响应面法优化制备塑料-锯末活性炭

将梧桐锯末和聚丙烯塑料按比例混合后，采用K2CO3活化法制备活性炭，基于中心组合实验设计(CCD)的响应面法(RSM)，以碘吸附值和亚甲基蓝吸附值为优化目标，优化工艺参数。结果表明，当塑料含量为19wt%、无水K2CO3与梧桐锯末质量比为1.73、活化温度为958℃、活化时间为91 min时，所制活性炭的性能最优，碘吸附容量为1320.97 mg/g，亚甲基蓝的吸附容量为471.95 mg/g，与二阶模型预测值接近，表明该模型具有较高的可信度。方差分析结果表明，盐料比、活化温度、活化时间提高对活性炭的碘吸附容量有显著的促进作用，而塑料含量对活性炭碘吸附容量有抑制作用；活化温度、活化时间对活性炭的亚甲基蓝吸附容量影响显著，与塑料含量均具有促进作用，而盐料比是非显著因素且有抑制作用。最优条件下所制活性炭的比表面积为1916.10 m2/g，总孔容为1.12 cm3/g，其中介孔高达70.10%。相比于单因素优化实验所制活性炭，比表面积提高了454.11 m2/g。FT-IR分析表明两种优化条件下所制活性炭的官能团基本没有变化，活性炭亚甲基蓝吸附量的提高主要是由于样品的比表面积增大。

Optimization of activated carbon preparation from sawdust and plastics using response surface method

Activated carbon was prepared from the mix of sycamore tree sawdust and polypropylene plastics by activation of K2CO3. Based on the central composite design (CCD) of response surface method (RSM), the preparation process was optimized, for the purpose of the highest methylene blue adsorption with higher iodine number. The optimum conditions were plastic content of 19wt%, K2CO3/sawdust mass ratio of 1.73, activation temperature of 958℃, and activation time of 91 min. The adsorption capacities of iodine and methylene blue were 1320.97 and 471.95 mg/g, with the predictive errors of 1.64% and 8.56%, respectively, which proves the high credibility of second-order model. The analysis of variance showed that the salt/sawdust ratio, activation temperature, and activation time were significant factors influencing the iodine adsorption capacity of activated carbon, which had a promoting effect, while plastic percentage had an inhibitory effect on the iodine adsorption capacity of activated carbon. The activation temperature and activation time had significant effects on the adsorption capacity of methylene blue on activated carbon, and had a promoting effect on the percentege of plastic. The salt/sowdust was a non-significant factor and had an inhibitory effect. The specific surface area, total pore volume and average pore size of the optimum sample were 1916.10 m2/g, 1.12 cm3/g, and 2.63 nm. Among them, the mesopore volume was 0.75 cm3/g, and the mesoporosity reached 70.10%. Compared with the activated carbon prepared by single factor optimization experiments, the specific surface area was increased by 454.11 m2/g. FT-IR analysis showed that the functional groups of the activated carbon prepared by the two optimization experiments did not change basically, and the increase of the activated carbon methylene blue adsorption was mainly due to the increase in specific surface area. The results suggested that the activated carbon optimized by response surface method has good absorptive property of macromolecules.