nsen Li

The Inhibition Effect of Tert-Butyl Alcohol on the TiO2 Nano Assays Photoelectrocatalytic Degradation of Different Organics and Its Mechanism

The inhibition effect of tert-butyl alcohol (TBA), identified as the •OH radical inhibitor, on the TiO2 nano assays (TNA) photoelectrocatalytic oxidation of different organics such as glucose and phthalate was reported. The adsorption performance of these organics on the TNA photoelectrode was investigated by using the instantaneous photocurrent value, and the degradation property was examined by using the exhausted reaction. The results showed that glucose exhibited the poor adsorption and easy degradation performance, phthalate showed the strong adsorption and hard-degradation, but TBA showed the weak adsorption and was the most difficult to be degraded. The degradation of both glucose and phthalate could be inhibited evidently by TBA. But the effect on glucose was more obvious. The different inhibition effects of TBA on different organics could be attributed to the differences in the adsorption and the degradation property. For instance, phthalate of the strong adsorption property could avoid from the capture of •OH radicals by TBA in TNA photoelectrocatalytic process.

Low temperature H2S removal with 3-D structural mesoporous molecular sieves supported ZnO from gas stream

A series of 3-dimensional (3-D) structural mesoporous silica materials, SBA-16, MCM-48 and KIT-6, was synthesized and supported with different ZnO loadings (10, 20, 30, and 40 wt%) by the incipient wetness method to evaluate the performances on H2S removal at room temperature. These materials were characterized by N2 adsorption, XRD, and TEM to investigate their textural properties. All the ZnO-loaded adsorbents exhibited the H2S removal capacity of bellow 0.1 ppmv. With the best ZnO loading percentage of 30 wt% on MCM-48 and KIT-6, 20 wt% on SBA-16 according to the results of breakthrough test, further increasing ZnO loading caused the decrease of the adsorption capacity due to the agglomeration of ZnO. Besides, the H2S adsorption capacities of the supports materials varied in the order of KIT-6>MCM-48>SBA-16, which was influenced primarily by their pore volume and pore size. With the largest pores in these 3-D arrangement materials, KIT-6 showed the best performance of supported material for ZnO, due to its retained superior physical properties as well as large pore diameter to allow faster gas-solid interaction and huge pore volume to disperse ZnO on the surface of it.

Efficient wastewater treatment and simultaneously electricity production using a photocatalytic fuel cell based on the radical chain reactions initiated by dual photoelectrodes

Efficient conversion of wastewater into clean energy was achieved by applying a radical chain reaction strategy in a solar responsive photocatalytic fuel cell (PFC) system. The system was constructed with two photoelectrodes where ferrous ions were added to enhance the radical reactions for organic pollutants degradation from the surface of electrodes to the whole solution system via coming into a continuous radical chain reaction. The results indicated that the short-circuit current (Jsc) and the power density (JVmax) obtained in the PFC system is up to 1.41-1.60 and 1.52-2.02 times larger than those of the PFC without ferrous ions. Meanwhile, the degradation rate of refractory organics (methyl orange, methylene blue, congo red and tetracycline) increased to 91.98%, 98.57%, 92.36% and 68.09% from 53.61%, 45.38%, 51.09% and 30.65% respectively after 90min operation. The proposed PFC with a radical chain reaction strategy provides a more economical and efficient way for energy recovery and wastewater treatment and implies a possibility of developing much higher efficient PFC system when applying the other electrodes.

High-efficient energy recovery from organics degradation for neutral wastewater treatment based on radicals catalytic reaction of Fe 2+ /Fe 3+ -EDTA complexes

A high-efficient photo-induced wastewater fuel cell (WFC) for neutral wastewater treatment was proposed in this paper based on radicals catalytic reaction of Fe3+/Fe2+- EDTA complexes in the system which has a lower redox potential than Fe3+/Fe2+ and can accelerate easily the conversion of slow catalytic step from Fe (III) to Fe (II). The results indicated that the WFC shows an excellent performance in a wide pH range of 5-9 and achieves optimal efficiency for organic degradation and electricity generation at pH 7.0. The removal ratio of organic pollutants (Rhodamine b, Phenol, and Methylene Blue) increased to 69.42%, 53.99% and 82.7% from 29.87%, 16.25% and 39% respectively after 3 h operation at an initial pH of 7.0. Meanwhile, the short-circuit current is up to 1.24-2.16 times that of the WFC without EDTA-ferrous complex. Furthermore, the system almost does not produce any sludge. The proposed WFC system can keep stable of Fe3+/Fe2+ in neutral solution and generate more intermediate active free radicals to treat neutral wastewater and recover the abundant chemical energy in organics.

Exhaustive Conversion of Inorganic Nitrogen to Nitrogen Gas Based on a Photoelectro-Chlorine Cycle Reaction and a Highly Selective Nitrogen Gas Generation Cathode

A novel method for the exhaustive conversion of inorganic nitrogen to nitrogen gas is proposed in this paper. The key properties of the system design included an exhaustive photoelectrochemical cycle reaction in the presence of Cl-, in which Cl· generated from oxidation of Cl- by photoholes selectively converted NH4+ to nitrogen gas and some NO3- or NO2-. The NO3- or NO2- was finally reduced to nitrogen gas on a highly selective Pd-Cu-modified Ni foam (Pd-Cu/NF) cathode to achieve exhaustive conversion of inorganic nitrogen to nitrogen gas. The results indicated total nitrogen removal efficiencies of 30 mg L-1 inorganic nitrogen (NO3-, NH4+, NO3-/NH4+ = 1:1 and NO2-/NO3-/NH4+ = 1:1:1) in 90 min were 98.2%, 97.4%, 93.1%, and 98.4%, respectively, and the remaining nitrogen was completely removed by prolonging the reaction time. The rapid reduction of nitrate was ascribed to the capacitor characteristics of Pd-Cu/NF that promoted nitrate adsorption in the presence of an electric double layer, eliminating repulsion between the cathode and the anion. Nitrate was effectively removed with a rate constant of 0.050 min-1, which was 33 times larger than that of Pt cathode. This system shows great potential for inorganic nitrogen treatment due to the high rate, low cost, and clean energy source.

The effect and mechanism of organic pollutants oxidation and chemical energy conversion for neutral wastewater via strengthening reactive oxygen species

Toxic and refractory organic pollutants are continually discharged into the water environment, which has become the crisis for the human living and sustainable development. However, organic pollutants also contain large amounts of chemical energy. In this paper, we studied the effect and mechanism of organic pollutants oxidation and chemical energy conversion for neutral wastewater via strengthening reactive oxygen species (ROS) of HO and O2- in a photocatalytic fuel cell (PFC) system, since ROS has the power to oxidize or even mineralize the organics and is environment-friendly to treat refractory organic pollutants. In our PFC system, the HO was enhanced by the cyclic radical chain reaction via the addition of Fe2+ and tetrapolyphosphate (TPP), while O2- was enhanced by setting an additional bias voltage at the anode which was favorable to O2 production. The results show that the HO and O2- concentration are highly enhanced, showing 8.28 and 8.99 times those of traditional PFC, respectively. Meanwhile, the degradation rate constant is remarkably increased by 6.52 times when methylene blue is used as a model pollutant. Furthermore, the performance of wastewater PFC is so improved that the short-circuit current density (Jsc) and maximum power density (JVmax) have been increased by a factor of 9.05 and 12.67 times in the same experiment, respectively.