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Journal : Reaktor

Synthesis of Matrix Si-K-HAs Gel from Geothermal Sludge and Peat Srie Muljani; Bambang Wahyudi Wahyudi; S Suprihatin; Ketut Sumada
Reaktor Volume 18 No. 2 June 2018
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (4869.103 KB) | DOI: 10.14710/reaktor.18.2.76-83

Abstract

The synthesis of matrix silica-potassium-humic acid gel (Si-K-HAs) has been performed successfully by gradual extraction and acidification method. The extraction was carried out in two stages: 1) extraction of humic substances from peat prepared by potassium hydroxide to produce potassium humate (K-HAS) solution, 2) extraction silica from geothermal sludge using K-HAs solution to produce Si-K-HAs solution. Acidification of Si-K-HAs solution prepared by citric acid (1-3N) to produce matrix gel of Si-K-HAs. The Si-K-HAs matrix gel products are characterized by Fourier Transform InfraRed (FTIR), X-ray fluroscence (XRF), and Brunauer–Emmett–Teller (BET) analysis. The acidification process was carried out in neutral to acid (pH 3-7) conditions and the results showed that at neutral pH no Si-K-HAs gel formed. IR spectra confirmed the presence of humic acid in the gel product, whereas XRF analysis confirmed the presence of potassium (K) and silica (SiO2) in the gel product. The molar ratio of SiO2:K2O in the product is 0.9 - 0.3 in the pH range of 3-5. Si-K-HAs powder can be used as soil fertilizer especially for soils that lack silica, humic, and potassium nutrients or for future application development. Keywords: gradual extraction; geothermal sludge; matrix gel; humic substance
Transformation of Calcium Carbonate Polymorph From Various Type of Shells by Carbonation Methods Srie Muljani; Erwan Adi Saputra; Ketut Sumada
Reaktor Volume 21 No. 1 March 2021
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1446.366 KB) | DOI: 10.14710/reaktor.21.1.27-34

Abstract

The utilization of shells can reduce the accumulation of shell wastes and increase the value of shells to achieve ecological and economic incentives. This study examines the transformation of calcium carbonate polymorph from several types of shells to understand the causes of their characteristics in order to suitable for their use. The types of shells used in this experiment are selected based on consumable and their habitats such as snail shells, crab shells, eggshells, batik mussels shells, and golden conch shells. The prepared shells calcinate at 900 °C, the reaction with hydrochloric acid, and carbonation by flowing CO2 into a stirred reactor to produce precipitated CaCO3. The characteristics of polymorph CaCO3  in the sintering temperature of 30, 50, and 70 ℃ were identified by XRD, FTIR, and SEM morphological. The result is that the polymorphs formed from each shell are different in shape, size, and crystallinity. At the temperature of 70 ℃, the rhombohedral calcite was obtained from snail shells, the cubic calcite was obtained from batik mussel shell, while rhombohedral calcite multilayers obtained (100%) from golden conch shells. The aragonite was obtained from batik mussel shells at 30 and 70 ℃. The pure vaterite (100%) was obtained from snail shells and crab shells at 50 ℃. The characteristic of polymorph formed might be useful as information for more suitable applications, especially as nano-bio materials, optical, or filler