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Rochmadi Rochmadi
Department of Chemical Engineering, Universitas Gadjah Mada, Jl. Grafika 2, Yogyakarta 55284, Indonesia
Chemical Engineering, Chemistry & Bioengineering Chemistry

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Equilibrium Modeling of Astaxanthin Extraction from Haematococcus pluvialis Putri Restu Dewati; Rochmadi Rochmadi; Abdul Rohman; Avido Yuliestyan; Arief Budiman
Indonesian Journal of Chemistry Vol 21, No 3 (2021)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.56965

Abstract

Astaxanthin is a natural antioxidant, and the highest content of this compound is found in Haematococcus pluvialis microalgae. Microwave-assisted extraction (MAE) is one of the environmentally friendly extraction methods and has many advantages. This study aims to investigate the extraction of astaxanthin through the MAE method using various solvents. Several equilibrium models were proposed to describe this solid-liquid equilibrium. The solid-liquid extraction equilibrium parameters were determined by minimizing the sum of squares of errors (SSE), in which equilibrium constants were needed for scaling up purposes. Previously, the microalgae were pretreated with HCl to soften their cell walls in order to improve the extraction recovery. In this study, dichloromethane, acetone, methanol, and ethanol were used as the solvents for extraction. The astaxanthin concentration was determined by high-performance liquid chromatography (HPLC) and spectrophotometry. Astaxanthin was found to attain equilibrium at 57.42% recovery in a single-step extraction. Thus, several steps were required in sequence to obtain an optimum recovery. The experimental data were fitted to three equilibrium models, namely, Henry, Freundlich, and Langmuir models. The experimental data were well fitted to all the models for the extraction in dichloromethane, methanol, ethanol and acetone, as evident from the almost same SSE value for each model.
Investigation of Crystal Size Distribution in Purification of Terephthalic Acid from Polyester Textile Industry Waste by Reactive Crystallization Bekti Marlena; Hary Sulistyo; Rochmadi Rochmadi
Indonesian Journal of Chemistry Vol 23, No 3 (2023)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.80820

Abstract

The purification of terephthalic acid recovered from an alkali-reduction wastewater by reactive crystallization was investigated. The crude terephthalic acid was reacted with sodium hydroxide solution to form a salt of disodium terephthalate, then acidified with sulfuric acid to get the terephthalic acid with higher purity. Effects of time, pH, concentration, and flow rate of secondary feed solutions, temperature, and stirring rate on Crystal Size Distribution (CSD) of terephthalic acid precipitate were investigated. The results showed that CSD was influenced by the concentration of reactants and the pH solution. On the other hand, time, temperature, flow rate of secondary solution, and stirring rate had no significant effects on the CSD, which the mean size of crystals ±3 μm. The mean size of crystals at solution pH 5, 4, and 3 were 6.03, 9.42, and 10.34 μm, respectively; meanwhile, at concentrations of 0.5, 0.3, and 0.1 M, were 7.57, 3.24, and 3.09 μm, respectively. The semi-batch reactive crystallization with double-feeding at constant pH and temperature produced monodispersed crystals. However, this method needs to be carried out more than once for terephthalic acid purification, which is intended for polyethylene terephthalate (PET) polymerization.
Co-Authors Abdul Rohman Arief Budiman Avido Yuliestyan Bekti Marlena Hary Sulistyo Putri Restu Dewati