纸浆纤维对钙离子吸附行为及机理

Adsorbing behavior and its mechanism of calcium ions on chemical wood pulp fibers

以去金属离子处理后的漂白硫酸盐桉木浆及针叶木浆为原料,研究纸浆纤维对Ca2+的吸附动力学及影响吸附的因素。结果表明:Ca2+初始浓度较低时,漂白化学木浆对Ca2+的吸附能力随着Ca2+初始浓度的增加而快速提高。Ca2+初始浓度0.471 7 mmol/L时,阔叶木浆达到饱和吸附,吸附量为0.016 0 mmol/g;针叶木浆在Ca2+初始浓度为0.220 1 mmol/L时就达到饱和吸附,吸附量为0.008 4 mmol/g,吸附能力与针阔叶浆各自所带羧基量一致。在pH 7.5、温度25℃条件下,符合Langmuir方程等温吸附线,且纸浆对Ca2+的吸附为单分子吸附。Ca2+浓度和pH的升高将使纸浆纤维对Ca2+的吸附能力提高,阔叶木浆和针叶木浆中Ca2+加入量为0.035 6和0.016 5 mmol/g时,木浆达到饱和吸附。pH超过7,纸浆表面游离羧基将完全被Ca2+吸附;纸浆纤维对Ca2+的吸附属放热吸附,提高温度将会降低纸浆纤维对Ca2+的吸附量。

The adsorbing kinetics and the factors of influencing calcium ion adsorption of both deionized BKP hard wood pulp and soft wood pulp were studied in this paper. The results showed that the adsorption capability of pulp fiber rise along with the augment of the beginning consistency of Ca^2＋ at a low Ca^2＋ consistency. The saturation adsorption capability of hard wood pulp is 0. 016 0mmol/g at the content of Ca^2＋ 0. 471 7 mmol/L, and the soft wood pulp being 0. 008 4 mmol/g at the content of Ca^2＋ 0. 220 mmol/L, which accords with the carboxyl content of pulps. At the conditions of pH 7.5 and 25 ℃, c,/Q and c, keep excellent linearity relationship, the R^2 being respectively 0. 95 and 0.99. It indicates the adsorption between pulp fiber and Ca^2＋ is chemistry adsorption, which accords with Langmuir isothermal equation, also belongs to single molecular adsorption. The adsorption capacity, of chemical wood pulp fiber on Ca^2＋ rise along with pH or content of Ca^2＋ , and the saturated adsorption content of Ca^2＋ of both BKP hard wood pulp and BKP soft wood pulp is 0. 035 6 mmol/g and 0. 016 5 mmol/g, the pulp being entirety saturated adsorption with Ca^2 ＋ after pH 7. Arising temperature will low the adsorption capacity, which belongs to exothermic adsorption between pulp fibers and Ca^2＋.