Abstract

The objective of this investigation was to assess the feasibility of replacing anthraquinone (AQ) as a yield enhancing catalyst in kraft pulping with Me-THAD. It was anticipated that residual Me-THAD on the washed pulp fibers would be air-oxidized to 2-methyl-anthraquinone (MAQ) during commercial fiber drying. While AQ is listed as a possible human carcinogen by the International Agency for Research on Cancer (IARC), MAQ is not. Also, MAQ was reported to actually retard the propagation of cancer cells in more than one refereed publication. In this study, it was observed that both of the methyl-substituted catalysts (MAQ and Me-THAD) were equal or more effective than AQ at increasing fiber yield when added to kraft pulping of both a softwood (southern pine) and a hardwood (eucalyptus). It was observed that pure Me-THAD powder oxidized to MAQ at room temperature (∼22 °C). The inference was drawn that residual Me-THAD on washed fibers from kraft/Me-THAD pulping also oxidized to MAQ. Extracts from such fibers from a eucalyptus pulp were carefully analyzed on a Thermo Scientific Trace 1310 with Orbitrap GC/MS. The unbleached fibers contained 20 μg/kg (ppb) of MAQ and ∼1 μg/kg of Me-THAD. When bleached using the D₀EpD₁ sequence to 90% Elrepho brightness, the fibers contained 3.5 μg/kg of MAQ and no Me-THAD. A preliminary assessment on the economics of Me-THAD synthesis at commercial scale is included.

摘要

本研究的目的是评估在硫酸盐法制浆中用 Me-THAD 代替蒽醌 (AQ) 作为产率提高催化剂的可行性。预计在商业纤维干燥过程中，洗涤过的纸浆纤维上残留的 Me-THAD 会被空气氧化成 2-甲基-蒽醌 (MAQ)。虽然 AQ 被国际癌症研究机构 (IARC) 列为可能的人类致癌物，但 MAQ 不是。此外，据报道，在不止一份参考出版物中，MAQ 实际上会延缓癌细胞的增殖。在这项研究中，观察到当添加到软木（南松）和硬木的牛皮纸制浆中时，这两种甲基取代的催化剂（MAQ 和 Me-THAD）在增加纤维产量方面与 AQ 相同或更有效（桉树）。观察到纯 Me-THAD 粉末在室温（~22°C）下氧化成 MAQ。推断来自牛皮纸/Me-THAD 制浆的洗涤纤维上残留的Me-THAD 也被氧化成MAQ。在带有 Orbitrap GC/MS 的 Thermo Scientific Trace 1310 上仔细分析了从桉树浆中提取的此类纤维。未漂白的纤维含有 20 μg/kg (ppb) 的 MAQ 和~1 μg/kg 的 Me-THAD。使用 D 漂白时₀ EpD ₁序列至 90% Elrepho 亮度，纤维含有 3.5 μg/kg MAQ 且不含 Me-THAD。包括对商​​业规模的 Me-THAD 合成的经济性的初步评估。