Chengzhu Zhu

PAHs in sediment cores at main river estuaries of Chaohu Lake: implication for the change of local anthropogenic activities

In the present study, 28 polycyclic aromatic hydrocarbons (PAHs) were investigated in four sediment cores collected from the main river estuaries of Chaohu Lake, one of the severely polluted lakes in China. The results indicate that elevated concentrations of total PAHs (Σ28PAH) were found in the samples from the estuary of Nanfei River (ENF), considering BaP-based total toxicity equivalent (TEQ-BaP) and toxic unit (TU) results; there are potential adverse environmental implications. The total organic carbon (TOC) played an important role on the accumulation of PAHs at ENF and the estuary of Tongyang River (ETY). The predominant PAHs are high molecular weight (HMW) homologous for all samples; as a result, industrial wastewater from a steel company is expectedly the key source of PAHs in ENF, while coke consumption would be the important source of PAHs at other three sampling sites. Vertical distribution of PAHs in the sediment cores could be explained by the local social and economic activities. Furthermore, a minor variation of PAH composition in the sediment core could be justified by the stable structure of energy consumption in the Anhui Province. These results justify the need for further enhancement of industrial wastewater treatment and development of renewable energies which are the key factors on the control of PAH pollution in China.

Simultaneous removal of nitrogen and phosphorus using autoclaved aerated concrete particles in biological aerated filters

AbstractAutoclaved aerated concrete particles (AACPs) were developed as alternative for the biofilter carriers. To obtain high biomass concentration, the biogenic stimulating properties of the AACPs were investigated. Meanwhile, the feasibility of using these particles as biological aerated filter media was assessed. The experimental results showed that the removal efficiencies of chemical oxygen demand (CODCr) and total nitrogen (TN) both increased with the increase in the ratio of CODCr to -N (C/N) in the biofilters. It could be demonstrated that the well-developed porous structures of AACPs were conducive to many microbial communities, resulting in an improvement of the permeability of biofilm layers and the pollutant removal efficiencies. The adoption of AACPs in such an environment significantly improved phosphate removal from wastewater. Our findings suggested that AACPs can play significant roles as carriers in simultaneous nitrification and denitrification by biological wastewater treatment systems.

Electrocatalytic degradation of bisphenol a in aqueous solution using β-PbO2/Ti as anode

In this paper, a novel Ti-base β-PbO2 electrode was successfully prepared by using electrodeposition. The prepared electrode was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and anode polarization curves. The electrocatalytic degradation efficiency of bisphenol A by using the novel Ti-base β-PbO2 as anode were examined as a function of supporting electrolyte types and concentrations, electrolysis time, initial BPA concentration, initial pH and current efficiency. The results showed that the removal efficiency of CODCr could reach up to 90.6% after 1.5-h electrolysis at initial bisphenol A concentration of 20 mg L−1, applied voltage of 20 V, electrode spacing of 7 cm, initial pH of 5, and NaCl concentration of 0.020 mol L−1. The electrocatalytic degradation of bisphenol A was induced by hydroxyl radical and other oxidative species attacking parent molecules. The degradation products mainly consisted of small straight chain compounds, CO2 and H2O.

Performance of selective catalytic reduction of NO with NH3 over natural manganese ore catalysts at low temperature

ABSTRACT Natural manganese ore catalysts for selective catalytic reduction (SCR) of NO with NH3 at low temperature in the presence and absence of SO2 and H2O were systematically investigated. The physical and chemical properties of catalysts were characterized by X-ray diffraction, Brunauer–Emmett–Teller (BET) specific surface area, NH3 temperature-programmed desorption (NH3-TPD) and NO-TPD methods. The results showed that natural manganese ore from Qingyang of Anhui Province had a good low-temperature activity and N2 selectivity, and it could be a novel catalyst in terms of stability, good efficiency, good reusability and lower cost. The NO conversion exceeded 85% between 150°C and 300°C when the initial NO concentration was 1000 ppm. The activity was suppressed by adding H2O (10%) or SO2 (100 or 200 ppm), respectively, and its activity could recover while the SO2 supply is cut off. The simultaneous addition of H2O and SO2 led to the increase of about 100% in SCR activity than bare addition of SO2. The formation of the amorphous MnOx, high concentration of lattice oxygen and surface-adsorbed oxygen groups and a lot of reducible species as well as adsorption of the reactants brought about excellent SCR performance and exhibited good SO2 and H2O resistance.

Photochemistry of the Mixed Aqueous Solution of Nitrobenzene and Hydrogen Peroxide Initiated with 266 nm UV Light

ABSTRACT The reaction microscopic mechanism of mixed aqueous solutions of nitrobenzene and hydrogen peroxide under different conditions was studied by the laser flash photolysis technique (266 nm). The main characteristic peaks in these transient absorption spectra were attributed and the build-up/decay trends of several transient species were investigated. The transient absorption peaks of 285 nm and 305 nm were attributed to when nitrobenzene aqueous solutions were irradiated by 266 nm UV light and the decay rate constant was k 285 nm = 1.22 × 104 s−1 and k 305 nm = 1.05 × 104 s−1 in the presence of N2. k 285 nm and k 305 nm increased to 1.32 × 104 s−1 and 2.05 × 104 s−1, respectively, in the presence of O2. OH radical can be produced through the 266 nm laser flash photolysis of hydrogen peroxide in aqueous solutions. The rate constant of the reaction between OH radical and nitrobenzene was measured to be (3.6–6.0) × 109 (L · mol−1 · s−1). The intermediate of the C6H5NO2-OH adduct can undergo secondary self-decay with a reaction rate of 2k/ϵl = 1.82 × 106 s−1. The C6H5NO2-OH adduct is able to react with O2 to form C6H5NO2-OHO2 with a rate constant of (6.6 ± 0.56) × 107 (L · mol−1 · s−1).