Morris Intraparticle Research Articles

Organo-modified Montmorillonite-based adsorbents for selective removal of Iron(II) from aqueous solutions

The use of clays for the adsorption of contaminants from water has gained significant attention in recent decades. Clays and their modified forms have been extensively studied for their ability to adsorb both inorganic and organic pollutants. The purpose of this study is to investigate the use of montmorillonite (k10), local montmorillonite (MMT-Na), and their 1,10-phenanthroline modified forms (k10-phen and MMT-phen) for the adsorption of iron(II) ions. Adsorption of iron(II) on k10 and MMT-Na has been observed to be physical; however, adsorption on k10-phen is chemical. Nevertheless, iron (II) adsorption on MMT-phen combines physical and chemical adsorption. To characterize all these clays, X-ray diffraction (XRD), Infrared spectroscopy (IR), thermogravimetric analysis (TGA), and BET nitrogen adsorption–desorption isotherm were performed. In order to determine the specific surface area of the clays, the BET and methylene blue methods were used, and both ways were quite similar. A cation exchange capacity (CEC) of 39 meq/100 g for k10 and 85 meq/100 g for MMT-Na is calculated. To optimize the Fe(II) adsorption on clays, pH, clay mass, and contact time were studied. The adsorption isotherms were analyzed using linear and nonlinear Langmuir, Freundlich, Dubinin-Radushkevich, Sips, and Toth isotherms. A study of adsorption kinetics was conducted using linear, nonlinear, and differential pseudo first and second orders. An Elovich model has been applied to the obtained data about chemisorption character. Boyd and Weber& Morris's intraparticle diffusions have also been examined. Upon adsorption of Fe(II) on all clays, the standard free energies were negative, confirming the spontaneous nature of the adsorption process. As a result of the endothermic nature of the adsorption, the enthalpies are positive. In the presence of other cations, k10-phen and MMT-phen demonstrated the most excellent selectivity in uptaking Fe(II).

Chemically activated carbon residue from biomass gasification as a sorbent for iron(II), copper(II) and nickel(II) ions

The main goal of this research was to investigate the possibility of the utilization of carbon residue from biomass gasification process with and without chemical activation as a low cost sorbent for iron(II), copper(II) and nickel(II) ions from an aqueous solution. Commercial activated carbon was used as a reference sample. Batch experiments were done to evaluate the influence of pH, initial metal concentration and contact time. The optimum pH required for maximum adsorption was found to be 4, 5 and 8, for iron, copper and nickel, respectively. According to the results, the removal of metals by carbon residue with and without chemical activation was higher than commercial activated carbon. The highest maximum experimental sorption capacities (qm,exp) for iron, copper and nickel by activated carbon residue were 21, 23 and 18mgg−1, respectively. The experimental equilibrium sorption data were tested for the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) equations. Depending on the system the Langmuir or Freundlich isotherms have been found to provide the best correlation. The kinetics of iron, copper and nickel sorption by different adsorbent materials followed the pseudo-second-order model. Other tested kinetic models were the pseudo-first-order and the Elovich models. Weber Morris's intraparticle diffusion model showed that there are two or three different stages for the removal of metals.

Kinetics and mechanism studies of p-nitroaniline adsorption on activated carbon fibers prepared from cotton stalk by NH4H2PO4 activation and subsequent gasification with steam

Activated carbon fibers (ACFs) were prepared for the removal of p-nitroaniline (PNA) from cotton stalk by chemical activation with NH(4)H(2)PO(4) and subsequent physical activation with steam. Surface properties of the prepared ACFs were performed using nitrogen adsorption, FTIR spectroscopy and SEM. The influence of contact time, solution temperature and surface property on PNA adsorption onto the prepared ACFs was investigated by conducting a series of batch adsorption experiments. The kinetic rates at different temperatures were modeled by using the Lagergren-first-order, pseudo-second-order, Morris's intraparticle diffusion and Boyd's film-diffusion models, respectively. It was found that the maximum adsorption of PNA on the ACFs was more than 510 mg/L, and over 60% adsorption occurred in first 25 min. The effect of temperature on the adsorption was related to the contacting time and the micropore structure of the adsorbents. And the increase of micropore surface area favored the adsorption process. Kinetic rates fitted the pseudo-second-order model very well. The pore diffusion played an important role in the entire adsorption period, and intraparticle diffusion was the rate-limiting step in the beginning 20 min. The Freundlich model provided a better data fitting as compared with the Langmuir model. The surface micrograph of the ACF after adsorption showed a distinct roughness with oval patterns. The results revealed that the adsorption was in part with multimolecular layers of coverage.