Low-cost sisal fibers/polypyrrole/polyaniline biosorbent for sequestration of reactive orange 5 from aqueous solutions

Sisal is a natural fibrous low-cost biomaterial that is frequently found in the surrounding environment and has no toxic effects. To upgrade its performance and applicability, sisal was modified with polypyrrole/polyaniline via in-situ chemical oxidative polymerization technique for reactive orange 5 elimination from aqueous media. Nowadays, dye pollution and its subsequent adverse effects have been of great concern for all around the world. The prepared composite was characterized by SEM, FTIR, and XRD analysis; they indicated that the polypyrrole and polyaniline were successfully coated on sisal. Optimum contact time was found at 120 min, and at the adsorbent dosage of 200 mg, almost 97 % of dye was removed. At low dye concentration (5−10 ppm), the efficiency of the sorption system was significantly acceptable (99 %). pH 2 had the maximum adsorption capacity due to attraction between negatively charged dye and positive nature of sisal composite. In view of thermodynamics, the process was endothermic and so better removal was observed at 45 °C. Langmuir/Freundlich and Pseudo-second order could satisfactorily expound the sorption system with R2 values of greater than 0.99, exhibiting that physisorption/chemisorption occurred. Sisal/polypyrrole/polyaniline was more than 5.69 times effective than raw sisal for dye adsorption. In the case of synthetic wastewater, the removal efficiency reached 81 %. Hence, the low-cost sisal/polypyrrole/polyaniline composite was a promising alternative for reactive orange 5 removal.