Yangmei Chen

Fe/S doped granular activated carbon as a highly active heterogeneous persulfate catalyst toward the degradation of Orange G and diethyl phthalate.

Fe/S doped granular activated carbon (Fe/SGAC) was synthesized with ferric nitrate, Na2S2O3 and (NH4)2S2O8 via an impregnation-precipitation, reduction-oxidation combining with aqueous-phase synthesis method treatment. Surface density of functional groups, surface area changes as well as the chemical state inside Fe/SGAC catalyst were studied by Boehm titration, N2 adsorption and X-ray photoelectron spectroscopy (XPS). The reactivity of the catalysts was tested by degrading Orange G (OG) and diethyl phthalate (DEP). The Fe/SGAC catalysts could significantly enhance the removal rate of OG as compared to persulfate alone and PS/GAC. And the catalytic capacity was also enhanced by S doping. But the degradation of DEP under the similar condition was inhibited by adsorption process because of the different hydrophobicities of OG and DEP molecule. Fe2O3/FeOOH (Fe(3+)) (represents ferrihydrite) together with FeO/Fe3O4 (Fe(2+)) and Fe2O3-satellite, which provide the new active site for persulfate catalyst was found to be the major components of iron element in Fe/SGAC catalyst; the existence of FeS2(S(-)) for sulfur element verified the assumption that the doped S element promoted the electron transfer between the persulfate species and iron oxide at the interface. COD removal experiment further confirmed that mostly contaminant removal was owed to the Fe/SGAC catalytic persulfate oxidation process.

Stormwater runoff pollutant loading distributions and their correlation with rainfall and catchment characteristics in a rapidly industrialized city.

Fast urbanization and industrialization in developing countries result in significant stormwater runoff pollution, due to drastic changes in land-use, from rural to urban. A three-year study on the stormwater runoff pollutant loading distributions of industrial, parking lot and mixed commercial and residential catchments was conducted in the Tongsha reservoir watershed of Dongguan city, a typical, rapidly industrialized urban area in China. This study presents the changes in concentration during rainfall events, event mean concentrations (EMCs) and event pollution loads per unit area (EPLs). The first flush criterion, namely the mass first flush ratio (MFFn), was used to identify the first flush effects. The impacts of rainfall and catchment characterization on EMCs and pollutant loads percentage transported by the first 40% of runoff volume (FF40) were evaluated. The results indicated that the pollutant wash-off process of runoff during the rainfall events has significant temporal and spatial variations. The mean rainfall intensity (I), the impervious rate (IMR) and max 5-min intensity (Imax5) are the critical parameters of EMCs, while Imax5, antecedent dry days (ADD) and rainfall depth (RD) are the critical parameters of FF40. Intercepting the first 40% of runoff volume can remove 55% of TSS load, 53% of COD load, 58% of TN load, and 61% of TP load, respectively, according to all the storm events. These results may be helpful in mitigating stormwater runoff pollution for many other urban areas in developing countries.

A hybrid genetic--neural algorithm for modeling the biodegradation process of DnBP in AAO system.

A hybrid artificial neural network - genetic algorithm numerical technique was successfully developed to model, and to simulate the biodegradation process of di-n-butyl phthalate in an anaerobic/anoxic/oxic (AAO) system. The fate of DnBP was investigated, and a removal kinetic model including sorption and biodegradation was formulated. To correlate the experimental data with available models or some modified empirical equations, the steady state model equations describing the biodegradation process have been solved using genetic algorithm (GA) and artificial neural network (ANN) from the water quality characteristic parameters. Compared with the kinetic model, the performance of the GA-ANN for modeling the DnBP was found to be more impressive. The results show that the predicted values well fit measured concentrations, which was also supported by the relatively low RMSE (0.2724), MAPE (3.6137) and MSE (0.0742)and very high R (0.9859) values, and which illustrates the GA-ANN model predicting effluent DnBP more accurately than the mechanism model forecasting.

Modification of properties of old newspaper pulp with biological method.

Modification of properties of old newspaper (ONP) deinked pulp with laccase and histidine was investigated. It was found that the optimum conditions for laccase-histidine treatment were: the concentration of laccase 0.9 U/g dry pulp, the concentration of histidine 1% relative to the dry pulp, room temperature, reaction time 1.5h, pH 7, the pulp consistency 5% and O(2) atmosphere. The results also showed that, in the optimum conditions, compared to the control pulp, the wet tensile strength, the carboxyl group content and water retention value of ONP treated with laccase and histidine were increased by 55.1%, 39.1% and 45.7%, respectively. Moreover, environmental scanning microscope images showed that more collapse and more fibrillation were observed on the laccase-histidine-treated fiber surface than the control samples, which led to form better bonding between fibers in handsheets resulting in the increase of the paper strength of laccase-histidine-treated ONP pulp.

Modification of old corrugated container pulp with laccase and laccase-mediator system.

Modification of the physical properties of old corrugated container (OCC) pulp with laccase or a laccase-mediator (ABTS, HBT, VA) system was investigated under select enzymatic concentrations and reaction times. The optimal conditions for laccase treatment shown to be using a laccase dose of 160U/g o.d. pulp, a treatment time of 20h at 25°C, pH 7 with a pulp consistency of 5%. Results showed that the Lac-HBT treated OCC pulp gave the best strength properties, improving tensile strength by 15.7%. The increase in the carboxyl group content of OCC laccase or Lac-HBT treated pulp led to the increase in the swelling ability and bonding between fibers. Microscope images showed the fiber surface became rougher and more collapsible after Lac-HBT treatment. FT-IR data showed that new carboxylic acid groups were formed during Lac-HBT treatment.

Effects of wet-pressing induced fiber hornification on hydrogen bonds of cellulose and on properties of eucalyptus paper sheets

Abstract The supramolecular structure of eucalyptus pulp cellulose was studied by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and water retention value (WRV) after subjecting the pulp to pressures of 0.1, 0.2, 0.3, 0.4 and 0.5 MPa. It was interpreted from the FTIR spectra of the sheets after pressing that the amount of intermolecular hydrogen bonds (HBinter) first increased and then decreased as a function of increasing pressure, while the number of the intramolecular hydrogen bonding (HBintra) exhibited an opposite trend. In the pressed fibers, the number of HBintra O(6)H· · ·O(3′) increased by 16% compared to the un-pressed fibers, while the number of HBinter O(2)H· · ·O(6) and O(3)H· · ·O(5) decreased by 23% at 0.3 MPa. XRD analysis showed that the crystallite size corresponding to the diffraction peaks for (002) lattice planes and the crystallinity of eucalyptus fibers were the lowest at a pressure of 0.3 MPa. Pressing produced an irreversible reduction of fiber pore volume, which was manifested by reduced WRV data.