Adsorption of Pb(II) by tourmaline-montmorillonite composite in aqueous phase.

In this study, a tourmaline-montmorillonite composite (TMMs) was synthesized by vacuum sintering to adsorb Pb(II) from aqueous phase. Different sintering temperature and proportion of tourmaline (TM) were first investigated by evaluating the adsorption capacity for Pb(II). The results indicated that the proper sintering temperature of the synthesis process and proportion of TM were 800 °C and 30.7% respectively. Batch experiments indicated Pseudo-second-order kinetic model and Freundlich adsorption isotherms fitted well with the adsorption characteristics of Pb(II) on TMMs, indicating that the adsorption progress of Pb(II) on TMMs related to chemical absorption and the maximum adsorption capacity was 303.21 mg/g. The background electrolyte concentration and solution pH have little effect on the adsorption behavior of TMMs. Adsorption mechanism of Pb(II) on TMMs might attribute to the electrostatic and complexation processes such as dissociation of metal ion bonds on the surface, hydroxylation on the surface of minerals, and self-polarization. The structure of TMMs was tested by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). This work provided a good reference for the application of tourmaline on treatment of heavy metals pollution in water.

Glucose enhanced the oxidation performance of iron-manganese binary oxides: Structure and mechanism of removing tetracycline.

In this work, iron-manganese binary oxides (FMO) modified with different proportions of glucose addition (FMOCx) by co-precipitation method showed good activity in activating hydrogen peroxide (H2O2) for tetracycline degradation. The structure and surface characterizations of the FMO and FMOCx were measured by XRD, FTIR, TEM, BET and XPS. With increased glucose addition, FMOCx has more surface functional groups such as -OH and -COOH, particle size decreases, surface area gradually increases, and the ratio of high valence iron and manganese also increases. In addition, the glucose might be oxidized by KMnO4 to form amorphous carbon on the catalyst surface. Glucose modified iron-manganese binary oxides FMOC3 (with 0.003 mol glucose added) showed the highest efficiency removal capability for tetracycline up to 85%, which attribute to it has a larger surface area, more surface functional groups and higher surface active Mn(IV) site content. The results also demonstrated that FMOC3 could efficiently activate hydrogen peroxide. This study proves that glucose modified iron-manganese binary oxides (FMOCx) can offered a possibility of degradation of refractory organic pollutants as an environmentally friendly catalyst in the absence of H2O2 or not.

Changes of heavy metal fractions during co-composting of agricultural waste and river sediment with inoculation of Phanerochaete chrysosporium.

The effects of Phanerochaete chrysosporium on the bioavailability of multiple heavy metals (Pb, Cd, Cu, and Zn) in river sediments were investigated by co-composting with the agricultural waste. The results showed that the Phanerochaete chrysosporium inoculation can greatly enhance the passivation on Cu, Pb and Cd during 60 days co-composting. The effects in the three metals followed the order: Cu > Cd > Pb. There were no differences for Zn whether inoculation with P. chrysosporium or not. Redundancy analysis (RDA) implied that more than 4/5 of the variation of all fractions data for all heavy metals was explained by all significant canonical axes. P. chrysosporium can change the significant parameters for each metal and enhance the explanatory power of RDA model. The inoculation can strengthen the effect of OM (organic matter) on the bioavailability of heavy metals, but weaken the contribution of pH.