The Physical And Chemical Properties Of Desalination Brine And Extraction Of Magnesium From Desalination Brine

Seawater desalination is a new advanced technology, which is particularly suitable for island and seaside cities.It can be used to produce freshwater and effectively alleviate the shortage of freshwater resources. Nowadays seawater desalination has been widely promoted in the world as well as China’s coastal areas. But this technology produces a lot of concentrated seawater which could seriously affect the marine environment. How to dispose the brine has become an important topic.This paper studies on Mg element from by-products of RO seawater desalination technology with the highest market share. Water quality analysis, extraction mechanism and kinetics of magnesium resource were included in this paper. Depending on the related principle of chemical thermodynamics and numerical simulation, more work should be done to verify and modify the dynamics model by experiments.The paper is divided into six chapters. Section one is literature summary. The second part is the analysis of the reverse osmosis desalination seawater. The third part is crystallization law of macro elements from concentrated seawater based on revers osmosis method through evaporation and concentration. The forth part is the preparation of Mg(OH)2 by using reverse osmosis desalination seawater. The fifth part is the thermodynamic mechanism. The sixth part is the conclusion.Firstly, we comprehensively analyze the physical and chemical properties of the reverse osmosis desalination and the feed raw water. Zhoushan water samples were chosen as the main research object and the extraction of magnesium from the RO desalination concentration were studied. Finally the thermodynamic mechanism was illustrated. The main conclusions are as follows:1、The physical and chemical properties of the reverse osmosis desalination brine differs from its raw seawater after the pretreatment, the interception of reverse osmosismembranes and other processes. DO, COD, κ, salinity,TDS and the concentration of major ions are all changed. RO brine contains a higher concentration of macro-elements.Magnesium concentration in concentrated seawater is 1.924 times of that in origin seawater,which makes it more suitable for the extraction of magnesium.2、Ca SO4 and KCl first precipitate in the progress of evaporation.Magnesium salts are more easily to be absracted after the separation of calcium sulfate and sodium chloride.Precipitation is a better way to extract magnesium from the concentrated seawater. CO2 is passed into the RO concentrated seawater in order to get rid of Ca2+ and increase the purity of magnesium salt.This paper provides theoretical guidance and innovative ideas by the comprehensive properties of reverse osmosis desalination concentrated sea water and the information could be referenced to extract Mg from desalination brine.