OPTIMASI BIOPROSES MODIFIKASI PERMUKAAN SERAT UNTUK PENINGKATAN KEKUATAN KERTAS

Fiber surface modification is a main process to improve paper quality. It is usually done mechanically through refining process. In this research the modification was done microbiologically by using Acetobacter xylinum. In principle, this process is carried out by growing bacterial cellulose on the fiber surface, which is similar to fibrillation by mechanical action. The modification was done at the short fibers at 5 duration reaction times and 4 level agitation speeds. The experiments were conducted in a 75 liter active volume bioreactor filled with a liquid inorganic media, 0.75% pulp consistency, at 30°C temperature, and pH 5.5. The washed pulp was then turned into sheets for testing purposes. The experiments show that at 37.5 Hz agitation speed and 1-3 hours reaction time, the paper strength and structure improve effectively. In addition, this optimized process also shows a potential energy saving up to 17.24% at agitation speed of 25,0 Hz.Keywords: fiber surface modification, Acetobacter xylinum, paper strength, short fibers ABSTRAK Modifikasi permukaan serat adalah proses inti pembuatan kertas untuk meningkatkan kualitas kertas. Pada umumnya modifikasi permukaan serat dilakukan secara mekanis melalui proses penggilingan. Pada penelitian ini modifikasi permukaan serat dilakukan secara mikrobiologis menggunakan Acetobacter xylinum. Proses ini berlangsung dengan cara menumbuhkan bakteri pembentuk selulosa pada permukaan serat sehingga serat terfibrilasi. Penelitian dilakukan pada serat pendek dengan variasi 5 durasi waktu reaksi dan 4 tingkat kecepatan agitasi. Proses modifikasi dilakukan dalam bioreaktor dengan volume aktif 75 liter menggunakan media anorganik cair, pada konsistensi pulp 0,75%, suhu 30°C, dan pH 5,5. Pulp hasil reaksi dicuci kemudian dibuat lembaran untuk diuji karakteristik fisiknya. Hasil pengamatan menunjukkan bahwa pada kondisi kecepatan agitasi 37,5 Hz dan waktu inkubasi 1-3 jam, bioproses modifikasi serat efektif untuk meningkatkan kekuatan kertas, memperbaiki struktur lembaran kertas, dan berpeluang menghemat energi sebesar 17,24% pada kecepatan agitasi 25,0 Hz.Kata kunci: modifikasi permukaan serat, Acetobacter xylinum, kekuatan kertas, serat pendek

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Chemical Modification as a Method of Improving Biocompatibility of Carbon Nonwovens

Materials ◽

10.3390/ma14123198 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3198

Author(s):

Justyna Frączyk ◽

Sylwia Magdziarz ◽

Ewa Stodolak-Zych ◽

Ewa Dzierzkowska ◽

Dorota Puchowicz ◽

...

Keyword(s):

Surface Modification ◽

Cellular Response ◽

Fiber Surface ◽

Thermal Conversion ◽

Cartilage Tissue ◽

Polar Component ◽

Nonwoven Fabrics ◽

Biological Compatibility ◽

Starting Point

It was shown that carbon nonwoven fabrics obtained from polyacrylonitrile fibers (PAN) by thermal conversion may be modified on the surface in order to improve their biological compatibility and cellular response, which is particularly important in the regeneration of bone or cartilage tissue. Surface functionalization of carbon nonwovens containing C–C double bonds was carried out using in situ generated diazonium salts derived from aromatic amines containing both electron-acceptor and electron-donor substituents. It was shown that the modification method characteristic for materials containing aromatic structures may be successfully applied to the functionalization of carbon materials. The effectiveness of the surface modification of carbon nonwoven fabrics was confirmed by the FTIR method using an ATR device. The proposed approach allows the incorporation of various functional groups on the nonwovens’ surface, which affects the morphology of fibers as well as their physicochemical properties (wettability). The introduction of a carboxyl group on the surface of nonwoven fabrics, in a reaction with 4-aminobenzoic acid, became a starting point for further modifications necessary for the attachment of RGD-type peptides facilitating cell adhesion to the surface of materials. The surface modification reduced the wettability (θ) of the carbon nonwoven by about 50%. The surface free energy (SFE) in the chemically modified and reference nonwovens remained similar, with the surface modification causing an increase in the polar component (ɣp). The modification of the fiber surface was heterogeneous in nature; however, it provided an attractive site of cell–materials interaction by contacting them to the fiber surface, which supports the adhesion process.

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