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

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.

ENVIRONMENTAL PERFORMANCE OF MICROBIAL FUEL CELL BASED LIVE SLUDGE FOR VOLTAGE PRODUCTION AND CONGO RED DYE REMOVAL

: In this work, Single chamber Microbial fuel cells (SCMFCs) are a versatile technology is depends on the interaction mechanisms of bacteria, to produce bioelectricity simultaneously and treat Congo red (CR) dye from aqueous solution at different pH (6.5-8). Electricity generation from the biodegradable organic substrate (sucrose) accompanied by decolorization of azo dye was investigated in the batch test results showed that more than 99% decolorization demonstrated at UV-Visible Spectrophotometer (500 nm) was achieved within 20 days and maximum output voltage (889 mv) had been obtained in an open circuit at a pH value of 7.5. Microbial community analysis showed that species in live sludge and the impact of bacteria grown on removal and voltage.