新聞廢紙的酵素脫墨

Abstract

溫室效應日趨嚴重，全球能源資源逐漸吃緊，再生資源利用與再生能源開發展露希望的曙光，若將資源重複利用，如回收廢紙再次解纖，以酵素改質並提升其利用性，即可藉此降低對森林的依賴與市場對原生纖維之需求。本試驗建立回收廢紙酵素脫墨處理流程，在近中性條件下酵素脫墨的結果與傳統化學鹼性脫墨流程進行比較，探討其脫墨效率之差異及再生紙漿脫墨性質之改善。 回收新聞紙經酵素處理後，紙面斑點數較少而均勻，脫墨效率均高於94.6％，且脫墨效率有隨酵素添加量較多而提高之趨勢，殘墨量則均低於1.28 ppm。且收率並無大幅下降，厚度亦可提升2 ~ 15%。未漂前紙漿白度則由空白組的41% ISO約略下降，但若經單段或多段漂白處理後，白度均可達到52% ISO以上，尤以F-P-Y三段漂白者效果最佳，可達62% ISO，遠超過市售新聞紙之需求，且使b*有下降的趨勢。酵素脫墨時添加量應以3 U/g pulp較為宜，低酵素添加配合漂白處理，可得高白度、高嵩度且強度可與化學脫墨製得之紙張相近，酵素添加量提升至5 U/g pulp則會導致抗張、零跨距抗張、破裂及耐折等強度有較明顯的降低。 酵素處理可減少系統中纖細物且不含鹼，使濾水速率得以增加。以SEM觀察化學及以Novozyme 342酵素脫墨處理所得回收紙之毯面，不論是空白組、化學處理組或酵素處理組，其毯面均可見細碎顆粒/纖細物的存在，但其數量仍以空白組最多，化學組次之，酵素處理組最少，顯示酵素具對系統中纖細物減量之效果。提高漂白藥劑用量後，化學法處理組纖維表面的纖毛明顯減少，然而酵素法處理組纖維表面較為平整而有紋路，微纖毛依舊存在且為數眾多，但微細纖維有減少的現象。

The greenhouse effect has become more serious, and has been shortage of energy resource gradually depending the development of the renewable energy and the reuse of the recyclable resources. Recycled paper can lower the market need of the virgin pulp and rely of forest resource. The aim of this paper was to establish a deinking sequence under neutral conditions for waste paper using commercially available enzymes. Comparisons of deinking efficiencies and paper properties between conventional and enzymatic deinking was made and these pulp characteristics were also evaluated. After the enzymatic deinking, the yields of the old newsprint pulp didn't reduce much, the surface of the handsheet was even and only few residual ink spot were seen, the lowest deinking efficiency was 94%, and the rate of thickness increase of the handsheet was increased by 2 ~ 15%. The brightness of the handsheet after enzymatic treatment was 40% ISO, which was lower than the blank. But it could increase to more than 52% ISO after one or multi-stage bleaching processes, especially at the F-P-Y bleaching sequence, brightness of resulting pulp increase to 62% ISO, which was better than those of commercial newspapers. And the b* value was reduced gradually. The optimum enzyme dosage of enzymatic deinking should be 3 U per gram of pulp. Low enzyme dosage deinking and followed with bleaching treatment higher brightness, higher bulkness could be obtained, and compatible strength handsheets compared to conventional chemical deinking pulp. It resulted in the reducing of tensile strength, zero-span tensile strength, burst strength and folding endurance of the recycled paper when the enzyme dosage increased to 5 U per gram of pulp. The enzymatic treatment can processed without alkali, and also increased the speed of drainage by hydrolyzing fines in pulp. By the observation of SEM, it could be found the exist of small particles/fines remained on the felt side of enzyme treated paper. The amount of these small particles on the paper of blank treatment were much more than those of from paper of conventional and enzymatic treatment. And it also showed reduction of fines in the resulting pulp. After raising the dosage of bleaching chemicals, the fibril on the fiber surface of conventional deinking paper was clearly reduced, while the microfibril on the fiber surface of enzymatic deinking paper was remained.