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Zhou, W., Apkarian, R., Wang, Z.L. and Joy, D. (2006) Fundamentals of Scanning Electron Microscopy (SEM). In: Zhou, W. and Wang, Z.L., Eds., Scanning Microscopy for Nanotechnology Techniques and Applications, Springer Science Business Media, New York.

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• TITLE: Double Acid-Base Extraction of Silicic Acid from Quartz Sand

  AUTHORS: Laksmita Prima Santi, Djoko Mulyanto, Didiek Hadjar Goenadi

  KEYWORDS: Ortho-Silicic Acid, Bangka-Belitung Quartz Sand, Acid-Base Dissolution, Pre-Washed

  JOURNAL NAME: Journal of Minerals and Materials Characterization and Engineering, Vol.5 No.6, November 15, 2017

  ABSTRACT: Silica is becoming more attractive as plant nutrient for non-graminae crops particularly in relation with drought-stress tolerant. Many efforts have been conducted to obtain an efficient technique to produce silica fertilizer worldwide, but the results are varying considerably due to various factors including raw material and extraction technique. This study was carried out to develop an efficient extraction technique for ortho-silicic acid (OSA-H4SiO4) from a Bangka-Belitung quartz sand by employing acid-base dissolution method. A 325-mesh size quartz sand was boiled in HCl solution at various concentrations. The optimum concentration was then used in the following experiment at several different volumes of solution. The sand obtained from optimum concentration and volume of HCl solution was then reacted with different amounts of NaOH (s), and heated until a wet mixture was obtained. As a reference the best extraction conditions were applied to a natural zeolite sample. All OSA analyses were done in triplicates with spectrophotometric method. Supporting evidences were collected from x-ray diffraction and scanning-electron-microscopy analyses of the treated samples. The yield of quartz sand-originated OSA was 183 g·kg-1 and significantly increased linearly with increasing weight of NaOH (R2 = 0.99**), whereas that from zeolite was only 104.2 g·kg-1 at 80 g NaOH. XRD and SEM data confirmed the evidences that the acid-base extraction disrupted the quartz mineral structure and as a consequence releasing more water soluble OSA.