title: Preparation of phosphinate-based ionic liquids for rare earth recovery

authors: Sanders, Sinead

subjects: Rare earth elements

abstract: The rare earth elements are vital components in many modern technologies, including  green energy technology such as wind turbines and electric vehicles, however the  extraction and separation of these elements remains a problem. Due to the similar  chemical properties of these elements, achieving pure single elemental concentrations of the REEs is difficult, often requiring multiple steps in the separation process, as well as the use of large volumes of harmful organic solvents. With the demand of these elements projected to grow in the coming decades, greener and more efficient extraction and separation methods need to be developed. 

In this work, a series of hydrophobic ionic liquids were prepared through simple neutralisation and protonation reactions. The successful synthesis and characterisation of camphyl phenyl phosphinic acid is also described and used as an anion precursor in IL preparation. Five phosphinate-based ionic liquids were successfully prepared and tested for the separation of the rare earth elements, as well as for cobalt/nickel separations. Both liquid-liquid extraction methods using a neat IL, and column chromatography methods using supported ionic liquids were tested. Results showed selectivity towards the heavy rare earth elements, achieving a La/Yb separation factor as high as 55.3. For the liquid-liquid extraction experiments, La extraction efficiencies of 99% were achieved for a majority of the tested ILs. For the Yb column extractions, high extraction efficiencies were also achieved, ranging from 85.5 - 99.9%. Repeated extractions of cobalt and nickel showed the stability of the column, with minimal decrease in extraction efficiencies over 10 repeated runs, and an average separation factor of 2.79 across these runs.

text: Preparation of phosphinate-based ionic liquids for rare earth recovery The rare earth elements are vital components in many modern technologies, including  green energy technology such as wind turbines and electric vehicles, however the  extraction and separation of these elements remains a problem. Due to the similar  chemical properties of these elements, achieving pure single elemental concentrations of the REEs is difficult, often requiring multiple steps in the separation process, as well as the use of large volumes of harmful organic solvents. With the demand of these elements projected to grow in the coming decades, greener and more efficient extraction and separation methods need to be developed. 

In this work, a series of hydrophobic ionic liquids were prepared through simple neutralisation and protonation reactions. The successful synthesis and characterisation of camphyl phenyl phosphinic acid is also described and used as an anion precursor in IL preparation. Five phosphinate-based ionic liquids were successfully prepared and tested for the separation of the rare earth elements, as well as for cobalt/nickel separations. Both liquid-liquid extraction methods using a neat IL, and column chromatography methods using supported ionic liquids were tested. Results showed selectivity towards the heavy rare earth elements, achieving a La/Yb separation factor as high as 55.3. For the liquid-liquid extraction experiments, La extraction efficiencies of 99% were achieved for a majority of the tested ILs. For the Yb column extractions, high extraction efficiencies were also achieved, ranging from 85.5 - 99.9%. Repeated extractions of cobalt and nickel showed the stability of the column, with minimal decrease in extraction efficiencies over 10 repeated runs, and an average separation factor of 2.79 across these runs.

year: 2023

title: Quantifying macrodetritus fluxes from a small temperate estuary

authors: Gladstone-Gallagher, Rebecca

subjects: Science & Technology

abstract: Empirical measurements of estuary-to-coast material fluxes usually exclude the fraction of primary production that is exported as macrodetritus (marine plant litter), potentially leaving a gap in our understanding of the role of estuaries as outwelling systems. To address this gap, we sampled water and suspended material seasonally from the mouth of Pepe Inlet, Tairua Estuary, New Zealand. From samples collected hourly over 24 h, we calculated the lateral tidal fluxes (import, export, net flux) of macrodetritus, particulate and dissolved forms of nitrogen (N) and phosphorus (P). Annually, the inlet was a net exporter of N and P (5145 and 362 kg respectively). However, macrodetritus accounted for <13 and <3% of seasonal N and P exports respectively. Macrodetritus is an obvious and visible source of estuary-to-coast subsidy, but our derived nutrient budgets suggest the dissolved and particulate forms dominate the net export of N and P (>87%). Nevertheless, seasonal pulses in the source and supply of macrodetritus may have consequences for the temporal scales over which this resource subsidy affects receiving ecosystems (e.g. intertidal sandflats). These mensurative investigations are useful to inform estuarine nutrient budgets that quantify the ecosystem services provided by temperate estuaries (e.g. contribution to fisheries food webs).

text: Quantifying macrodetritus fluxes from a small temperate estuary Empirical measurements of estuary-to-coast material fluxes usually exclude the fraction of primary production that is exported as macrodetritus (marine plant litter), potentially leaving a gap in our understanding of the role of estuaries as outwelling systems. To address this gap, we sampled water and suspended material seasonally from the mouth of Pepe Inlet, Tairua Estuary, New Zealand. From samples collected hourly over 24 h, we calculated the lateral tidal fluxes (import, export, net flux) of macrodetritus, particulate and dissolved forms of nitrogen (N) and phosphorus (P). Annually, the inlet was a net exporter of N and P (5145 and 362 kg respectively). However, macrodetritus accounted for <13 and <3% of seasonal N and P exports respectively. Macrodetritus is an obvious and visible source of estuary-to-coast subsidy, but our derived nutrient budgets suggest the dissolved and particulate forms dominate the net export of N and P (>87%). Nevertheless, seasonal pulses in the source and supply of macrodetritus may have consequences for the temporal scales over which this resource subsidy affects receiving ecosystems (e.g. intertidal sandflats). These mensurative investigations are useful to inform estuarine nutrient budgets that quantify the ecosystem services provided by temperate estuaries (e.g. contribution to fisheries food webs).

year: 2017

title: Introducing the Draft Learning Progression Framework for Maori in the New Zealand Curriculum

authors: Crombie, Winifred

subjects: Māori education

abstract: This paper introduces the draft Learning Progression Framework for Māori in mainstream schools which we prepared in the first half of 2003 for the New Zealand Ministry of Education. Readers are invited to contact the authors if they wish to make any suggestions in relation to the final content of the document.

text: Introducing the Draft Learning Progression Framework for Maori in the New Zealand Curriculum This paper introduces the draft Learning Progression Framework for Māori in mainstream schools which we prepared in the first half of 2003 for the New Zealand Ministry of Education. Readers are invited to contact the authors if they wish to make any suggestions in relation to the final content of the document.

year: 2003-09