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Subject: search.filters.subject.Acid treatment

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    Influence of acid-treatment on waste lignin for synthesis of carbon nanoparticles
    (2019-01-01)
    Ngamthanacom, Nutchaporn
    ;
    Kaewtrakulchai, Napat
    ;
    Chaiwat, Weerawut
    ;
    Chuenchom, Laemthong
    ;
    Fuji, Masayoshi
    Waste lignin (WL) obtained from paper mills, was studied for its potential application in preparing carbon nanoparticles (CNPs) with high porosity. This was done by impregnation of 0, 5, 10 and 20% concentrations of phosphoric acid under various carbonization temperatures (600, 700, 800 and 900°C). The physicochemical properties of CNPs were characterized through nitrogen sorption, X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Fourier transforms infrared spectroscopy (FTIR). Nitrogen sorption revealed that the condition using 10% concentration of phosphoric acid treatment at a carbonization temperature of 700°C formed carbon nanoparticles with a highly porous structure (Surface area 27.65 m<sup>2</sup> /g and pore volume 0.07 cm<sup>3</sup> /g). Additionally, in order to high surface area, porosity and concentrated carbon nanoparticle.
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    Improvement of mesoporosity of carbon cryogels by acid treatment of hydrogels
    (2008-11-01)
    Kraiwattanawong, Kriangsak
    ;
    Mukai, Shin R.
    ;
    Tamon, Hajime
    ;
    Lothongkum, Anchaleeporn W.
    Wattle tannin-furfural (TFu) gels are synthesized by the sol-gel polycondensation of wattle tannin with furfural by using sodium hydroxide as a catalyst and cured at 363 K. After cured, the TFu hydrogels are treated in hydrochloric acid (HCl) solutions with various variables as follows: aging temperature, HCl concentration and pH. TFu cryogels aged are then freeze-dried and pyrolyzed under an inert atmosphere to obtain TFu carbon cryogels. The TFu and carbon cryogels were characterized by N<inf>2</inf> adsorption and scanning electron microscope. The high HCl concentration yields the increase of mesopore volume almost twice especially at high temperature and the mesopore size distribution can be greatly developed sharper and narrower when the high concentration of HCl or/and the high temperature are used. Moreover, this method is the versatile approach for developing the mesopore structure of the low and high porous TFu hydrogels and has no serious problem of weight loss after treatment. © 2008 Elsevier Inc. All rights reserved.
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    Improvement of mesopore structure of resorcinol and formaldehyde carbon cryogels by acid solution
    (2008-01-01)
    Kraiwattanawong, K.
    ;
    Kitchaiya, P.
    ;
    Neramittagapong, A.
    ;
    Praserthdam, P.
    ;
    Tamon, H.
    Resorcinol and formaldehyde (RF) carbon cryogels are prepared by sol-gel polycondensation by using sodium carbonate (C) as a catalyst with water (W) as solvent, immersed in acid solution, hydrochloric acid (HC1), dried by freeze-drying technique and then carbonized under inert atmosphere, respectively. Compared with their carbon precursors, both V<inf>mes</inf> and mesopore size distributions of all carbon cryogels can be developed since the pore shrinkage is the crucial role in the change of pore structure of carbon gels. HC1 may promote the strength of small pore structure and increase the pore shrinkage of large pore structure. Consequently, the treatment of HC1 does not only enhance the partial collapse of large pore structure, the treatment also increases the strength of small pore structure to inhibit the shrinkage of this structure during carbonization as well. © 2008 Trans Tech Publications, Switzerland.