Application of slurry magnesium hydroxide in water treatment
Slurry magnesium hydroxide has the following advantages when used for water purification: high activity, good removal effect on suspended solids, COD, BOD oil, odor, heavy metal ions, phosphates, sulfates, acids, dyes, phenols, and silicates in wastewater, with a removal rate of 75%-99%, especially suitable for papermaking wastewater, electroplating wastewater, domestic sewage, printing and dyeing wastewater, leather wastewater, high fluoride wastewater, and acidic wastewater.
Application of slurry magnesium hydroxide in drinking water purification and arsenic removal
Arsenic in drinking water is a carcinogen, and arsenic removal from drinking water has become a topic of general concern. When slurry magnesium hydroxide is used for drinking water purification, it will not cause the introduction of trivalent iron 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, inhibit the growth of bacteria and algae, and will not cause adverse consequences when added in excess.
Magnesium hydroxide can quickly and strongly adsorb arsenic with chemical bonds, and it is more economical to remove arsenic with magnesium hydroxide than with other arsenic removal systems. Magnesium hydroxide has been approved as a water treatment agent and is used as a pH adjuster in flocculation treatment. Low cost, low equipment cost.
Application of slurry magnesium hydroxide in the treatment of acidic wastewater
Compared with alkalis such as caustic soda or limestone, slurry magnesium hydroxide can control the pH value to no more than 9 when treating acidic wastewater, while the pH value of limestone is 12.5 and the pH value of caustic soda reaches 14. Therefore, the use of slurry magnesium hydroxide to treat acidic wastewater is better than caustic soda or limestone, because the appropriate pH value, nutrient conditions and alkalinity must be guaranteed during the biochemical treatment of wastewater, and it is difficult to control its alkalinity with caustic soda or limestone.
Application of slurry-like magnesium hydroxide in the treatment of heavy metal-containing wastewater
Magnesium hydroxide is easy to adsorb and remove heavy metal ions such as Ni, Cd, Mn, Cr, etc. that are harmful to the environment from various industrial wastewaters due to its large specific surface area and strong adsorption capacity. When using magnesium hydroxide slurry to treat chromium-containing wastewater, ferrous sulfate is first used to reduce Cr under acidic conditions, and then magnesium hydroxide emulsion is added to neutralize the acid in the wastewater on the one hand, and the chromium ions and iron ions in the wastewater are formed into hydroxide precipitation and removed on the other hand, so that the chromium in the wastewater meets the discharge standard. When magnesium hydroxide slurry is used to treat lead-containing wastewater, the lead removal rate can be above 96% while neutralizing the acid in the wastewater.
Application of slurry-like 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. It has a large discharge volume, complex composition, and deep chromaticity. In particular, various dyes with good water solubility and strong coloring power make traditional treatment methods difficult to work. 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 was used to decolorize direct gray printing and dyeing industrial wastewater. Studies have shown that magnesium hydroxide has a good decolorization effect. Under the conditions of magnesium salt addition of 600 mg/L and pH value of 11, the decolorization rate is over 98%. The saturated adsorption capacity of magnesium hydroxide on direct gray dyes was determined to be 2.122 g/g.
Application of slurry magnesium hydroxide in dephosphorization and deammonium removal
The use of slurry magnesium hydroxide, light-burned magnesium oxide, dolomite and other magnesium compounds has a significant effect on dephosphorization and deammonium removal. When treating sewage and wastewater with a PO concentration of less than 1200 mg/L, the phosphorus removal rate is over 90%. If the concentration of ammonium ions in industrial wastewater is greater than 100 mg/L and the molecular ratio of NH and PO is greater than or equal to 1.0, slurry magnesium hydroxide can be used for treatment, and the molecular ratio of Mg and PO is controlled to be greater than or equal to 1.0. Stirring and mixing at a pH of 7.5 forms MgNH4PO4·6H2O, and then removes ammonium and phosphorus. The resulting precipitate is separated and recovered by filtration and used as fertilizer. This is also applicable to other wastewaters containing HP0 and NH.
Application of slurry magnesium hydroxide in flue gas desulfurization
Desulfurization using magnesium hydroxide materials began in the mid-1970s and quickly became popular in Japan after the 1980s. It has become increasingly mature and perfect and has become the mainstream process of flue gas desulfurization in Japan. Magnesium hydroxide as a flue gas desulfurizer 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 the high-incidence area of red tide in the East China Sea
The magnesium hydroxide co-precipitation method is applied to the investigation of phosphate in the water body in the high-incidence area of red tide in the East China Sea. The detection limit of this experimental method is 0.004 mol/L. This method is compared with the traditional phosphomolybdenum blue method. The conventional phosphomolybdenum blue method is higher than the coprecipitation method. This 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 coprecipitated by magnesium hydroxide, such as 1-phosphoribose. At this time, the measured value of the coprecipitation method is closer to the true phosphate content in the water body.
The coprecipitation method can provide more reliable data for sample analysis in the low-phosphorus stage during the red tide outbreak. The measurement data provided by the coprecipitation method were used to analyze the changes in phosphate in the water body during the red tide outbreak. The overall distribution trend of phosphate in the Yangtze River Estuary is that the content is higher along the coast and gradually decreases toward the open sea. During the red tide outbreak, as the red tide algae proliferate, the phosphate in the water body is consumed in large quantities, and the surface phosphate concentration decreases rapidly; in the red tide extinction stage, the phosphate concentration in the surface water body gradually rises, while the bottom layer gradually settles due to the death of the algae and the phosphate concentration increases.
Other applications of slurry magnesium hydroxide
Using slurry magnesium hydroxide to remove waste gas containing HC1 and Cl in chlor-alkali plants is more economical, effective, safe and harmless than the traditional caustic soda method. Slurry magnesium hydroxide can also be used as an absorbent to remove toxic gas HC1 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 antacids.
High-alkalinity magnesium hydroxide emulsion can be used to clean metal parts, such as surface cleaning of steel and cast iron parts, and removal of aluminum oxide film on the surface of metal aluminum. The characteristics are that it does not cause any harm to the skin of operators, is safe and economical, and does not generate mud and scale.