Papers by Author: Jin Luo

Abstract: The affecting factors and kinetic characteristics of antimony (Sb) adsoption onto a type of the coconut shell activated carbon were investigated in this study. The results showed that: the Sb adsorption obeyed the pseudo-second-order kinetics equation, and the coefficients of determination (R²) were higher than 0.97, inferring that this process was mainly the monolayer chemical adsorption. With the reduction of the particle size, the adsorption capacity of activated carbon gradually increased. With the increase of temperature, activated carbon adsorption of antimony content increased gradually, but on the whole the temperature had a limited effect on the adsorption of activated carbon. Effect of the solution pH on antimony adsorption onto the activated carbon was mainly divided into the following two stages: with a pH value of 1 to 3, antimony removal rate was about 60%, and with a pH value of 5 to 11, the removal rate was about 20%.

Abstract: The single-factorial design of experiments and response surface methodology was applied to optimize ultrasonic-assisted regeneration of coconut shell activated carbon. With the pH values of the solution, solid-liquid ratio, irradiation time chosen as the independent variable and the activated carbon release of antimony as response values, the central composite design method was used to study each of the variables and their interactions on coconut shell activated carbon regeneration. The results of this study showed that: the optimum pH value was 13; solid-liquid ratio was 372 mL·g^-1; irradiation time was 6.7 h. The average content of the release of Sb from the activated carbon was 6233.95 μg·g^-1 under the optimum condition. Regeneration rate of the activated carbon was 84.45%. This demonstrated that the adsorption efficiency of Sb was close in regenerative carbon and the original carbon. The results proved that the ultrasonic-associated coconut shell activated carbon regeneration process was accurate and reliable, and can provide a reference for the regeneration of coconut shell activated carbon which had adsorbed Sb.

Abstract: Coralyne is a kind of protoberberine alkaloids with strong anticancer activity in animal models, which could induce single-stranded adenine rich nucleic acids (poly (dA)) to form a duplex structure. And poly (dA) could be absorbed on the surface of gold nanoparticles (AuNPs) to enhance the stability against NaCl induced aggregation. However, coralyne induced poly (dA) to form double-stranded DNA, which then left the AuNPs resulting in the arrgregation by NaCl. This paper investigated the conditions and effects of using poly (A40) as a probe for the coralyne detection. The detection of coralyne used 100 mM HEPES and 200 mM NaCl as the buffer solution. The poly (A40) was 250 nM in the experiment for the protection of AuNPs aggregation caused by buffer solution. UV-visible spectroscopy was employed to detect the colorimetric changes in the aggregated condition of AuNPs. From blank to 1000 nM of coralyne, a linear response was obtained with R² = 0.862. The limit of detection was 100 nM. Results showed that the detection of coralyne with poly (A40) was achievable by using unmodified AuNPs.

Abstract: Adsorption effects of three kinds of activated carbons and a type of machine-made charcoal on the removal of antimony from acidic aqueous solution were investigated and compared. With an initial antimony solution concentration of 1000 μgL^-1, the antimony adsorption by selected adsorbents were found to descend in the following order: machine-made charcoal (52.4%) > coconut activated carbon (42.6%) > coal based activated carbon (31.1%) > apricot stone based activated carbon (24.6%). The machine-made charcoal has the best adsorption capacity with a maximum adsorption values of 523.76 μgL^-1. Five kinetic models were used for the fitting of the process of antimony adsorption, including Elovich, parabola diffusion, second order, first order and double-constant. Results showed that parabola diffusion and double-constant rate equation were the most suitable models in describing the relationship of antimony adsorption with time in acidic aqueous solution, implying that the adsorption kinetics of the antimony by the selected adsorbents in water might be a surface diffusion. Three adsorptive capacity indicators (iodine number, methylene blue number and phenol number) were determined in this paper. However, machine-made charcoal, which has a relatively high adsorption capacity, is of the lowest levels of the adsorptive capacity indicators. Thus, some complex mechanisms might be involved for the antimony adsorption by the machine-made charcoal, consequently considering the mechanism for the adsorption of antimony by the charcoal has not been verified, a further study still needs to be done.

Abstract: This paper reports an investigation regarding the effects of temperature, pH, dissolved oxygen (DO) concentration and agitation on total phosphorus (TP) release in sediment form Baihua Lake. The results showed that an increase in the temperature led to a sharp increase in the TP release in the examined sediment. The TP release from the sediment decreased as the pH value increased until approximately pH = 7, and increased when pH > 7. There was phosphorus release in both aerobic and anoxic conditions, although the release quantities of TP were significantly higher in the anoxic condition than those in the aerobic condition. In addition, the TP release increased with agitation.

Abstract: Release kinetics of phosphorus in 17 sediments samples collected from Baihua Lake were determined, and the relationship between the phosphorus release kinetic parameters and the sediment composition was also investigated. The results showed that both the Elovich equation and power function equation were valid models for describing the phosphorus release data in the 17 sediments. Within the beginning 12 h, the rate of phosphorus release was high, and then decreased. Our correlation analysis demonstrates that there were no significant correlations between the maximum capacity of phosphorus release (Qmax) and the content of total nitrogen (TN), organic matter (OM), calcium-bound phosphorus (Ca-P), and organic phosphorus (OP). But the correlation between Qmax and iron/aluminum-bound phosphorus (Fe/Al-P) content was positive (R2 = 0.6064, P < 0.01), suggesting that Fe/Al-P might be the main contributor to the released phosphorus in the sediments.

Abstract: Release kinetics of two selected heavy metals (Cu and Zn) in a sediment sample collected from the inlet of Baihua Lake was determined. The results show that the double-constant equation was considered as the best-fit equations describing the relationship of Cu and Zn release and time in the sediment from the inlet of the lake (R2 = 0.9759, 0.9226, P<0.01). The effects of temperature, acidity, salinity, and the water/soil ratio on the releasing of heavy metals in sediment sample were also investigated. The heavy metals release would increase as the temperature increased. A low pH value could promote the heavy metals release. The heavy metals in the sediment tended to be released under a relatively high salinity condition. The amount of the heavy metals released from the sediment decreased with the increase of the water/soil ratio.

Abstract: This paper reports a study on the distribution characteristics of sulfate-reducing bacteria (SRB) in seventeen sediment samples collected from Baihua Lake (a man-made deep plateau reservoir in Guizhou Province, China), and analyzes the correlations between the SRB content and pH value, organic matter (OM), AVS, Fe, Hg, As, Cu, Ca, Mg in the sediments. The results showed that the sediment collected from the sampling site of Yapengzhai had the highest population of SRB, and the sediment from the sampling site of Longtan SRB presented the lowest population of SRB. Moreover, there were positive correlations between SRB and OM, AVS, Fe, Hg, As, Cu, Ca, Mg whereas the negative correlations existed between the SRB content and pH value.

Abstract: Assessment of the pollution for the selected six heavy metals (Pb, Cu, Zn, Fe, Mn and Ni) in ten surface sediments sampled from Aha Lake in a dry season was made in the present investigation. Principal component analysis (PCA) was used to assess the sources of the heavy metals contamination and two components were extracted. Analysis of the lake characteristics and point source pollution revealed that the discharge of industrial effluent and coal mining wastewater were the possible sources of these heavy metals contamination. Based on the speciation characteristics of heavy metals in sediments, the method ratio of secondary phase to primary phase (RSP) was applied to evaluate the loadings and the bioavailability of these heavy metals. The RSP evaluation exhibited that Pb, Zn, Fe, Mn and Ni were mainly associated with Fe-Mn oxides besides residual phase, while Cu mainly existed in organic phase and residual phase. In summary, the potential risk posed to the lake caused by the heavy metals was high and descended in the order of Mn > Ni > Zn > Pb > Cu > Fe.

Abstract: A quantitative structure property relationship (QSPR) study was performed in this work to develop models for predicting reaction rate constants for reductive debromination of polybrominated diphenyl ethers (PBDEs) by zero-valent iron (ZVI). Both multiple linear regression (MLR) and artificial neural network (ANN) methods were employed for QSPR studies based on the experimental kinetic data of the fourteen PBDE congeners. Both the developed MLR and ANN models could give satisfactory prediction abilities, and the performance of the ANN model seems slightly better than that of the MLR model. In addition, energy of lowest unoccupied molecular orbital (ELUMO) and total energy (TE) were found to be the two relatively important variables in the ANN model via the assessment using both the Garson’s algorithm and connection weight approach.