Polymer Ligands Derived from Jute Fiber for Heavy Metal Removal from Electroplating Wastewater

Abstract

Industrial operations, domestic and agricultural activities worldwide have had major problems with various contaminants caused by environmental pollution. Heavy metal pollution in wastewater also a prominent issue; therefore, a well built and economical treatment technology is demanded for pollution-free wastewater. The present work emphasized pure cellulose extracted from jute fiber and further modification was performed by a free radical grafting reaction, which resulted in poly(methyl acrylate) (PMA)-grafted cellulose and poly(acrylonitrile)-grafted cellulose. Subsequently, poly(hydroxamic acid) and poly(amidoxime) ligands were prepared from the PMA-grafted cellulose and PAN-grafted cellulose, respectively. An adsorption study was performed using the desired ligands with heavy metals such as copper, cobalt, chromium and nickel ions. The binding capacity (q_e) with copper ions for poly(hydroxamic acid) is 352 mg g^-1 whereas q_e for poly(amidoxime) ligand it was exhibited as 310 mg g^-1. Other metal ions (chromium, cobalt and nickel) show significance binding properties at pH 6. The Langmuir and Freundlich isotherm study was also performed. The Freundlich isotherm model showed good correlation coefficients for all metal ions, indicating that multiple-layers adsorption was occurred by the polymer ligands. The reusability was evaluated and the adsorbents can be reused for 7 cycles without significant loss of removal performance. Both ligands showed outstanding metals removal capacity from the industrial wastewater as such 98% of copper can be removed from electroplating wastewater and other metals (cobalt, chromium, nickel and lead) can also be removed up to 90%.

Keywords: adsorption; graft copolymer; jute cellulose; poly(amidoxime) ligand; poly(hydroxamic acid); wastewater.

Scheme 1

PMA-grafted jute cellulose, PAN-grafted jute cellulose, poly(hydroxamic acid) (PHA), poly(amidoxime) (PA) and PHA /or PA-metal complex (CL indicated a anhydroglucose unit).

Figure 1

FT-IR spectra of (a) jute cellulose, (b) PMA-grafted cellulose, (c) poly(hydroxamic acid) ligand and (d) copper complex with poly(hydroxamic acid) ligand.

Figure 2

FT-IR spectra of (a) jute cellulose, (b) PAN-grafted cellulose and (c) poly(amidoxime) ligand.

Figure 3

FE-SEM micrograph of (a) jute cellulose, (b) PMA-grafted cellulose, (c) poly(hydroxamic acid) ligand and (d) poly(hydroxamic acid) ligand-copper complex.

Figure 4

FE-SEM micrograph of (a) jute cellulose, (b) PAN-grafted cellulose, (c) poly(amidoxime) ligand, and (d) poly(amidoxime) ligand-copper complex.

Figure 4

FE-SEM micrograph of (a) jute cellulose, (b) PAN-grafted cellulose, (c) poly(amidoxime) ligand, and (d) poly(amidoxime) ligand-copper complex.

Figure 5

X-ray diffraction (XRD) patterns of (a) cellulose, (b) PMA-grafted cellulose, (c) PHA ligand and (d) PHA–Cu. complex.

Figure 6

XRD patterns of (a) cellulose, (b) PAN-grafted cellulose (c) poly(amidoxime) ligand and (d) PA–Cu complex.

Figure 7

(left) Thermogravimetry analysis (TGA) thermograms of cellulose (a), PMA-grafted cellulose (b), poly(hydroxamic acid) ligand (c), PHA-copper complex (d) and (right) thermograms of cellulose (a), PAN-grafted cellulose (e), poly(amidoxime) ligand (f), PA–copper complex (g).

Figure 8

The effect of pH on the adsorption of heavy metal ions by the jute cellulose-based polymer ligands: (a) PHA (left graph) and (b) PA ligand (right graph); experimental variables: 0.5 g of ligand (PHA or PA), 15 mL of distilled water, 5 mL of sodium acetate buffer solution at pH 3–6, 5 mL of 0.2 M metals solution and stirred for 2 h.

Figure 9

The kinetic character of Lagergren’s pseudo first-order on the adsorption of metal ions by the jute cellulose-based polymer ligands: (a) PHA and (b) PA ligand; experimental variables: 0.5 g of ligands (PHA or PA), 15 mL of distilled water, 5 mL of pH 6 buffer solution, 5 mL of 0.2 M synthetic metals ions solution and stirred for 2 h.

Figure 10

The kinetic character of pseudo second-order on the adsorption of metal cations by the jute cellulose-based polymer ligands: (a) PHA and (b) PA ligand; experimental variables: 0.5 g of ligands (PHA or PA), 15 mL of distilled water, 5 mL of pH 6 buffer solution, 5 mL of 0.2 M synthetic metals cations solution and stirred for 2 h.

Figure 11

The influent of initial concentration of metal ions in solution on the adsorption of metal by the jute cellulose-based polymer ligands: (a) PHA and (b) PA ligand; experimental variables: 0.5 g of ligands (PHA or PA), 15 mL of distilled water, 5 mL of pH 6 buffer solution, 5 mL of 0.2 M synthetic metals ions solution and stirred for 2 h.

Figure 12

Langmuir isotherm curves obtained by linear fitting on the adsorption of metal ions metal by the jute cellulose-based polymer ligands: (a) represent PHA and (b) represent PA ligand; experimental variables: 0.5 g of ligands (PHA or PA), 15 mL of distilled water, 5 mL of pH 6 buffer solution, 5 mL of 0.2 M synthetic metals ions solution and stirred for 2 h.

Figure 13

Freundlich isotherm curves obtained by linear fitting on the adsorption of metal ions metal by the jute cellulose-based polymer ligands: (a) represent PHA and (b) represent PA ligand; experimental variables: 0.5 g of ligands (PHA or PA), 15 mL distilled water, 5 mL pH 6 buffer solution, 5 mL of 0.2 M synthetic metals ions solution and stirred for 2 h.

Figure 14

Wide scan of the X-ray photoelectron spectra (XPS) of jute cellulose-based PA ligand binding with copper (a) and jute-cellulose-based PHA ligand binding with copper based (b).

Figure 15

Reusability studies of the poly(hydroxamic acid) ligand (a) and poly(amidoxime) ligand (b) in 7 cycles of sorption/desorption experiment for copper ions.