Browsing by Author "Chang, Yu-Hsin"

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Removal of Hg(2+) from Aqueous Solution Using a Novel Composite Carbon Adsorbent
(2009-05-15)
Chang, Yu-Hsin
;
Hsieh, Kuo-Huang
;
Chang, Feng-Chih
;
應用化學系
;
Department of Applied Chemistry
A novel composite carbon adsorbent (GCA) has been prepared by immobilizing activated carbon and genipin-crosslinked chitosan into calcium alginate gel beads via entrapment and applied to the removal of mercury (Hg(2+)) ions from aqueous solution (e.g., drinking water). Two bead sizes and two mixing ratios of components were obtained and characterized. Batch experiments were performed to study the Uptake equilibrium and kinetics, of Hg(2+) ions by the GCA. The Hg(2+) adsorption capacity of GCA was found to be dependent of pH and independent of size of the adsorbent. The Hg(2+) adsorption rate of GCA increases with decreasing its bead size. However, both adsorption capacity and rate of GCA for Hg(2+) increase with increasing its chitosan content. Otherwise, it was shown that the GCA has higher Hg(2+) adsorption capacity and rate than activated carbon, which might he caused by the incorporation of chitosan into the GCA. The maximum Hg(2+) adsorption capacity of GCA was found to be 576 mg/g, which is over seven times higher than that of activated carbon. Our results reveal the uniform distribution of activated carbon and chitosan within the alginate gel bead and that Hg(2+) ions can diffuse inside the bead. It also demonstrated the feasibility of using this GCA for Hg(2+) removal at low pH values. The Hg(2+) absorbed beads of the GCA can be effectivelY regenerated and reused using H(2)SO(4). (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 2445-2454, 2009
Removal of Hg2+ from Aqueous Solution Using a Novel Composite Carbon Adsorbent
(2009-05-15)
Chang, Yu-Hsin
;
Hsieh, Kuo-Huang
;
Chang, Feng-Chih
;
應用化學系
;
Department of Applied Chemistry
A novel composite carbon adsorbent (GCA) has been prepared by immobilizing activated carbon and genipin-crosslinked chitosan into calcium alginate gel beads via entrapment and applied to the removal of mercury (Hg2+) ions from aqueous solution (e.g., drinking water). Two bead sizes and two mixing ratios of components were obtained and characterized. Batch experiments were performed to study the Uptake equilibrium and kinetics, of Hg2+ ions by the GCA. The Hg2+ adsorption capacity of GCA was found to be dependent of pH and independent of size of the adsorbent. The Hg2+ adsorption rate of GCA increases with decreasing its bead size. However, both adsorption capacity and rate of GCA for Hg2+ increase with increasing its chitosan content. Otherwise, it was shown that the GCA has higher Hg2+ adsorption capacity and rate than activated carbon, which might he caused by the incorporation of chitosan into the GCA. The maximum Hg2+ adsorption capacity of GCA was found to be 576 mg/g, which is over seven times higher than that of activated carbon. Our results reveal the uniform distribution of activated carbon and chitosan within the alginate gel bead and that Hg2+ ions can diffuse inside the bead. It also demonstrated the feasibility of using this GCA for Hg2+ removal at low pH values. The Hg2+ absorbed beads of the GCA can be effectivelY regenerated and reused using H2SO4. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 2445-2454, 2009
Removal of Hg2+ from aqueous solution using alginate gel containing chitosan
(2007-06-05)
Chang, Yu-Hsin
;
Huang, Chih-Feng
;
Hsu, Wei-Ju
;
Chang, Feng-Chih
;
應用化學系
Glutaraldehyde-crosslinked alginate gel containing chitosan (AGCC) used for the removal of Hg2+ ions from aqueous solutions. Three bead sizes were obtained and performed to study the uptake equilibrium and kinetics of Hg2+ by AGCC (ca. an hour). The adsorption capacity was found to be independent of adsorbent particle size indicating that sorption occurs in the whole AGCC bead. A high initial rate of Hg2+ uptake was followed by a slower uptake rate suggesting intraparticle diffusion as the rate-limiting step. The rate of Hg2+ uptake increases with decreasing AGCC bead size. AGCC also enhanced the rate and the capacity of Hg2+ adsorption. The maximum Hg2+ adsorption capacity of AGCC was found 667 mg/g, which is over 20 times higher than that of alginate bead. Our results reveal the well-distributed chitosan powders in the alginate gel bead and Hg2+ ions can reach inside the chitosan bead. It indicates the feasibility of using AGCC as metal adsorbent at low pH values, and allows the regeneration of adsorbent. Hg-+(2) ions adsorbed on AGCC bead were desorbed effectively about 95% by H2SO4 at the third cycle. The use of AGCC for the removal of Hg2+ ions from the waste streams appears to be promising. (c) 2007 Wiley Periodicals, Inc.
Thermal properties of polystyrene nanocomposites formed from rigid intercalation agent-treated montmorillonite
(2007-07-15)
Yei, Ding-Ru
;
Fu, Hue-Kuan
;
Chang, Yu-Hsin
;
Kuo, Shiao-Wei
;
Huang, Jieh-Ming
Polystyrene (PS)/clay nanocomposites were prepared with two different new intercalation organophilic clays, the phosphonium salt (APP) and the ammonium 4-(4-adamantylphenoxy)-1-butanamine (APB) salts, by emulsion polymerization technique. X-ray diffraction and transmission electron microscopy were performed to characterize the layered structures of APB- and APP-treated polymer-clay nanocomposites, and both resulted in exfoliated structures. Molecular weights of PS obtained from these nanocomposites are slightly lower than the virgin PS formed under similar polymerization conditions. Coefficient of thermal expansion showed approximately a 44-55% decrease for APB- and APP-intercalated clay nanocomposites relative to the pure PS. Both T-g and thermal decomposition temperature of the PS component in the nanocomposite are higher than the virgin PS, implying that the presence of clay is able to enhance thermal stabilities of the PS. (c) 2007 Wiley Periodicals, Inc.