible to reutilize aggregate sludge for construction applications and solve its environmental disposal problem.

Improvement of High-Volume Fly Ash Cementitious Material Using Single Alkali Activation

This research aimed to present the improvement of the cementitious material in high-volume fly ash using only one alkali activator. Fly ash was used as a partial replacement for Portland cement type I, varying from 0 to 60% by weight of the binder. Concentrations of NaOH varying from 0.00 to 1.25 molar were used as alkali activator. Paste properties and mortar compressive strength at the ages of 3, 7, 14, 28, 60, and 90 days of water curing were investigated. The results reveal that fly ash paste with an alkali activator provides shorter initial setting time when compared to control paste without alkali activator. The use of 0.50 molar NaOH concentration in mortar containing fly ash not exceeding 50% by weight of binder provides the highest compressive strength at any age of curing. At that concentration, there is a significant increase in the 28-day compressive strength of up to 45% over that of the control mortar. In addition, higher NaOH concentration (not exceeding 1.00 molar) has a significant positive effect on the compressive strength of mortar with higher fly ash content, especially over longer curing periods.

Evaluation of flexural properties and characterisation of 10-mm thin geopolymer based on fly ash and ladle furnace slag

The formulation and flexural properties of thin fly ash geopolymers with thickness of merely 10 mm and replacement of ladle furnace slag to fly ash in thin geopolymer were presented. The formulation was discussed in terms of NaOH molarity, solid aluminosilicates-to-liquid alkali activator (S/L) mass ratio, and alkali activator (Na 2 SiO 3 /NaOH) mass ratio. Thin fly ash geopolymers with flexural strength and Young's modulus of 6.2 MPa and 0.14 GPa, respectively, were obtained by using 12 M NaOH, S/L ratio of 2.5 and Na 2 SiO 3 /NaOH ratio of 4.0. A high Na 2 SiO 3 /NaOH ratio was implemented for thin geopolymer synthesis to produce a more viscous slurry which helped to retain the shape of a thin geopolymer. The incorporation of ladle furnace slag up to 40 wt.% reported an increment of 26% in flexural strength up to 7.8 MPa as compared to pure fly ash geopolymers and the stiffness was increased to 0.19 GPa. Denser microstructure with improved compactness was observed as the ladle furnace slag acted as the filler. New crystalline phases of calcium silicate hydrate (C–S–H) were formed and coexisted with the geopolymer matrix, which consequently enhanced the flexural strength of thin fly ash geopolymer. This proved that the ladle furnace slag has the potential to be utilised in geopolymer synthesis and will enhance the flexural properties of thin geopolymers. The flexural performance of thin geopolymers in this study was considerably good as the thin geopolymers exhibited comparatively similar flexural strengths, but a higher strength/thickness ratio as compared to geopolymers with thickness greater than 40 mm.

Prediction of compressive strength of geopolymer concrete using machine learning techniques

AbstractGeopolymer concrete (GPC) is the result of an inorganic polymerization reaction that takes place in presence of an alkaline medium in the materials such as fly ash and slag, which are rich in silicates and aluminates. In this study, an artificial neural network (ANN), multiple linear regression, and the multivariate nonlinear regression (MNLR) models were designed to predict the 28 days compressive strength of the GPC. To train the models, a total of 289 data sets were used, which were published by different researchers in the open literature. The input parameters, namely, binder content, amount of slag, rest period, curing temperature, curing period, the ratio of NaOH/Na2SiO3, amount of superplasticizer, extra water added, the molarity of NaOH, alkaline activator to binder ratio, amount of coarse, and fine aggregate were used. The performance of the ANN model was better than the multi linear regression (MLR) and multi non‐linear regression (MNLR) models to estimate the strength. The sensitivity analysis on ANN was also performed to study the influence of each parameter. The sensitivity analysis shows that the ratio of NaOH/Na2SiO3 significantly affects the compressive strength of GPC.

Influence of Various Design Parameters on Compressive Strength of Geopolymer Concrete: A Parametric study by Taguchi Method

Global warming is one of the severe environmental effects, faced by the current generation. Studies show that, Carbon di-oxide (CO2) is the major cause for the global warming and is mainly due to huge production of Ordinary Portland Cement (OPC). Supplementary cementitious materials can reduce this effect by reducing the requirement materials instead of OPC for the construction purposes. Geopolymer Concrete (GPC) is a new generation concrete, which does not require OPC. In this study, Fly Ash (FA) was used to produce GPC. Various parameters are considered in the present study. Taguchi’s method is used for analyzing the parameters. An empirical relation is developed to predict the compressive strength of GPC based on the different parameters. Thirty-six mixes were casted to determine the effect of curing temperature, curing time, rest period, ratio of Alkaline Activator solutions (AAs), ratio of activators to FA, molarity of NaOH and replacement level of FA with OPC on the compressive strength. Contribution of each parameter was estimated by ANOVA. Results show that, addition of OPC had a significant effect on the compressive strength of GPC. The mix with 20% OPC, 14M NaOH, curing temperature of 60oC, curing time of 36hrs, rest period of 48hrs, AAs to FA ratio 0.3 and ratio of alkaline solutions 2.5 was found to have the maximum compressive strength. A regression equation is developed to determine the compressive strength of GPC with respect to the parameters considered.

Evolution of room-cured alkali-activated silicomanganese fume-based green mortar designed using Taguchi method

This paper presents the results of a study conducted to synthesize alkali-activated mortars (AAMs) at room temperature. The AAMs were prepared using silicomanganese fume (SiMnF) and ground granulated blast furnace slag (GGBFS) as precursor materials (PMs) and sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) as alkaline activators (AAs). The composition of the AAMs was designed and optimized using the Taguchi method. Five factors with four levels each were investigated in this study, including the ratio of GGBFS to PMs (0–4.5), sand to PMs ratio (1.5–2.4), molarity of NaOH (4–10 M), Na2SiO3/NaOH ratio (2–3.5) and AAs to PMs ratio (1.5–2.4). Based on the orthogonal array proposed by the Taguchi method, 16 AAMs were cast with varying flow and unit weight to evaluate the compressive strength at 3, 7 and 28 days. The strength data was statistically analysed by employing ANOVA and response surface methods to investigate the effect of experimental variables. AAM with 30:70 proportion of GGBFS and SiMnF, Na2SiO3/10 MNaOH of 2.5, AAs/PMs ratio of 0.5 and sand to PMs ratio of 1.5 attained optimum strength. Based on the SEM and EDS analysis, the molar ratios among the major constituent elements intertwined in the cemented matrix were established which contributed to the formation of alkaline products and microstructural densification of the optimum mixture.

Investigation into the permeability and strength of pervious geopolymer concrete containing coated biomass aggregate material

Waste palm oil products can be recycled in the production of pervious geopolymer concrete (PGC) for long-term sustainable development. PGC is a non-slip porous pavement concrete that allows water to pass through. Biomass aggregate (BA) is produced by burning palm oil biomass and is introduced as a replacement for natural aggregate (NA). BA is mixed with fly ash (FA) and alkaline liquid (AL) and heated in an oven at 80 °C for 24 h to produce coated biomass aggregate (CBA). PGC containing CBA is commonly used as a cement substitute in concrete. This study aims to develop and evaluate the effect of rainfall intensity on the ability of PGC to reduce stormwater runoff. Coating BA with geopolymer paste resulted in improved properties, better Aggregate crushing value (ACV), Aggregate impact value (AIV), water absorption and higher compressive strength compared with BA. Results indicated, a PGC with a FA/CBA ratio of 1:7, CBA of 5–10 mm, NaOH molarity of 10 M, Na2SiO3/NaOH ratio of 2.5, and AL/FA ratio of 0.5 when cured in an oven for 24 h at 80 °C, gave the optimum ratio for compressive strength of 13.7 MPa and water permeability of 2.1 cm/s. Both BA and CBA revealed a viable alternative aggregates for producing PGC and that the compressive strength of PGC made with CBA was 51% greater than cement pervious concrete containing NA. The results also showed that the reduction in runoff was due to the permeable concrete and decreased runoff with the increased rainfall intensity.

Strength and microstructure behaviour of high calcium fly ash based sustainable geo polymer concrete

PurposeConcrete is a building material widely used for the infrastructural development. Cement is the binding material used for the development of concrete. It is the primary cause of CO2 emission globally. The purpose of this study is to develop sustainable concrete material to satisfy the present need of construction sector. Geopolymer concrete (GPC) is a sustainable concrete developed without the use of cement. Therefore, investigations are being conducted to replace the cement by 100% with high calcium fly ash (FA) as binding material.Design/methodology/approachHigh calcium FA is used as cementitious binder, sodium hydroxide (NaOH) and sodium silicates (Na2SiO3) are used as alkaline liquids for developing the GPC. Mix proportions with different NaOH molarities of 4, 6, 8 and 10 M are considered to attain the appropriate mix. The method of curing adopted is ambient and oven curing. Workability, compressive strength and microstructure characteristics of GPC are analysed and presented.FindingsAn increase of NaOH in the mix decreases the workability. Compressive strength of 29 MPa is obtained for Mix-I with 8 M under ambient curing. A polynomial relationship is obtained to predict the compressive strength of GPC. Scanning electron microscope analysis is used to confirm the geo-polymerisation process in the microstructure of concrete.Originality/valueThis research work focuses on finding some alternative cementitious material for concrete that can replace ordinary portland cement (OPC) to overcome the CO2 emission owing to the utilisation of cement in the construction industry. An attempt has been made to use the waste material (high calcium FA) from thermal power plant for the production of GPC. GPC concrete is the novel building material and alternative to conventional concrete. It is the ecofriendly product contributing towards the improvement of the circular economy in the construction industry. There are several factors that affect the property of GPC such as type of binder material, molarity of activator solution and curing condition. The novelty of this work lies in the approach of using locally available high calcium FA along with manufactured sand for the development of GPC. As this approach is rarely investigated, to prove the attainment of compressive strength of GPC with high calcium FA, an attempt has been made during the present investigation. Other influencing parameter which affects the strength gain has also been analysed in this paper.

Effect of NaOH molarities to the microstructure and sodium storage performance of the Sn-MOF derived SnO2 microporous rod

In this study, we demonstrated a facile method to prepare a novel SnO2 microporous rod with various microstructures by controlling NaOH molarities in precursor synthesis processes. Four different molarities of NaOH solution (0.005 M, 0.048 M, 0.12 M and 0.5 M) were used together with o-phthalic acid in Sn-MOF synthesis to determine the effect of ligand [o-C6H4 ] concentration on microstructure evolution. It was found that increasing NaOH molarity can effectively decrease the size of Sn-MOF rods. Then, the SnO2 microporous rods were obtained by calcinating the as-prepared Sn-MOF as microstructures. Under an optimized experimental condition (NaOH molarity of 0.12 M), the SnO2 rods shows a modest initial coulombic efficiency of 61.3% with a high reversible sodium storage capacity of 503 mAh g−1 after 150 cycles at 50 mA g−1. Moreover, an impressive reversible sodium storage capacity of 206 mAh g−1 can be obtained at long-term cycling performance (800 cycles at current density of 2 A g−1). Effects of morphologies to electrochemical performances have been further discussed in aspects of intrinsic resistance, pseudocapacitive contribution, surface area and porous structure and microstructural stability, and the enhanced electrochemical performance could be attributed to factors of enhanced pseudocapacitive charge contribution, optimized microstructures, and structural stability, which ensure the SnO2−0.12 M to have a good rate performance and cyclability. This nanoscale-engineering method adopted here could be a promising path to fabricate SnO2-based anodes with novel microstructures for sodium storage applications.

Mechanical and Durability Characteristics Assessment of Geopolymer Composite (GPC) at Varying Silica Fume Content

The present study aimed at assessing mechanical and durability characteristics of ground granulated blast furnace slag (GGBS)-based geopolymer composites at 5%, 10%, 15%, 20%, 25%, and 30% replacement proportion of silica fume at 12 molarity of NaOH. Mechanical properties were assessed using compression and tension tests, whereas durability characteristics were evaluated using ultrasonic pulse velocity test (UPV), acid test, and rapid chloride permeability test (RCPT), and water absorption (WA) test. Additionally, reduction in mass and strength were also determined due to the acid action on the developed composites. A correlation of compressive strength was also established with the splitting tensile strength, UPV, RCPT, and WA. The presence of silica fume and high NaOH concentration in GPC tends to improve the mechanical strength up toa certain level. UPV values obtained were falling in the range of medium to good category. Chloride ion penetration and water absorption values were reduced by around 23% and 26%, respectively, at 10% silica fume replacement. Mass loss and strength loss were reduced as the % of silica fume increased. A good correlation of compressive strength was obtained with tensile strength, UPV, and RCPT with a coefficient of determination of 0.9681, 0.9665, and 0.9208, respectively. Poor correlation was obtained between compressive strength and water absorption.

Mechanical properties and micro-mechanisms of marine soft soil stabilized by different calcium content precursors based geopolymers

Soil stabilization has long been a scientifically and technologically challenging topic to address. It is essential to develop cementitious materials with a “low carbon footprint” by replacing ordinary Portland cement (OPC) with industrial waste based geopolymers. This concept is regarded as a greener approach to soil stabilization technology development. This study compared the mechanical properties and microstructure of marine soft soil stabilized by low-calcium content geopolymers, high-calcium content geopolymers and OPC via unconfined compressive strength (UCS) testing, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Low-calcium content and high-calcium content geopolymers were produced by alkali-activated coal-bearing metakaolin (CMK) and ground-granulated blast furnace slag (GGBS), respectively. The results indicated that a relatively high alkaline activator/precursor (A/P) ratio, Na2SiO3/NaOH ratio, and NaOH concentration were beneficial to the strength development of CMK-treated samples but were unfavorable for that of GGBS-treated samples. The optimum A/P ratio and Na2SiO3/NaOH ratio for the CMK-treated samples were 1.5 and 75:25, and those for the GGBS-treated samples were 1.0 and 25:75. The recommended NaOH molarity for practical applications was 12 M. At the same precursor content, the CMK-treated samples showed a lower strength than the OPC- and GGBS-treated samples because of their low reactivity at ambient temperature. The GGBS-treated samples showed a higher strength than the OPC-treated samples when the precursor content was higher than 20 wt%. As the curing time increased, the strength of the CMK-treated samples increased linearly, while the strength of the OPC- and GGBS-treated samples increased logarithmically, and a reduction was found in the strength of the GGBS-treated samples at later stages of curing. Increasing the temperature accelerated the formation of cementitious products and shortened the curing time, especially for the CMK-treated samples. The stabilization effect of CMK, GGBS, and OPC on marine soft soil was mainly attributed to the formation of the dense three-dimensional gel network structure. The hydration products of the OPC-treated samples were C-S-H gels, ettringite (AFt), and Ca(OH)2, whereas C-(A)-S-H gels were observed in the GGBS-treated samples, and N-A-S-H gels were observed in the CMK-treated samples.

Utilization of a novel artificial intelligence technique (ANFIS) to predict the compressive strength of fly ash-based geopolymer

Fly ash (FA) is widely used to synthesize geopolymers, but it is heterogeneous as it consists of reactive, partially reactive, and inert parts, which may influence the behavior of the resultant geopolymer. Therefore, in this experimental and analytical work, at first, the reactivity of the FA was assessed by modified Chapelle test, which was further investigated by conducting a dissolution test to study the influence of temperature (20, 60, and 100 °C) and time (6 – 24 h). Afterward, geopolymer paste was synthesized by varying: (i) alkaline to precursor ratio (0.3 – 0.5), (ii) sodium silicate to sodium hydroxide ratio (2 – 3), and (iii) curing temperature and age. Based on the additional parameter of the molarity of NaOH including the above-mentioned parameters, an adaptive neuro-fuzzy inference system (ANFIS) to predict the compressive strength was optimized. A prominent increase in reactivity was observed at 60 °C as compared to 20 °C. The compressive strength improved significantly at A/P ratio of 0.4 and 0.5 resulted in improved compressive strength in particular for the 2.5 SS/SH ratio which was verified by FTIR. Analytical results by ANFIS were compared with the multivariate adaptive regression spline (MARS) model in terms of R2, RMSE, and MAE it was concluded that the ANFIS model showed better correlation and significantly fewer errors as compared to the MARS model. Finally, the developed model was checked and validated by employing the real experiment test results based on parametric values obtained from the ANFIS model. The developed model of this study can provide a novel approach for the design of geopolymers based on artificial intelligence technique.

Stabilization of Indian peat using alkali-activated ground granulated blast furnace slag

Peat is an exceptionally problematic soil for construction purposes and is often stabilized by traditional stabilizers (like cement), which emits 0.95-ton carbon dioxide (CO2) per ton of cement during their production. Alkali-activated ground granulated blast furnace slag (GGBS) with its low carbon dioxide (approximately 0.07-ton CO2) emissions and higher strength gain provides a promising substitute to traditional stabilizers. Therefore, this study presents the viability of alkali-activated GGBS-stabilized Indian peat. The three types of peats (sapric, fibric, and hemic) were collected to cover a wide range of variations of fibre (6–73%) and organic content (21–79%). The sodium hydroxide (NaOH) molarities (M) of 6, 9, 12, and 15 were used to activate specimens, with GGBS percentages of 10, 20, and 30% by weight of dry peat and alkali/binder ratios of 0.5, 0.7, and 0.9. The test results show that the UCS of peat-GGBS depends on the molarity of NaOH, A/B, electrical conductivity (EC), pH, curing period, and organic content of the peat-GGBS matrix. The optimum combination for the peat-GGBS blend is 20% GGBS, NaOH molarity of 9, and A/B ratio of 0.7. Furthermore, it was found that UCS increases with the curing period and decreases with organic content (OC). The formation of aluminium silicate, sodium aluminosilicate, and potassium aluminosilicate responsible for strength gain is confirmed by XRD. The FESEM micrographs reveal that these products result in the filling of pore spaces to form a smooth and dense soil-binder matrix.

Strong etching formulation (time and rate) for PADC with deep depth bulk etch rate study

Aqueous NaOH with ethanol (strong) etchant is widely used. It shortens etching time effectively compared to normal etching conditions (6.25N NaOH at 70 °C). Two equations have been proposed to calculate the etching time with NaOH molarity and ethanol volume. Another two empirical equations were introduced for estimating the bulk etch rates of PADC etched in strong etchant. Up to now, there were no such equations available in the literature that can predict etching time and Vb of PADC with etchant molarity and ethanol volumes. The proposed equations were compared to fundamental Vb models stemming from literature. Fast etching enables the follow-up of bulk etch rate variation versus depth in the detector material up to ≈80μ m. In agreement with previous studies, an equation is given which allows such variations to be expressed under the form of a reciprocal bulk etch rate normalized to depth (i.e., removed layer).

Effect of elevated temperature on polypropylene fiber reinforced alkali-activated high calcium fly ash paste

This paper examined the mechanism of polypropylene fiber (PP) reinforced alkali-activated high calcium fly ash paste (AHFP) exposed to high temperature. The PP was added into the AHFP mixture at the dosages of 0, 0.5, 1.0 and 1.5 % wt of fly ash. The 10 M (molar) NaOH, Na2SiO3/NaOH ratio of 2.0, and liquid/binder ratio of 0.60 were used. Compressive and flexural strengths, and microstructure of AHFP after exposed to 200, 400, 600 and 800 °C were studied. The results showed that the use of PP at 0.5 % wt of fly ash resulted in the best improvement in compressive strength of paste. For flexural strength, a slightly higher PP content at 1.0 % wt of fly ash was the optimum. For exposure to high temperature, the residual flexural strength was nearly one third at 400 °C and reduced to 8–12 % for temperatures beyond this. With the increasing exposed temperature, the air void and large capillary pore increased, but the medium capillary pore and gel pore reduced. The results indicated that the mechanisms of weight and strength losses of AHFP were due to thermo-hygral damage around 220−320 C, followed by thermo-mechanical damage at 430−660 C and thermo-chemical damage at 700 C onwards.

Effect of hierarchical ZSM-5 zeolites on product distribution of low rank coal fast pyrolysis in a fluidized bed

A series of hierarchical ZSM-5 zeolites were prepared by seed induction method and alkali-treated method. The crystal structural, textural and acidic properties were characterized by XRD, TEM, NH3-TPD, and N2-sorption. The effect of hierarchical ZSM-5 zeolites on the product distribution of low rank coal fast pyrolysis in a fluidized bed was investigated. The results showed that the specific surface area, mesoporous pore volume and average pore size of the zeolites increase to different degrees after alkali treatment. Hierarchical ZSM-5 zeolites could promote the cyclization of aliphatics and the dissociation of phenol pool of volatile from coal pyrolysis, increasing the content of light aromatics. The yield of light aromatics reaches the maximumwhen the zeolites used are treated with 0.3 mol NaOH, in which the content of mono-aromatics and naphthalene/methylnaphthalene increases by 2.7 times and 0.9 times, respectively, compared with microporous zeolites. The performance of catalysts decreases when treated with 0.4 mol NaOH due to the excessive desilication.

The Production of Zeolite Y Catalyst From Palm Kernel Shell for Fluid Catalytic Cracking Unit

Exorbitant costs of fluid catalytic cracking unit (FCCU) catalysts coupled with their ever-increasing demand have led researchers to develop alternative materials from indigenous sources. In this study, the zeolite Y component of the FCCU catalyst was synthesized from palm kernel shells. Leaching was carried out with the aid of citric acid to remove impurities. The synthesis process was done using alkaline hydrothermal treatment while varying reagent concentration and reaction time. The resultant products were characterized using XRF, XRD, FTIR, BET, and SEM analysis. The XRD and XRF showed a high silicate content level, while an 85% reduction in iron oxide impurities was observed after leaching. The process carried out at a duration of 9 hours, a temperature of 80°C with a NaOH molarity strength of 2 mol/L, had the highest SiO2 and Si/Al ratio value. A spongy, porous zeolite crystal was formed with the presence of hydroxyls in its sodalite cage. All samples had a combination of types II & I adsorption isotherms, Si/Al ratio of 2–5, and specific surface area within 80–260 m2/g, which indicates the presence of intermediate mesostructured Zeolite Y catalyst. Synthesized zeolite Y showed a more significant gap in its structural formation as the addition of NaOH decreased the grain size by 14.3%. FTIR highlighted the significant functional groups present in the novel compound, which, when compared to previous works, proves its suitability.