Rachel S. Popelka-Filcoff

Copper removal using bio-inspired polydopamine coated natural zeolites.

Herein, for the first time, natural clinoptilolite-rich zeolite powders modified with a bio-inspired adhesive, polydopamine (PDA), have been systematically studied as an adsorbent for copper cations (Cu(II)) from aqueous solution. Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) revealed successful grafting of PDA onto the zeolite surface. The effects of pH (2-5.5), PDA treatment time (3-24h), contact time (0 to 24h) and initial Cu(II) ion concentrations (1 to 500mgdm(-3)) on the adsorption of Cu(II) ions were studied using atomic absorption spectroscopy (AAS) and neutron activation analysis (NAA). The adsorption behavior was fitted to a Langmuir isotherm and shown to follow a pseudo-second-order reaction model. The maximum adsorption capacities of Cu(II) were shown to be 14.93mgg(-1) for pristine natural zeolite and 28.58mgg(-1) for PDA treated zeolite powders. This impressive 91.4% increase in Cu(II) ion adsorption capacity is attributed to the chelating ability of the PDA on the zeolite surface. Furthermore studies of recyclability using NAA showed that over 50% of the adsorbed copper could be removed in mild concentrations (0.01M or 0.1M) of either acid or base.

Non-labile silver species in biosolids remain stable throughout 50 years of weathering and ageing

Increasing commercial use of nanosilver has focussed attention on the fate of silver (Ag) in the wastewater release pathway. This paper reports the speciation and lability of Ag in archived, stockpiled, and contemporary biosolids from the UK, USA and Australia, and indicates that biosolids Ag concentrations have decreased significantly over recent decades. XANES revealed the importance of reduced-sulfur binding environments for Ag speciation in materials ranging from freshly produced sludge to biosolids weathered under ambient environmental conditions for more than 50 years. Isotopic dilution with (110 m)Ag showed that Ag was predominantly non-labile in both fresh and aged biosolids (13.7% mean lability), with E-values ranging from 0.3 to 60 mg/kg and 5 mM CaNO3 extractable Ag from 1.2 to 609 μg/kg (0.002-3.4% of the total Ag). This study indicates that at the time of soil application, biosolids Ag will be predominantly Ag-sulfides and characterised by low isotopic lability.

Evaluation of relative comparator and k 0 -NAA for characterization of Aboriginal Australian ochre

Ochre is a significant material in Aboriginal Australian cultural expression from ceremonial uses to its application on many types of artifacts. However, ochre is a complex material, with associated surrounding minerals potentially challenging the overall analysis. In recent literature several studies have attempted to characterize ochre by a variety of techniques to understand procurement and trade. However, ochre is difficult to differentiate on major elemental or mineralogical composition and requires a detailed analysis of its geochemical “fingerprint”. Neutron activation analysis (NAA) provides the high sensitivity (sub-ppm), precision and accuracy in multi-elemental analysis required for ochre. The elements of interest for ochre generally include rare earth elements (REEs) and certain transition metal elements as well as arsenic and antimony. Data from relative comparator NAA (MURR, University of Missouri, USA) is compared with data from k0-NAA OPAL (ANSTO, Lucas Heights, Australia). A discussion of the two methods will be examined for their utility in “fingerprinting” the provenance of ochre. The continuing importance of NAA to archaeometry will also be discussed.

Towards identification of traditional European and indigenous Australian paint binders using pyrolysis gas chromatography mass spectrometry

We report a pyrolysis GC-MS method capable of analysing Indigenous Australian and European binders typically used in the manufacture of culturally important painted works. Eleven different traditional European binders and ten different Indigenous Australian binders were examined. The method allows discrimination between highly complex and impure lipid, resin, polysaccharide, wax, and protein-based binders. Each was found to have characteristic pyrolysis products that were unique to the binder material, demonstrating the potential for differentiation of these binders on Australian Aboriginal artworks towards identification and conservation of cultural heritage.

HyLogger™ near-infrared spectral analysis: a non-destructive mineral analysis of Aboriginal Australian objects

Cultural heritage materials from Indigenous cultures often use geological raw materials such as natural rock and mineral pigments. For analysis, these complex human-altered materials require high-resolution, non-destructive methods, and in the case of intricate designs, a point-by-point analysis and mapping capability is desirable. The CSIRO Australia HyLogger™ technology has been adapted from mineral exploration and mining applications to the high-resolution non-destructive infrared and visible light spectroscopic mineral analysis of Aboriginal Australian objects. Aboriginal Australian people primarily applied mineral pigments such as hematite and kaolinite to wood, fibre, bark, resin or other organic substrates, making non-destructive in situ scientific analyses of cultural objects challenging. This proof of concept study demonstrated the utility of the near-IR technology for the visual and mineralogical analysis of six Aboriginal Australian objects, of varying size and pigment application, as case studies for the development of methods to identify and differentiate types of mineral pigments regardless of the substrate or binder. While many identified pigments such as hematite and goethite were expected for the red, orange and yellow pigments, HyLogger™ in combination with The Spectral Geologist™ software identified additional mixtures of previously unknown mineral components. White minerals, such as calcite and pyrophyllite, were identified along with kaolinite in mixtures in white pigments on the artefacts. Analyses of individual spectra were used for interpretation of spectral features for specific pigments. Additionally, classes of pigment groups were identified for spectral analysis. This manuscript presents the novel application of the near-IR technology to Australian Aboriginal artefacts for characterisation and high-resolution near-IR spectroscopy of applied mineral pigments. These results challenge and add to prior knowledge about the mineralogical composition of traditional Aboriginal Australian inorganic pigments.

A multidisciplinary investigation of a rock coating at Ngaut Ngaut (Devon Downs), South Australia

Abstract This paper presents the results of a multidisciplinary investigation into a dark rock coating at the Ngaut Ngaut heritage complex in South Australia (SA) using geological and botanical examination, Raman microscopy, x–ray powder diffraction, scanning electron microscopy and infrared analyses. The coating analysed contains a mixture of calcite, quartz, gypsum and weddellite. The presence of calcite and quartz can be explained by the underlying clastic fossiliferous limestone, while the most probable explanation for the origin of the gypsum is via ground water. The weddellite was likely formed from solutions derived from the reaction of calcite with oxalic acid through the intervention of surface microflora, such as algae. This article provides the first record of weddellite in any context in SA. These findings have a number of implications—one being that the oxalate mineral in the rock coating could potentially be used to conduct accelerator mass spectrometry radiocarbon analysis and thereby refine our understanding of the rock art chronology at Ngaut Ngaut. A greater understanding of the rates of accumulation may also be useful for management purposes, as the nature of the rock coating may be contributing to long–term exfoliation. Indeed, it is argued that algal colonisation of the limestone (together with other probable microfloral activities) is likely involved in the production of a film over the porous surface, leading to salt weathering

Microelemental characterisation of Aboriginal Australian natural Fe oxide pigments

This manuscript presents the first comprehensive microcharacterisation of Fe oxide minerals used in Aboriginal Australian mineral pigments. The combination of X-ray fluorescence microscopy (XFM) and light microscopy provides a broad characterisation as well as the ability to spatially match visual observation with elemental composition. A novel method for casting pigment samples in a pattern on a slide was used for consistent elemental mapping. Semiquantitative bulk data was also collected and compared to the microscopic and microelemental data. These analyses demonstrate the ability to document the variability in ochre pigments in Australia, as well as which elements drive the variation within and between ochre source locations. The methods developed provide a more comprehensive understanding of other complex natural mineral pigments worldwide.

Microbial composition analyses by 16S rRNA sequencing: A proof of concept approach to provenance determination of archaeological ochre

Many archaeological science studies use the concept of “provenance”, where the origins of cultural material can be determined through physical or chemical properties that relate back to the origins of the material. Recent studies using DNA profiling of bacteria have been used for the forensic determination of soils, towards determination of geographic origin. This manuscript presents a novel approach to the provenance of archaeological minerals and related materials through the use of 16S rRNA sequencing analysis of microbial DNA. Through the microbial DNA characterization from ochre and multivariate statistics, we have demonstrated the clear discrimination between four distinct Australian cultural ochre sites.

Thermal decomposition of Australian uranium ore concentrates: characterisation of speciation and morphological changes following thermogravimetric analysis

In this manuscript, we report the analysis of eight uranium ore concentrates (UOCs) from three operating Australian uranium mines using thermogravimetric analysis to investigate whether the thermal decomposition of these UOCs can be used to differentiate between sources. Micro-Raman spectroscopy and X-ray diffraction were also used to identify the different phases present within the original UOC material, as well as chart their decomposition with the increasing temperature. UOCs of different species were able to be differentiated from one another, while the moisture content, a variable component within the UOCs, did distinguish between U3O8 samples sourced from Ranger and Olympic Dam. The effect of elevated temperatures on the diverse UOC morphologies of the three UOCs was also examined.

Glass fragments from portable electronic devices: Implications for forensic examinations.

Personal electronic devices (PEDs) are now widespread in the community. Many such devices have glass display screens that, despite being a relatively strong and specialised material, are vulnerable to breakage. Unlike other glass objects that are usually thrown away when they break, PEDs can still function with a broken or cracked screen and it is not uncommon for their owners to keep using them in this condition. Broken PED screens, therefore, might represent a new and significant source of glass fragments that are present on the clothing and belongings of the general public and individuals suspected of offences involving the breaking of glass. The forensic implications of this new source of glass fragments in the community were investigated. PED glass is easily recognised using scanning electron microscopy-energy dispersive X-ray analysis and refractive index measurement and is easily distinguished from domestic and automotive soda-lime glass using these methods; as a consequence there should be no confusion of soda-lime glass fragments and PED glass fragments in forensic glass casework. In cases where the objective is to compare recovered glass fragments to a putative PED source, comparison using refractive index measurement and elemental analysis achieves good discrimination between sources.