Showcasing pollution research
Click on the links below to see highlights of recent published pollution research at the University of Melbourne:
- Hydrological and water quality performance of Waste Tire Permeable Pavements: Field monitoring and numerical analysis.
- Speciation of inorganic arsenic in aqueous samples using a novel hydride generation microfluidic paper-based analytical device (µPAD)
- Comparative assessment of the characteristics and Cr(VI) removal activity of the bimetallic Fe/Cu nanoparticles pre- and post-coated with carboxymethyl cellulose
Hydrological and water quality performance of Waste Tire Permeable Pavements: Field monitoring and numerical analysis.
Authors: Ramin Raeesi, Yunxin Xue, Mahdi M Disfani, Meenakshi Arora
Journal of Environmental Management | December 2022 | Vol. 323
Permeable pavements can reduce the amount of surface runoff and peak flow rate and delay the occurrence of peak flow by allowing water to infiltrate underground similar to natural undeveloped catchments. Such suite of benefits of permeable pavements have made them one of the preferred stormwater control measures in most of the integrated land and water programs. Waste tire permeable pavements (WTPPs), as a relatively new permeable pavement technology, are designed with a surface layer made of up to 50% recycled tire particles. This study aims to investigate the hydrological performance of WTPPs to divert surface runoff and their impact on water quality. A large-scale trial in Australia was constructed and a comprehensive field performance monitoring program including double-ring infiltrometer tests and water quality testing was conducted to evaluate the performance of WTPP in real field conditions. Quality assurance tests on samples of the WTPP surface layer were conducted for permeability in the laboratory, and numerical simulations were done to estimate the surface runoff and investigate the sensitivity of the results to important design parameters. The physically-based models used for numerical simulations were developed in MUSIC X by replicating the layers of the constructed permeable pavement system as well as the impervious part of the trial site. The results indicated that the constructed system is capable of mitigating the surface runoff from the studied site, although only 25% of the discharge area was covered with WTPP. The infiltration rate of the WTPP over nine months with and without maintenance was studied. The results revealed that the infiltration rates even in areas without maintenance after nine months were found to be above the recommended values from ASCE permeable pavements task committee, but lower than the areas that were regularly maintained highlighting the importance of a regular maintenance regime for permeability recovery over time. Water quality tests were done on samples taken over a 17 month-long period indicating that the WTPP system successfully reduced most of the studied pollutants and chemical indicators, including most of the heavy metals, total suspended solids (69%) and turbidity (88%) by physically filtering the water.
Speciation of inorganic arsenic in aqueous samples using a novel hydride generation microfluidic paper-based analytical device (µPAD)
Authors: ME Bonacci, M Almeida, Y Zhang, SD Kolev
Microchimica Acta | 2022 | Vol. 189, Article 243, 1-10
The development of the first microfluidic paper-based analytical device (µPAD) for the speciation of inorganic arsenic in environmental aqueous samples as arsenite (As(III)) and arsenate (As(V)) which implements hydride generation on a paper platform is described. The newly developed µPAD has a 3D configuration and uses Au(III) chloride as the detection reagent. Sodium borohydride is used to generate arsine in the device’s sample zone by reducing As(III) in the presence of hydrochloric acid or both As(III) and As(V) (total inorganic As) in the presence of sulfuric acid. Arsine then diffuses across a hydrophobic porous polytetrafluoroethylene membrane into the device’s detection zone where it reduces Au(III) to Au nanoparticles. This results in a color change which can be related to the concentration of As(III) or total inorganic As (i.e., As(III) and As(V)) concentration. Under optimal conditions, the µPAD is characterized by a limit of detection of 0.43 mg L−1 for total inorganic As (As(III) + As(V)) and 0.41 mg L−1 for As(III) and a linear calibration range in both cases of 1.2–8.0 mg As L−1. The newly developed µPAD-based method was validated by applying it to groundwater and freshwater samples and comparing the results with those obtained by conventional atomic spectrometric techniques.
Comparative assessment of the characteristics and Cr(VI) removal activity of the bimetallic Fe/Cu nanoparticles pre- and post-coated with carboxymethyl cellulose
Authors: A Mondal, M Arora, B Kumar Dubey, K Mumford
Chemical Engineering Journal | 2022 | Vol. 444 |
High redox activity and superior magnetic property of nano-scale zero valent iron (nZVI) leads to the formation of surface oxide layers and large agglomerates, limiting its application in remediation activities. To inhibit surface oxidation and to overcome the aggregation challenge, copper (Cu) doped bimetallic iron/copper (Fe/Cu) nanoparticles with/without polymeric stabilization (carboxymethyl cellulose (CMC)) were chemically synthesized and compared with bare iron (Fe) nanoparticles for hexavalent chromium (Cr(VI)) removal. CMC stabilization of Fe/Cu nanoparticles was carried out in both post and pre-grafting pathways to evaluate the role of stabilization method on nanoparticle characteristics and reactivity. Detailed material characterization and CMC bonding mechanisms onto nanoparticle surface were explored by performing TEM, FTIR, XRD, XPS, and TGA analysis. TEM results showed spherical morphology of nanoparticles with better stability and smaller particle size for CMCpre-Fe/Cu (∼25 nm). Batch experiment results exhibited lower Cr(VI) removal efficiency for stabilized nanoparticles in contrast with bare nanoparticles (CMCpost-Fe/Cu (20.68%) < CMCpre-Fe/Cu (41.79%) < Fe/Cu (58.19%) < Fe (62.09%)) – attributable to the electrostatic repulsion between stabilized nanoparticles and Cr(VI) species. Contrary to other materials, despite the low Cr(VI) removal efficiency of stabilized nanoparticles, CMCpre-Fe/Cu showed a faster initial adsorption rate (22.23 mg·g−1.min−1). Acidic pH and particle dispersion were found to impact the removal process positively. XPS analysis of the materials before and after the reaction described the removal mechanism as a synergistic effect of adsorption, reduction, and precipitation. In conclusion, Cu doping can boost the removal process by facilitating reductive pathways, and polymer coating may result in reduced Cr(VI) removal from wastewater due to surface charge properties.