活性炭表面酸性含氧官能团对吸附甲醛的影响

利用Bothem滴定法测定了化学浸渍处理的活性炭表面酸性含氧官能团浓度,研究表面酸性含氧官能团对甲醛吸附的效应。结果表明,HNO3浸渍处理能有效增大活性炭表面的羧基、酚羟基和内酯基浓度;H2O2浸渍处理主要增大了活性炭表面的酚羟基浓度;随着NaOH浓度的增大,活性炭表面的酚羟基、内酯基和羰基浓度大致呈先增大后减小的趋势,这是由于NaOH的化学清洗作用和酸碱中和反应所致;HNO3浸渍处理的活性炭表面的酸性含氧官能团浓度显著超过NaOH、H2O2浸渍处理的活性炭,而30%(质量分数)NaOH浸渍处理的活性炭和30%(体积分数)H2O2浸渍处理的活性炭吸附甲醛的饱和时间比HNO3浸渍处理的活性炭吸附甲醛最大饱和时间分别多4.0、1.5 h,说明酚羟基能够显著影响活性炭吸附甲醛的效果。

The effect of acid functional groups of modified activated carbon on formaldehyde absorption

Few groups of activate carbons (AC)were modified by dipping them in different impregnating solutions , and the oxygen-containing acidic functional groups on the surface of modified AC were determined by Bothem titration method so as to give insight into the effect of the oxygen-containing acidic functional groups on formaldehyde absorption. The results showed that more carboxyl, phenolic hydroxyl and lactone groups were found on the surface of HNO_3 modified AC, while only phenolic hydroxyl group on AC was increased after dipping in H_2O_2. The molality of phenolic hydroxyl, lactone and carbonyl groups on surface of NaOH modified AC presented the tendency of increased first and decreased later with increasing the mass fraction of NaOH solution. Both the number of acidic functional groups and surface structure of AC were relevant to formaldehyde adsorptions however, the phenolic hydroxyl group was the key factor that affects formaldehyde adsorption due to its chemical reaction with formaldehyde.