Slurry magnesium hydroxide has the following advantages when it is used for water purification: high activity, it is effective against suspended solids, COD, BOD oil, odor, heavy metal ions, phosphate, sulfate, acid, dye, phenol, Silicate has a good removal effect, and the removal rate can reach 75%-99%. It is especially suitable for papermaking wastewater, electroplating wastewater, domestic sewage, printing and dyeing wastewater, tannery wastewater, high-fluorine wastewater, and acid wastewater.
Application of Slurry Magnesium Hydroxide in Drinking Water Purification and Arsenic Removal
Arsenic in drinking water is a carcinogen, and the removal of arsenic in drinking water has become a subject of widespread concern. When the slurry-like magnesium hydroxide is used for drinking water purification, it will not cause the introduction of ferric and aluminum ions like aluminum and iron-based water purifiers, which will affect human health, and can ensure that there are essential minerals in the water and inhibit bacteria , The growth of algae, when added too much, will not cause adverse consequences.
Magnesium hydroxide can quickly and strongly adsorb arsenic with chemical bonds, and using magnesium hydroxide to remove arsenic is more economical than using other arsenic removal systems. Magnesium hydroxide has been approved as a water treatment agent and is used as a pH regulator in flocculation treatment. The cost is low, and the cost of required equipment is low.
Application of Slurry Magnesium Hydroxide in Treatment of Acidic Wastewater
Compared with alkalis such as caustic soda or limestone, the slurry-like magnesium hydroxide can control the pH value to no more than 9 when the slurry-like magnesium hydroxide is used to treat acid-containing wastewater, while the pH value of limestone is 12.5. Caustic soda pH will reach 14. Therefore, the use of slurry-like magnesium hydroxide to treat acidic wastewater is better than caustic soda or limestone, because when wastewater is biochemically treated, appropriate pH, nutritional conditions and alkalinity must be ensured, and it is difficult to control its alkalinity with caustic soda or limestone.
Application of Slurry Magnesium Hydroxide in the Treatment of Wastewater Containing Heavy Metals
Due to its large specific surface area and strong adsorption capacity, magnesium hydroxide can easily absorb and remove heavy metal ions such as Ni, Cd, Mn, Cr, etc. that are harmful to the environment from various industrial waste liquids. When using magnesium hydroxide slurry to treat chromium-containing wastewater, first reduce Cr with ferrous sulfate under acidic conditions, and then add magnesium hydroxide emulsion to neutralize the acid in the wastewater on the one hand, and make the chromium ions and iron in the wastewater The ions are removed by precipitation through the formation of hydroxides, so that the chromium in the wastewater can meet the discharge standard. When magnesium hydroxide slurry is used to treat lead-containing wastewater, the removal rate of lead can be over 96% while neutralizing the acid in the wastewater.
Application of Slurry Magnesium Hydroxide in the Treatment of Printing and Dyeing Wastewater
Printing and dyeing wastewater is a type of industrial wastewater that is extremely harmful to the environment. Its large discharge volume, complex composition, and deep color, especially various dyes with good water solubility and strong coloring power, make traditional treatment methods difficult to be effective. In recent years, research on the use of magnesium hydroxide to treat printing and dyeing wastewater has been carried out at home and abroad. The principle is to use positively charged magnesium hydroxide to adsorb negatively charged anionic dyes to decolorize dye wastewater. Magnesium hydroxide is used to decolorize the direct gray printing and dyeing industrial wastewater. The research shows that magnesium hydroxide has a good decolorization effect. Under the condition that the addition amount of magnesium salt is 600mg/L and the pH value is 11, the decolorization rate can reach over 98%. The saturated adsorption capacity of magnesium hydroxide to direct gray dye was determined to be 2.122g/g.
Application of Slurry Magnesium Hydroxide in Dephosphorization and Deammonization
The dephosphorization and ammonium removal effect of magnesium compounds such as slurry magnesium hydroxide, light-burned magnesium oxide and dolomite lime is remarkable. When treating sewage and wastewater with PO concentration less than 1200mg/L, the removal rate of phosphorus is over 90%. If the ammonium ion concentration in industrial wastewater is greater than 100mg/L, and the molecular ratio of NH and PO is greater than or equal to 1.0, it can be treated with slurry-like magnesium hydroxide to control the molecular ratio of Mg and PO to be greater than or equal to 1.0, and the pH value is 7.5. Stir and mix to form MgNH4PO4·6H2O, and then remove ammonium and phosphorus, and the resulting precipitate is separated and recovered by filtration and used as fertilizer. The same applies to other wastewater containing HPO and NH.
Application of Slurry Magnesium Hydroxide in Flue Gas Desulfurization
The use of magnesium hydroxide for desulfurization began in the mid-1970s and became popular in Japan after the 1980s. It has become increasingly mature and has become the mainstream process for flue gas desulfurization in Japan. Magnesium hydroxide is used as a flue gas desulfurizer, which has the characteristics of simple process, easy operation and control, and by-products can be recycled. The main advantage is that the operation process is easy to control, and has obvious technical, economic and environmental benefits.
Application of Slurry Magnesium Hydroxide in Red Tide High Incidence Areas in the East China Sea
The magnesium hydroxide co-precipitation method was applied to the investigation of phosphate in the water body of the East China Sea red tide high incidence area. The detection limit of this experimental method is 0.004 mol/L. This method is compared with the traditional phosphomolybdenum blue method, and the conventional phosphomolybdenum blue method is higher than the co-precipitation method. It shows that there may be a large number of phosphorus compounds that are unstable under acidic conditions in the water body, and they cannot be co-precipitated by magnesium hydroxide, such as 1-phosphate ribose. At this time, the measured value of co-precipitation method is closer to the real phosphate content in water.
The co-precipitation method can provide more reliable data for the analysis of samples in the low phosphorus stage during red tide outbreaks. The change of phosphate in the water during the red tide outbreak was analyzed by the measurement data provided by the co-precipitation method. The general distribution trend of the phosphate in the Changjiang Estuary is that the content is higher along the coast and gradually decreases towards the outer sea. During the red tide outbreak, with the proliferation of red tide algae, the phosphate in the water body is consumed in large quantities, and the phosphate concentration in the surface layer drops rapidly; during the red tide extinction stage, the phosphate concentration in the surface water body gradually rises, while the phosphate concentration in the bottom layer gradually rises due to the death of algae. high.
Application of Slurry Magnesium Hydroxide in Other Aspects
Compared with the traditional caustic soda method, the use of slurry-like magnesium hydroxide to remove waste gas containing HCl and Cl in chlor-alkali plants is more economical, effective, safe and harmless. Slurry magnesium hydroxide can also be used as an absorbent to remove the toxic gas HCl generated in the incinerator.
About 5% of magnesium hydroxide is used in the pharmaceutical industry every year. Pharmacopoeia-grade magnesium hydroxide includes high-purity powder tablets and emulsions containing 30% magnesium hydroxide, all of which are used as antacid drugs.
Highly alkaline magnesium hydroxide emulsion can be used to clean metal parts, such as the surface cleaning of steel and cast iron parts, the removal of aluminum oxide film on the surface of metal aluminum, etc. It is characterized by no harm to the operator’s skin, safe and economical, and no mud formation.