Thanyalak Chaisuwan

Release of monomeric sugars from Miscanthus sinensis by microwave-assisted ammonia and phosphoric acid treatments.

Microwave-assisted ammonium hydroxide (NH4OH) followed by phosphoric acid (H3PO4) treatments were used to release monomeric sugars from Miscanthus sinensis grown in Cha-Chueng-Sao province, Thailand. Treatment with 1.0% (w/v) NH4OH, 15:1 liquid-to-solid ratio (LSR) at 120 °C temperature for 15 min liberated 2.9 g of monomeric sugars per 100 g of dried biomass, whereas the corresponding yield for a treatment with 1.78% v/v H3PO4, 15:1 LSR at 140 °C for 30 min was 62.3 g/100 g. The two-stage pretreatment, treatment with NH4OH at 120 °C temperature for 15 min followed by treatment with H3PO4 at 140 °C for 30 min, impressively provided the highest total monomeric sugar yield of 71.6 g/100 g dried biomass.

Efficient process for ethanol production from Thai Mission grass (Pennisetum polystachion).

Mission grass (Pennisetum polystachion) obtained from Tak Province, Thailand, possesses the potential to become a lignocellulosic biomass for bioethanol production. After the grass underwent milling and alkaline pretreatments, it was subjected to acid and enzymatic hydrolysis. The glucose hydrolyzate from the grass was detoxified to remove inhibitory compounds and degradation products such as furfural and 5-hydroxymethylfurfural. Overliming at pH 10 produced the highest ethanol yield. Among various strains of bakers yeasts, Saccharomyces cerevisiae TISTR 5596 with a yeast concentration of 10% v/v produced the maximum ethanol yield at 16 g/L within 24h, which is among one of the fastest ethanol producing microorganisms compared to other strains of S. cerevisiae as well as other ethanol-producing microorganisms.

Advanced and economical ambient drying method for controlled mesopore polybenzoxazine-based carbon xerogels: Effects of non-ionic and cationic surfactant on porous structure

Polybenzoxazine has been successfully synthesized by a facile quasi-solventless method and used as a precursor for producing carbon xerogels via an ambient drying method, rather than usually used CO2 critical or freeze drying. In this work, we aim to study the effect of non-ionic (Synperonic NP30) and cationic (CTAB) surfactants on porous structure of polybenzoxazine-based carbon xerogels. Of particular interest is the formation of inter-connected structure of mesoporous carbon xerogels with mesopore diameters in the range of 15-36 nm by using different concentrations of the cationic surfactant. In addition, carbon xerogel nanospheres with the size of 50-200 nm are also obtained through the emulsion process. The mesopore diameters start to decrease when the carbon xerogel nanospheres are formed at the cationic surfactant concentration of equal to or exceeding 0.030 M. By using the non-ionic surfactant, the properties of the obtained carbon xerogels are shifted from mesoporous materials for the reference carbon xerogel (no surfactant added) to microporous materials at higher concentrations of the non-ionic surfactant (0.009-0.180 M). The carbon xerogel microspheres with the diameter size of about 2.5 μm are also obtained through the emulsion process when the concentration of the non-ionic surfactant is at 0.180 M.

Capability of Thai Mission grass (Pennisetum polystachyon) as a new weedy lignocellulosic feedstock for production of monomeric sugar

Mission grass (Pennisetum polystachyon) grown in Pakchong District, Nakornratchasima Province, Thailand, with high cellulose and hemicellulose contents were harvested to determine the fermentable monomeric sugars for bioethanol production by two-stage microwave/chemical pretreatment process. Microwave-assisted NaOH pretreatment effectively removed approximately 85% lignin content in Mission grass, using 3% (w/v) NaOH, 15:1 liquid-to-solid ratio (LSR) at 120 °C temperatures for 10 min. As a result, in the second stage, microwave-assisted H2SO4 pretreatment of an alkaline-pretreated Mission grass solid releasedan impressively high fermentable sugar content (34.3±1.3 g per 100 g of dried biomass), consisting mainly of 31.1±0.8 g of glucose per 100 g of dried biomass, using 1% (w/v) H2SO4, 15:1 LSR at 200 °C temperature for a very short pretreatment time (5 min). The total monomeric sugar yield obtained via two-stage microwave/chemical process was 40.9 g per 100 g of dried biomass.

Synthesis and characterization of M-MCM-48 (M = Cr, Ce) from silatrane via sol–gel process

Chromium and cerium incorporated into MCM-48 framework are hydrothermally synthesized via sol–gel process without any additives and characterized by X-ray diffraction, N2 adsorption/desorption, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Diffuse reflectance UV–vis spectroscopy, and Thermogravimetric analysis. Results indicate that the materials possess a long-range ordered structure, high specific surface area, and narrow pore size distribution. SEM images illustrate the edge-truncated octahedron morphology of Cr-MCM-48 while Ce-MCM-48 preserves the truncated octahedron of the MCM-48 parent material. TEM images show the pore network of Ia3d symmetry after loading metals. Spectroscopic data confirm the existence of metals in the framework and extra-framework. At low Cr content, Cr-MCM-48 contains only Cr(VI) species while rich Cr content loading results in both the Cr(VI) and Cr(III) species. The hydrothermal stability of MCM-48 is enhanced by carefully incorporating metals into the parent material.

Porous Materials from Polybenzoxazine

Publisher Summary This chapter introduces the preparation of porous polybenzoxazine and porous carbon derived from polybenzoxazine. By taking advantage of the molecular design flexibility of polybenzoxazine and using the appropriate preparation methods, porous materials with various pore dimensions and pore structures are synthesized. Because of the simplicity and versatility, porous carbon materials derived from polybenzoxazine have a great potential in various advanced applications. Porous materials, especially porous carbon, have been extensively studied over the past decade and have been used in various applications, such as water purification, gas separation, catalyst supports, electrode material for energy storage devices, adsorbents, molecular sieves, thermal insulation, etc. According to the International Union of Pure and Applied Chemistry (IUPAC) definition, porous materials can be classified into three categories based on their pore sizes: microporous, mesoporous, and macroporous. Porous carbon materials have been conventionally prepared by pyrolysis and physical or chemical activation of organic precursors, such as coals, woods, polymers, etc. at elevated temperatures in inert atmospheres. These porous carbon materials, such as activated carbon and molecular sieving carbons, generally have broad pore size distributions in both micro- and mesopore ranges. The products obtained from these processes are mesoporous carbon materials with broad pore size distributions and a reasonable amount of microporosity.

High performance of polybenzoxazine membranes for ethanol-water separation via pervaporation technique

Abstract Pervaporation process is used to separate the ethanol–water mixture by partial vaporisation through a non-porous selectively permeable polybenzoxazine membrane synthesised using bisphenol-A, formaldehyde and two different types of diamine, 1,6-hexanediamine (hda) and ethylenediamine (eda), which are denoted as poly(BA-hda) and poly(BA-eda) respectively. It is found that both membranes with a thickness of 200 μm are suitable for the ethanol–water separation via pervaporation process at a feed temperature of 70°C. However, poly(BA-eda) membrane provides higher permeation flux and separation factor with increasing ethanol concentration.

Influences of M–Sn intermetallics (M = Ni, Cu) prepared by mechanical alloying on phenol hydroxylation

This work discusses the effect of the crystal structure of Ni–Sn and Cu–Sn intermetallic catalysts on phenol hydroxylation. All catalysts were prepared via the mechanical alloying (MA) technique which is a green process for catalyst preparation. The results showed that the prepared catalysts consisted of monoclinic (Ni3Sn4 and Cu6Sn5) and hexagonal (Ni3Sn and Cu6Sn5(HT)) crystal structures. The catalytic activity of all synthesized catalysts for phenol hydroxylation demonstrated that both Ni3Sn4 and Ni3Sn exhibited better catalytic activity than Cu6Sn5 and Cu6Sn5(HT), and Ni3Sn, having a hexagonal crystal structure, showed the best catalytic activity (>97% conversion) at 363 K, 3 h, 1 : 4 phenol : H2O2, and 50 mg of catalyst content, giving CAT (60.28% yield) and HQ (36.82% yield) with no over-oxidation of CAT and HQ as time elapsed.

Evaluation of highly efficient monomeric sugar yield from Thai Tiger grass (Thysanolaena maxima)

Tiger grass (Thysanolaena maxima) is considered an important perennial energy crop in Southeast Asia with a high productivity and a low requirement for fertilizer. The monomeric sugar yield from T. maxima by two-stage microwave/chemical pretreatment and enzymatic hydrolysis is evaluated. The optimal conditions of the pretreatment were investigated by varying reaction times, reaction temperatures and chemical concentrations to maximize the amount of obtained monomeric sugar. The T. maxima was treated with microwave-assisted NaOH pretreatment using 15:1 liquid-to-solid ratio (LSR), 1% (w/v) NaOH at 140 °C for 15 min, followed by microwave-assisted H2SO4 pretreatment using 15:1 LSR, 0.5% (w/v) H2SO4 at 200 °C for 5 min. The maximum monomeric sugar released was 30.2 g/100 g of NaOH-pretreated solids. The enzymatic hydrolysis of the microwave-/chemical-pretreated T. maxima at pH 4.8, 45 °C for 120 h using enzyme amount of 160 μl/g pretreated solids produced an impressive maximum sugar yield of 110.4 g/100 g of NaOH-pretreated solids.

Simple route to bismuth titanate from bismuth glycolate precursor via sol-gel process

Abstract Bismuth titanate (Bi4Ti3O12) is successfully synthesised using bismuth glycolate as a bismuth source and acetic acid and ethanol as solvents via sol–gel process without adding a complexing agent. The synthesis parameters investigated are acetic acid to ethanol ratio, mechanical stirring time, calcination time and temperature. It is found that an increase in the acetic acid to ethanol ratio causes an increase in the gelation time, and the calcination temperature is the key factor in transformation to a crystalline Bi4Ti3O12 perovskite phase. The perovskite phase of Bi4Ti3O12 in a nanoplate shape is obtained after stirring the precursor mixture solution containing 0·1 acetic acid to ethanol ratio for 1 h at room temperature, followed by calcination of the dried gel at 600°C for 1 h.