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Delamination is one of the most typical failure modes of fiber-reinforced polymer composite laminates. Thus, investigating and improving the delamination behavior of these laminates are of vital importance. The present research discovers and investigates the role of the alkaline treatment of twill-woven flax fabric on the delamination resistance of flax fiber-reinforced epoxy composite laminates. Initially, flax fibers were treated with different sodium hydroxide solution concentrations (2–5–10%) for 2 h. The influence of alkaline treatment on fiber characteristics was evaluated by performing a single-yarn tensile test, scanning electron microscopy, and Fourier transform infrared spectroscopy analysis for treated and untreated flax fibers. The appropriate treatment condition was selected based on the properties obtained from the tests conducted on the fiber level. Subsequently, to discover the role of alkaline treatment on delamination resistance, flax fabric was treated with the selected treatment condition for further composite fabrication. The treated and untreated flax fiber-reinforced epoxy composites were fabricated using a hand lay-up technique followed by hot compression. Interlaminar shear strength, double cantilever beam, and end-notch flexural tests were carried out for treated and untreated composites to determine the effect of alkaline treatment on the delamination resistance. The results proved that the alkaline treatment of flax fabric significantly improved the delamination resistance of treated composite laminates compared to untreated ones. The interlaminar shear strength, the mode I interlaminar fracture toughness (propagation), and mode II interlaminar fracture toughness were improved by 27.3%, 14%, and 24.9%, respectively, for treated composite laminates compared to untreated ones. [ABSTRACT FROM AUTHOR]

In this research, a novel cellulosic fiber from the Cannonball tree was extracted and alkalized. The alkalisation was done for 45 min using a 5% NaOH solution. The cellulose percentage of the alkalized fiber was elevated to 69.23% from 54.96%. The increase in the crystallinity index (72.73% from 65.29%) of alkalized fiber was recognized via XRD analysis. Thermogravimetric analysis established that after alkalization maximal deterioration peak of (362.94 °C from 357.21 °C) and kinetic activation energy (67.5 kJ/mol from 60.33 kJ/mol) are enhanced. Lignin, wax, and impurity-free exterior layers are seen in the FE-SEM images of alkalized fiber. The absence of impurity elements in the EDX spectrum of alkalized CBFs indicated the abolishment of contaminants on the fibre's exterior. After the NaOH treatment, CBF tensile strength (71.5 ± 25 Mpa from 42.2 ± 10.5), and tensile modulus (4.15 ± 1.572 GPa from 2.1 ± 789) were increased. All the above findings concluded that CBFs are potential materials for reinforcement in fiber-reinforced plastics. [ABSTRACT FROM AUTHOR]

The effect of acid treatment on TS-1 zeolite prior to alkaline treatment with TPAOH solution is investigated. 1H MAS NMR, UV–Vis, XPS, XRF, N2-sorption and TEM are applied to characterize the acid and/or alkaline treated TS-1 samples. It is found that acid treatment destructs the Si–O-Ti bonds of the framework, and promotes the conversion of 4-coordinated Ti into 6-coordinated Ti. Then in the subsequent alkaline treatment, part of framework Si–O-Si bonds are hydrolyzed and mesopores are formed. Meanwhile, the dissolved Si and Ti species could be incorporated back into the framework directed by TPAOH. Compared with TS-1-A, which is synthesized without acid treatment, TS-1-HA remains more active center and enhanced accessibility. Therefore, it shows high catalytic performance in cyclohexanone ammoximation reaction. [ABSTRACT FROM AUTHOR]

The flexural and impact response of completely biodegradable natural composites, specifically bamboo and pineapple leaf fiber (PALF) reinforced composites, is investigated using a combination of experimental and simulation techniques. The flexural strength and bending modulus are determined through 3-point bending tests while varying the weight fraction of the selected natural fibers from 5 to 15%. The impact of alkaline treatment at different percentages of 2 to 10% on the same properties such as flexural strength and bending modulus is also investigated. Subsequently, simulation techniques are employed to determine the behavior of the natural composite materials under bending loads. Finite element models are utilized to analyze the normal, and shear stresses in the composite structures. The research findings unveiled that incorporating a 10% weight fraction of bamboo fiber along with an 8% NaOH treatment led to the most significant enhancement in flexural strength, showcasing a notable advancement of 111.02%. Within the PALF fiber reinforced composite, employing 2% NaOH treated PALF fiber at a 15% weight fraction yielded an impressive improvement of 125.6%. [ABSTRACT FROM AUTHOR]

Rice husk being the major agro-waste could serve as the renewable source of silica. This silica could be a replacement for industrial and pharmaceutical applications. Industrial grade silica require purity ranging from 80 to 100% necessitating the elimination of organic and metallic impurities from biomass. This study compares the ability of pre-treatment process in improving the purity of silica. Silica with difference in purity is extracted by employing simple (conventional alkaline treatment—CAT) and rigorous (soaking/acid/alkaline—SAA) pretreatment on husk. The alkali earth metal removal percentage are 41.71%, 81.69%, and 40.37% for Na, K, and Mg respectively by adopting SAA method. In addition, the significance of impurity elimination is reflected in the textural properties where the SAA silica exhibited an 80% increase in BET surface area compared to CAT silica. SAA silica was purely amorphous whereas CAT silica showed crystalline phase in XRD analysis. Ultrasonication effect on size reduction was more pronounced. The binding nature of elements from XPS analysis indicated the presence of silica as silicon oxide and silicon dioxide. The elemental composition of SAA silica revealed drastic decrease in the contents of Fe2O3, K2O, and Al2O3 compared to CAT silica. The difference in silica arises from the soaking process imparting hydrophilic nature to the husk increasing the hydroxyl group on its surface. The interaction between the hydroxyl group and the acid during pre-treatment aided in impurity elimination. This suggests the SAA pretreatment as suitable process for efficient extraction of silica through impurity elimination. [ABSTRACT FROM AUTHOR]

Composite materials increasingly use biofibres because of their lightweight, remarkable strength, stiffness, and biodegradability. Nanofillers are becoming more common in bio-nanocomposite (BNC) applications in industries like aeronautics and marine engineering. Research is underway to determine the effects of nanofiller alumina (Al2O3) and magnesia (MgO) on BNC tensile, bending, and impact properties when coupled with reinforcing surface-treated jute fibres. Vacuum-bagged composite laminates were made by adding Al2O3 and MgO nanofiller (50 nm in diameter) to the epoxy range from 1 to 4% by weight. One set of fibres was treated with a 5% NaOH solution to see the effect of surface treatment and nanofillers on the mechanical properties of the composite. Surface-treated jute-reinforced composite outperformed untreated in tensile, bending, and impact properties. While on the additive inclusion of 3% of nanofiller, the highest properties were achieved, the treated jute-reinforced MgO-filled laminates increased the tensile strength by 60%, flexural strength by 67%, and impact strength by 42% as compared to laminates without nanofillers. SEM images show an array of imperfections, including interfacial performance, fibre breakage, fibre withdrawal, agglomeration, cracks, and voids. Surface treatment and nanofillers were shown to enhance the BNC's mechanical properties. [ABSTRACT FROM AUTHOR]

Natural fibers are environmentally friendly materials incorporated into polymer matrices as reinforcement agents. Several fibers are available in nature, such as cotton, jute, sisal, bamboo, hemp, banana, coir, and flax. However, in some cases, poor compatibility between fiber/polymer is observed, limiting their utilization. To overcome this disadvantage, chemical treatments can be applied to the fibers to alter their chemical composition, surface morphology, and mechanical properties. In comparison with other methods, mercerization is a popular methodology largely used to modify the properties of fibers once is inexpensive and does not require toxic chemicals. The main modifications caused by mercerization regarding chemical composition are the removal of wax, oils, and impurities of the surface of the fibers, besides a decrease in lignin and hemicellulose contents, and an increase in cellulose content. Fiber surface morphology becomes cleaner, and mechanical parameters, such as tensile strength and rigidity, are generally improved. Although these are some common modifications, mercerization process parameters must be well-adjusted to obtain optimized results. Unlike other published articles, this review covers the mercerization parameters adopted for several types of natural fibers to establish a correlation between the main effects of the process on the physical–chemical, morphological, and mechanical properties of the fibers. [ABSTRACT FROM AUTHOR]

The treatment method of natural fiber is one of the factors that influences its properties. There are several reports on sodium hydroxide (NaOH) treatment of many natural fiber. Though there are works on NaOH treatment of the fruits fiber, however, works on Borassus flabellifer Leaf fiber (BFLF) is sparsely reported. Hence no report on the optimum conditions for sodium hydroxide treatment of Borassus Flabellifer Leaf fiber. Therefore, this study aimed at establishing the optimum concentration and time for alkaline treatment on the properties of BFLF. The fiber extraction was carried out using water retting method for 24 h. Experimental design was carried out using Design Expert 12.0 adopting Central composite design in response surface methodology. NaOH concentration of 0–5 wt% and time of 1–12 h were used as the independent variables. The responses were water absorption, elongation (%), modulus of elasticity and tensile strength. The surface morphology of the fiber was studied using scanning electron microscope (SEM) and the functional group changes established using Fourier transform infrared (FTIR) spectroscopy to indicate effect of NaOH treatment (FTIR) spectroscopy to show the functional group changes due to NaOH treatment. The optimum concentration and treatment time was established as 2 wt% NaOH and 4 h, respectively, with corresponding responses of water absorption, tensile strength, modulus of elasticity and elongation (%) were 2.07%, 977.378 MPa, 6971.02 MPa, 5.178%, respectively. Using these optimum treatment conditions of time and NaOH concentration, the responses were validated to be 1.88%, 920.019 MPa, 6943.73 MPa, 4.99 mm having a desirability of 0.963. The SEM revealed rough surfaces and increased porosity for the treated fiber compared to the untreated. The FTIR spectra showed reduction in peaks representing lignin at wavelength of 3321.1 cm−1 to 3306.1 cm−1, which indicated that the NaOH treatment resulted to decrease in lignin in the fiber. The properties of the BFLF obtained at the optimum treatment conditions were within range of other fibers used in composite materials development, hence, BFLF treated at these conditions is suitable for composite development. [ABSTRACT FROM AUTHOR]

In this study, the thermo-chemical pretreatment was used to enhance methane production from rice husk (RH) co-digested with the cow manure (CM) at seven different levels of carbon to nitrogen (C/N) ratio, (75.7:1, 68.5:1, 57.6:1, 46.6:1, 35.7:1, 24.7:1 and 13.8:1). All C/N compositions were found significant in enhancing methane production and stable anaerobic co-digestion. The experimental results disclosed that the C/N of 24.7:1 had proved optimum with methane enhancement capability of 76% as compared with control (C/N 75.7:1). The other compositions also showed the methane enhancement, which ranged from 37 to 67% having C/N of 68.5:1, 35.7:1, 46.6:1, 57.6:1 and 13.8:1 provided 67%, 70%, 42%, 38% and 37% methane enhancement respectively as compared with control. The thermo-chemical alkaline (NaOH) pre-treatment had significantly enhanced the lignocellulosic digestibility and reduced the lignin contents up to 40%. The 7.5% NaOH pre-treatment of RH helps in the reduction of pre-treatment time from several days to one hour. To determine the morphological changes in the structure of RH due to the pre-treatment, the scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were also studied. The role of pretreatment for the rice husk and co-digestion in methane enhancement was the prime focus of the current study. Biochemistry process parameters like total volatile fatty acids, alcohol, pH, chemical oxygen demand and volatile solids removal were monitored to optimize the anaerobic co-digestion process. [ABSTRACT FROM AUTHOR]

A novel hierarchical Cu/ZSM-5 was prepared over alkaline treatment and incipient wet impregnation method for the catalytic ozonation of polyvinyl alcohol (PVA). Under the optimum preparation conditions, hierarchical Cu/ZSM-5 exhibited an excellent mineralization performance during the PVA degradation process, and the removal rate of TOC after 60 min of reaction was 47.86%, much higher than that of ozonation alone (5.40%). Its high catalytic activity could attribute to the large pore volume (0.27 cm3/g) and pore size (6.51 nm) which are beneficial for the distribution of loaded copper and adsorption performance for PVA. Compared to ·OH, 1O2 (2.66 times in 10 min) contributed more to the removal of PVA. The degradation of PVA was a combined process of direct ozone oxidation, catalytic ozonation and adsorption. With its high catalytic performance and stability, hierarchical Cu/ZSM-5 has a very broad application prospect in the process of catalytic ozonation of refractory pollutants. [ABSTRACT FROM AUTHOR]

In this research, carbon powder produced from bagasse, solid waste of sugarcane production, was used as raw material for creating screen-printed carbon electrode (SPCE), which is named SPAC600. Bagasse was carbonized at 600 °C under N2 flows to produce carbon. The carbonized bagasse was then treated with alkaline solution to leach out the impurities; therefore, the result, AC600, provides a significant increase in surface area from 24.8 to 197.10 m2 g−1. Alkaline treatment also changed the morphology of carbon powder into smaller flakes and removed C–H- aromatic vibration and C–O stretching within Fourier transformed- infrared (FTIR) spectra. The treatment also increases the electric conductivity from 10.01 S/cm to 25.39 S/cm. Alkaline leaching also increases the electrochemical performance of the electrode, proven by the significant increase of anodic current density, Ipa from 5.5 to 12.8 μA, for screen-printed carbon without alkaline leaching (SPC600) and SPAC600, respectively. Furthermore, ferrocene addition to the working electrode (WE) part of the prepared SPCE even increases the electrochemical performance as an analytic electrode, proven by the anodic current density of 173.0 μA. Even though the performance is still lower than a commercial SPCE which provides anodic current density up to 2000 μA, further treatment and modification may enhance the performance of the SPAC600. [ABSTRACT FROM AUTHOR]

Although epoxy resins have many advantages, their use needs to be expanded by improving their mechanical properties, including a wide variety of material quality, easy processing, negligible shrinkage due to curing, and good adhesiveness to many forms of fiber materials. The research focuses cost-effective utilization of palmyra fiber treated with 5% alkali solution and different volume percentages of S-glass fiberglass incorporated by epoxy resin developed by hand layup technique. The final epoxy hybrid composite consists of different weight ratios of palmyra/S-glass fiberglass as 25:75, 50:50, and 75:25. Influences of palmyra (treated) fiber dispersion quality on density, voids, mechanical and moisture absorption performance of the epoxy hybrid composite is studied by ASTM rule. The elevated output characteristics performance is compared with untreated fiber composite. Based on the rule of mixture, composite density is varied and Archimedes’ principle measures voids. The alkali treated composite samples showed good tensile stress, flexural and impact strength. While compared to untreated fiber composite, the tensile, flexural, and compressive strength of TPF/GF(25:75) composite was improved by 19.58%, 29%, and 14.3%, respectively. The reduced water absorption behaviour was observed on the treated composites. The effect of fiber dispersion on the mechanical failure of hybrid composite is studied by SEM analysis. [ABSTRACT FROM AUTHOR]

The structural, thermal, morphological, and mechanical properties of ecocomposites based on a High-Impact Polystyrene (HIPS) reinforced with açaí (Euterpe oleracea) fibers were evaluated. They were made using 5 wt% açaí fibers treated using 5% NaOH (FT5) and 7% NaOH (FT7). According to a SEM analysis, the alkaline treatment allowed us to remove of the low-molecular weight compounds. The FT5 ecocomposite had a higher elongation, (2.9 ± 0.5)%, and impact of resistance, (98 ± 2) J/m, probably due to the presence of mechanical anchoring, which improved its mechanical properties. The FT7 ecocomposite had a slightly higher thermal stability, with a total mass loss of 87.78%. [ABSTRACT FROM AUTHOR]

Orange bagasse (OB) is an abundant lignocellulosic residue in Brazil, and few studies have explored this raw material for cellulose and nanocellulose obtainment. The objective of this study was to obtain cellulose-based materials from OB through three one-step alkaline extraction processes using NaOH (chemical (CH), autoclaving (AC), and ultrasonication (US)). The obtained samples were characterized according to their composition, morphology, crystallinity, thermal stability, water and oil absorption capacity, solubility, and swelling capacity. Nanocellulose was also produced and characterized according to its composition, morphology (atomic-force microscopy), and crystallinity. The cellulose content of materials obtained from OB ranged from 33.7 to 85.4%, with a cellulose recovery of 65.3 to 100%. The combination of alkaline and autoclaving treatments was more efficient in obtaining a material with higher cellulose content, higher crystallinity, and thermal stability. Alkaline treatment combined with ultrasonication was less effective in obtaining a material with higher cellulose contents. Crystallinity and surface morphology of samples affected their functional properties. An increase in crystallinity of samples led to a decrease in water and oil holding capacities, swelling in water, and solubility, while an increase in porosity resulted in higher water and oil holding capacities, swelling in water, and solubility. The nanocellulose obtained had 60% crystallinity with a yield of 4.4% (each 100 g of raw OB subjected to the sequential treatments yielded 4.4 g of nanocellulose). Cellulose-based materials obtained in this study can be used as fibers source in food products, as substrates in fermentation processes, and it can also be used to obtain nanocellulose as performed in this study. [ABSTRACT FROM AUTHOR]

Over the last few decades, chemical and physical studies on bowed string musical instruments have provided a better understanding of their wooden finished surface. Nevertheless, until now only a few of them investigated the effects of the chemical pre-treatments in the traditional making procedures. Those treatments are believed to affect wood properties, its interaction with the following treatments (i.e. varnish application) and its vibro-mechanical behaviour (that may contribute to the acoustical properties of musical instruments). In this study, two traditional alkaline treatments were applied to reference samples of spruce wood, the wood commonly used to make violins' soundboards. An integrated analytical strategy, which combines infrared spectroscopy, analytical pyrolysis coupled to gas chromatography-mass spectrometry, and gel permeation chromatography, was employed to investigate the chemical alterations of lignocellulosic polymers (cellulose, hemicellulose, and lignin). Results have shown that the selected alkaline treatments induce the partial hydrolysis of the hemicellulose chains and a slight decrease in the crystallinity of cellulose. We could also prove: (i) the cleavage of lignin-carbohydrate complexes formed by the covalent bonds between hemicellulose and lignin in spruce wood, and (ii) the partial breaking of the hydrogen bonds network in cellulose. According to the literature, the alteration of the lignin-carbohydrate complexes is responsible for changes in wood mechanical behaviour. Hence, future perspectives of this research could outline new knowledge on the vibro-mechanical behaviour of the violin soundboard and the consequent acoustics. [ABSTRACT FROM AUTHOR]

Bone-implant bonding can be achieved by stimulating the apatite formation with the alkaline chemical process applied to the surface of Ti and its alloys. Although the bioactivity can improve the osseointegration feature of the implant, the shortening of the implant life due to the risk of infection during implantation is a problem frequently encountered in biomedical applications and causes the removal of the implant. Therefore, in this study, NaOH pretreatment was performed on Ti plates to create a nano-networked surface that can stimulate apatite formation. It aimed to reduce the risk of infection by loading antibiotics on these surfaces. After alkali treatment, a nano-network structure with 80–150 nm pore sizes with alpha titanium and sodium hydrogen titanate phases was formed. It has been observed that this surface provides apatite formation when kept in simulated body fluid for 3 days. The appearance of an inhibition zone after drug loading proved its antibacterial property. At the same time, the cell viability of the drug-loaded alkaline treated surface was 85%. It was concluded that antibiotic-loaded nano-networked NaOH surfaces could be recommended for dental and orthopedic implants in terms of both cellular behavior and infection risk. [ABSTRACT FROM AUTHOR]

This research work is based on the isolation of cellulosic fibers from Tunisian olive sawdust (TOS) by alkaline treatment using a solution of NaOH at different concentrations: 5% w/v (TOS5) and 20% w/v (TOS20). The valorization of these cellulosic supports was assessed by the adsorption ability of methylene blue (MB), chosen as a model compound of organic dyes. SEM and FTIR analyses have shown that alkaline treatment produces a delignification of TOS and an elimination of hemicellulose. A transformation of cellulose I to cellulose II was shown by XRD following the decrease of the crystallinity indices passing from TOS5 (∼37%) to TOS20 (∼30%). The spectroscopic study confirmed that the intermolecular and intramolecular hydrogen bonds have a primordial role in the forms and the structural stability of the cellulosic substrates. Thereby, the deconvolution of OH stretching vibration band confirmed the transition from cellulose I to cellulose II by the occurrence of a new band at 3,080 cm−1 for TOS20. The increase of iodine adsorption values (ISV) from 40 mg·g−1 for TOS5 to 65mg·g−1 for TOS20 is behind the improvement of the accessibility of cellulosic support with alkaline treatment of TOS. The adsorption of MB onto the surface of cellulosic substrates in aqueous mixtures was studied quantitatively. The corresponding isotherms in basic medium have shown the formation of a monolayer following the Langmuir model characterized by 14 mg·g−1, 52 mg·g−1 and 76 mg·g−1 onto the TOS, TOS5 and TOS20, respectively. The desorption efficiency of MB in acid medium increased with 37%, 57% and 71% for TOS, TOS5 and TOS20, respectively. Hence, the extracted cellulosic fibers are likely to be a promising adsorbent for the removal of organic dye from aqueous solutions. [ABSTRACT FROM AUTHOR]

The influence of alkaline treatment on the thermal and mechanical properties of polypropylene (PP) reinforced with fibers from macadamia nutshell (5 to 30 wt%) was studied. To improve the interaction between fiber and matrix, the fibers were submitted to an alkaline treatment, as well as a coupling agent (MAPP) was used. The composites were obtained in a thermokinetic mixer, milled, and injected. Then, the degradation temperature and the loss of mass of the composites, pure PP, and fibers were evaluated. The mechanical properties of the composites were also evaluated. The results indicated that the degradation peak of composites occurred at higher temperatures, which indicated that composite exhibited higher thermal stability at higher temperatures. The addition of raw and treated macadamia fibers to the PP increased the stiffness of the composites, as well as the use of a coupling agent when compared to the neat PP. However, the incorporation of 30 wt% treated fiber to the PP showed an enhancement of 67.5% in the tensile modulus. The morphological analysis enabled to evaluate the efficiency of the coupling agent and the treated fibers adhered to matrix. The response surface methodology (RSM) technique showed that the higher fiber content added to the PP enhanced the stiffness, and consequently reduced the impact strength of the materials. [ABSTRACT FROM AUTHOR]

The present study demonstrates an effective alkaline protocol for the extraction of quality hemicellulose using NaOH and NH4OH combination from sugarcane bagasse for the production of xylooligosaacharides (XOs). For achieving maximum recovery of hemicellulose, the statistical optimization technique was adapted, while considering alkali concentration and temperature, as important process parameters, for all of the alkaline tested protocols like individual or mixed alkalis. The comparative study exposed that mixed alkalis promoted higher recovery of hemicellulose (68% wt xylose), which is relatively higher (up to 1.3-times) than the individual alkali protocols, such that it contained predominantly the xylose (xyl/ara ratio was 3.94) in the form of xylan. In perception, the synergistic action of different alkalis (weak and strong bases) have strongly influenced the selective cleavage of lignin-carbohydrate linkages, thereby enabling the higher release of hemicellulose under the modest reaction conditions (10% alkali conc. and 120 °C). Moreover, the analytical characterization witnessed that it is composed of majorly xylose with less or no undesired residual biomass constituents, including lignin. Upon evaluating the resultant hemicelluloses for XOs production via acidic hydrolysis, the hemicellulose obtained through the mixed alkalis protocol exhibited exceptional, resulting in ~ 13% wt XOs yield with a high degree of polymerization (2–4 units); it is relatively ~ 2.8-times higher than the result of other hemicelluloses. In addition, the formation of gaseous ammonia during the reaction of the mixed alkalis could potentially contribute to the reduction of overall processing cost through recovery and reuse strategy during the large-scale XOs production. [ABSTRACT FROM AUTHOR]

Lignocellulosic materials (some natural fibers) have relevant mechanical properties when incorporated in polymeric matrices, being a renewable source to replace synthetic fibers; however, for good adhesion and durability, it is necessary to modify the fibrous surface structure in order to eliminate unwanted compounds. This work aims to evaluate different conditions of alkaline treatment of tobacco stalk waste using 10 and 15 wt% sodium hydroxide (NaOH) during an exposure time of 3 or 5 h. Thermal, chemical, and morphological characterizations as well as kinetic analysis were performed. Through Fourier transform infrared spectroscopy, it was possible to identify the partial removal of compounds such as lignin, hemicellulose, and extractives, increasing the thermal stability, which was proven by thermogravimetric analysis. Furthermore, X-ray diffraction shows a higher crystallinity index from cellulose after the alkaline treatment. Through the kinetic analysis, it is possible to observe that both methods presented similar activation energy values (Ea). In addition, after the alkaline treatment there was a reduction in Ea, the most evident result being observed in the TSW\10\5 sample, which presented an average value of Ea of 223.95 ± 15.79 kJ/mol by the Flynn–Wall–Ozawa method and 218.74 ± 24.69 kJ/mol by the Friedman method. Scanning electron microscopy showed the exposure of the microfibrils and an enhancement of roughness after alkaline treatment. Tobacco stalk wastes has potential application as reinforcing filler in composite materials since surface alkaline modification provides higher fiber/matrix adhesion through the removal of amorphous compounds. [ABSTRACT FROM AUTHOR]

Anaerobic digestion is a sustainable approach to deal with wastes with beneficial production of sustainable energy. In the anaerobic digestion processes, an increase in ammonia concentration hinders the efficacy of biogas production. The current study focused on minimizing the ammonia effect by the addition of zeolite as an adsorbent in a fluidized bed anaerobic reactor using poultry slaughterhouse waste as the substrate. The effects of zeolite dosage were investigated at mesophilic and thermophilic temperatures. Biomethane potential, volatile solids reduction, chemical oxygen demand, total volatile fatty acids concentration, ammonia–nitrogen levels, and pH were monitored. The initial biomethane potential test revealed that poultry slaughterhouse waste produces methane for up to 610 ml/g volatile solids (intestinal residues) and 200 ml/g volatile solids (feathers) at mesophilic conditions, 675 ml/g volatile solids (intestinal residues) and 276 ml/g volatile solids (feathers) at thermophilic conditions. The amendment with zeolite had significantly reduced chemical oxygen demand for up to 57%. Volatile solids reduction increased from 13 to 19%. Ammonia–nitrogen concentrations also decreased (15.5 mg/l) due to the application of zeolite. Enhanced biogas production of 700 ml/g volatile solids was observed after 25 days. It can be concluded that the addition of zeolite can significantly enhance biogas production by reducing the ammonia concentration in anaerobic digesters. [ABSTRACT FROM AUTHOR]

Treatment and disposal of sewage sludge is still a worldwide challenging problem. Improper sludge treatment results in severe environmental impact and endangering public health. Moreover, sewage sludge disposal is a cost-intensive process. Therefore, pathogen removal and solid reduction are indispensable for sludge disposal management. In this study, a novel electrochemical method in alkaline media was developed to break down the sludge structure at room temperature. A reduction of 24.85% in total solids and 46.42% in volatile solids was achieved, which represents approximately a 25% reduction in the sludge disposal cost when compared to conventional treatment methods. Also, a 90% reduction in energy consumption was demonstrated when compared to other electrochemical methods. The post-processed samples characterization showed that a large quantity of organic material was released from the sludge samples into the liquid phase, which indicates the potential to reduce the residence time in anaerobic digesters and to generate more biogas. The proposed treatment demonstrated the feasibility of pathogen removal and biosolid production for safe landfilling or agriculture applications such as fertilizers. [ABSTRACT FROM AUTHOR]

The kinetics are studied of topochemical reactions of the formation of calcium hydrosilicate in a multicomponent aqueous system consisting of waste products of boric acid production. The waste products include silicon dioxide and calcium sulfate in equal molar fractions, an alkali metal hydroxide in a stoichiometric ratio to the molar content of calcium sulfate and silicon oxide for obtaining hydrosilicate calcium, and the volume of water calculated to obtain a solution of alkali metal sulfate with a concentration below saturation. Data are obtained on the kinetics of the formation of calcium hydrosilicates in different modes of processing (normal conditions with constant stirring; ultrasonic action at a temperature of 20°C; microwave exposure with constant stirring at a temperature of 95°C; and autoclaving at a temperature of 220°C). It is found that the fastest reaction rate is characteristic of microwave treatment, and the largest proportion of reacted alkali metal hydroxide is obtained during autoclave treatment. [ABSTRACT FROM AUTHOR]

In recent years, silicon-organic hybrid solar cells have attracted tremendous research attention owing to their low production cost and high performance. In the present work, tapered silicon nanowires (TSiNWs) were synthesized on random micro-pyramids (RM pyramids). On this binary structure, a poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) polymer was spin-coated. The tapering of SiNWs was performed by immersing the samples in NaOH solution. It was found that the tapering time affects significantly the reflectivity, the minority carriers lifetime and the coverage rate of Si surface by the PEDOT:PSS film. Indeed, an optimal tapering time of 6 s was determined. This time was sufficient to good incident light trapping and to reduce the surface defects. This simple and low-cost surface structuring technique holds high potential for improving the performance of hybrid solar cells with large junction area. [ABSTRACT FROM AUTHOR]

Chronic kidney disease is prevalent, affecting more than one in ten adults. In this population, metabolic acidosis is considered a key underlying pathophysiological feature, tying together bone mineral disorders, sarcopenia, insulin resistance, vascular calcification, pro-inflammatory and pro-thrombotic states. This review aims to address the paucity of literature on alkalinizing agents, a promising treatment option that has known adverse effects. [ABSTRACT FROM AUTHOR]

Wet-spun fibers were prepared from plant-based cellulose nanofibers (CNFs) via a novel approach proposed in a previous report. This method is based on the use of a simple NaOH treatment and the minimization of the use of harmful reagents. The CNF gels prepared using an 8% NaOH solution exhibited good preservation of the cellulose I crystal structure, contributing to the high tensile properties of the spun fibers. This study further explored this approach, and a CNF suspension with 8% NaOH was spun into a 2% sulfuric acid coagulation bath at different spinning rates (1–100 m/min). Straight long fibers with a circular cross-section were obtained at all spinning rates. The orientation index of the CNFs and the tensile properties of the CNF spun fibers increased slightly with increasing spinning rate. However, these values were lower than the values expected based on the previous reports. The aggregation of CNFs in the NaOH solution likely affected these properties. Nevertheless, the advantages of this method, namely the lack of use of toxic solvents and the minimal use of organic solvents, were demonstrated. Furthermore, a high wet strength can be expected due to the formation of interdigitated linkages between the CNFs. These CNF filaments are promising for applications in smart textiles, biosensors, and structural reinforcement. [ABSTRACT FROM AUTHOR]

The feasibility of converting biomass into bio-oil and the effect of an alkaline treatment during biomass liquefaction was studied. Sweet sorghum bagasse (SSB) was treated with NaOH concentrations of 0.5, 1.0, 3.0 and 6.0 M. The experiments were conducted in a temperature range of 260–320 °C in N2. The results showed that the alkaline treatment affected the product distribution of SSB liquefaction. The highest yield of bio-oil (53.2 wt%) and phenols extracted (≈ 40.0 wt%) were obtained at 320 °C and NaOH aqueous solution of 3.0 M. The ATR-FTIR results indicated the presence of carboxyl, ketone, ester and aromatic ring structures in the bio-oils. The absorption intensities of all the bio-oils at 1100 cm−1 (primary alcohols) substantially decreased with an increase in temperature and NaOH concentration. At given reaction temperature, the use of 3.0 and 6.0 M NaOH resulted in the extraction of more identifiable phenol derivatives than were obtained with the lower concentrations of NaOH. These results suggest that a temperature of 320 °C and a NaOH concentration of 3.0 M yields the best results among the temperatures and concentrations tested, and also that alkaline treatment is feasible for liquefaction and extraction of phenols from the bio-oil. [ABSTRACT FROM AUTHOR]

Alkaline treated ZSM-5 zeolite was used in heavy oil upgrading process under atmospheric oxygen flow. Alkaline treatment was employed to induce mesopores in ZSM-5 catalyst structure to alleviate the mass transfer and reduce diffusion limitations. XRD, BET and XRF analyses were employed to investigate the effect of alkaline treatment. Effect of oxygen atmospheric flow, supplied by air stream, on heavy oil catalytic cracking process was investigated in a fixed bed reactor. Obtained liquids were analyzed by FTIR and GC/SIMDIS. Results revealed that percent of light oil (naphtha + kerosene) produced was nearly doubled in the presence of 5 wt% oxygen in the feed. Conversion of heavy oil (content with the BPT higher than 370 °C) was enhanced from 45.7% up to 58.1% by applying air stream. Viscosity reduction was elevated from 40% in nitrogen atmosphere to 53% in presence of 5 wt% oxygen content. Spent catalysts were characterized by TGA, XRD and BET analyses in order to determine coke deposition and catalyst structural stability. Oxidative cracking increased the amount of coke production over the catalyst, however, structural stability of the catalyst was not altered compared to conventional cracking process and crystalline structure of the catalyst was preserved after 5 h time on stream. [ABSTRACT FROM AUTHOR]

This work aims to evaluate the alkaline treatment using NaOH of the agroindustrial residues of grape stalks (GS) and yerba mate (YM) in order to improve their adhesion in applications in the area of polymer composites. The samples were evaluated according to the chemical analysis, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and kinetic study. It was observed that after the alkaline treatment, there was a change in the morphology of the samples due to the partial removal of lignin and hemicellulose, which is consistent with the chemical analysis and FTIR. The activation energy (Ea) found was of 252.79 ± 21.07 kJ mol−1, 218.99 ± 3.28 kJ mol−1, 236.05 ± 9.50 kJ mol−1 and 216.25 ± 14.87 kJ mol−1 for GS, GSNaOH, YM and YMNaOH samples, respectively, confirming the fibers that present a larger amount of lignin require higher activation energy for the degradation. Thus, this material has the potential to be used as a reinforcing filler in composite materials because of the modifications caused by the alkaline treatment, which improves the matrix/fiber interface. [ABSTRACT FROM AUTHOR]

In this paper, the effect of some parameters of a two-step surface-modification process, consisting of alkaline treatment followed by chitosan/bioactive glass nanocomposite coating, on the surface morphology of Ti–6Al–4V alloy is investigated. According to the results, the heat treatment of the alkaline-treated sample is critical to obtain a crack-free structure. It was also found that the deposition of three composite layers with the immersion time of 3 min for each layer is optimal to develop a desirable distribution of the composite nanoparticles on the surface. In other words, a coordinated optimization approach of composite-coating variables is required to control the morphology of the deposits. [ABSTRACT FROM AUTHOR]

Inferior mechanical properties are hindering the growth of using natural fibre reinforced polymeric composites in many structural applications. One of the popular solutions to this issue being reported in the literature is the addition of nano or micro reinforcements such as carbon nanotubes, ceramic particles, glass particles, clay, rubber additive etc., which is expensive. Furthermore, questions are raised over biodegradability of said composites. The current study investigated the effect of micro-crystalline cellulose (MCC) particles and alkaline treatment on the tensile, bending and impact properties of jute woven fabric reinforced bio-epoxy composite. The composite samples were made by compression moulding using manufacturer provided curing conditions. Alkaline treatment of jute fabric was found to have positive relationships with tensile and flexural properties, whereas it had negative with the impact strength of bio-composite. It is found that up to 7% addition of MCC particles, tensile, bending and charpy impact strength were improved by 48%, 52% and 100% respectively. Beyond this percentage, the mechanical properties were found to be deteriorated. [ABSTRACT FROM AUTHOR]

The hierarchical HZSM-5 was prepared via dealumination and desilication of commercial Al-rich HZSM-5, and characterized by X-ray diffraction, 27Al magic-angle spinning nuclear magnetic resonance, inductively coupled plasma mass spectrometry, scanning electron microscope, transmission electron microscope, N2 adsorption-desorption, NH3 temperature-programmed desorption, performed thermogravimetric and Raman spectrum. The results showed that partial framework of HZSM-5 was removed after steam treatment at 0.15 MPa, 500°C for 3 h. HZSM-5 with high specific surface area and much mesoporosity was obtained by the subsequent alkaline treatment. The regulation of acid quantity was achieved by altering the concentration of alkaline. Dealumination and desilication of Al-rich HZSM-5 zeolites became more effective using a combination of steam and alkaline treatments than using alkaline treatment alone. Methanol aromatization reaction was employed to evaluate the catalytic performance of treated HZSM-5 at 0.15 MPa, 450°C and MHSV of 1.5 h–1. The results indicated that after steam treatment, HZSM-5 further treated with 0.2 mol/L NaOH exhibits the best catalytic performance: the selectivity of aromatics reached 42.1% and the lifetime of catalyst attained 212 h, which are much better than untreated HZSM-5. [ABSTRACT FROM AUTHOR]

The aim for this work is to investigate the effect of alkaline treatment on the mechanical, physical and thermal properties of roselle (RF)/sugar palm fiber (SPF) reinforced thermoplastic polyurethane hybrid composites. RF/SPF hybrid composites were fabricated at different NaOH concentrations (3%, 6% and 9%) by melt mixing and compression molding. The mechanical, physical and thermal properties of RF/SPF hybrid composites were measured. The morphological properties of the tensile fractured sample were examined using scanning electron microscope. Obtained results indicated that the effect of NaOH treatment on the surface improved mechanical, physical and thermal properties accompanied by lower impact resistance. The highest tensile is 14.26 MPa, flexural strength is 14.05 MPa and impact strength is 23.76 kJ/M2) was obtained from treatment 6% NaOH concentration on RF/SPF hybrid composites. Adhesion bonding between fiber and matrix was evident by using Scanning electron microscopy (SEM) micrograph of hybrid composite tensile fractured. Scanning electron micrograph of tensile fractured surfaces of the NaOH treated RF/SPF hybrid composites revealed good adhesion bonding between fiber and matrix. Fourier transform infrared spectroscopy analysis was used to observe the effectiveness of NaOH treatment in the removal impurities on fiber surfaces. Thermogravimetric analysis showed that the treated RF/SPF hybrid composites had improved the thermal stability. Physical properties showed lower water uptake of the treated thermoplastic polyurethane hybrid composites. The lowest water uptake is 7.97% and thickness swelling is 6.49% obtained from 9% NaOH concentration after soaked in water for 7 days. Overall, the surface treatment on RF/SPF hybrid composite has enhanced the composite properties and suitable for automotive part application; battery holder and bottom based. [ABSTRACT FROM AUTHOR]

Abstract: IM-5 series zeolites (I-xat-0.05TPABr) were prepared by treating the pristine IM-5 zeolites in a mixed solution of NaOH and TPABr (tetrapropylammonium bromide) with different NaOH concentrations (CNaOH). It was found the porosity and acidity of modified IM-5 zeolite changed obviously with CNaOH. When used for alkylation of benzene with ethanol, the modified I-xat-0.05TPABr exhibited better reaction stability than the unmodified IM-5 zeolite, and I-0.5at-0.05TPABr showed the best stability. Typically, the reaction stabilities of I-xat-0.05TPABr catalysts were directly related to the hierarchical factor, besides the carbon deposition rate.Graphical Abstract: [ABSTRACT FROM AUTHOR]

The influence of ZSM-5 (SiO2/Al2O3 = 50) treatment with a tetrabutylamine hydroxide (TBAOH)/NaOH mixture having different mole ratios on its physicochemical properties and catalytic performance in the reaction of methanol to gasoline (MTG) was investigated. It was found that, with increasing ratio TBA+/OH-, the crystallinities, micropore surface areas, micropore volumes, the amounts of strong acid sites and Brönsted acid sites gradually increased, and the mesopore volumes decreased. The treatment with pure TBAOH (TBA+/OH- = 1.0) ensured the formation of narrow and uniform intracrystalline mesoporosity and the large amounts of strong or Brönsted acid sites on the zeolite, which contribute to the highest liquid hydrocarbon yield in the reaction of MTG. [ABSTRACT FROM AUTHOR]

The influence of ZSM-5 (SiO2/Al2O3 = 50) treatment with a tetrabutylamine hydroxide (TBAOH)/NaOH mixture having different mole ratios on its physicochemical properties and catalytic performance in the reaction of methanol to gasoline (MTG) was investigated. It was found that, with increasing ratio TBA+/OH-, the crystallinities, micropore surface areas, micropore volumes, the amounts of strong acid sites and Brönsted acid sites gradually increased, and the mesopore volumes decreased. The treatment with pure TBAOH (TBA+/OH- = 1.0) ensured the formation of narrow and uniform intracrystalline mesoporosity and the large amounts of strong or Brönsted acid sites on the zeolite, which contribute to the highest liquid hydrocarbon yield in the reaction of MTG. [ABSTRACT FROM AUTHOR]

The effect of alkaline treatment of coir on polypropylene/coir composite properties was investigated, using a two-factor central composite design where NaOH concentration and reaction time were varied. Alkaline treatment favored delignification, and at certain conditions, increased composite stiffness without loss in tensile strength. Increase in cellulose concentration likely increases the number of free hydroxyls, which is less favorable to composite mechanical properties. Treatments with 2 and 9% NaOH for 5 h resulted in cellulose concentration of about 50 and 70%, respectively. Treatments with high concentrations and for long periods are disadvantageous to composite properties, resulting in lower tensile strength likely due to the increased number of free hydroxyls as well as to possible breaks in cellulose structure. A desirability function, used to optimize the delignification process, revealed the highest tensile modulus and strength (3.5 GPa and 31 MPa, respectively) could be obtained at 5.75% NaOH and reaction time of 3 h. [ABSTRACT FROM AUTHOR]

Zeolite synthesis has been achieved by alkaline treatment of a local clay, pyrophyllite. The chemical, textural and structural characteristics of the modified clay were evaluated and compared to those of the raw clay. The samples were characterized by X-ray fluorescence, nitrogen adsorption-desorption studies, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and thermoanalysis (TG-DSC). The pyrophyllite was converted to porous hydroxysodalite (HS), nearly pure, which has a surface area of 19.56 m2 g-1 with a spherical structure and cubic system. [ABSTRACT FROM AUTHOR]

In this paper, using a method of wide-angle X-ray diffraction, sizes of cellulose nanoscale crystallites were determined and phase transition of nanosized crystallites CI into CII was studied after treatment of cellulose samples with solutions of sodium hydroxide with various concentrations, 5 to 20% (1.3 to 6.1 M). It was found that the phase transition proceeds in a certain interval of hydroxide concentrations; moreover, a correlation between average concentration (C) of hydroxide and average lateral sizes (D) of nanocrystallites was observed. Methods of chemical thermodynamics of nanophases allowed to derive an equation, which describes the relationship between C and D: lnC = lnCo–KD–1, where Co is maximum concentration of hydroxide, which is required for the phase transition of large crystals of CI. Thus, the decrease in hydroxide concentration at the phase transition CI into CII, is explained by decreasing of lateral size of CI nanocrystallites. By means of the derived equation, minimum, average and maximum lateral sizes of CI nanocrystallites were determined, as well as polydispersity in lateral sizes of crystallites was studied. It has been shown that crystallites of organo-solvent celluloses were the most uniform, whereas aggregated crystallites of Kraft celluloses were the most heterogeneous. [ABSTRACT FROM AUTHOR]

Virgin activated carbon (VAC) was chemically activated by hydrochloric acid and aqueous ammonia to obtain different surface functionalities and nanopore distributions. The N-tailored AC (NAC) acquired by alkali treatment significantly enhanced the cadmium sorption capacity, while the Cl-tailored AC obtained by acidic modification decreased the sorption capacity compared with that of VAC. With increasing ammonia concentration in the basic treatment, the NAC surface area was increased with declining pore volume and diameter, which increased the adsorption capacity for Cd(II) removal. However, increasing HCl concentration in the acidic modification decreased the surface area, with increasing pore volume and diameter, which decreased the cadmium adsorption capacity. The basic treatment created more alkaline-rich sites such as nitrogen-containing functional groups, on the carbon surface, thereby improving cadmium removal efficiency. However, the acidic treatment generated a stronger acidic chemical structure and much more the formation of the acyl- and alkyl chloride groups that greatly inhibited the Cd(II) sorption capacity. [ABSTRACT FROM AUTHOR]

A novel alkaline-treated multi-component biosorbent composed of pine, oak, hornbeam and fir sawdust biomasses was evaluated to eliminate a common hazardous dye [malachite green (MG)] from aqueous solution in this study. Batch biosorption studies were carried out using this base-modified biosorbent under varying biosorption conditions of: pH, MG concentration, modified biosorbent loading and reaction time. The experimental results showed that this easy modification application (using 0.3-M sodium hydroxide) was able to enhance the biosorption potential of natural biosorbent from 35.230 to 78.926 mg g under the same study conditions. The obtained equilibrium data were modelled using Freundlich, Langmuir, Sips and Dubinin-Radushkevich isotherm models. Also, the biosorption kinetics were analyzed using the pseudo-first-order, pseudo-second-order, logistic and intra-particle diffusion models. It was found that the biosorption data of the isotherm and kinetics were best represented using Sips and logistic models. Hereby, this modified biosorbent can be used for bioremediation of contaminated areas with such deleterious dyes. [ABSTRACT FROM AUTHOR]

Hierarchical ZSM-5 has been synthesized and treated with alkali (NaCO) solutions. The catalysts are characterized with many techniques and studied in the hydration of cyclohexene. The characterization results show that with increasing the concentrations of alkaline solutions, the crystallinities increase and then decrease; the sever treatment leads to the destroy of the zeolite crystals; the external surfaces and mesopore volumes increase; the amounts of weak and strong acid sites, as well as the Brønsted acid sites increase and then decrease, while the amounts of Lewis acid sites increase. In the hydration of cyclohexene, both the conversions of cyclohexene and the selectivity of cyclohexanol first increase and then decrease. The best performance is obtained over ZSM-5 treated with 0.5 M NaCO solution with 13.0 % cyclohexene conversion and 99.3 % selectivity of cyclohexanol. [ABSTRACT FROM AUTHOR]

A pilot-scale side-stream reactor process with single-stage sludge alkaline treatment was employed to systematically investigate characteristics of excess sludge hydrolysis and acidification with alkaline treatment and evaluate feasibility of recovering a carbon source (C-source) from excess sludge to enhance nutrient removal at ambient temperature. The resulting C-source and volatile fatty acid specific yields reached 349.19 mg chemical oxygen demand (COD)/g volatile suspended solids (VSS) d and 121.3 mg COD/g VSS d, respectively, the process had excellent C-source recovery potential. The propionic-to-acetic acid ratio of the recovered C-source was 3.0 times that in the influent, which beneficially enhanced biological phosphorus removal. Large populations and varieties of hydrolytic acid producing bacteria cooperated with alkaline treatment to accelerate sludge hydrolysis and acidification. Physicochemical characteristics indicated that recovered C-source was derived primarily from extracellular polymeric substances hydrolysis rather than from cells disruption during alkaline treatment. This study showed that excess sludge as carbon source was successfully recycled by alkaline treatment in the process. [ABSTRACT FROM AUTHOR]

The drying process in typical pulp production generates strong hydrogen bonding between cellulose microfibrils in refined cell walls and increases the difficulty in obtaining uniform cellulose nanofibers. To investigate the efficacy of alkaline treatment for cellulose nanofibrillation, this study applied a bead-milling method in NaOH solutions for the nanofibrillation of dried pulps. NaOH treatments loosened the hydrogen bonding between cellulose microfibrils in dried pulps and allowed preparation of cellulose nanofibers in 8 % NaOH with a width of approximately 12-20 nm and a cellulose I crystal form. Both the nanofiber suspensions prepared in 8 and 16 % (w/w) NaOH were formed into hydrogels by neutralization because of surface entanglement and/or interdigitation between the nanofibers. When the dried pulp was fibrillated in 16 % (w/w) NaOH, the sample after neutralization had a uniquely integrated continuous network. These results can be applied to the preparation of high-strength films and fibers with cellulose I crystal forms without prior dissolution of pulps. [ABSTRACT FROM AUTHOR]

The effect of alkaline treatment on the properties of low-density polyethylene/natural rubber/water hyacinth fiber (LDPE/NR/WHF) composites was studied. LDPE/NR/WHF and LDPE/NR/WHF composites were prepared using a Brabender Plasticorder. The LDPE/NR/WHF composites showed higher tensile strength, Young's modulus, and melting temperature ( T) but lower molar sorption and interparticle spacing ( d) than did the LDPE/NR/WHF composites. Fourier transform infrared spectroscopy (FTIR) results confirmed that alkaline treatment removed hemicellulose and lignin in WHF, as evidenced by the disappearance of the absorption bands at 1732.79 and 1250.91 cm. The LDPE/NR/WHF composites demonstrated less thermal stability and rougher surface after alkaline treatment. [ABSTRACT FROM AUTHOR]

Four types of kenaf bast fibers were prepared via a combination of Wise treatments, for delignification, and alkaline treatments, for the removal of hemicellulose. Each type of kenaf bast fiber with different refining processes were nano fibrillated by grinding. Resulting, cellulose nanofiber (CNF) sheet was obtained from CNF by vacuum filtration (Scheme 1). The structures and properties of these CNF sheets then were investigated to determine how the CNF components had affected these properties. All of the CNFs from different refining processes were classified as a cellulose I type by X-ray diffraction. However, the mechanical properties (Young's modulus, tensile strength and toughness) of the CNF sheet with Wise treatment were higher than the properties of the other three CNF sheets. These results strongly suggested that alkaline treatment was unnecessary for the removal of hemicellulose, and that the application of the Wise treatment effectively imparted high mechanical properties to the cellulose microfiber.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The effects of alkaline treatment on the physical properties of ZSM-5 catalysts and on their activities for methanol to aromatics conversion have been investigated. A mild alkaline treatment (0.2 and 0.3 mol/L NaOH) created mesopores in the parent zeolite with no obvious effect on acidity. The presence of mesopores gives the catalyst a longer lifetime and higher selectivity for aromatics. Treatment with 0.4 mol/L NaOH decreased the number of Brønsted acid sites due to dealumination and desilication, which resulted in a lower deactivation rate. In addition, more mesopores were produced than with the mild alkaline treatment. As a result, the lifetime of the sample treated with 0.4 mol/L NaOH was almost five times that of the parent ZSM-5. Treatment with a higher alkaline concentration (0.5 mol/L) greatly reduced the number of Brønsted acid sites and the number of micropores resulting in incomplete methanol conversion. When the alkaline-treated catalysts were washed with acid, some of the porosity was restored and a slight increase in selectivity for aromatics was obtained. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Hierarchical ZSM-11 zeolites (Z- xat) were prepared by treating the pristine ZSM-11 zeolite in a solution of NaOH with different concentrations ( C). It was found the porosity and acidity (concentration, strength, distribution and accessibility factor of Brønsted and Lewis acid sites) of modified ZSM-11 zeolite changed obviously with C. When used for alkylation of benzene with dimethyl ether, the modified Z- xat exhibited better reaction stability than the unmodified HZSM-11 zeolite. Typically, the reaction stability of Z- xat zeolite catalysts was directly related to the mesopore volume, besides the weak-medium acid concentrations determined by Py-IR technique. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

This study focused on investigating the feasibility of purifying polyhydroxybutyrate (PHB) from mixed culture biomass by alkaline-based chemical treatment. The PHB-containing biomass was enriched on acetate under non-sterile conditions. Alkaline treatment (0.2 M NaOH) together with surfactant SDS (0.2 w/v% SDS) could reach 99% purity, with more than 90% recovery. The lost PHB could be mostly attributed to PHB hydrolysis during the alkaline treatment. PHB hydrolysis could be moderated by increasing the crystallinity of the PHB granules, for example, by biomass pretreatment (e.g. freezing or lyophilization) or by effective cell lysis (e.g. adjusting alkali concentration). The suitability of the purified PHB by alkaline treatment for polymer applications was evaluated by molecular weight and thermal stability. A solvent based purification method was also performed for comparison purposes. As result, PHB produced by mixed enriched cultures was found suitable for thermoplastic applications when purified by the solvent method. While the alkaline method resulted in purity, recovery yield and molecular weight comparable to values reported in literature for PHB produced by pure cultures, it was found unsuitable for thermoplastic applications. Given the potential low cost and favorable environmental impact of this method, it is expected that PHB purified by alkaline method may be suitable for other non-thermal polymer applications, and as a platform chemical. [ABSTRACT FROM AUTHOR]

Hypnea musciformis (Wulfen in Jacqu.) J. V. Lamour. (Rhodophyta) was investigated for its carrageenan production. Traditionally, the desulfation process for carrageenans has been promoted by an alkaline treatment of up to 3 h by conventional heating during carrageenan extraction. New extraction techniques based on microwave irradiation may accelerate this reaction with the advantages of reduced consumption of solvents, energy, and extraction time, suggesting the feasibility of this method as a 'Green' technology. In this study, aqueous- and alkali-treated carrageenans from H. musciformis collected along Quintana Roo coast of Yucatan Peninsula (Mexico) were extracted by conventional method and by microwave-assisted extraction (MAE). Microwave irradiation in closed vessels was used to carry out the alkaline modification. The influence of temperature (85, 95, and 105 °C) and extraction time (10 and 20 min) in MAE was investigated in terms of yield, sulfate, and 3,6-anhydrogalactose contents, and Fourier transformed infrared spectra. Although lower carrageenan yields were obtained during MAE extraction, the κappa/iota hybrid carrageenan obtained by this novel method is comparable to that extracted by conventional technique. At the maximum temperature used for MAE (105 °C), an increase of 3,6-anhydrogalactose as well as an increase of the κappa-proportion was observed indicating that MAE could be an adequate procedure for carrageenan extraction of H. musciformis; however, further extraction parameters should be tested to optimize extraction. [ABSTRACT FROM AUTHOR]