| Mercury and mercury-containing compounds are widely used in the preparation of PVC by acetylene.The main use of mercury in China is to prepare mercury catalysts.Nowadays,a large amount of waste mercury catalyst produced by the use of the acetylene method for the preparation of PVC,although recycled,still has some problems such as high energy consumption or long process.Therefore,it is of great research value and practical significance to seek a new method for recycling waste mercury catalyst.This paper combines the traditional regeneration process with microwave energy to propose a recycling method for waste mercury catalyst,which provides a new idea for recovering mercury and regenerating activated carbon from waste mercury catalyst.This paper mainly studies the following aspects:The removal process of mercury under microwave and conventional heating conditions was first studied.In the case of conventional heating.In the case of conventional heating,the holding time is short;the calcination temperature has a more significant effect on the mercury removal rate than the holding time.When the calcination temperature is higher than 450?,the removal limit can be reached in a shorter time.At 400?and 450?,the mercury removal rate increases with increasing holding time,and the removal limit is reached over time.Then,in order to reveal the regeneration mechanism of waste mercury catalyst in traditional regeneration process and compare it with microwave regeneration,the conventional regeneration research of waste mercury catalyst was carried out.With water vapor as carrier gas,the optimal regeneration conditions were established by single factor experiment and the best.Regenerated activated carbon under conditions was characterized.The optimum regeneration conditions were determined: 900?,1.5 h,nitrogen flow rate of 100 L/h,water vapor flow rate of 30 L/h.At last,the process and regeneration mechanism of waste mercury catalyst regeneration under microwave conditions were systematically studied.The specific process can be divided into the following three types: microwave heating-ultrasonic spray regeneration;microwave heating-carbon dioxide activation regeneration;microwave regeneration under soda lime pretreatment.The optimal conditions for these three microwave processes were established.The results of these three processes all show that the microwave has a good removal effect on the impurities in the waste mercury catalyst(mainly inactivated different forms of mercury),and the carbon of the waste mercury catalyst in the case of less energy consumption in a shorter time.The matrix realizes pore regeneration.The results of these three processes all show that the microwave has a good removal effect on the impurities in the waste mercury catalyst,and the pore-regeneration of the carbon matrix of the waste mercury catalyst is realized in a shorter time and less energy consumption.At the same time,the regenerated activated carbon activated by microwave heating-ultrasonic spray was used to adsorb methyl orange and Congo red in organic printing and dyeing wastewater,and the results of adsorption experiments were obtained.The adsorption capacity of these activated activated carbons for methyl orange or Congo red was significantly higher than that of the other activated carbons,and the maximum adsorption amount reached 529.1 mg/g,indicating that the regenerated activated carbon is a low-cost adsorbent with high adsorption capacity.The adsorption mechanism of regenerated activated carbon was characterized.The results show that the Langmuir isotherm can be used to describe the adsorption behavior of regenerated activated carbon on methyl orange and Congo red dye.The Langmuir model shows adsorption as a single layer with uniform surface adsorption. |
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