Characterization and application of wood-ZrO2 sorbent for simultaneous removal of chromium (III) and chromium (VI) from binary mixture

A new woodchips-ZrO2 biosorbent (W-ZrO2) was synthesized using wood residue material generated from the oak tree (Quercus robur) during furniture manufacturing. Biosorbent was tested for the simultaneous removal of both chromium (Cr) ions: Cr(III) and Cr(VI), in the binary component solution. Biosorbent characterization was performed by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD). To define optimal process parameters for simultaneous removal of both Cr species, effects of pH, temperature, sorbent dosage and Cr ions concentration on the sorption process were investigated. Sorption of Cr ions onto W-ZrO2 was highly pH-dependent. Optimal pH for simultaneous removal of both Cr(III) and Cr(VI) ions is 4.0 with removal efficiency over 99.5 % in both cases. Equilibrium experimental results are the best fitted by the Langmuir sorption isotherm model. The maximal sorption capacities of the biosorbent for simultaneous removal of Cr(III) and Cr(VI) ions in binary-component system are 16.18 and 83.52 mg g−1, respectively. The present study shows that using wood residue material to produce a low-cost sorbent can effectively decrease the water pollution simultaneously removing both chromium species from water and also reduce wood waste and increase reuse/recycling options.

Removal of Congo Red and Methyl Red using Low Density Polyethylene-Chitosan Nanoparticles Biocomposite in Single and Binary-component System

The low density polyethylene-chitosan nanoparticles (LDPE/CHNP) biocomposite was applied as a biosorbent for the adsorption of Congo red (CR) anionic dye and methyl red (MR) a cationic dye an in single and binary system. The effect of parameter pH, contact time, initial concentration, adsorbent dosage and temperature were studied on the two dyes in single and the binary component system. Kinetic studies showed that adsorption on LDPE/CHNP in a single and binary-component system follows pseudo-second order kinetics. The values of CR in single and binary system were gotten to be 0.9996 and 0.9984 respectively, while the values of MR in single and binary system were 0.9994 and 0.9983 respectively. The adsorption equilibrium study was tested with both Langmuir and Freundlich isotherm and the result showed they agree more with Langmuir have an values for CR in single and binary system to be 0.9995 and 0.9991 respectively, while the values of MR in single and binary system were 0.9954 and 0.9983 respectively; which implies that the adsorptions were more of chemisorption than physiosorption reaction. In the single and binary systems, the result reveals that CR had higher adoption efficiency than MR which could be because the chelation between cations and chitosan chains, which decreased the electrostatic interaction between Methyl red and chitosan nanoparticles of the biocomposite. The LDPE/CHNP biocomposite has proved to be an efficient adsorbent for CR (anionic dye) and MR (cationic dye) in single and two-component system which are frequently encountered composition of industrial effluents.