@article{
author = "Spasojević, Miroslav and Ribić Zelenović, Lenka and Trišović, Tomislav",
year = "2009",
abstract = "During the electrolysis of an aqueous solution of xylose, two parallel reactions take place on the cathode i.e. the reduction of xylose to xylitol and hydrogen evolution. To favor the desired reaction of xylose reduction, amalgamated zinc is used to perform the reduction in this study. The catalytic amalgamated coating is formed by the electrodeposition of a zinc coating having desired properties on a copper mesh from a sulfate bath and its subsequent immersion into the HgCl2 solution to obtain the amalgamated zinc of adequate concentration. The present study focuses on the kinetics and mechanism of two parallel reactions of hydrogen evolution and xylose reduction on amalgamated zinc from a solution containing xylose and Na2SO4 as a basic electrolyte. The hydrogen evolution reaction occurs through two parallel mechanisms, either in the presence or absence of xylose. At lower overpotentials, hydrogen is evolved on zinc oxide in three consecutive elementary steps. The overall rate of the hydrogen evolution reaction within the limiting current range is governed by the heterogeneous chemical step involving a Zn-H species. At potentials more negative than -2.0 V, the reaction takes place on the metal surface through the Volmer-Heyrovsky mechanism. Xylose is adsorbed on the metallic zinc. At potentials more negative than -1.25 V, the adsorbed xylose molecules are reduced with Zn-H to xylitol. The cathodic polarization curves, in either the presence or absence of xylose, were used to determine the cathodic current efficiency for xylitol production, which is in good agreement with the values obtained by other methods., Tokom elektrolize vodenog rastvora ksiloze na katodi se paralelno odigravaju dve reakcije: redukcija ksiloze do ksilitola i reakcija izdvajanja vodonika. Da bi se favorizovala željena reakcija redukcije ksiloze u ovom radu je redukcija izvođena na amalgamu cinka. Katalitička prevlaka amalgama formirana je na taj način što je izborom parametara elektrolize iz sulfatnog kupatila na bakarnoj mreži najpre istaložena prevlaka cinka željenih karakteristika, a zatim zamakanjem prevlake u rastvor HgCl2 dobijen amalgam cinka odgovarajuće koncentracije. Ispitivana je kinetika i mehanizam paralelnih reakcija izdvajanja vodonika i redukcije ksiloze na amalgamu cinka iz rastvora koji sadrži ksilozu i Na2SO4 kao osnovni elektrolit. Reakcija izdvajanja vodonika se odigrava preko dva paralelna mehanizma, i u prisustvu i u odsustvu ksiloze u rastvoru. Na nižim prenapetostima reakcija izdvajanja vodonika se odvija na oksidu cinka sa tri konsekutivna elementarna stupnja. Heterogeni hemijski stupanj u kome učestvuje čestica Zn-H kontroliše ukupnu brzinu reakcije u oblasti granične struje. Na potencijalima negativnijim od -2,0 V reakcija izdvajanja vodonika se dominantno odigrava na metalnoj površini Folmer-Heirovskim reakcionim mehanizmom. Ksiloza se adsorbuje na metalnom cinku. Na potencijalima negativnijim od -1,25 V adsorbovani molekuli ksiloze se reduju sa Zn-H do ksilitola. Na osnovu katodnih polarizacionih krivih u odsustvu i u prisustvu ksiloze određeno je katodno iskorišćenje struje po ksilitolu.",
publisher = "Čačak : University of Kragujevac - Faculty of Agronomy",
journal = "Acta agriculturae Serbica",
title = "The kinetics of the electrochemical reduction of xylose on amalgamated zinc, Kinetika elektrohemijske redukcije ksiloze na amalgamu cinka",
pages = "11",
volume = "14",
number = "28",
url = "https://hdl.handle.net/21.15107/rcub_dais_14863"
}
