# Characterization and Application of Calotropis Procera Fiber as a Sustainable Filter for Oil Removal from Aqueous Emulsion

## TL;DR

This paper explores using fibers from Calotropis procera to create a sustainable filter for removing oil from water mixtures.

## Contribution

The study is the first to apply Calotropis procera fibers for oil removal and provides the most detailed chemical analysis of these fibers.

## Key findings

- CP fibers are tubular with strong anisotropy and adsorb oil mainly at internal surfaces.
- The fibers showed over 95% oil removal efficiency under agitation with low fiber mass.
- Fibers retained effectiveness for oil adsorption through three reuse cycles.

## Abstract

Fibers extracted from Calotropis procera (CP) fruits were successfully used to filter engine oil from a synthetic
oil-in-water effluent. Fiber morphology was examined by scanning electron
(SEM) and optical (OM) microscopies, while their structural, vibrational
and chemical properties were systematically studied by thermogravimetric
analysis (TG), X-ray diffraction (XRD), and Fourier transform infrared
(FTIR) spectroscopy. It was first demonstrated that the fibers are
tubular with strong anisotropy and that when placed in oil, most oil
adsorption occurs at their internal surfaces, a region with higher
hemicellulose concentration. Contact angle experiments and standard
gravimetric measurements confirmed that the fibers are hydrophobic,
while FTIR results have suggested a small amount of water retained
within the fiber walls after forced submersion. Using a cylindrical
filter in continuous mode and a semispherical filter in batch mode,
the percentile of oil removal (OR %) was 67% for 200 mg of fiber mass
(FM) and a flow rate (Q) of 172 mL min–1 and higher
than 95% when the effluent is under agitation at 140 rpm and FM of
30 mg. The OR % variation data with FM in the cylindrical filter was
consistent with a constant removal ratio as a function of penetration
depth, whereas the results for the semispherical geometry have indicated
an increase in OR % with effluent speed. The fibers retained their
effectiveness throughout three reuse cycles, consistently adsorbing
more than 50% of the emulsified oil. Thus, this study represents the
first report on the application of CP fibers as an oil filter for
oil-in-water emulsions and provides the most detailed chemical composition
analysis of these fibers to date.