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Mercury (Hg) is toxic and can affect human health through soil entering food chain. Spinach absorb easily heavy metals. Corn stover biochar can improve soil structure and physicochemical property. This study wanted to establish a Hg-corn stover biochar-soil-spinach model including 1 control group (without HgCl2 and corn stover biochar) and 24 treatment groups (with HgCl2 or/and corn stover biochar). Hg concentration was 0, 1, 2, 4, and 6 mg kg−1, respectively. Corn stover biochar contents were 0%, 1%, 3%, 5%, and 7% w/w, respectively. The results showed that residual Hg concentrations was the largest and water soluble and exchangeable Hg as well as carbonate bound Hg concentrations were the lowest among five Hg forms. Hg concentrations in four Hg treatment groups were higher than the control group in dose-dependent manner. The deposition of 6 mg kg−1 Hg was the highest. Corn stover biochar decreased Hg migration from soil to leaching solution and spinach, and passivation effect of 7% concentration of corn stover biochar was the best. Besides, corn stover biochar relieved the increase of methyl Hg caused by Hg in soil. Moreover, Hg concentration in roots was the highest and Hg concentration in stems was the lowest in spinach. Furthermore, Hg absorbed by roots was more than the sum of Hg absorbed by stems and leaves. In addition, we also found that the measured soil Hg concentrations were coincided with the predicted soil Hg concentrations under 1, 2, and 4 mg kg−1 Hg concentrations, except 2 mg kg−1 Hg at 7% C. Under 6 mg kg−1 Hg concentration, measured soil Hg concentrations was lower than that of the predicted soil Hg concentrations. Taken together, our findings indicated that corn stover biochar can increase edible safety of spinach by immobilizing Hg in soil and be used as an organic amendment.

We report a facile impregnation–solvothermal method for the preparation of mesoporous TiO2(B) nanowires (TNWs(B)) supporting with Fe2O3 nanoparticles (NPs). Open tunnel and porous structure of TNWs(B) provided a confined micro-environment for the stabilization of well-dispersed nanoparticles. The intact fibrous morphology structure, high crystallinity and porosity were remained for TNWs(B) after supporting by nanoparticles. UV−visible DRS analysis indicated that the loading of Fe2O3 on TNWs(B) promoted light harvesting ability and further extended the absorption range. The photocatalytic experiments showed that Fe2O3/TNWs(B) had remarkable catalytic activity for photochemical oxidation of organic pollutants Direct Red 4BS in presence of H2O2 and exhibited excellent tolerance with respect to organic matter poisoning, which was attributed to favorable synergetic effect of Fe2O3 NPs and TNWs(B) support. Compared with P25, the composite material taking the advantage of fibrous morphology was more easily separated from reaction system simply by sedimentation. Moreover, the greatest interest of our finding would be exploring that impregnation duration had significant effect on size and location of NPs supported on TNWs(B). When impregnation duration time was higher than 12 h, NPs with d

A novel photocatalytic membrane reactor (PMR) system was reported by the usage of TiO 2 nanotube (TNT) photocatalysts and microfiltration (MF) membranes. TNTs were prepared by hydrothermal method and the optimal preparation conditions were determined. Results showed that prepared TNT had good photocatalytic activity which was 2.5 times higher than that of P25 in reactive brilliant blue X-BR degradation. Due to its one-dimensional structure, the membrane flux in TNT separation was also 4–5 times higher than P25 no matter what kind of membrane was applied. Surface morphology analysis predicted less membrane fouling and better recycling in TNT PMR system.

This paper presents an asymptotic analysis of a stochastic logistic population model with nonlinear diffusion term. The classical probability method is applied to obtain the criteria of asymptotic behavior for the considered model. The numerical simulations validate the efficiency of the theory analysis.