Xylanase-Aided Chlorine Dioxide Bleaching of Bagasse Pulp to Reduce AOX Formation

Abstract

Xylanase pretreatment was used to improve the chlorine dioxide bleaching of bagasse pulp. The pulp was pretreated with xylanase, which was followed by a chlorine dioxide bleaching stage. The HexA content of the pulp and the AOX content of the bleaching effluent were measured using UV-Vis and GC-MS methods, respectively. The results showed that a good correlation occurred between HexA and kappa number. HexA content of the pulp decreased significantly after the xylanase pretreatment. The AOX content of the bleaching effluent decreased as HexA was removed from the pulp. It was found that AOX could be reduced by up to 29.8%, comparing XD0 with a D0 stage. Fourier transform infrared spectroscopy (FTIR) was employed to determine the breakage of chemical bonds in the pulp. It revealed that some lignin and hemicellulose were removed after xylanase treatment. The GC-MS results showed that some toxic chloride such as 2,4,6-trichlorophenol could be completely removed after xylanase pretreatment.

Aplikasi Enzim Di Industri Pulp Dan Kertas: I. Bidang Pulp (Enzyme Application in Pulp and Paper Industry: I. Pulp Section)

“…Beberapa teknologi kimiawi yang sudah digunakan adalah menyisipkan tahapan asam dan suhu tinggi di antara proses pemasakan dan pemutihan, menggunakan bahan kimia pemutih elektrofilik seperti bahan kimia berdasar klorin dan ozon (Vuorinen et al, 1999) dan asam perasetat (Tavast et al, 2011). Namun teknologi ini memiliki keterbatasan terkait dengan isu lingkungan seperti pembentukan senyawa klor-organik dan menurunnya kualitas pulp misalnya viskositas karena penggunaan ozon (Pouyet, Chirat and Lachenal, 2013) Berdasarkan batasan tersebut, teknologi enzim (biobleaching) mulai diperkenalkan untuk proses bleaching karena teknologi ini sederhana dan efektif untuk menurunkan biaya penggunaan bahan kimia bleaching sehingga kandungan AOX pada efluen menurun (Fillat and Roncero, 2009b;Sharma et al, 2014;Dai et al, 2016). Selain itu proses ini juga tidak membutuhkan investasi yang terlalu besar (Dai et al, 2016).…”

“…2. Penggunaan xilanase pada proses biobleaching dapat menurunkan konsumsi bahan kimia pemutihan sejumlah 15-20% (Saleem et al, 2009;Nie et al, 2015;Dai et al, 2016) tanpa mengubah kondisi di pabrik. Bahan kimia klorin akan menurun lebih dari 30% sehingga senyawa organoklorin yang terbentuk pada efluen menurun sejumlah 15-20% dapat dicapai sehingga biaya produksi berkurang (Thakur, Jain and Mathur, 2012;Valenzuela et al, 2014;Dai et al, 2016).…”

Pulp and Paper Mill Effluent Management

“…Xylanase was used to pre-treat bagasse pulp before chlorine dioxide bleaching to reduce AOX formation (Dai et al 2016). The pulp's hexeneuronic acid content was reduced by the xylanase treatment and the AOX formation decreased by up to 29% relative to the DO stage without enzymatic pre-treatment.…”

Absorbable Organic Halide Reduction Research in Elemental Chlorine-Free Bleaching of Eucalyptus Kraft Pulp

“…In recent years, chlorine dioxide was adopted as the main reagent of bleaching [2,3]. The advantage is that the formation of dioxins and absorbable organic halogens (AOx) was reduced in effluent [4,5]. As one of the main kind of persistent organic pollutants (POPs) from bleaching process, AOx has the characteristics of permanent residual, bioaccumulation, high toxicity, long-range migration and semi-volatile [6].…”