Hg0 capture by sorbents was a promising technology to control Hg0 emission from coal-fired power plants and smelters. However, the design of a high performance sorbent and the predicting of the extent of Hg0 adsorption were both extremely limited due to the lack of adsorption kinetics and structure–activity relationship. In this work, the adsorption kinetics of gaseous Hg0 onto MoS3/TiO2 was investigated and kinetic parameters were obtained by fitting breakthrough curves. According to the kinetic parameters, the removal efficiency, the adsorption rate and the capacity for Hg0 capture were accurately predicted. Meanwhile, the structure–activity relationship of metal sulfides for gaseous Hg0 adsorption was built. The chemical adsorption rate of gaseous Hg0 was found to mainly depend on the amount of surface adsorption sites available for the physical adsorption of Hg0, the amount of surface S2 2– available for Hg0 oxidation and gaseous Hg0 concentration. As MoS3/TiO2 showed a superior performance for capturing high concentrations of Hg0 due to the large number of surface adsorption sites for the physical adsorption of gaseous Hg0, it has promising applications in recovering Hg0 from smelting flue gas.

The utilization of HSO, produced using SO from nonferrous metal smelting flue gas as a source of S, is extremely restricted due to Hg contamination; therefore, there is great demand to remove Hg from smelting flue gas. Although the ability of Cu/TiO to capture Hg is excellent, its resistance to HO and SO is very poor. In this study, Cu/TiO was treated with HS to improve its resistance to HO and SO for capturing Hg. The chemical adsorption of Hg on Cu/TiO was primarily through the HgO route, which was almost suppressed by HO and SO due to the transformation of CuO into CuSO. Besides the HgO route, the HgS route also contributed to the chemical adsorption of Hg on modified Cu/TiO. As the CuS on modified Cu/TiO was inert to HO and SO, the chemical adsorption of Hg on modified Cu/TiO through the HgS route was barely inhibited. Meanwhile, the HgS route was predominant in the chemical adsorption of Hg on modified Cu/TiO. Therefore, modified Cu/TiO exhibited an excellent resistance to HO and SO, and its Hg capture capacity from simulated flue gas was up to 12.7 mg g at 100 °C.

In this report, a novel nanocomposite of highly dispersed CeO2 on a TiO2 nanotube was designed and proposed as a peroxidase-like mimic. The best peroxidase-like activity was obtained for the CeO2/nanotube-TiO2 when the molar ratio of Ce/Ti was 0.1, which was much higher than that for CeO2/nanowire-TiO2, CeO2/nanorod-TiO2, or CeO2/nanoparticle-TiO2 with a similar molar ratio of Ce/Ti. Moreover, in comparison with other nanomaterial based peroxidase mimics, CeO2/nanotube-TiO2 nanocomposites exhibited higher affinity to H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB). Kinetic analysis indicated that the catalytic behavior was in accordance with typical Michaelis-Menten kinetics. Ce(3+) sites were confirmed as the catalytic active sites for the catalytic reaction. The first interaction of surface CeO2 with H2O2 chemically changed the surface state of CeO2 by transforming Ce(3+) sites into surface peroxide species causing adsorbed TMB oxidation. Compared with CeO2/nanowire-TiO2, CeO2/nanorod-TiO2, and CeO2/nanoparticle-TiO2, the combination of TiO2 nanotube with CeO2 presented the highest concentration of Ce(3+) thus leading to the best peroxidase-like activity. On the basis of the high activity of CeO2/nanotube-TiO2, the reaction provides a simple method for colorimetric detection of H2O2 and glucose with the detection limits of 3.2 and 6.1 μM, respectively.

In situ photodeposition of MoS2 on graphitic C3N4 surfaces for enhanced photocatalytic H2 evolution from water.