The metal ion adsorption and electrokinetic properties of sepiolite modified by 3-(trimetoxysilyl)propyl metaacrylate was studied. The characterization of modified sepiolite was made by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron micrograph (SEM), and differential thermal analysis/thermogravimetry (DTA/TG). The adsorption behavior of Fe(III), Mn(II), Co(II), Zn(II), Cu(II), and Cd(II) metal ions on modified sepiolite from aqueous solutions was investigated as a function of equilibrium pH, temperature, and ionic strength. The adsorption experiments were carried out using a batch method. The initial and final concentrations of heavy metals were determined by means of atomic absorption spectrophotometry. The zeta potential of the modified sepiolite suspensions was measured as a function of metal ion concentration and equilibrium pH using a Zeta Meter 3.0. The results showed that the amount of adsorbed metal ions increased with solution pH, and that the modified sepiolite adsorbed Cu(II) and Mn(II) ions more than other metal ions. It was found that the temperature had an important effect on metal ion adsorption and that the adsorption process was endothermic in nature. Equilibrium isotherms for the adsorption of metal ions were measured experimentally. Results were analyzed by the Freundlich and Langmuir equations and determined the characteristic parameters for each adsorption isotherm. The isotherm data were reasonably well correlated by Langmuir isotherm. Maximum monolayer adsorption capacity of modified sepiolite for Cu(II), Mn(II), Zn(II), Fe(III), Co(II), and Cd(II) metal ions was calculated from 12.3x10(-5), 11.7x10(-5), 9.0x10(-5), 8.2x10(-5), 5.7x10(-5), and 1.8x10(-5)molL(-1), respectively. The affinity order of adsorption was Cu(II)>Mn(II)>Zn(II)-Fe(III)>Co(II)>Cd(II). The results indicate that modified sepiolite is good adsorbent for the removal of metal ions from aqueous solutions.

The measurement of heavy metal concentrations in plants is important both for determining their ability to remove these pollutants from the air to increase its quality, and for the monitoring of air quality. Previous studies have mostly focused on the use of annual leaves of broadleaved species as biomonitors. In this study, the aim was to determine the heavy metal accumulation of the perennial needles of some conifers. In almost all the species studied, concentrations of heavy metals were found to increase with the age of the tree, but this increase was not linear. There were significant differences between the species in terms of heavy metal accumulation. The highest concentrations were for Fe in Pinus nigra, Zn in Picea pungens, Pb in Pinus sylvestris, and for all the other heavy metals in Abies bornmulleriana. This study indicates that A. bornmulleriana is particularly useful as a biomonitor for many heavy metals, and also has the potential to remove heavy metals from the air.

Annual rings are good indicators for determining the increase in the amount of heavy metals in the atmosphere from past to the present. Air pollution has rapidly increased in Ankara over the past 20years. In particular, there is a serious increase in the concentration of heavy metals that adversely affect human health. In this study, the accumulation of Al, Zn, Cu, Co, Fe, Mn, Cr, Cd, Na, Ca, Ba, P, Mg, As, and B on Acer platanoides rings has been determined using the GBC Integra XL-SDS-270 ICP-OES instrument. Based on our experimental findings, we determined that the concentration of heavy metals accumulated on the rings over the past 20years varied and that there was a significant correlation between heavy metal concentration in air and heavy metal accumulation on trees. The main reasons for this increase were an increase in the amount of exhaust emission gases and most importantly the transport of heavy metals by the prevailing winds from heavy industrial plants established after 1990 in Ankara. As a result, when the values were examined, we found that except for Na, all the elements, which showed differences at statistically significant levels, were in considerably high quantities in the bark. On average, the values obtained for bark were 6 times higher than those obtained for wood. In terms of elements that showed statistically significant level of differences, this difference was the lowest in P (1.61 times higher), Mg (2.52 times higher), and B (3.94 times higher) and the highest in Mn (23.87 times higher), Al (22.0 times higher), and Fe (14.27 times higher). In the case of Na, we found that the value obtained for wood was 1.64 times higher than that obtained for bark.=20