磷酸低温活化蔗渣基中孔生物炭及其影响因素

以甘蔗渣为原料,磷酸为活化剂,采用低温活化法制备蔗渣基中孔生物质炭.采用L9(34)4因素3水平正交实验,探讨制备蔗渣基中孔生物质炭的实验方案与工艺条件;分析了浸渍比、烘干时间、活化温度、活化时间在3个不同水平下,对蔗渣基生物质炭碘吸附值、亚甲基蓝吸附值的影响.结果表明,对蔗渣基生物质炭孔结构和得率影响最大的因素是活化温度,影响最小的因素是烘干时间;实验范围内,提高活化温度有利于材料中孔结构的形成;最佳条件下制备的蔗渣基生物质炭其低温氮气等温吸附线有明显的回滞环, BET比表面积和总孔容分别为939 m2/g和1.35 mL/g,中孔占总孔容比例为89%,亚甲基蓝吸附值高达240 mg/g,远高于木质净水用活性炭国家一级标准(135 mg/g),属于典型的中孔炭.

Preparation and its influence factors of mesoporous activated carbon from bagasse with phosphoric acid activation at low temperature

Mesoporous biomass-based activated carbons were prepared with bagasse as raw materials by H3PO4 activation at low temperature. A L934 (four three-level factors) orthogonal design table was established to discuss the influences of H3PO4 ratio, dry time, activation temperature and activation time on the iodine value and methylene blue values of the activated carbons. The experimental results show that the most important factor on the pore structure and yield of activated carbon was found out to be the activation temperature, while the minimal impact factor is the dry time. In the experimental range, the increase of activation temperature was conducive to the formation of mesopore. The nitrogen adsorption isotherm of bagasse activated carbon under optimum conditions have obvious hysteresis loop. The specific surface area of activated carbons was 939 m2/g by BET method. It was shown that the activatewd carbon was typical mesoporous carbon with 1.35 mL/g total pore volume, of which 89% was mesopore. The methylene blue value of carbon prepared under optimal conditions reached 240 mg/g, which is far above the national first level for wooden granular activated carbon used for water purification (135 mg/g).