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Seawater bittern is a liquid that still exists after most of the NaCl has crystalized in the production of salt from seawater. The main components of the liquid are MgCl2 and NaCl. This study aims to recover the NaCl present in bittern through the precipitation method with NaOH and evaporation. The initial stage of this research was collection of bittern in the salt production process in a salt pond. The obtained bittern samples were then added with NaOH to precipitate the MgCl2 components as Mg(OH)2 and leave NaCl as filtrate. The precipitate and the filtrate were separated by filtration. The obtained NaCl filtrate is then evaporated to obtain high purity NaCl. The product obtained was then determined the NaCl contents by argentometric titration. NaCl crystal was characterized using FTIR spectroscopy XRD spectroscopy, and Scanning Electron Microscope (SEM). The recovery results showed that the NaCl obtained had a high purity of 98.75% w/w and yield 30,45%. The IR spectra and diffractogram obtained showed compatibility with the characteristics of the reference NaCl.

Adsorption of anionic dyes Congo Red (CR) on HDTMA surfactant-modified zeolite A has been studied. The zeolite A, which is synthesized from coal fly ash, was modified with surfactant hexdeciltrimethylammonium bromide (HDTMA-Br) as much as 200% cation exchange capacity (CEC) of the zeolite. The effect of pH, contact time and initial concentration on the CR adsorption has been evaluated.The adsorption was carried out in a batch reactor at various pH, contact time and initial concentration on the given temperature. The amount CR adsorption varies as a function of pH, contact time and initial concentration of solution. Adsorption model of Langmuir and Freundlich from empirical data is used for this experiment. The Langmuir isotherm is more suitable for this adsorption. The experimental data fulfilled pseudo second-order kinetic models. The surfactant-modified zeolite A is more effective than zeolite A without modified on the adsorption of CR in aqueous solution.

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Zeolite A has been synthesized by a modified alkali fusion followed hydrothermal process. Hydrothermal was performed at a temperature of 90 °C for 4 h in a stainless steel reactor. Characterization of the synthesized zeolite was conducted using various techniques, i.e. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) and measurement of cation exchange capacity (CEC). The characterization results showed that zeolite A was selectively obtained by this method. The diffract gram, SEM image, and IR spectra of the synthesized zeolite A showed a similarity with the commercially available zeolit A.