The effectiveness of sodium hydroxide (NaOH) and sodium carbonate (Na 2. ) on the impurities removal of saturated salt solution

Transcription

1 Journal of Physics: Conference Series PAPER OPEN ACCESS The effectiveness of sodium hydroxide (NaOH) and sodium carbonate (Na 2 ) on the impurities removal of saturated salt solution To cite this article: C Pujiastuti et al 2018 J. Phys.: Conf. Ser View the article online for updates and enhancements. This content was downloaded from IP address on 21/07/2018 at 10:51

2 The effectiveness of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) on the impurities removal of saturated salt solution C Pujiastuti *, Y Ngatilah, K Sumada, S Muljani Chemical Engineering, Engineering Faculty, University of Pembangunan Nasional Veteran East Java *caeciliapujiastuti@gmail.com Abstract. Increasing the quality of salt can be done through various methods such as washing (hydro-extraction), re-crystallization, ion exchange methods and others. In the process of salt quality improvement by re-crystallization method where salt product diluted with water to form saturated solution and re-crystallized through heating process. The quality of the salt produced is influenced by the quality of the dissolved salt and the crystallization mechanism applied. In this research is proposed a concept that before the saturated salt solution is recrystallized added a chemical for removal of the impurities such as magnesium ion (), calcium (), potassium (K) and sulfate (SO4) is contained in a saturated salt solution. The chemical reagents that used are sodium hydroxide (NaOH) 2 N and sodium carbonate (Na 2) 2 N. This research aims to study effectiveness of sodium hydroxide and sodium carbonate on the impurities removal of magnesium (), calcium (), potassium (K) and sulfate (SO 4). The results showed that the addition of sodium hydroxide solution can be decreased the impurity ions of magnesium () 95.2%, calcium ion () 45%, while the addition of sodium carbonate solution can decreased magnesium ion () 66.67% and calcium ion ( ) 77.5%, but both types of materials are not degradable sulfate ions (SO 4). The sodium hydroxide solution more effective to decrease magnesium ion than sodium carbonate solution, and the sodium carbonate solution more effective to decrease calcium ion than sodium hydroxide solution. 1. Introduction Salt is a product that is needed in various processes such as fish preservatives, community consumption, health, supporting industrial activities and the pharmaceutical industry. Each designation needs different salt quality, such as salt for consumption salt require requirement of 94,7% NaCl content, for salt industrial supporting like soda industry needed NaCl content of 98,4% [1] while for industry salt NaCl content is close to 98,50% [2]. The crude salt or traditional salt is produced by the first stage evaporation to sediment of calcium ion, the second stage evaporation is to concentrate of sea water, and the last stage is crystallization [3]. The quality of salt product is influenced significantly with seawater quality and production facilities [4,5]. The salt product has low quality with NaCl content 85-95% and the others are its impurities such as magnesium chloride (Cl 2), magnesium sulfate (SO 4), calcium sulfate (SO 4), and potassium Chloride (KCl). The increasing of the salt quality can be done through a variety of ways like hydroextraction (washing with saturated salt solution), and re-crystallization [6]. The re-crystallization Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by Ltd 1

3 methods is salt product dissolved with water until form saturated salt solution and then crystallization again. The saturated salt solution before crystallization still contain impurities such as magnesium chloride (Cl 2), magnesium sulfate (SO 4), calcium sulfate (SO 4), and potassium Chloride (KCl) [7]. The improvement of salt product quality can be done by chemical or added of some kind of chemicals, the chemicals generally used such as Sodium hydroxide (NaOH) [8,9], sodium carbonate (Na 2), calcium chloride (Cl 2) and others. The addition of such chemicals aims to bind and precipitate impurities contained in the salt such as magnesium (), calcium (), sulfate (SO 4) and potassium (K) ions. The reactions that occur in addition of sodium hydroxide (NaOH), sodium carbonate (Na2), calcium chloride (Cl 2) [10] as below [11]: Cl NaOH (OH) NaCl (1) Cl 2 + Na NaCl (2) SO 4 + Na 2 + Na 2SO 4 (3) SO NaOH (OH) 2 + Na 2SO 4 (4) Base on reaction 1 and 2 above, added of sodium hydroxide (NaOH) and sodium carbonate will increase NaCl content on salt product [12]. Precipitation of calcium and magnesium from seawater have been carried out using CO 2 at ph value between 8.0 and 9.0 [9,15]. The precipitated solids were consist of H 2O at ph 8.0of H 2O and 3H 2O between ph 8.3 and 9.0 in the seawater system [9]. This research is proposed a concept that before the saturated salt solution is re-crystallized added a chemical for removal of the impurities such as magnesium ion (), calcium (), potassium (K) and sulfate (SO4) is contained in a saturated salt solution. 2. Materials and Method This research was conducted on a batch laboratory scale, the traditional salt that use as the study material in this study was obtained from Gresik city in East Java. The quality of salt is determined by gravimetric method for sulfate (SO4), stoichiometry for sodium chloride (NaCl), and Titrimetry for calcium () and magnesium (). Sodium hydroxide solution 2N and sodium carbonate solution 2N use for impurities removal. The Block diagram of the study as shown in Figure 1 Traditional salt Analyzed of NaCl,, and SO 4 Water Dissolution of salt Saturated salt Solution Filtration NaOH 2 N or Na 2 2 N Solution Precipitation Reaction Filtration Solid (Precipitat) Filtrate Analyzed of NaCl,, and SO 4 2

4 3. Results and Discussions Figure 1. Schematic Diagram of Research a. Chemical composition of the traditional salt Table 1 showed the results of elemental analysis and compound analysis in traditional salts as raw materials and the saturated salt solution is a solution obtained from 360 g of salt dissolved with 1 liter of water using ICP-OES and gravimetry analisis. Table 1. Chemical composition of traditional salt No Parameters Concentration (%) Traditional salt Saturated salt 1 Sodium chloride (NaCl) 90, Magnesium () Sulfate (SO4) 0,056 0, lcium () 0, The chemical composition of the saturated salt solution that use as raw material in this research. The saturated salt solution contains magnesium (), sulfate (SO 4) and calcium () ions that will be precipitated using sodium hydroxide (NaOH) or sodium carbonate (Na 2). a. The Influence of sodium carbonate (Na 2) solution added on impurities removal NaOH Na NaOH Impurities Removal (%) NaOH ph Na Volume ratio (NaOH or Na 2 /saturated solution) Volume ratio (NaOH or Na2CO3/saturated solution) (a) (b) Figure. 2. Effect of Na 2 and NaOH on a) impurities removal and b) ph Figure 2 shows the effect of NaOH and Na 2 on impurities removal and ph. 2 N to saturated salt solution will increase percentage of impurities removal. The highest ion removal percentage is calcium () ion reached 77.5 %, magnesium () ion % and sulfate (SO 4) ion 0,00 %, it is will on added 60 ml Na 2 per one liter of saturated salt solution. The increasing ratio of Na 2 2 3

5 N/Saturated salt solution will increase percentage of solid composition. The highest ion solid composition is calcium oxide (O) ion reached 79.3 %, magnesium oxide (O) 0.9 %, chloride (Cl) 19,1 % and sulfate (SO 4) 0,00 %, it is will on added 60 ml Na 2 per one liter of saturated salt solution. b. The Influence of volume sodium carbonate (Na 2) solution added on ion concentration Cl Concentration (%) Cl Concentration (%) Volume Ratio of Na 2 /saturated solution Volume ratio of NaOH/saturated solution (a) (b) Figure. 3. Correlation ratio of Na 2C /Saturated salt solution to ion concentration Figure 3 shows correlation ratio of Na 2C /Saturated salt solution to ion concentration. Tthe increasing ratio of NaOH 2 N to saturated salt solution will increase percentage of impurities removal. The highest ion removal percentage is magnesium () ion reached 95.2 %, calcium () ion % and sulfate (SO 4) ion 0,00 %, it is will on added 60 ml NaOH per one liter of saturated salt solution. The increasing ratio of NaOH 2 N/Saturated salt solution will increase percentage of solid composition. The highest ion solid composition is chloride (Cl) ion reached 54.5 %, magnesium oxide (O) 40.7 %, calcium oxide (O) 2,3 % and sulfate (SO 4) 0,00 %, it is will on added 60 ml NaOH per one liter of saturated salt solution. 4. Conclusion Based on the results of research can be concluded several things including: 1. The addition of sodium hydroxide (NaOH) 2 N solution is more effective in removal of magnesium ions () than calcium ions (). the percentage of magnesium removal is 95.2 % and calcium () %. 2. The addition of sodium carbonate (Na 2) 2 N solution is more effective in removal of calcium ions () than magnesium ions (). the percentage of calcium removal is 77.5 %, and magnesium () ion % 3. The addition of sodium hydroxide (NaOH) 2 N solution and sodium carbonate (Na 2) 2 N solution cannot separate sulfate ions (SO 4) 4

6 Acknowledgment We would like to thank the to the Ministry of Research and Technology, Indonesia, for its financial support through Hibah Penelitian Unggulan. We also thank to the team of Material Research group, Chemical Engineering Department, UPN Veteran Jawa Timur. 5. References [1] National Standardization Agency of Indonesia SNI standard for consumption salts [2] National Standardization Agency of Indonesia SNI standard for industrial salts [3] Sedivy VM 2009 Environmental Balance of Salt Production Speaks in Favour of Solar Salt Works. Global NEST Journal [4] Diyono I, et al 2002 Improving Public Salt Quality By Chemical Treatment, Journal of Coastal Development [5] Myers DM and Bonython CW 2007 The Theory of Recovering Salt from Sea-water by Solar Evaporation Applied Chemistry Journal [6] Rathnayaka D DT 2014 Development of a Process to Manufacture High Quality Refined Salt from Crude Solar Salt Int l Journal of Advances in Chemical Engg., & Biological Sciences (IJACEBS) [7] Mottershead R and Davidson P 2009 The Yannarie Solar Project : Design of Solar Salt Field In Western Australia to Safe Guard the Natural Environment, Global NEST Journal [8] Irving, L 1926 The precipitation of calcium and magnesium from sea water, J. Mar. Bio [9] Jijun, Z., Junsheng, Y. Xia,L 2012 Study on the removals of calcium and magnesium from seawater using CO 2, Chem. Ind. and Eng. Program [10] Pujiastuti C, Sumada K, Ngatilah Y, Hadi P 2016 Removal of, K, SO 4 Ions from Seawater by Precipitated Method, Matec Webb Conference Proceeding, 58, 1022 [11] Rathnayaka D.D.T 2014 Development of a Process to Manufacture High Quality Refined Salt from Crude Solar Salt, Int l Journal of Advances in Chemical Engg., & Biological Sciences (IJACEBS) [12] Keith E. Chave 1971 Chemical reactions and the composition of sea water, Journal of Chemical Education, [13] Volodymyr M. Kovalevych et al.2006 Chemical composition of seawater in Neoproterozoic: Results of fluid inclusion study of halite from Salt Range (Pakistan) and Amadeus Basin (Australia, Precambrian Research ELSEVIER [14] John B K Towards The Improvement of Salt Extraction At Lake Katwe, International Journal of Scientific & Technology Research [15] Yu H, X Li Gao, Wei Su B, Gao CB 2012 A New Method to Remove the lcium and Magnesium from the Sea Water with CO 2 Advanced Materials Research,