Corn cob biochar for the removal of lead ions (II): simultaneous optimization of four response variables

The study of the parameters involved in the pyrolysis process for biochar production has become extremely important for the success of its production and application. Then, this study aimed to optimize four response variables simultaneously by the iterative seemingly unrelated regression (ISUR) method, where these variables are linked to biochar production and application. Corn cob biochars were produced from experimental design in factorial experiment design (23) with central points, being the energy required in the process obtained by Arduino. Thus, the production yield and the energy required throughout the process were considered as two of the response variables of this study. The biochars were then activated with sodium hydroxide (NaOH). Lead adsorption was carried out in non-activated biochars as well as in chemically activated ones. These were the third and fourth response variables of this study. Finally, pyrolytic conditions were optimized by adjusting to the ISUR method, followed by the study of parameters. The optimization results for biochar production have as an optimal point, 390.5 degrees C, heating rate of 9.36 degrees C min-1, and residence time of 74.57 min. By using biochar produced under these conditions, a lead removal of 9.12 ppm in non-activated biochar and 99.00 ppm in chemically activated biochar is obtained. From the study of the parameters, it was possible to conclude that there is a wide combination of the parameters that could provide the range of the response variables of interest in this study.