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Pengaruh Konsentrasi Natrium Silikat terhadap Laju Korosi Paduan Aluminium dalam Lingkungan Natrium Klorida 3,5% Rukiah Rukiah; Diding Mandala Putra; Solihudin Solihudin; Yeni Wahyuni Hartati; Atiek Rostika Noviyanti
ALCHEMY Jurnal Penelitian Kimia Vol 16, No 2 (2020): September
Publisher : UNIVERSITAS SEBELAS MARET (UNS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/alchemy.16.2.40927.218-226

Abstract

Korosi merupakan proses penurunan kualitas logam akibat reaksi logam dengan lingkungannya. Air laut merupakan salah satu sistem yang korosif karena tingginya kadar ion klorida. Ion silikat dengan konsentrasi optimum mampu memperlambat laju korosi pada logam, seperti aluminium. Penelitian ini menguji pengaruh ion silikat dalam larutan natrium klorida 3,5% terhadap laju korosi aluminium yang diuji dengan metode potensiostat dan dihitung dengan Ekstrapolasi Tafel. Pengaruh konsentrasi ion silikat terhadap laju korosi diamati pada variasi konsentrasinya yaitu 0, 25, 50, 75, dan 100 mM. Konsentrasi optimum natrium silikat untuk menurunkan laju korosi adalah 25 mM,  laju korosi turun dari 0,0118 menjadi 0,0084 mm/tahun. Sebaliknya, penambahan konsentrasi natrium silikat hingga 100 mM,  dapat meningkatkan laju korosi menjadi 0,101 mm/tahun.The Effect of Sodium Silicate Concentration on the Corrosion Rate of Aluminum Alloy in Sodium Chloride 3.5%. Corrosion is a process of decreasing the quality of metals due to the reaction of metals with their environment. Seawater is one of the corrosive systems because of the high levels of chloride ions. Silicate ions with optimum concentrations can slow the rate of corrosion in metals, such as aluminum. This research examines the effect of silicate ions on the aluminum corrosion rate in a solution of sodium chloride 3.5%, tested by the potentiostat method and calculated by Tafel extrapolation. The effect of silicate ion concentration on the corrosion rate was observed in various concentrations of 0, 25, 50, 75, and 100 mM. The optimum concentration of sodium silicate in reducing the corrosion rate is 25 mM, in which the corrosion rate drops from 0.0118 to 0.0084 mm/year. Conversely, increasing the concentration of sodium silicate to 100 mM increased the corrosion rate to 0.101 mm/year.
Isolation of Silica-Lignin Composites from Rice Husk and Their Adsorption to Cr(VI) Yati B. Yuliyati; Seli Listiani; Solihudin Solihudin; Atiek Rostika Noviyanti
ALCHEMY Jurnal Penelitian Kimia Vol 14, No 2 (2018): September
Publisher : UNIVERSITAS SEBELAS MARET (UNS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/alchemy.14.2.19818.267-276

Abstract

Rice husk is the most abundant agricultural waste in Indonesia. It can be used as a precursor for multifunctional materials such as silica-lignin composite for adsorbents. Silica-lignin can reduce heavy metal content in an industrial waste, such as the content of Cr(VI). This study aims to isolate and characterize silica-lignin composite, and determines the isotherm type of silica-lignin for hexavalent chromium adsorption. The isolation from rice husk used an alkali extraction method. Confirmation of typical functional groups in the silica-lignin composite was characterized by FTIR, while the morphology was characterized by SEM, respectively. The results reveal that the silica-lignin isolation was successfully performed.  FTIR spectra indicate a typical wavenumber of the silica-lignin.  The SEM image of the composite showed homogeneous morphology. The silica-lignin adsorption process on hexavalent chromium followed a Brunauer–Emmett–Teller (BET) isotherm type indicated by multilayer adsorption with a surface area of 948.8421 mg. g-1.