KOH Powder Research Articles

Influence of preparation conditions on the physical structure and surface properties of enteromorpha clathrate bio-char

Bio-char with rich pore structure was obtained by pyrolysis of enteromorpha clathrate (EC) and subsequent activation process. The effect of pyrolysis methods, KOH concentrations used in activation and heating rate was studied. A new method that combined pyrolysis and activation into one step was proposed. The bio-char obtained via slow pyrolysis at 450°C and 700°C had a certain pore structure. The bio-char obtained via fast pyrolysis had almost no effective pore structure and a large amount of organic matters still exist in the bio-char, while it had the largest specific surface area after activation by KOH at 800°C. Therefore, bio-char that is a kind of by-product in the process of making bio-oil by fast pyrolysis of EC is worthy of further exploration. As the KOH concentration of the impregnated solution increased, the specific surface area first increased and then decreased. The bio-char obtained via impregnation and activation with 3 mol/L KOH had the highest specific surface area (1128.85 m2/g) and pore volume (0.789 cm3/g). If the processes of pyrolysis and activation were combined into one step via mixing KOH and EC, the structure of cell tissue in the EC was reserved. The sample that prepared by mixing 2 g dried EC with 0.1 g KOH powder has the highest specific surface area (724.66 m2/g) and better pore structure. The best heating rate was 5°C/min for impregnation method and 2°C/min for one step method.

Hydrophobic Starch-Based Films Using Potato Washing Slurries and Spent Frying Oil.

Starch is a promising candidate for preparing biodegradable films with useful gas barriers and thermoplastic capabilities. However, these materials are hydrophilic and brittle, thus limiting their application range. To overcome these drawbacks, it has been hypothesized that starch can be hydrophobized and plasticized during the starch-based film production using a single-step approach and following transesterification principles. In this work, KOH powder and spent frying oil (SFO) were used as an alkaline catalyst and a source for triacylglycerides, respectively, to promote the modification of starch. Different ratios of SFO (w/w related to the dried starch weight) were tested. When compared to the neat films (without a catalyst and SFO), the incorporation of at least 15% SFO/KOH gave rise to transparent, hydrophobic (water contact angles of ca. 90°), stretchable (ca. 20×), elastic (ca. 5×), and water tolerant starch-based films, contrary to the films produced without the catalyst. ATR-FTIR and 1H NMR revealed structural differences among the produced films, suggesting that starch was modified with the SFO-derived fatty acids. Therefore, adding KOH during the potato starch/spent frying oil-based film’s production was determined to be a promising in situ strategy to develop starch-based materials with improved hydrophobicity and flexibility, while valorizing the potato chip industry’s byproducts.

A novel purification method of activated carbon-supported carbon nanotubes using a mixture of Ca(OH)2 and KOH as the ablation agent.

Transition metals (Fe, Co, Ni) supported on activated carbons with different pore diameters (<2 nm, 10 nm, 50 nm) to synthesize carbon nanotubes (CNTS) are first investigated in this study. Through several characteristic analyses, Ni supported on 50 nm activated carbon is verified to be the most efficient catalyst among the samples for CNT growth. The optimum conditions for CNT growth are at a growth temperature of 750 °C with a reaction time of 45 min. Furthermore, a novel purification method for CNTs is proposed, in which KOH and Ca(OH)2 powder are pre-mixed with the crude CNTs and CO2 and N2 gas are introduced into this mixture. When KOH and Ca(OH)2 powder are used at a ratio of 2 : 1 under the atmosphere of CO2 and N2 at the temperature of 750 °C for 1 h, almost all of the amorphous carbon is ablated. Compared with KOH powder, the addition of Ca(OH)2 not only advances the ablation effect, but reduces the damage to CNTs.

Extremely high surface area of activated carbon originated from sugarcane bagasse

In this study, the extremely high specific surface area of activated carbon originated from sugarcane bagasse was produced by dry chemical activation. In this process, KOH was used as a chemical agent and directly mixed sugarcane bagasse carbon with KOH powder, which has been treated in a solid form. In particular, the influences of the impregnation ratio and activation temperature were investigated. The as-prepared activated carbons were characterized by Brunauer-Emmet-Teller (BET), which aims to determine the surface area of activated carbon and Raman Spectra analysis to examine the vibration modes of material characteristics. The maximum specific surface area of the activated carbon reached 3554 m2/g at 800 °C and an impregnation ratio of 1:4. Furthermore, the Raman spectra of activated carbon exhibited graphite structure for sample in impregnation ratio 1:2 and 1:3 due to having of G and G−1 band. This material is essential for make battery.

Contribution to the Process Development for Lactulose Production through Complete Valorization of Whey Permeate by Using Electro-Activation Technology Versus a Chemical Isomerization Process.

Whey permeate (WP) is a co-product of a cheese or casein production process that is regarded as an environmental pollutant because of its high organic load and is creating a major disposal problem for the dairy industry. However, it can be used as a suitable substrate to meet the increasing demand of producing a prebiotic lactulose through the isomerization of lactose present in the WP under adequate alkaline conditions. The goal of this study was to produce lactulose in situ of WP using electro-activation (EA) technology and compare the productivity of EA with conventional chemical isomerization at potassium hydroxide (KOH)-equivalent solution alkalinity in the feed medium. Electro-isomerization was conducted under different current intensities of 300, 600, and 900 mA for 60 min of EA with a 5 min sampling interval using 6, 12, and 18% (w/v) WP solutions. Chemical isomerization was carried out at the KOH-equivalent solution alkalinity to that measured in the EA solution at each 5 min interval using KOH powder as a catalyst. The outcomes of this study revealed that the production of lactulose using the EA approach was current intensity-, WP concentration-, and reaction time-dependent and produced the highest lactulose yield of 36.98% at 50 min of EA-time under 900 mA current intensity using 6% WP as a feed solution, whereas a maximum lactulose yield of 25.47% was achieved by the chemical isomerization at the solution alkalinity corresponding to that of the EA under 900 mA current intensity at 50 min in the 6% WP solution. Furthermore, a greater yield of lactulose was obtained using the EA technique for all reaction conditions compared to the chemical process at the equivalent solution alkalinity. Therefore, the results of this work suggest that the EA can be an emergent sustainable technology for achieving dual objectives of prebiotic lactulose production and concurrent valorization of WP using it as a feed medium.

Sustainable Valorization of Whey by Electroactivation Technology for In Situ Isomerization of Lactose into Lactulose: Comparison between Electroactivation and Chemical Processes at Equivalent Solution Alkalinity.

The demand for production of prebiotics at a commercial scale is rising due to the consumers’ growing health awareness. Whey, a coproduct of the dairy industries, is a suitable feed medium to produce a prebiotic lactulose through the isomerization of lactose under alkaline conditions. The aim of the present study was to compare the isomerization of lactose into lactulose in situ of whey by using electroactivation technology with the chemical isomerization method using KOH as catalysis under equivalent solution alkalinity. Electroisomerization of lactose into lactulose was performed by using whey solutions of 7, 14, and 21% (w/v) dry matter under current intensities of 300, 600, and 900 mA, respectively, during 60 min with a sampling interval of 5 min. The conventional chemical method was carried out using KOH powder as catalyst at the alkalinity that corresponded to that measured in the electroactivated whey at each 5 min interval. The results showed that lactulose production was dependent on the whey concentration, current intensity, and EA time. The highest lactulose yield of 32% was achieved under a 900 mA current intensity at 60 min for a 7% whey solution. Thereafter, the EA conditions were compared to those of a conventional chemical isomerization process by maintaining similar alkalinity in the feed solutions. However, no lactulose was produced by the chemical process for the equivalent solution alkalinity as in the EA technique. These results were correlated with the solution pH, which reached the required values in a 7% whey solution with values of up to pH 11.50, whereas the maximum pH values that were obtained at higher whey concentrations were around 10–10.50, which was not enough to initiate the lactose isomerization reaction. The outcomes of this study suggest that EA is an efficient technology to produce lactulose using whey lactose.

서천화력발전소 매립 석탄재에서 분리한 미연탄소의 재활용 방안

Abstract Feasibility of utilizing unburned carbon residue in coal ash as a potential precursor for the production of activated carbon wasassessed to seek for solution to recycle unburned carbon residue. The unburned carbon concentrate generated from the 4 stagesof cleaner flotation has a grade of 87% carbon. The crystalline impurities in the concentrate included quartz and mullite.Unburned carbon had a low specific surface area of 10m 2 /g, which might be related to a high degree of coalification of domesticanthracite coal. Carbon particles were mostly porous and have a turbostratic structure. When 1g of carbon was activated with6g of KOH powder, the highest specific surface area value of 670m 2 /g was achieved. Low wettability of unburned carbon par-ticles, which was resulted from high temperature combustion in a boiler, might cause poor pore formation when they were acti-vated by KOH solution. The activated carbon produced in this study developed micropores, with an equivalent quality of * Received : November 5, 2013 · Revised : December 12, 2013 · Accepted : December 24, 2013Corresponding Author : Sujeong Lee (E-mail : crystal2@kigam.re.kr)Mineral Resources Research Division, Korea Institute of Geoscience & Mineral Resources, 124 Gwahang-no, Yuseong-gu, Daejeon,305-350 KoreaTel : +82-42-868-3125 / Fax : +82-42-868-3418ⓒThe Korean Institute of Resources Recycling. All rights reserved. This is an open-access article distributed under the termsof the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permitsunrestricted non-commercial use, distribution and reproduction in any medium, provided the original work is properly cited.

Reactions of (phenylethynyl)sulfones with tricyclo[4.1.0.02,7]heptanes

Methyl-, phenyl-, p-chlorophenyl-, and p-tolyl(phenylethynyl)sulfones under photochemical or thermal initiation add to the central bicyclobutane C1–C7 bond of 1-R(H, Me, Ph)-tricyclo[4.1.0.02,7]heptanes anti-selectively, and form norpinic adducts containing a phenylethynyl group in a geminal to substituent R position, and an endo-oriented sulfonyl group in position 7. The corresponding ketones were prepared by the hydration of the anti-adducts by the method of Kucherov. The ketone with a methylsulfonyl substituent under reflux in toluene in the presence of KOH powder and the phase-transfer catalyst (TEBA-Cl) afforded the tricyclic sulfone.

ALKYLATION OF 2-ACETYLAMINO-5-(BENZIMIDAZOL-2-YL)THIAZOLE DERIVATIVES

Alkylation of 2-acetylamino-5-(benzimidazol-2-yl)thiazole derivatives has been studied. In the system DMSO—KOH powder methylation of the amide-group nitrogen atom takes place mainly, while in the acetone-concentrated aqueous KOH system, the pyrrole nitrogen atom in the imidazole ring is preferentially methylated. Authors: E. B. Usova, E. Yu. Kambulov, V. E. Zavodnik, and G. D. Krapivin. English Translation in Chemistry of Heterocyclic Compounds , 1999, 35 (2), pp 231-239 http://link.springer.com/article/10.1007/BF02251716

Facile preparation of graphene sheets from synthetic graphite

Graphene sheets were prepared from the raw graphite by 67–70% HNO3 oxidation under refluxing at 140°C for 4h, followed by the treatment with KOH powder in an automatic mortar at room temperature for 1h and subjecting to the 1-methyl-2-pyrrolidinone (NMP) solution for exfoliation. The obtained graphene sheets were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, atom force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The KOH in the process was found to play a key role in the preparation of the graphene sheets and can be regarded as a reducing agent.

Transformations of dialkyl(4-hydroxy-2-butynyl)-(3-phenylallyl)ammonium bromides in an KOH aqueous solution or in the presence of powdered KOH

Under the action of a twofold excess of KOH and heating in aqueous solution, and also under the conditions of the Stevens rearrangement (with KOH powder and a small amount of methanol) dialkyl-(4-hydroxy-2-butynyl)(3-phenylallyl)ammonium bromides form dialkyl[4-(1-phenylallyl)-2,5-dihydro-2-furyl]amines. Rearrangement–cleavage reaction also occurs under the same conditions.

Polyfluoroalkyl derivatives of nitrogen. Part 48. The addition of N-halogenoamines (CF3)2NX to cyclohexa-1,3- and -1,4-dienes; a new synthesis of NN- bistrifluoromethylaniline

Treatment of cyclohexa-1,3-diene with the N-halogenoamines (CF3)2NX (X = Cl or Br) at –78 °C gives a mixture of the 1 : 1 adducts, trans-(CF3)2N–[graphic omitted]H and cis- and trans-(CF3)2N–[graphic omitted]H2; in contrast (CF3)2NI affords the former adduct exclusively. All three amines react with cyclohexa-1,4-diene under analogous conditions to yield the 1 : 1 adduct trans-(CF3)2N–[graphic omitted]HX only. Dehydrohalogenation of the 1,3-diene adducts (X = Cl or Br) with various bases (KOH powder, PriONa, ButOK) affords a mixture of 1- and 2-(NN-bistrifluoromethylamino)cyclohexa-1,3-diene. The latter diene forms a Diels–Alder adduct with trifluoronitrosomethane and the diene mixture dehydrogenates readily over a Pd–C catalyst at 180–190 °C to give NN-bistrifluoromethylaniline exclusively in high yield.