Taking citric acid-modified pepper straw-based biochar as the object, an optimal process for the adsorption process of methylene blue was studied. The dosage of modified carbon, methylene blue concentration, adsorption time, temperature, solution pH, and shaker speed were taken as investigation factors and methylene blue adsorption as investigation index, the Plackett-Burman (P-B) design was used to screen out the factors of significant effects. And further combined with the Box-Behnken Design (BBD) response surface method, the significant factors were optimized and verified and analyzed to obtain the optimal adsorption process parameters. The results showed that among the selected 6 factors, the order of significance affecting the adsorption capacity of methylene blue was modified carbon dosage > methylene blue concentration > shaking table rotation speed. The interaction effect between the significant factors was as follows: dosage of modified carbon and rotating speed of shaking table > dosage of modified carbon and concentration of methylene blue > concentration of methylene blue and rotating speed of shaking table. After optimization, the optimum adsorption conditions were obtained as follows: the dosage of modified carbon was 45.40 mg, the concentration of methylene blue was 86.00 mg/L, and the rotating speed of the shaking table was 130 r/min. Under these conditions, the adsorption capacity of methylene blue could reach 41.03 mg/g, the difference between the verified value and the model predicted value of 42.24 mg/g was 2.87%, therefore, the P-B/BBD method is stable and effective in optimizing the adsorption process of modified biochar for methylene blue, which provides a data reference for optimizing the adsorption process of carbon materials.

modified biochar  /  methylene blue  /  adsorption process  /  Plackett-Burman design  /  Box-Behnken response surface method