The commonly used photocatalyst, TiOl (anatase), has been immobilized on porous nickel using 3 wt.% polyvinyl alcohol (PVA) as the binder. The results show that sulfosalicylic acid (SSal) can be degraded on the developed catalytic system. The adsorption characteristics on TiOz-Ni system have been investigated. The observance of photocalytic degradation of SSal under pH values and initial concentrations can be explained by the adsorption behavior of SSal. The parameters of the Langmuir-Hinshelwood expression have been determined by different experimental ways and the results are satisfactory.

The conventionally employed zero-valent iron (Fe0) particles suffer a formation of surface oxides to lower their activity prior to use. During their using process for contaminant remediation, such oxide formation is also encountered, while the cumbersome handling of particles impedes the Fe0 recovery. To conquer the drawbacks, a Fe0 film was synthesized by electrodepositing ferrous ion cathodically on titanium (Ti) substrate to form a new Fe0/Ti system. X-ray diffraction (XRD) revealed that the freshly electrodeposited (FED) Fe0 film was free of oxides, which was attributed to the particularity of electrodeposition procedure. Reduction results of 10.0 mg/L chromium [Cr(VI)] indicated that the FED Fe0 film had higher activity than the oxide-covered counterpart. Further analysis of the pH-dependent Cr(VI) reduction reaction indicated that the Fe0/Ti system kept its activity and could be reused for further Cr(VI) reduction at pH 3.0 and 4.0, while it was inactivated at pH 5.0 and 7.0. Due to the easy handling of Fe0/Ti system, the inactivated Fe0 was recovered significantly through a cathodic reduction.

Thiswork investigated the effect of co-existing organic matters on aqueous Cr(VI) reduction by electrodeposited zero-valent iron (ED Fe0) at neutral pH. The ED Fe0 prepared in a solution containing mixture of saccharin, l-ascorbic acid and sodium dodecyl sulfate showed higher activity in reducing the aqueous Cr(VI) at neutral pH than that prepared without any organic presence. XRD and SEM indicated that the structure of ED Fe0 was significantly improved to nano-scale by the presence of organic mixture in the preparation solution. Further, the ED Fe0 activity in the Cr(VI) reduction at neutral pH was increased by the co-existence of citric acid or oxalic acid in the chromate solution. Electrochemical impedance spectroscopy (EIS) demonstrated that the corrosive current increased with the concentration of organic matter in the reaction solution. With the co-existing organic matters in the preparation solution, the ED Fe0 corroded more rapidly due to its nano-size, thus the Cr(VI) reduction by the ferrous iron was accelerated. With the co-existing organic matters in the reaction solution, the Cr(VI) reduction was accelerated by a Fe(II) complex as the main electron donor, and a prevention of the passivation due to the Fe(III) and Cr(III) complexes also accelerated the Cr(VI) reduction.

The photocatalytic (PC) degradation kinetics of sulfosalicylic acid (SSA) at different pH using TiO2 microspheres were elucidated by modeling. The resultant model had special consideration of adsorption and pH. The adsorption isotherms showed that the LC/MS2-identified intermediateswereweakly adsorbed on the TiO2 microspheres, thus their adsorptionwas neglected in the modeling. By contrast, the SSAwas significantly adsorbed, thus its adsorption retained as an item in the model. Consequently, a non-first-order modelwas obtained. Through the modeling, itwas elucidated that the reaction rate increased non-linearly with the SSA adsorption equilibrium constant. Meanwhile, it was elucidated that a pH increase favored the hydroxyl radical production to accelerate the SSA degradation, while impeded the SSA adsorption to slower it, hence a neutral pH caused the fastest SSA degradation.

In this work, the oxidation mechanism of hypophosphite anion (H2PO2-) in acidic and alkaline media in the presence of Ni(Ⅱ) specie was investigated by using electrochemical impedance spectroscopy (EIS) and density functional theory (DFT). In EIS, three major electrochemical processes in the electroless deposition process were found, when the solution pH ranged from 5.5 to 9.5. To understand the microscopic mechanisms involved, all participate species in the reaction pathways were calculated by the DFT method along with a natural bond orbital (NBO) analysis. Two emulating reactions were demonstrated: Path (Ⅰ) passes through a primary dehydrogenation (D-RP), and Path (Ⅱ) includes a primary addition of OH-(A-RP) on the hypophosphite anion. By comparison of the energy levels of all species, it can be concluded that Path (Ⅱ) is energetically favorable under both acidic and alkaline conditions. The DFT and NBO analysis can provide strong evidence for the loops detected in the EIS, especially especially for the inductive loop (IL-M) in the medium-frequency domain that is caused by the formation of [NiI-H3PO2(OH)] and the capacitive loop (CL-L) in the lowfrequency domain by [H2PO2(OH)]. The combination of electrochemical analysis (EIS) and first principle theory (DFT) analysis proves that it is helpful to explore the nature of the interaction between anodic and cathodic reactions in the electroless deposition process.