Experimental study on synthesis of biological dust suppressant by microbial fermentation

Dust suppressant is an important way to improve the efficiency of water medium for dust control,and common dust suppressant used in coal mines is generally chemical dust suppressant.With the low surface activity,higher cost,poor biodegradability,as well as environment pollution and other issues associated with chemical dust suppressant,this paper aims to develop a new generation of dust suppressant,biological dust suppressant,with high surface activity and natural environment friendly.A technological process for synthesizing biological dust suppressant (BDS) from bacillus subtilis by fermentation has been developed and optimized with response surface optimization method and Design Expert software to explore optimal fermentation conditions of strains.X ray diffractometer and Infrared spectrum were used to explore the crystal type and functional group structure of BDS.The surface tension of BDS solution was tested by surface tensiometer to study the environmental tolerance under different temperatures,acidity and salinity conditions,and the wettability of BDS was compared with Alcohol ethoxylate (AEO) measured by interface rheometer and SEM.The results of the research demonstrated as follows:firstly,the fermentation broth received by activation,optimization and culture of Bacillus subtilis is purified to obtain BDS by acidizing precipitation,ultrasonic extraction and vacuum evaporation.Secondly,the BDS can be produced to the maximum capacity of 2.09 g/L under the conditions of temperature=37.56 ℃,pH=7.99,rotating speed=220 r/min,inoculant=2.17%,and liquid loading=59.89 mL.Thirdly,the BDS is an amorphous active and structurally isotropic substance with long alkane chains and polypeptides.Fourthly,the surface tension of water can be reduced below 27 mN/m with the critical micelle concentration of 30 mg/L,and BDS can still maintain the surface tension in the range of 27-30 N/m under the changeable conditions of temperature below 70 ℃,pH between 5-9 or NaCl content below 15%.Fifthly,the superior wettability of 6 mg/L BDS,which can reduce the wetting angle of coal dust to 11.19°,is increased by 63.5% compared with 500 mg/L AEO.This research for biological dust suppressant synthesizing by microbial fermentation provides a new way of thinking and scheme to solve the problem of weak surface activity and insufficient environmental protection faced by traditional dust suppressants.