The Enteromorpha prolifera biochar and 4A zeolite-modified biochar based on different pyrolysis temperatures were prepared. The biochar of good biocompatibility with Bt was selected by studying the effects of different biochar on the survival rate and salt tolerance of Bacillus thuringiensis (Bt). The biochar microspheres loaded with Bt were prepared with sodium alginate, pectin, and chitosan. The effects of the addition of biochar on the particle size and ball formation rate of the microspheres were investigated. The structure of the microspheres was characterized by SEM and FTIR, and the SR of the microspheres under different pH conditions were evaluated. The results showed that 4A zeolite-modified biochar prepared at 500 celcius (GH500) had good compatibility with Bt, and could improve the salt tolerance of Bt. The prepared microspheres have a uniform shape and particle size, and their swelling characteristics were pH-responsive, the microspheres containing biochar exhibited good swelling properties under alkaline conditions.
