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Layered double hydroxides (LDHs) of MgM3+ (M3+=Al and Cr) were synthesized by coprecipitation method to form Mg/Al and Mg/Cr LDHs. The materials were applied as adsorbents of malachite green in aqueous solution. The physical properties of Mg/Al and Mg/Cr were analyzed using XRD, FTIR, BET and TGDTA characterizations. The XRD pattern shows the characteristic of LDHs which has diffraction at 11.470 (003) and at 34.690 (012) for Mg/Al and 12.450 (003) and at 380 (012) for Mg/Cr. The interlayer spaces of Mg/Al and Mg/Cr LDHs were 7.71 Å and 7.62 Å, respectively. The surface area of Mg/Al was higher than Mg/Cr. The FTIR spectra confirm that the intense peak at 1385 cm-1 denotes vibration of nitrate bond and M-O band in under 1000 cm-1. Thus the Mg/Al and Mg/Cr LDHs were applied as adsorbents to remove malachite green in aqueous solution. The results of malachite green adsorption showed that malachite green was adsorbed onto Mg/Al and Mg/Cr followed pseudo second order and Langmuir adsorption parameter. The adsorption capacity of malachite green for Mg/Al and Mg/Cr was 44.444 mg/g and 33.784 mg/g, respectively. The thermodynamic study showed that the adsorption process was spontaneous, endothermic and favored in high temperature. The regeneration process showed that Mg/Al and Mg/Cr LDHs has high stability structure toward reusability of adsorbent until three cycles adsorption process.

Spatio-temporal methods have been developed for the estimation of concentrations of pollutants such as particulate matter and nitrogen dioxide for application in epidemiological studies. A limited number of city-specific spatio-temporal ozone (O3) models have been proposed until today. Our aim was to develop a spatio-temporal land use regression (LUR) model that estimates daily concentrations of O3, for the whole year, as well as the warm (April-September) and cold season (October-March), within the greater Athens area. We developed models using a semiparametric approach including linear and smooth functions of spatial and temporal covariates and a bivariate smooth thin plate function. The final set of explanatory variables was selected based on the adjusted-R2. We tested the final model in temporal and spatial terms following a leave-one out monitor approach. The adjusted-R2 in the leave-one-out cross validation was 0.73 for the annual model (warm: 0.65 and cold: 0.70). The spatial terms in our annual model explained 32.9% and the temporal 63.2% of the variability in O3. The developed models showed good validity when comparing predicted and observed measurements for the 2015 data. Spatio-temporal LUR modeling provides a useful tool for estimating O3 spatio-temporal variability with adequate accuracy for subsequent use in epidemiological studies.

Searching for low cost, accessible, simple implementation, and environmentally friendly adsorbents has been one of the concern of researchers in recent years. Therefore, the aim of this study was to investigate the efficient phenol removal from a synthetic aqueous solution using iron-coated pumice and LECA as an available adsorbents. Bath adsorption experiments were carried out to evaluate the effects of the independent variables such as pH (3-5-7-9-11), initial concentration of phenol (10-50mg/L), contact time (10-60 min) and different concentrations of pumice and LECA (0.2-1 g/100 cc) on the phenol adsorption. The results of the experiments showed that there was a direct relationship between the phenol removal efficiency and increasing the contact time and the adsorbent dosage but it has reverse relationship with the increasing of pH and phenol initial concentration. The optimal condition of parameters for phenol removal were 200 rpm agitation speed, 0.6 g adsorbent dosage, 30 min contact time, and 20 mg/L initial phenol concentration. The study of isotherm and kinetic models showed that the experimental data of the phenol adsorption process were correlated with Freundlich (R2pumice=0.9749, R2LECA=0.9487) and Pseudo-second order (R2pumice=0.9745, R2LECA=0.9486) models. Based on this study’s results, the modified pumice and LECA have a high ability to remove the phenol compounds from aqueous solution.

In this work, the ArcGIS technology combines analogue and digital geospatial data to derive multiple resolution meshes with a triangulated irregular networks (TINs) approach that serves to integrate the geospatial data such as surface topography, hydro graphic features and land surface characteristics into an adaptive representation of a basin biosystem. The ArcGIS model that has been developed is applied at the municipal level to a small remote settlement with less than 2000 people in Northern Greece. The aim was a site assessment for constructing an artificial wetland (ATW) system as a viable solution to the wastewater management problem and protection of biosystems. This study demonstrates that there are discrepancies in Greece between the existing open geospatial data and on the basis of the results from our study we can conclude that this combination of local maps and geographic information in ArcGIS with a TIN approach increases our knowledge of the physical terrain. It accordingly facilitates the analysis and implementation of action plans by selecting suitable sites for construction of ATW systems in small remote settlements. We moreover discuss problems regarding spatial data quality and scale and provide suggestions for improvement while the desktop classification steps can be easily reproduced for other data-similar countries.