Increasing NaOH Concentration Research Articles

Effect of synthesis parameters on crystal structure and magnetic properties of cobalt zinc ferrite (Co0.5Zn0.5Fe2O4) nanoparticles

Co0.5Zn0.5Fe2O4nanoparticles have been successfully synthesized by coprecipitation method with varying NaOH concentrations and synthesis temperatures. X-ray diffraction (XRD) analysis confirmed that Co0.5Zn0.5Fe2O4 nanoparticles have spinel cubic crystal structure with crystallite size ranging from 7.9 to 21.4 nm. The crystallite size increase relatively by increasing NaOH concentration and synthesis temperature which related to the nucleation and crystal growth mechanism of nanoparticles during synthesis. The transmission electron microscope (TEM) image showed that the sample was aglomerated. The selected area electron diffraction (SAED) image showed the diffraction ring as representation of miller plane and confirmed that sample was polycrystalline. Magnetic measurement indicated that Co0.5Zn0.5Fe2O4 nanoparticles shows ferimagnetic behaviour and tend to be superparamagnetic with decreasing crystallite size. The increase in coercivity and maximal magnetization also have been found by increasing NaOH concentration and synthesis temperature. It is attributed to single domain existence and an increasing of crystallinity degree. The Fourier transform infrared spectroscope (FTIR) spectra also confirmed the existence of symmetric stretching vibration bands of metal ions near 563-609 cm−1 and 316-493 cm−1 in tetrahedral and octahedral sites, respectively.

Size dependent magnetic and antibacterial properties of solvothermally synthesized cuprous oxide (Cu2O) nanocubes

Cuprous oxide (Cu2O) nanocubes were fruitfully synthesized via facile solvothermal route. The crystalline nature and structural confirmation of the synthesized nanocubes was revealed by XRD and Raman studies. The oxygen defects and luminescent abilities were explored by PL studies. The FTIR metal–oxygen vibrations present in Cu2O nanocubes was observed at 510 cm−1. The typical nanocube morphology and the decrease in particle size with NaOH concentration increase was revealed by SEM images. The particle sizes of the best performed nanocubes (2 µm) have been tested for antimicrobial properties. The particle size effect on improved diamagnetic behavior of 5 × 10−3 emu/g was reported for 6 µm scale range. The enhanced antibacterial properties against Gram-positive (Bacillus thuringiensis) and Gram-negative (Pseudomonas aeruginosa) bacteria were reported.

Fiber Evolution during Alkaline Treatment and Its Impact on Handsheet Properties

To understand the swelling effects of alkaline treatment on the morphological properties of fibers and physical properties of handsheets, bleached softwood kraft pulp was treated with NaOH at different concentrations. The results showed that the fiber swelling increased, but the shrinkage and elongation of the paper at a NaOH concentration of 6% or higher did not improve. Dissolution of amorphous material occurred during the treatment together with peeling reactions. The fiber length and shape factor decreased and the fines content increased with an increasing alkali concentration. The cellulose crystallinity decreased with an increasing NaOH concentration. This was confirmed by X-ray diffractometry, which also showed that some cellulose I was converted to cellulose II, especially at higher NaOH concentrations (> 9%). The fiber curl and kink indices increased and the handsheet density decreased with an increasing NaOH concentration. However, the tensile index decreased more steeply than the density with an increasing NaOH concentration, possibly because of the lower number and strength of the interfiber bonds, increased kinks, and reduced fiber strength and length. The handsheet extensibility first increased and subsequently decreased as the NaOH concentration increased, which indicated that well-controlled NaOH treatment could be used to improve the extensibility of paper.

Molecular insights to alkaline based bio-fabrication of silver nanoparticles for inverse cytotoxicity and enhanced antibacterial activity

High demand for silver nanoparticles due to their extensive applications in different field has raised need of eco-friendly green synthesis with determined biomedical effects. This study proposes a novel rapid controlled alkaline based green synthesis of antibacterial silver nanoparticles from Calotropis gigantea for reduced cytotoxic effects. Silver nanoparticles termed as FAg, FAg1N, and FAg5N were synthesized with the help of floral extract of Calotropis gigantea as reducing and capping agent in presence of UV light and NaOH for catalysis and were characterized for their physiochemical properties by FESEM, DLS, UV–Visible spectrophotometry and FTIR. Facile synthesized Silver nanoparticles FAg1N and FAg5N showed enhanced antibacterial effects than FAg with increased NaOH concentration. Cytotoxic effect was found to be reduced at optimized alkaline conditioned FAg1N than FAg and FAg5N. Molecular dynamics study depicted the significant role of configurational change in “Calotropin” at variable alkalinity for controlling the size and physiological properties of synthesized AgNPs. The mechanism of cytotoxicity was revealed as consequences of variability in the interaction of Sod1 and P53 proteins with AgNPs surface for oxidative stress induction and programmed cell death.

One-pot hydrothermal synthesis of micaceous iron oxide pigment from jarosite waste

In this study, jarosite waste was adopted as feed material for micaceous iron oxide (MIO) pigment preparation by a one-pot hydrothermal reaction. The formation of MIO started from jarosite decomposition into akaganeite (β-FeOOH) nanoparticles in alkali solution, which then recrystallized and transformed into MIO crystals under high temperature and OH− concentration. The influences of NaOH concentration and reaction temperature on MIO formation were investigated. It was found that MIO formed when NaOH concentration and reaction temperature were equal to or higher than 2 M and 180°C, respectively. With an increase of NaOH concentration or reaction temperature, the particle size of MIO increased, leading to darkened color of the product. Moreover, quality evaluation indicated that the synthesized MIO fulfilled the required characteristics of micaceous iron oxide pigments for paints and the international standard of ISO 10601-2007 MIO-A1.

The effects of alkali treatment on the mechanical and chemical properties of pineapple leaf fibres (PALF) and adhesion to epoxy resin

The focus of this study was to obtain the optimum alkaline treatment for pineapple leaf fibre and its effect on the mechanical and chemical properties, surface topography, heat resistivity, as well as its interfacial bonding with epoxy matrix. There were 6 different treatment conditions set for the fibre. The morphology of a single fibre observed under the Digital Image Analyzer indicates slight reduction in fibre diameter with increasing NaOH concentration. The Scanning Electron Microscope (SEM) results show the deteriorating effect of alkali, which can be seen from the removal of impurities and increase in surface roughness. The mechanical analysis indicates that 6% NaOH treatment with 3-hour immersion period yielded the highest tensile strength. The adhesion between single fibre and epoxy resin was analysed through the micro-droplet test. Alkaline treatment results in better mechanical bonding between fibre and epoxy resin. It was found that 6% NaOH treatment with 1-hour immersion yielded highest interfacial shear stress. However, as NaOH concentration went above 6 %, the fibre started to show reduction in mechanical properties, as well as fibre-matrix interlocking. The TGA analysis implies that alkaline treatment improved the thermal stability and heat resistivity of the fibre.

Kinetics and pathways for nitrosamine formation in amino acid-based carbon dioxide capture systems

Amino acids are emerging as alternative solvents for absorption-based CO2 capture, but their potential to form the harmful byproducts nitrosamines is not well understood. This study investigated the formation of nitrosamines from model amino acids sarcosine, proline, and taurine under desorber- and absorber-relevant conditions. Special attention was paid to the effects of base and the formation of volatile nitrosamines. Under simulated desorber conditions, all three amino acid solvents with organic base monoethanolamine (MEA) formed more total nitrosamines than those with inorganic base sodium hydroxide (NaOH). Increasing base concentration decreased the formation of N-nitrososarcosine (NSAR) in both NaOH- and MEA-based sarcosine solvents. By measuring NSAR formation under varying base concentration and CO2 loading, it was shown that both sarcosine carbamic acid (SARCOOH) and deprotonated sarcosine (SAR−) contributed to NSAR formation. Volatile nitrosamine N-nitrosodimethylamine (NDMA) was detected in sarcosine solvents at levels three orders of magnitude lower than NSAR. Kinetic modeling showed that 61%–110% of the accumulated NDMA was formed through NSAR decomposition. NDMA formation from NSAR was promoted by increasing MEA concentration, but suppressed by increasing NaOH concentration. Under simulated absorber conditions, NaOH- and MEA-based solvents formed total nitrosamines at similar rates for sarcosine, proline, and taurine. In sarcosine solvents, NDMA formed at levels three orders of magnitude lower than NSAR, similar to that under desorber conditions.

Appraisal on Strength Characteristics of Alkali-Activated GGBFS with Low Concentrations of Sodium Hydroxide

This paper investigates the effect of low concentrations of sodium hydroxide (NaOH) and alkaline ratio (wt. of alkali silicate/alkali hydroxide) on the physical and mechanical properties of alkali-activated GGBFS. Parameters considered are activator concentration (1, 2, 3, 4, 5, 6, 7, 8, 9M) and alkaline ratio (1, 1.5, 2, 2.5, 3). Normal consistency, initial setting time and compressive strength tests were performed considering GGBFS as binder and alkaline solution as fluid medium with varying NaOH concentration and alkaline ratio. The obtained results indicated that change in NaOH concentration has significant effect on consistency, initial setting time and compressive strength of alkali-activated GGBFS. Change in alkaline ratio showed a significant effect in initial setting time and compressive strength of alkali-activated GGBFS. Compressive strength of mortar cubes cast with 4M NaOH with an alkaline ratio of 1.5 cured at room temperature produced a strength of 41 MPa at 28 days. XRD analysis indicated that increase in NaOH concentration resulted in increase in the intensity of albite peaks. SEM analysis indicated a complete dissolution of slag grains, and the gel was observed to be homogenous on slag particles at higher activator concentration.

Effect of Synthesis Parameters on Crystals Structures and Magnetic Properties of Cobalt Nickel Ferrite Nanoparticles

Co0.5Ni0.5Fe2O4 magnetic nanoparticles have been successfully synthesized by coprecipitation method with varying synthesis temperature and NaOH concentration. X-ray diffraction (XRD) analysis confirmed that Co0.5Ni0.5Fe2O4 nanoparticles have spinel cubic crystal structure. The particle size of the sample synthesized at 3 M NaOH was 7.3 nm and then increased with the increase of NaOH concentration. It is caused by the increase of particle growth rate. The particle size of the sample synthesized at 30 °C was 10.2 nm and then increased with the increase of temperature. The lattice parameter of the sample was constant at 8.5 Å with varying synthesis temperature and NaOH concentration. The maximum magnetization and the coercivity of the sample synthesized at 3 M NaOH was 11.3 emu·g-1 and 0.1 kOe, respectively, and then increased with the increase of NaOH concentration. It is caused by the increase of crystallite size in a single domain. The maximum magnetization and the coercivity of the sample synthesized at 30 °C was 9.9 emu·g-1 and 0.1 kOe, respectively, and then increased with the increase of temperature. Transmission Electron Microscopy (TEM) image showed that the sample was agglomerated. Selective Area Electron Diffraction (SAED) image shows that sample is confirmed peak is appearing in XRD. The Fourier Transform Infra-Red (FTIR) spectra confirmed that vibration of octahedral and tetrahedral metal-oxide bond is 601.8 cm-1 and 370.3 cm-1. The purpose of this work is to investigate the effect of synthesis temperature and NaOH concentration on the relation between crystal structure and magnetic properties.

Chemical Kinetics of Alkaline Pretreatment of Napier Grass (Pennisetum purpureum) Prior Enzymatic Hydrolysis

Background:Napier grass is a naturally abundant waste material that can be cultivated over a vast area of land which makes it a viable source for sugar and bioethanol production.Introduction:The presence of lignin in the biomass makes cellulose inaccessible for conversion to useful products, however, in order to provide for efficient utilization of the waste material, reagent and energy, a study on the kinetics of lignin removal from Napier grass was carried out in this work using 1 and 3 w/w % NaOH at temperatures between 80 and 120°C.Materials & Methods:Based on the investigation, there was increased lignin removal for increased NaOH concentration. Kinetic parameters were also determined and it was observed that, the reaction of lignin in Napier grass with NaOH obeys a pseudo-zero or pseudo-fractional order kinetics. Furthermore, the orders of the reaction for the pretreatment conditions of 3 w/w% NaOH at 100°C and those of 3 and 1 w/w NaOH at 120°C gave close reaction orders of 0.2, 0.22 and 0.24 respectively after 110 minutes, which implies that, for the three cases, the residual lignin in the extract was almost the same at the pretreatment conditions while slight differences are evident in their pseudo rate constants. Also, it was observed that, the activation energy of the reaction reduced significantly as the concentration of NaOH increased from 1w/w - 3 w/w%.Conclusion:Based on the AIL and the total lignin (i.e.AIL + ASL) in the Napier grass, the recorded delignification efficiencies at the optimum pretreatment time of 17.5 h are 90 and 76% respectively. In addition, the adopted Differential Technique (DT) combined with the Ostwald Method of Isolation (OMI) can be accurately used to study the kinetics of lignin removal from Napier grass.

The effect of synthesis parameter on crystal structure and magnetic properties of Ni0.5Zn0.5Fe2O4 magnetic nanoparticles

Nickel Zinc Ferrite (Ni0.5Zn0.5Fe2O4) magnetic nanoparticles have been successfully synthesized using the co-precipitation method with variation of synthesis temperature and concentration of NaOH. X-ray diffraction (XRD) analysis confirmed that Ni0.5Zn0.5Fe2O4 nanoparticles have spinel cubic crystal structure. The XRD profile of sample showed that the crystallinity increases with the increase of synthesis temperature. Meanwhile the XRD profile of sample showed the crystallinity decreases with the increase of NaOH concentration. Crystallite size of samples were in the range of 11.1-16.0 nm. There is no significant change in the lattice parameter size for the samples synthesized with increase of temperatures and NaOH concentrations. Transmission electron microscope (TEM) image showed that the sample was agglomerated. The selected area electron diffraction (SAED) image showed the diffraction ring as representation of Miller plane and confirmed that sample was polycrystalline. The maximum magnetization (σs) at 15 kOe of the samples increases with the increase of crystallite size and crystallinity. The coercivity (Hc) of the samples increases with the increase of crystallite size.

Synthesis of Fe-Fe2B catalysts via solvothermal route for hydrogen generation by hydrolysis of NaBH4

In this study, iron sulfate heptahydrate (FeSO 4. 7H 2 O) and sodium borohydride (NaBH 4 ) were used to synthesize Fe-Fe 2 B nanocrystals via the solvothermal route. Synthesis of Fe-Fe 2 B nanocrystals was carried out under Argon (Ar) gas atmosphere with aqueous solutions of FeSO 4 .7H 2 O and NaBH 4 at various concentrations and reaction time. The phases and microstructures of nanocrystals thus formed were characterized by X-Ray diffraction (XRD) spectroscopy and scanning electron microscopy (SEM). Surface areas of nanocrystals were measured by a surface area and pore-size analyzer using nitrogen adsorption-desorption method together with Brunauer-Emmett-Teller (BET) equation. The vacuum dried nanoparticles were calcined under both Ar and air at 500 oC. Nano-cylindrical structures Fe-Fe 2 B were observed while calcinating under Ar atmosphere; whereas more irregular shaped particles were obtained by calcination under air. The surface areas of nanocylinders were determined as 12 m 2 /g, 5.5 m 2 /g and 16.5 m 2 /g, for vacuum dried, Ar-calcined and O 2 -calcined products respectively. The catalytic effect of those nanocrystals for hydrogen generation were studied by determining reaction rates in aqueous alkaline solutions of NaBH 4 . Their catalytic activities were investigated by varying the amount of catalysts, and the concentrations of NaBH 4 and NaOH. The effect of temperature on the catalytic activity was also studied by varying the temperatures from 25-70 °C. It was noticed that the catalytic activity of vacuum dried nanocrystals was the highest, and it decreased with the increase in NaOH concentration. With 0.01 g of Fe-Fe 2 B catalyst in 1 % w/w NaBH 4 concentration at 25 °C, the hydrogen production rate was 570 mL of H 2 .g -1 .m -1 , which reached to 1230 at 50 °C and 2700 mL at 70 °C.

Changes in Lignin Chemistry of Switchgrass due to Delignification by Sodium Hydroxide Pretreatment

Switchgrass was pretreated with sodium hydroxide (NaOH) at various concentrations and pretreatment times to investigate how delignification caused by NaOH affects its lignin chemistry. NaOH resulted in significant delignification ranging from 44.0 to 84.6% depending on pretreatment intensity. While there was no significant glucan loss due to NaOH pretreatment, higher NaOH concentrations removed xylan by up to 28.3%. Nitrobenzene oxidation (NBO) was used to study changes in lignin chemistry, and indicated that at higher NaOH concentrations, the amount of 4-hydroxygenzaldehyde (Hy) degraded from p-hydroxyphenyl propanol (H) lignin units was significantly reduced (p < 0.05). However, amounts of syringic (SA) and vanillic (VA) acids generated from syringyl (S) and guaiacyl (G) degradation were greater at higher NaOH concentration. S/G ratio (=0.62 raw switchgrass) did not significantly (p > 0.05) change with 15 min pretreatment, but it increased to 0.75 and 0.72, respectively, with 30 and 60 min pretreatments (p < 0.05). Increase in NaOH concentration did not significantly (p > 0.05) change S/G ratio, but H/G ratio (=0.48 raw switchgrass) decreased significantly to 0.14 regardless of pretreatment times. Overall, the H unit was found to be more susceptible to NaOH than S and G unit monolignols. Though changes in lignin chemistry due to NaOH concentration were observed, their impact on cellulolytic enzyme action during hydrolysis could not be fully understood. Further studies on lignin isolation may help to determine how these changes in lignin chemistry by NaOH impact cellulolytic enzymes.

The effect of NaOH on lowering interfacial tension of oil/alkylbenzene sulfonates solution.

Six sodium para-dimethyl alkylbenzene sulfonates (PDABS, abbr. p-S12-5, p-S14-5, p-S16-5, p-S18-5, p-S16-6 and p-S16-8, respectively) have been synthesized. The structures and the purities of the products have also been confirmed by 1H-NMR and mass spectrometry. Crude oil and its equivalent alkanes were chosen as oil phases. The effect of the NaOH concentration on the interfacial tension (IFT) of PDABS was investigated by using a spinning drop tensiometer. The results showed that, in a certain range of NaOH concentrations, p-S14-5, p-S16-5 and p-S18-5 produced ultra-low IFT (∼10−3 mN m−1). NaOH was roughly similar to NaCl in aqueous solutions in terms of its effect on interfacial concentration and arrangement of PDABS at the interface. With the increase in the concentration of NaOH, the electric double layer of hydrophilic groups in PDABS was compressed to become smaller and the electrostatic interactions between hydrophilic groups weakened, which resulted in an increase in interfacial concentration of PDABS. Continuing to increase the concentration of NaOH, the electrical double layer was further compressed; water molecules could incorporate into the interface through loose hydrophilic groups. Therefore, these two aspects of variations caused IFT to display the trend of decreasing and then increasing with increase of NaOH concentration. However, at higher NaOH concentrations, PDABS molecules were driven into the oil phase by the salting out effect, and this process resulted in a decrease of IFT for water-soluble p-S12-5 and p-S14-5. For oil soluble p-S18-5, this process had little effect on the effective distribution in the oil phase. The effective distribution of PDABS in the oil phase played an important role in stabilizing the interface and reducing IFT. There was no clear evidence that NaOH reduced the IFT between oil and water by showing a synergistic effect between PDABS and active species formed in situ with acidic components in the crude oil.

Effect of NaOH Concentration and Adding Sequences on Structural and Magnetic Properties of Ni0.4Co0.6Fe2O4 Nanopowders Prepared Via Co-precipitation Route

Ni0.4Co0.6Fe2O4 nanopowders were prepared via the co-precipitation route followed by annealing treatment. The structural and magnetic properties of the as-synthesized samples were determined by XRD, FT-IR, TG-DSC, and PPMS measurements, respectively. The XRD patterns indicated a single-phase cubic spinel structure for all the Ni-Co ferrite samples, regardless of adding sequences of the reactants or NaOH concentration. The analysis of the XRD patterns revealed that the enhancement in lattice constant with increasing NaOH concentration is related to the prevention of oxidization of Co2+ ions in the Ni-Co ferrite lattice. The FT-IR spectra indicated that samples prepared in the B process have fewer impurities than those prepared in the A process. The enhancement in saturation magnetization with the increase in sodium hydroxide concentration could be attributed to the strengthening of super-exchange interaction between A and B sublattices, due to replacements of Co3+ ions (magnetic moment of 0 μ B) by Co2+ ions (magnetic moment of 3 μ B) at B sublattices. The obvious increase in the coercivity field with the increase in concentration of NaOH solutions can be interpreted in terms of enhancement of magneto-crystalline anisotropy that originated from gradual substitutions of Co3+ ions with Co2+ ions at the octahedral sites.

Low temperature hydrothermal sintering process for the quasi-complete densification of nanometric α-quartz

We report the first successful densification of polycrystalline α-quartz. The innovative hydrothermal sintering process was used as a low temperature route on sol-gel silica nanoparticles (350MPa, 300°C, 90min) in presence of water or aqueous sodium hydroxide solution (from 0.2M up to 5M). For the lowest NaOH concentrations, amorphous silica densification is observed, reaching a compactness of 86%. The basic physical-chemical mechanism proceeds through dissolution-precipitation. When NaOH concentration increases, the kinetics of dissolution are faster, nanoparticles totally dissolve and α-quartz is stabilized during precipitation. 98% dense α-quartz is obtained, the crystallite size increases with NaOH concentration.

Effect of TS-1 Treatment by Mixed Alkaline on Propylene Epoxidation

Titanium silicate-1 (TS-1) was treated with a mixed alkaline of tetrapropyl ammonium hydroxide (TPAOH) and NaOH. It was characterized by XRD, nitrogen physical adsorption, SEM, FT-IR, UV–Vis and ICP-OES, and studied in propylene epoxidation. The mixed alkaline treatment with TPAOH/NaOH solution did not destroy the MFI structure of TS-1. With increasing NaOH concentrations, the relative crystallinity and the framework titanium decreased to some extent while the mesopore volume, mesopore diameter, and extra-framework titanium increased appreciably. When NaOH concentration was 0.0333 mol L−1, the best catalytic performance was obtained.

Structure Sorting of Large‐Diameter Carbon Nanotubes by NaOH Tuning the Interactions between Nanotubes and Gel

AbstractThe structure separation of synthetic single‐wall carbon nanotube (SWCNT) mixture species with diameters larger than 1.2 nm still remains a challenge. Here, an NaOH‐assisted gel chromatography method is used for the structure separation of the SWCNT mixture with a diameter range of 1.2–1.7 nm, in which NaOH is used to tune the interaction between distinct (n, m) SWCNTs and gel. Incrementally increasing NaOH concentration in SWCNT dispersion selectively enhances the adsorbability of different‐structure SWCNTs and enlarges their interaction difference with gel, leading to their structure separation after applying into a gel column system. On this basis, a two‐step method is developed for further improving the structure purity of the separated SWCNTs by combining overloading and stepwise elution. These results are well demonstrated by the optical spectra of the separated SWCNTs. This work paves a way for single‐chirality separation of large‐diameter SWCNTs using gel chromatography technique and is an advanced progress in the structure control of SWCNTs.

Effect of Calcium Carbonate on Compressive Strength and Physical Properties of Alkali-Activated Lightweight Concrete

This study presents the compressive strength and physical properties of alkali-activated lightweight concrete. Alkali-activated lightweight concrete was synthesized with fly ash, calcium carbonate and sodium hydroxide solution. Calcium carbonate was designed to replace part of fly ash at 5 and 10 wt.%. Sodium hydroxide solution at 5, 7.5 and 10 M was used as a liquid solution. Liquid to ash ratio (L/A ratio) at 0.45 was designed and aluminium powder was used as a foaming agent. The results showed that, the compressive strength of alkali-activated lightweight concrete made with fly ash was increased with NaOH concentration increased. The maximum compressive strength at 6.0 MPa was obtained from 10M NaOH mixture. For fly ash-calcium carbonate system, the compressive strength of lightweight concrete was improved when containing calcium carbonated, especially at 5 and 7.5 M NaOH mixtures. The maximum of compressive strength at 8.1 MPa and bulk density were obtained from the 5 wt.% calcium carbonated with 10M NaOH mixture. Water absorption and voids of all mixtures trend to decrease with increased NaOH concentration. XRD showed the sodium aluminum silicate hydrated as an alkali-activated product and composed of Si/Al atomic ratio at 2.1 and Na/Al atomic ratio at 1.4, respectively. Bulk density and compressive strength of alkali-activated lightweight concrete made with both fly ash and fly ash-calcium carbonated were acceptable in accordance with the specified criteria of TIS 2601. The well pore structure distribution of alkali-activated lightweight concrete was acceptable.

Influence of NaOH concentration on microstructure and properties of cured alkali-activated calcined clay

Microstructure of cured mixes composed of kaolinitic-illitic raw clay calcined at 700°C and sodium hydroxide (4–14M) was investigated using X-ray diffraction, Fourier-transform infrared spectroscopy, Scanning electron microscopy and Thermal analysis. The change of the properties (flexural strength, density, water absorption, open porosity and electrical conductivity) versus NaOH concentration was evaluated and the possible formation of zeolite ZK-14 within the geopolymer matrix from the amorphous clay phases (mainly metakaolinite) was examined. Sodium carbonate was detected as a carbonation product. Due to heating, geopolymers were characterized by dehydration and subsequent recrystallization into nepheline. The development of the fibrous-zeolitic phase was favored by the increase of NaOH concentration and its impact on the studied properties was somewhat advantageous. The rise of alkali concentration within 4–11.5M enhanced the extent of geopolymerization. The water absorption kinetic obeyed a pseudo-first order equation and the constant was in the range (18.38–51.01)×10−2min−1.