Application of Activated Carbon Adsorbents Prepared from Prickly Pear Fruit Seeds and a Conductive Polymer Matrix to Remove Congo Red from Aqueous Solutions

Abstract

The present work was aimed to evaluate the adsorption properties of activated carbons based on prickly pear seeds (PPS) and conductive polymer matrix based on polyaniline (PANI) for the removal of anionic Congo red (CR) dye from aqueous solutions. The adsorbent was prepared by polymerization of aniline in the presence of activated PPS by phosphoric acid and sodium hydroxide. The samples were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and the Brunauer–Emmett–Teller (BET) methods. The adsorption kinetics were studied using UV-visible (UV/Vis) spectroscopy. The characterization data suggest that the adsorption of the Congo red dye is enhanced because PANI chain molecules, which are especially accountable for removal through π—π interaction and H-bonding with the CR, are adsorbed/tethered onto the acid-activated PPS (PPSH), and thus surmount the mass transfer limitation by being best exposed to the CR-adsorbed molecule. The adsorption kinetics follows the pseudo-second order process. The correlation coefficients (R2) for Langmuir, Freundlich and Tempkin showed that the adsorption values obey Freundlich and Tempkin isotherm models. Moreover, the isotherm was most accurately described by the Freundlich model, and the maximum removal percentage was calculated to be 91.14% under optimized conditions of pH 6.6, 1 g/L of adsorbent dosage, and an initial CR dye concentration of 20 mg·L−1. Importantly, the hybrid adsorbent exhibited the highest adsorption capacity (80.15%) after five cycles of the adsorption–desorption process. Thermodynamic parameters, such as entropy changes, enthalpy changes and Gibbs free energy, were also evaluated. These results indicated that the PANI matrix can generally be better utilized for the removal of Congo red dye when appropriately dispersed on the surface of suitable support materials. These results provide a new direction to promote the separable adsorbents with increasing performance for adsorption of dye impurities from wastewater.

Recent Advances in the Removal of Organic Dyes from Aqueous Media with Conducting Polymers, Polyaniline and Polypyrrole, and Their Composites

“…A separate class of adsorbents is represented by the polyaniline-coated carbonaceous materials, e.g., activated carbon [ 7 , 64 ]; activated carbonized peanut shells [ 65 ]; activated carbons based on prickly pear seeds [ 66 ]; carbonized tea waste [ 67 ]; graphene [ 47 , 68 ]; multiwall carbon nanotubes [ 8 ] or reduced graphene oxide [ 30 , 69 , 70 ]. Only exceptionally, polyaniline was decorated in a reverse manner by an inorganic component, such as copper(II) oxide [ 71 ].…”

Facile Synthesis and Electrochemical Characterization of Polyaniline@TiO2-CuO Ternary Composite as Electrodes for Supercapacitor Applications

“…Polyaniline (PANI) is one of the most common conducting polymers due to its distinct environmental stability, superior chemical/physical properties, thermal stability, ease to synthesis, and reversible doping/dedoping process [ 6 , 7 , 8 ]. They are commercially important polymers used extensively in many applications [ 9 , 10 ]. In recent years, hybrid materials based on CPs and inorganic materials have been investigated at length by incorporating the inorganic materials in a CP matrix.…”

Experimental Design, Equilibrium Modeling and Kinetic Studies on the Adsorption of Methylene Blue by Adsorbent: Activated Carbon from Durian Shell Waste

“…The precursor used for activated carbon production is plant biomass activated carbon (activated carbon lignocellulose) which is a complex carbohydrate polymer with main components including cellulose, lignin, and hemicellulose. Lignocellulosic activated carbon can be found in agricultural and industrial waste such as duckweed [ 2 ], potato stalks and leaves [ 3 ], bamboo plants [ 4 ], mango leaves [ 5 ], tea residues [ 6 , 7 , 8 ], rice husk [ 9 , 10 ], sawdust [ 11 ], durian seeds and peel [ 12 , 13 , 14 , 15 , 16 , 17 , 18 ], neem leaves [ 19 ], moringa leaves and seeds [ 20 , 21 ], mangosteen peel [ 22 , 23 , 24 , 25 ], chitosan [ 26 ], pear fruit seeds [ 27 ] and acorn shells [ 28 ]. The activated carbon made from agricultural food waste has high economic efficiency in wastewater treatment due to abundant raw materials and low cost.…”