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All Journal The Journal of Pure and Applied Chemistry Research
Diah Mardiana
Brawijaya University
Chemical Engineering, Chemistry & Bioengineering Chemistry Materials Science & Nanotechnology Medicine & Pharmacology

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Acid Isolation Techniques for Silica isolation from Rice Husk and Determination of Its Physicochemical Properties Siti Mutrofin; Leo Krisna; Diah Mardiana; Rachmat Triandi T
The Journal of Pure and Applied Chemistry Research Vol 11, No 1 (2022): Edition January-April 2022
Publisher : Chemistry Department, The University of Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.jpacr.2022.011.01.641

Abstract

Previous research showed that rice husk has a high silica content so it becomes an alternative for processing rice waste. The acid leaching method is a technique to isolate silica by adding an acid solution. The research aim is to obtain the optimum silica yield and determine the chemical ash content of rice husks (rice IR-64,). Rice husks were first calcined at two various temperatures and times. The average yields obtained were 19.54% (500oC / 1 hr), 18.42% (500oC / 2 hrs), 25.03% (700oC /1 hr), and 22.4% (700oC/2 hrs). The physical appearance of ash was grains and white (700 oC/1hr), that were rinsed with 1 M HCl solution to remove impurities. Added 1 M NaOH was to form sodium silicate. The last step was to isolate silica using different concentrations of HCl and HNO3 (3 M, 2 M, and 1 M). The highest result was 99.87% of silica under HNO3 1 M solution. An infrared study supports that the isolated product was silica, with the presence of prominent peaks at 1102 cm-1 (stretching Si-O) and 471 cm-1 (bending Si-O). A unique peak at 958 cm-1 for Si-O-Ca present at the isolated silica using HCl 3 M, gives information on inosilicate type structure. X-ray diffraction analysis with QualX application showed that silica had cristobalite and wollastonite peaks, and the value of crystallinity index was about 63.91%.
The Development of Diazinon Sensors using Polyvinyl Alcohol (PVA) Membrane CuO on Surface Screen-Printed Carbon Electrode (SPCE) as a Receptor Anisa Resti; Ani Mulyasuryani; Diah Mardiana
The Journal of Pure and Applied Chemistry Research Vol 8, No 2 (2019): Edition May-August 2019
Publisher : Chemistry Department, The University of Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.jpacr.2019.008.02.468

Abstract

The development of Diazinon sensor has been studied using polyvinyl alcohol (PVA-CuO membrane on the surface of the screen-printed carbon electrode (SPCE) as a receptor. The membrane used consisted of polyvinyl alcohol (PVA) 5% (w/v), citric acid 5% (w/v), glutaraldehyde 4% (v/v), Diazinon solution 40 ppm (v/v), and CuO 5% (w/v). This study established the effect of Diazinon at 0.01,0.02 and 0.03 (w/w). besides, the concentration of CuO was 0.5 and 1 (w/w). Signal measurements were carried out in the concentration range of the Diazinon 10-12 - 10-5 M solution in Britton-Robinson buffer at pH 2 - 5. Besides, the influence of the electrolyte type was studied using HCl pH 4, 10-5 M KCl, pH 3 phosphate, and phosphate-KCl pH 3 buffers. The results of the Diazinon sensor characterization showed that the highest sensitivity was obtained at 42 mV/decade with a response time of 180 seconds.
Co-Authors Ani Mulyasuryani Anisa Resti Leo Krisna Rachmat Triandi T Siti Mutrofin