Fabrication and Characterization of Functional Biobased Membranes from Postconsumer Cotton Fabrics and Palm Waste for the Removal of Dyes

Abstract

Textile industries currently face vast challenges for the active removal of colored wastewater. Indeed, sustainable, recyclable, and green approaches are still lacking to achieve this aim. Thus, the present study explored the utilization of highly functional, green, recyclable, fully bio-based, and cost-effective composite membranes from post-consumer cotton fabrics and palm waste for wastewater treatment purposes. Highly functional cellulose nanofibers (CNF) were produced from waste cotton fabrics and filter paper using an acid hydrolysis technique. The yield of nanofibers extracted from waste cotton fabrics and filter paper was 76.74 and 54.50%, respectively. The physical, chemical, and structural properties of nanofibers were studied using various advanced analytical techniques. The properties of isolated nanofibers were almost similar and comparable to those of commercial nanofibers. The surface charge densities were -94.0, -80.7, and -90.6 mV for the nanofibers of palm waste, cotton fibers, and filter paper, respectively. After membrane fabrication using vacuum and hot-pressing techniques, the characteristics of the membrane were analyzed. The results showed that the average pore size of the palm-waste membrane was 1.185 nm, while it was 1.875 nm for membrane from waste cotton fibers and filter paper. Congo red and methylene blue dyes were used as model solutions to understand the behavior of available functional groups and the surface ζ-potential of the membrane frameworks' interaction. The membrane made from palm waste had the highest dye removal efficiency, and it was 23% for Congo red and 44% for methylene blue. This study provides insights into the challenges associated with the use of postconsumer textile and agricultural waste, which can be potentially used in high-performance liquid filtration devices for a more sustainable society.

Keywords: cellulose membranes; cellulose nanofibers; dye removal; palm waste; postconsumer cotton waste; sustainability.

Figure 1

(a) FT–IR spectra of palm waste, cotton fabric, filter paper, and extracted nanofibers in the range of 4000 to 500 cm¯¹ of wavenumber indicating the change in functional group intensity, (b) XRD patterns of palm waste, waste cotton fabrics, filter paper, and extracted nanofibers, (c) ζ–potential of nanofibers extracted from palm waste (square black dot), waste cotton fabric (blue circle), and Whatman filter paper (yellow triangle) as a function of pH.

Figure 2

Microscopic characterization of CNF isolated from palm waste, waste cotton fabric, and filter paper. Optical microscopic images of CNF isolated from palm waste (a), postconsumer cotton fabrics (b), and Whatman filter paper (c). Field emission scanning electron microscopic (FESEM) images captured at an acceleration voltage of 5.0 kV of cellulose nanofibers isolated from palm waste (d), cotton waste (e), and filter paper (f). Field emission transmission electron micrographs (FETEM) at an accelerating voltage of 300 kV of empty fruit bunch nanofibers (g), cotton waste nanofibers (h), and Whatman filter paper nanofibers (i). Nanofibers characterized with atomic force microscopy (AFM) of empty fruit bunch nanofibers (j), cotton waste nanofibers (k), and Whatman filter paper nanofibers (l). Nanofiber width distributions measured from FETEM images for empty fruit bunch nanofibers (m), cotton waste nanofibers (n), and Whatman filter paper nanofibers (o).

Figure 3

Thermogravimetric analysis (a) and derivative thermogravimetric curves (b) of source materials (palm waste, postconsumer cotton fabric, and filter paper) and isolated cellulose nanofibers.

Figure 4

(a) X-ray diffractogram of cellulose membranes fabricated from palm waste (EFB–M), postconsumer cotton fabric (CF–M), and filter paper (WFP–M), (b) surface hydrophilic properties of fabricated membrane framework determined by water drop test contact angle, and thermal stabilities of membranes evaluated by thermogravimetric analysis (c) and derivative thermogravimetric curves (d).

Figure 5

FESEM images of CNF membranes fabricated from palm waste nanofibers (EFB–M) (a), cotton nanofibers (CF–M) (c), and Whatman filter paper nanofibers (WFP–M) (e). Surface roughness of the membranes from FESEM images determined with ImageJ software for EFB–M (b), CF–M (d) and WFP–M (f). Inset showing bright field optical images of EFB–M (a), CF–M (c), and WFP–M (e).

Figure 6

(a) Plot of N₂ adsorption–desorption isotherms of volume adsorbed versus relative pressure (P/P₀) and (b) BJH pore size distributions for the fabricated membranes from palm waste nanofibers, cotton nanofibers, and Whatman filter paper nanofibers.

Figure 7

Removal of dyes using functional CNF membranes by direct filtration mode at initial dye concentrations of 10 mg L⁻¹. UV-visible spectroscopy showing a decrease in absorbance of dye after dye removal test versus the control (Cnt) at wavelength λ_max = 668 nm for methylene blue (a) and at wavelength λ_max = 478 nm for Congo red (b) for membranes fabricated from palm waste (EFB–M or M₁), cotton fabric (CF–M or M₂), and Whatman filter paper (WFP–M or M₃); molecular structure of dyes and their possible interactions with the membranes are shown (right).

Figure 7

Removal of dyes using functional CNF membranes by direct filtration mode at initial dye concentrations of 10 mg L⁻¹. UV-visible spectroscopy showing a decrease in absorbance of dye after dye removal test versus the control (Cnt) at wavelength λ_max = 668 nm for methylene blue (a) and at wavelength λ_max = 478 nm for Congo red (b) for membranes fabricated from palm waste (EFB–M or M₁), cotton fabric (CF–M or M₂), and Whatman filter paper (WFP–M or M₃); molecular structure of dyes and their possible interactions with the membranes are shown (right).

Figure 8

Synthesis of cellulose nanofibers from waste cotton fabrics. The bleaching mixture as discussed in the text was used for the production of long cellulosic fibers and then formic acid was used for the production of CNF.