Activated Carbon from Paper Waste as Potential Adsorbents for Methylene Blue and Hexavalent Chromium

Environmental pollution is a significant problem and is increasing gradually as more and more harmful pollutants are being released into water bodies and the environment. Water pollutants are dangerous and pose a threat to all living organisms and the ecosystem. Paper waste is one of the most widespread and largest wastes in the world. This research aims to address two important problems simultaneously: the reduction in solid waste in the environment using activated carbon from paper waste as potential adsorbents and the removal of harmful contaminants from water. Carbon from paper waste was activated with H2O2, HNO3, and KMnO4 for the adsorption of Cr(VI) and MB. SEM, EDX, FTIR, Raman, and BET were used to determine the properties of the materials. The surface morphology of the materials consisted of amorphous particles. EDX shows that all activated samples have a higher content of (O) than carbon paper waste. Adsorption studies showed that there was a stronger interaction between the pollutants and the adsorbent at a higher initial concentration (200 mg/L) than at the lower initial concentrations. The contact time data show that uptake increases when the interaction time between the contaminant and the adsorbent is increased. The tests for the pH of the solution show that the adsorption of Cr(VI) decreases when the pH is gradually increased, whereas the adsorption of MB increases when the pH of the solution is increased. The results fit better with the Freundlich isotherm and PSO models. The temperature studies show that the enthalpy was positive, indicating that the uptake process is endothermic. The Gibbs free energy values were all negative, indicating that adsorption between the adsorbents and the pollutants was favored. After four consecutive cycles, all the samples retained more than 60% of their uptake capability

Magnetite Functionalized Nigella Sativa Seeds for the Uptake of Chromium(VI) and Lead(II) Ions from Synthetic Wastewater

The aim of the present study was to utilise pristine and magnetite-sucrose functionalized Nigella Sativa seeds as the adsorbents for the uptake of chromium(VI) and lead(II) ions from synthetic wastewater. Prestine Nigella Sativa seeds were labelled (PNS) and magnetite-sucrose functionalized Nigella Sativa seeds (FNS). The PNS and FNS composites were characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The FTIR analysis of both adsorbents revealed the presence of vibrations assigned to 1749 and 1739 cm-1 (-C=O) for ketonic group for both adsorbents. The amide (-NH) peak was observed at 1533 and 1527 cm-1 on FNS and PNS composites, respectively, whilst the carboxyl group (-COOH) were observed at 1408 cm-1 on both adsorbents. The XRD results of FNS and PNS composites showed a combination of spinel structure and y-Fe2O3 phase confirming the formation of iron oxide. The influence of operational conditions such as initial concentration, temperature, pH, and contact time was determined in batch adsorption system. The kinetic data of Cr(VI) and Pb(II) ions on both adsorbents was described by pseudo-first-order (PFO) model which suggested physisorption process. The sorption rate of Cr(VI) ions was quicker, it attained equilibrium in 20 min, and the rate of Pb(II) ions was slow in 90 min. Freundlich isotherm described the mechanism of Pb(II) ions adsorption on PNS and FNS composites. Langmuir best fitted the uptake of Cr(VI) ions on PNS and FNS. The results for both adsorbents showed that the removal uptake of Pb(II) ions increased when the initial concentration was increased; however, Cr(VI) uptake decreased when the initial concentration increased. The adsorption of Cr(VI) and Pb(II) ions on both adsorbents increased with temperature