Yalong Zhao

Heterogeneous Fenton degradation of bisphenol A using Fe3O4@β-CD/rGO composite: Synergistic effect, principle and way of degradation

In this study, a multi-component catalyst, β-cyclodextrin (β-CD) and reduced graphene oxide (rGO) co-modified Fe3O4, was fabricated via one-pot solvothermal method and used as a synergistic catalyzer for Bisphenol A (BPA) removal. The study found that catalytic reactions of BPA followed the pseudo-first-order kinetics model, and the correlation rate constants (kobs) were calculated. Compared with Fe3O4@β-CD (0.02173u202fmin-1), Fe3O4/rGO (0.09735u202fmin-1) and Fe3O4 (0.01666u202fmin-1), the composite (0.15733u202fmin-1) exhibited stronger catalytic ability to remove BPA from aqueous solution under the same conditions, which were attributed to the synergistic enhancement effect among the components. The introduction of rGO in the composites was beneficial to the generation of •OH, and the role of β-CD might enhance the utilization of •OH. A possible three-element catalytic schematic diagram was described. The effects of pH, dosage of the catalyst, initial H2O2 and NH2OH concentrations on the removal efficiency were further investigated. The removal of BPA and TOC retained 78.2u202f±u202f2.4% and 52.9u202f±u202f2.5% after five cycles, indicating its excellent stability and reusability. Furthermore, a probable reaction pathway of BPA removal was suggested by analyzing the intermediate products. All results indicated that the composite had high and stable catalytic performance, which made it have potential application on the industrial treatment of wastewater.

Methodology of spatial risk assessment for arsenic species associated with sampling and analysis results optimization

The conventional risk assessment methods may be defective for more effective health risk assessment due to ignoring heavy metal species and the accuracy and integrity of sampling and analysis results. Using the accurate and integral data to quantify the human health effects of metal species can provide great support for more effective health risk assessment. This study presents a new methodology to optimize sampling and analysis results for implementing the spatial human health risk of heavy metal species in contaminated sites. The method integrated Entropy method and Inverse Distance to a Power (IDW) for obtaining the effective risk, and mapping the visual risk distribution of metal species. The results of its application with ingesting arsenic via oral route on adults showed that carcinogenic and non-carcinogenic risks of As were influenced by its species. The risk of HAsO4-2, H3AsO3, H2AsO4-, H2AsO3- and AsS(OH)HS- exceeded threshold that was significantly harmful to human health in study area. This method broadened the scope of human health risk assessment and provided a basis for government policy-making and site remediation.

High efficiency and rapid degradation of bisphenol A by the synergy between adsorption and oxidization on the MnO2@nano hollow carbon sphere

In this research, a novel efficiency MnO2@Nano hollow carbon sphere (MnO2@NHCS) nanocomposite was prepared by one-pot hydrothermal reaction with KMnO4 solution. The adsorption and oxidization performance of MnO2@NHCS were assessed by degradation of bisphenol A (BPA) at different conditions. The effect of dosage of MnO2@NHCS, pH, initial concentration of BPA, temperature and humic acid were investigated systematically. Moreover, the characterizations of MnO2@NHCS were measured by a series of techniques, such as XRD, FESEM, HRTEM, TGA and XPS. Notably, hollow structure of nano carbon sphere was still retained with uniform MnO2 nanosheets covered. The results show that the removal rate of BPA was 95.3% within 10u2009min and BPA can be almost decomposed in 30u2009min under the optimal conditions. Additionally, the MnO2@NHCS remained stable and had a high regeneration efficiency (more than 85%) after 3 cycles (360u2009min). The reaction intermediates/products of oxidation of BPA were analyzed and the possible degradation pathways of BPA were proposed. These research results demonstrate that the MnO2@NHCS is a fleet and efficient material for BPA degradation in aqueous environment.

Establishing a method to assess comprehensive effect of gradient variation human health risk to metal speciation in groundwater

A method was proposed to evaluate comprehensive effects of pHs and total metal concentration (TMC) variation for metal speciation human health risk in groundwater. The method used for the health assessment considered comprehensive and mutative effects caused by oral ingestion of groundwater based on human health risk assessment model and MINTEQ simulation. The results demonstrated that the dissolution rate of Ni2+ was affected by pH and Ni total concentration (total-Ni). With the increase of pH, the Ni2+ dissolved rate was smaller in the higher total-Ni at same pH. Ni2+ was dominant components contributed to health risk in groundwater. With the increase of pH in various total-Ni, HINi keep constant at first, and then decreased gradually. The HINi values of Ni speciation above acceptable level only in high total-Ni with alkaline conditions. The obtained results to verify that metals speciation were determined in health risk, and variation factors (pH and metal total concentration) played important role in risk estimation. These results provide basic information of heavy metal pollution control as well as remediation management.

Establishing a health risk assessment for metal speciation in soil—A case study in an industrial area in China

An improved method was proposed which integrates the distribution of metal speciation simulated by chemical equilibrium model, different exposure models and average daily intake dose modified by analytic hierarchy process for human health risk assessment of metal species (MS). With the rapid development of economic and urbanization, the metals pollution had become more serious in industrial areas. Adverse effects of soil contaminants on human health in typical industrial area should be assessed to evaluate the risks of soils in these areas. The method was applied to study nickel (Ni) species health risks in soil of industrial areas. The pH possessed significant impact to determine distribution/existence and solubility of Ni species, followed by DOC. The non-carcinogenic risk (HQ) of Ni species were less than 1 in each sampling points, except Ni2+. In addition, the carcinogenic risk (CR) of different Ni species were less than 10-6, except for FANi and Ni2+.