Dr Ying Cheng

The graphene oxide (GO) reduction by microorganisms has garnered considerable interest, yet the specific mechanisms underlying the bacteria secretion of reducing substances for GO reduction remain unclear. This study aims to learn that bacterial extracellular components can reduce graphene oxide through direct (contacting GO) and indirect (not contacting GO) reduction experiments. The subsequent investigation focused on identifying the specific substances secreted by bacteria capable of GO reduction. The results of non-targeted metabolomics revealed differential expression of cacid (L-AA) demonstrates a significant up-regulation. The further experiment involved the supplementation of L-AA in the reduction system of Lysinibacillus sp. with GO, demonstrating enhanced reduction efficacy, with the ID/IG ratio of reduced graphene oxide (rGO) increasing to 1.073 after 4 d of reduction with 0.5 g L-1 L-AA. Therefore, the mediation of GO reduction by L-AA secreted by Lysinibacillus sp. is proposed as a viable mechanism, offering novel insights into microbial GO reduction.

The application of portable chromatography¿mass spectrometer (GC¿MS) is restrained by its detection limits without the development of proper sample pre-concentration methods. The primary focus of this paper is to introduce a practical field measurement methodology for the analysis of volatile organic compounds (VOCs) in soil vapour and groundwater using a portable gas (GC¿MS)system for application to in situ assessment of vapour intrusion from VOC contamination. A solid-phase micro-extraction (SPME) technique was applied for sample pre-concentration before the GC¿MS¿ measurement. Practical in-field soil gas SPME sampling methods have been developed to optimise the SPME extraction efficiency to then ultimately improve the detection limits of portable GC¿MS. An Australian site impacted by a chlorinated VOC, trichloroethylene (TCE), was the subject of the case study. To rapidly assess soil vapour samples in subsurface soil, in-house-developed retractable soil vapour sampling probes (SVSPs) were installed at the site in clusters at depths of 1 m, 2 m and 3 m below ground level at each sampling location. Use of the SVSPs for sampling enabled the generation of a three-dimensional map and distribution contours for TCE concentrations using the in situ measurement results of a portable GC¿MS analysis for vapour intrusion investigation. The results of the portable GC¿MS¿ analysis were compared with the results from conventional USEPA methods, such as TO-15 and Method 8265 for soil vapour and groundwater samples, respectively. This work demonstrates that the developed methodology of using a portable GC¿MS system has the capability for in-field quantitative analysis of VOCs for rapid contaminated site vapour intrusion assessment.

Rhizoremediation potential of different wild plant species for total (aliphatic) petroleum hydrocarbon (TPH)-contaminated soils was investigated. Three-week-old seedlings of Acacia inaequilatera, Acacia pyrifolia, Acacia stellaticeps, Banksia seminuda, Chloris truncata, Hakea prostrata, Hardenbergia violacea, and Triodia wiseana were transplanted in a soil contaminated with diesel and engine oil as TPH at pollution levels of 4,370 (TPH1) and 7,500 (TPH2) mg kg-1, and an uncontaminated control (TPH0). After 150 days, the presence of TPH negatively affected the plant growth, but the growth inhibition effect varied between the plant species. Plant growth and associated root biomass influenced the activity of rhizo-microbiome. The presence of B. seminuda, C. truncata, and H. prostrata significantly increased the TPH removal rate (up to 30% compared to the unplanted treatment) due to the stimulation of rhizosphere microorganisms. No significant difference was observed between TPH1 and TPH2 regarding the plant tolerance and rhizoremediation potentials of the three plant species. The presence of TPH stimulated cluster root formation in B. seminuda and H. prostrata which was associated with enhanced TPH remediation of these two members of Proteaceae family. These results indicated that B. seminuda, C. truncata, and H. prostrata wild plant species could be suitable candidates for the rhizoremediation of TPH-contaminated soil.

Traditional contaminated site characterisation approaches are time-consuming, labour-intensive, and demand a high level of expertise. This case study provides a rapid field-based solution to investigating a VOC contaminated site and its vapour incursion by combining soil vapour and groundwater survey. To fully assess the volatile organic compound (VOC) distribution in a contaminated site, a number of self-developed soil vapour sampling probes (SVSPs) were placed vertically at different locations in a grid with different depths. Hence, 3D subsurface contour maps for VOC concentrations in soil vapour can be obtained and used to help identify hot spots and the migration patterns of VOCs. This SVSP is "easy-to-install" in the field and a cost-effective solution for rapid assessment of soil vapour samples. The SVSPs can be installed both vertically and horizontally. If there is a requirement to take soil vapour samples beneath an existing building from a potential contamination source zone, SVSPs can be horizontally installed beneath the building without compromising its structural integrity. In addition, to ascertain the correct groundwater channels that are likely to carry contaminants from a potential source zone, an electrical resistivity tomography technique was employed to provide the preliminary information for groundwater delineation in a complex groundwater channel network.

Once petroleum hydrocarbons (PHs) are released into the soil, the interaction between PHs and soil media is dependent not only upon the soil properties but also on the characteristics of PHs. In this study, the key factors influencing the interactions between PHs and soil media are discussed. The key factors include: 1) the characteristics of PHs, such as volatility and viscosity; and 2) soil properties, such as porosity, hydraulic properties and water status, and organic matter; and 3) atmospheric circumstances, such as humidity and temperature. These key factors can be measured either ex-situ using conventional laboratory methods, or in situ using portable or handheld instruments. This study overviews the current ex/in situ techniques for measuring the listed key factors for PH contaminated site assessments. It is a tendency to apply in situ methods for PH contaminated site characterisation. Furthermore, handheld/portable Fourier transform infrared spectroscopy (FTIR) instrument provides tremendous opportunities for in-field PH contaminated site assessment. This study also reviewed the non-destructive FTIR spectroscopy analysis coupling with handheld FTIR for in-field PH contaminated site characterisation, including determining the concentration of total PH, dominant PH fractions and soil key properties for PH transport modelling.

Green-reduced graphene oxide (G-rGO) film electrode and bio-reduced graphene oxide (B-rGO) film electrode are used as anodes in microbial fuel cells (MFCs) to examine their performance in electricity generation. The anodes were characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). Furthermore, the electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were applied to explore the electrochemical performance. The internal resistances of G-rGO group was 243.87 O with the maximum power densities and output voltage at 18.77 W·m-3 and 760 mV, respectively. However, the internal resistances of unmodified group and B-rGO group were larger at 375.21 O and 299.11 O. Besides, lower power density and output voltage were shown at 8.97 W·m-3 and 480 mV for control group and 13.16 W·m-3 and 635 mV for B-rGO group. Above all, it demonstrates that G-rGO film anodes performed better and can be applied as anode materials in MFC to accelerate electricity generation.

A new functional biomaterial based on Burkholderia vietnamiensis C09V (C09V) was immobilized on beads and used for simultaneous removal of both heavy metals and crystal violet (CV). The results showed that removal of CV and metal ions using immobilized cell bead (biomaterial) was more efficient than that of free cells, wherein 89.4% of CV and 64.1% of Cu(ii) were removed after 42 h of using the biomaterial, whilst only 27.1% of CV and 23.9% of Cu(ii) were removed by free cells. Similar results were also observed in the CV and Cr(vi) removal. Fourier transform infrared spectroscopy (FTIR) revealed the change of functional groups in the presence of heavy metals. Scanning electron microscopy (SEM) showed that the existence of Cu(ii) and Cr(vi) affected the cellular morphology of the strain. X-ray energy-dispersive spectrometer (EDS) indicated that Cu(ii) and Cr(vi) adsorbed. Further Cr(vi) reduced to Cr(iii) was observed by X-ray photoelectron spectroscopy analysis (XPS). Finally, reusability and wastewater application were carried out, which shows that this functional material has a potential for co-removal of CV and heavy metals.

This study introduced a patented novel methodological system for automatically analysis of Fourier Transform Infrared Spectrometer (FTIR) spectrum data located at 'fingerprint' region (wavenumber 670-800 cm-1), to simultaneously determinate multiple petroleum hydrocarbons (PHs) in real mixture samples. This system includes: an object oriented baseline correction; Band decomposition (curve fitting) method with mathematical optimization; and Artificial Neural Network (ANN) for determination, which is suitable for the characteristics of this IR regions, where the spectra are normally with low signal to noise ratio and high density of peaks. BTEX components are potentially lethal carcinogens and contained in many petroleum products. As a case study, six BTEX components were determinate automatically and simultaneously in mixture vapor samples. The robustness of the BTEX determination was validated using real petroleum samples, and the prediction results were compared with gas chromatography-mass spectrometry (GC-MS).