Synthesis of a high characteristics activated carbon from walnut shell for the removal of Cr (VI) and Fe (II) from aqueous solution: single and binary solutes adsorption
Volume 12, Issue 4, Autumn 2015, Pages 28-51
M. Ghasemi, A. A. Ghoreyshi, H. Younesi, S. Khoshhal Khoshhal
Abstract A high performance activated carbon was synthesized using walnut shell as a solid waste through a two-step zinc chloride chemical activation-thermal pyrolysis process. Characterization results demonstrated its porous structure with very good textural properties such as high BET surface area (1223 m2/g) and high total pore volume (0.85 cm3/g). The final adsorbent was used for adsorption of Fe (II) and Cr (VI) from aqueous solution. Effect ofpH, initial concentration of metal ions, temperature, and contact time on adsorption capacity of the adsorbent was investigated. Adsorption results revealed that the maximum removal of Fe (II) and Cr (VI) ions, occurred at pH 4. 5 and 2 respectively, were 96.2% and 99% at 313K. The equilibrium and kinetics data for adsorption of single-component ions were well described by the Sips isotherm and the pseudo-nth-order models, respectively. The impact of competing ions was studied by adsorption of a binary solution of Fe (II) and Cr (VI) ions. The binary adsorption isotherm was described by the modified Langmuir model and model parameters were found following an optimization procedure by genetic algorithm. Finally, the developed walnut-shell based activated carbon showed higher adsorption efficiency compared to other activated carbons at similar conditions.
Fabrication and Evaluation of Functionalized Nano-titanium Dioxide (F-NanoTiO2)/ polysulfone (PSf) Nanocomposite Membranes for Gas Separation
Volume 11, Issue 4, Autumn 2014, Pages 40-49
A. Dehghani Kiadehi, M. Jahanshahi, A. Rahimpour, A. A. Ghoreyshi
Abstract TiO2 nanoparticles were pretreated with ethelendiamine (EDA) to synthesize amine-functionalized TiO2. The mixed matrix membranes (MMM) comprised of amin-functionalized TiO2 inside polysulfone (PSf) matrix were fabricated and characterized for gas separation. The effects of the amin-functionalized TiO2 loading on the gas permeation properties of the MMM were investigated by varying the amin-functionalized TiO2 loading in the PSf matrix from 0ñ10 wt%. The fabricated amin-functionalized TiO2/PSf MMM were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared spectroscopy (FT/IR) and pure gas permeation test. Gas permeation measurement showed that MMMs embedded with different amount of amin-functionalized TiO2 exhibited different separation performances. For example, in MMMs containing 10 wt% amin-functionalized TiO2, the permeability of N2, CH4, CO2 and O2 increased up to 0.69, 0.8, 3.5 and 1.1 GPU respectively. Due to the higher interaction of amine groups on F-nano TiO2 with polar gases, amin-functionalized TiO2 possessed better performances in terms of permeability and selectivity in comparison to pure TiO2. The results revealed that the functionalization of TiO2 has improved the gas permeability of prepared membranes.