Extraction of micro fibrous cellulose from coconut husk by using chlorine free process: Potential utilization application as a filter aid

•Micro cellulose fibers were extracted by using renewable and potent source of cellulose.•Green- chlorine free method was utilized for the extraction by using the optimized reaction conditions.•Admirable yield obtaining as white colored, rod shaped cellulose fibers having size 14 µm and good crystallinity.•Physico-chemical changes were evidenced by the analytic methods like FT-IR, XRD, SEM, EDX and HR TEM.•The swelling investigations showed that cellulosic fibers show vivid swelling at pH 9.4, 37 °C temperature within 6 h contact time. Cellulose is one of the most important linear, hydrophobic biopolymers built-up of several units of d-glucopyranose unite through beta-1,4-Glycosidic linkage. Due to these structural features, porous nature, swelling property and strength, cellulose has many industrial and biomedical applications. In this work, we have effectively isolated micro fibrous cellulose from waste coconut husk after removing lignin, hemicellulose, and other impurities by repeated water washings, mechanical, alkali (NaOH) and chlorine free green hydrogen peroxide bleaching. This process provides about 42% w/w white to off white soft micro fibrous long and individual cylindrical rod-like microfibril having fiber size of ∼ 14 µm. The extracted micro fibrous cellulose was evaluated for structural, morphological, crystalline, and thermal properties by using FTIR, SEM, HR-TEM, XRD, and DSC. The swelling capacity of extracted micro fibrous cellulose was investigated at different pH for different contact hours. The maximum percentage swelling capacity (PSC) (991.7%) was observed in 6 h at pH 9.4 which is comparable to PSC obtained (975%) at pH 7.4 in 24 h. The property of porous nature, and high surface area, enable it to use as an eco-friendly filter aid for effective removal of colored impurities from different chemicals and pharmaceutical substances, ensuring high quality purified material. [Display omitted]