Virk Antar Puneet, Puri Minakshi, Gupta Vijaya, Capalash Neena, Sharma Prince
Department of Biotechnology, Panjab University, Chandigarh, India.
PLoS One. 2013 Aug 15;8(8):e72346. doi: 10.1371/journal.pone.0072346. eCollection 2013.
The development in the deinking process has made recycled fiber a major part of the raw material for pulp and paper industry. Enzymes have revolutionized the deinking process obtaining brightness levels surpassing conventional deinking processes. This study explores the deinking efficiencies of bacterial alkalophilic laccase (L) and xylanase (X) enzymes along with physical deinking methods of microwaving (MW) and sonication (S) for recycling of old newsprint (ONP).
The operational parameters viz. enzyme dose, pH and treatment time for X and L deinking were optimized statistically using Response Surface Methodology. Laccase did not require any mediator supplementation for deinking. Deinking of ONP pulp with a combination of xylanase and laccase enzymes was investigated, and fiber surface composition and morphological changes were studied using X-ray diffraction, fourier transform infrared spectroscopy and scanning electron microscopy. Compared to the pulp deinked with xylanase (47.9%) or laccase (62.2%) individually, the percentage reduction of effective residual ink concentration (ERIC) was higher for the combined xylanase/laccase-deinked pulp (65.8%). An increase in brightness (21.6%), breaking length (16.5%), burst factor (4.2%) tear factor (6.9%), viscosity (13%) and cellulose crystallinity (10.3%) along with decrease in kappa number (22%) and chemical consumption (50%) were also observed. Surface appeared more fibrillar along with changes in surface functional groups. A combination of physical and enzymatic processes (S-MW-XL) for deinking further improved brightness (28.8%) and decreased ERIC (73.9%) substantially.
This is the first report on deinking of ONP with laccase without any mediator supplementation. XL pretreatment resulted in marked improvement in paper quality and a new sequence being reported for deinking (S-MW-XL) will contribute further in decreasing chemical consumption and making the process commercially feasible.
脱墨工艺的发展使回收纤维成为制浆造纸工业原料的主要组成部分。酶彻底改变了脱墨工艺，使纸张白度超过传统脱墨工艺。本研究探讨了嗜碱细菌漆酶（L）和木聚糖酶（X）的脱墨效率，以及微波（MW）和超声处理（S）等物理脱墨方法对旧新闻纸（ONP）回收利用的效果。
采用响应面法对木聚糖酶和漆酶脱墨的操作参数（即酶用量、pH值和处理时间）进行了统计学优化。漆酶脱墨无需添加任何介体。研究了木聚糖酶和漆酶联合用于ONP纸浆脱墨的效果，并通过X射线衍射、傅里叶变换红外光谱和扫描电子显微镜研究了纤维表面组成和形态变化。与单独使用木聚糖酶（47.9%）或漆酶（62.2%）脱墨的纸浆相比，木聚糖酶/漆酶联合脱墨纸浆的有效残余油墨浓度（ERIC）降低百分比更高（65.8%）。还观察到白度提高（21.6%）、裂断长提高（16.5%）、耐破因子提高（4.2%）、撕裂因子提高（6.9%）、粘度提高（13%）和纤维素结晶度提高（10.3%），同时卡伯值降低（22%）和化学品消耗降低（50%）。表面出现更多原纤化现象，表面官能团也发生了变化。物理和酶法联合脱墨工艺（S-MW-XL）进一步提高了白度（28.8%），并显著降低了ERIC（73.9%）。
这是关于不添加任何介体的漆酶用于ONP脱墨的首次报道。XL预处理显著改善了纸张质量，所报道的新型脱墨顺序（S-MW-XL）将进一步有助于降低化学品消耗并使该工艺具有商业可行性。
