Conductance based sensing and analysis of soluble phosphates in wastewater

Abstract

The current standard method used for measuring soluble phosphate in environmental water samples is based on a colourimetric approach, developed in the early 1960s. In order to provide an alternative, label free sensing solution, a molecularly imprinted polymer (MIP) was designed to function as a phosphate receptor. A combination of functional monomer (N-allylthiourea), cross-linker and monomer/template ratios were optimised in order to maximise the binding capacity for phosphate. When produced in membrane format, the MIP's ability to produce a reversible change in conductance in the presence of phosphate was explored for fabrication of a sensor which was able to selectively detect the presence of phosphate compared to sulphate, nitrate and chloride. In wastewater samples the sensor had a limit of detection of 0.16 mg P/l, and a linear range between 0.66 and 8 mg P/l. This is below the minimum monitoring level (1 mg P/l) as required by current legislation for wastewater discharges, making the sensor as developed promising for direct quantification of phosphate in environmental monitoring applications.

Assessment of molecularly imprinted polymers as phosphate sorbents

“…Any removal of phosphate found was typically associated with standard error. The results from this study corresponds those reported byWarwick et al (2014a) who indicated that TU NIP was able to remove only 1% phosphate at C0 = 0.78 mg PO4 3-/L. However, this contradicts the same work done byWarwick et al (2014a) who reported the TU MIP removing 22% phosphate at C0 = 0.78 mg PO4 3entirely surprising asWarwick et al (2014a) also reported large error associated with phosphate removal by TU MIP.…”

“…Lastly, the thiourea imprinted polymer showed to bind 22% of the phosphate, while the non-imprinted polymer (NIP) only bound 1%. This was, however, not entirely convincing of thiourea's ability to be effectively imprinted as the thiourea MIP deviated largely from the mean (Warwick et al, 2014a). trimethylolpropane trimethacrylate (TRIM) were compared.…”

A molecular imprinted polymer based sensor for measuring phosphate in wastewater samples

“…Experiments using various phosphate concentrations in deionised water (0.03 to 31 mg P L -1 ) were completed to assess the relationship between the change in conductance produced with concentration and a correlation (r 2 ) of 0.97 was established. Furthermore the MIP sensor selectively detected the presence of phosphate compared to sulphate, nitrate and chloride and the binding was found to be reversible, enabling the re-use of the membrane for multiple measurements (Warwick et al, 2013b).…”

Radiation induced synthesis of molecularly imprinted polymers

“…The functionalizationof polymer surfaces with molecular recognition capability gained attention due to the potential usage of molecularly imprinted polymersfor analytical applications [28]. The surface grafting methodology increases the accessibility of the target moleculeto the binding sites when compared to bulk polymerization.…”