Study On The Synthesis And Adsorption Properties Of High Active MgO

A huge amount of magnesium resource in the westem saltlakes is not utilized effectively due to the limitation of the technicals and economic conditions. An important way to make full use of the magnesium resource in westem saltlakes is to develop magnesium produets such as active MgO, which is very important to economy and society. Active magnesium oxide is an important inorganic functional material, which is widely used in many fields including rubber, refractory materials, catalysis, environment protection?such as wastewater treatment, harmful gas adsorbent? and so on. The methods to prepare different morphologies and high active magnesium oxide were studied. The avtive magnesium oxides prepared by different methods were used as the adsorbents, and the adsorption behaviors of the active magnesium oxides to Pb²⁺ were studied. The main research contents are follows:The magnium oxide was prepared by calcining the raw material, the effects of calcinations temperature and time on activity of MgO were studied.The CAA value was lowest when the raw material was calcined at450°C for 4h and the value was 48.47 s, and the highest iodine number is 82.74mg/g; Hexagonal magnesium hydroxide with a mean particle size of 1?m was prepared by hydrothermal method, and optimal calcinations conditions for the preparation of active magnesium oxide is 400°C for 5h, the CAA value of hexagonal magnesium oxide was 24.85 s, and the iodine number is 161.42mg/g.The flower-like hydromagnesite and nesquehonite whisker were prepared by the carbonation method under normal pressure using magnesium hydroxide as raw materials. The optimal operating conditions for hydromagnesite precursor calcination are:calcination temperature at 650°C,calcination duration for 2h, the lowest CAA value of flower-like magnesium oxide was 11.50 s, and highest iodine number is 216.72mg/g; and for nesquehonite whisker the operating calcination temperature is 600°C, the lowest CAA value of magnesium oxide whisker was 8.45 s, and highest iodine number is 262.14mg/g.The influence of crystallization temperature, sodium citrate content, reaction time, stirring speed on the conversion of Mg2+ and morphology of nesquehonite whisker was studied, and the effect of sodium citrate on crystallization process was also illuminated. The results show that the reaction temperature can be raised to 90 °C and the conversion of Mg2+ can be reached to 80% with the additive of 0.2%?w/w? sodium citrate. The uniform nesquehonite whisker of which the aspect ratio is 28 and the crystallinity is 99.19% without Cl- and Na+ was successfully prepared under the optimized crystallization time and stirring speed of 30 min, 200r/min.The active magnesium oxide exhibits excellent Pb²⁺removal performance, and the maximum adsorption capacity is 364mg/g. The adsorption isotherm curve can be well correlated by Langmuir equation.