Browsing by Author "Potter, Ian D."

Now showing 1 - 3 of 3

Exploiting Ion–Dipole and Ion‑Exchange interactions for the removal of Aminopyridines from aqueous environments using Polymer inclusion membranes
(Springer, 2023-07-12) Mwakalesi, Alinanuswe J.; Potter, Ian D.
Aminopyridines, such as 4-amino-2-chloropyridine (ACP), are not only starting materials for many useful chemicals but also decomposition by-products that are extremely stable in an aqueous environment. Aliquat 336 has proved useful as a car- rier in polymer inclusion membranes (PIMs) for the extraction and transport of small organic anions through ion-exchange processes. However, less attention has been paid to the use of the carrier for the extraction of neutral or cationic organic compounds like aminopyridines. The current study focuses on using PIMs containing Aliquat 336 to target ACP using ion–dipole interactions. The investigations were performed using both experimental methods and computational model- ling. The findings indicated that ACP was transported through a combination of both passive and facilitated diffusion in the rate-determining steps. Significant facilitated transport occurred when PIMs contained 10 wt% or more Aliquat 336. The transport of ACP was fundamentally driven by pH but also benefited from a chloride gradient that resulted in the concurrent transport of orthophosphate. An optimal membrane composition delivered a reasonable flux of 413 (± 9) × 10–8 mol m−2 s−1 and good transport efficiency of 98% for ACP. Our findings provide more incentive for the continued development of PIM chemistry to target troublesome organic pollutants and recover useful chemicals from water sources.
Removal of picloram herbicide from an aqueous environment using polymer inclusion membranes
(Elsevier Ltd, 2020-04-06) Mwakalesi, Alinanuswe J.; Potter, Ian D.
The picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) herbicide is widely applied to control the growth of woody plants and it has been frequently detected in aqueous environments due to its poor adsorption by soils and high leaching potential. Consequently, the removal of picloram from contaminated environmental waters is of major concern due to its adverse impacts on aquatic organisms, soils and animals. The development of a method for the extraction and transport of picloram from aqueous solutions using a polymer inclusion membrane (PIM) composed of cellulose triacetate, trioctylmethylammonium chloride (Aliquat 336) and 2–ni- trophenyl octyl ether (NPOE) is reported. The experimental method was optimized for the PIM composition, and the type and concentration of stripping reagent. The optimized method demonstrated good performance in- dicators of flux and transport efficiency for picloram during non-competitive and competitive transport ex- periments. The PIM was also successfully applied in a passive sampling device to recover picloram at the maximum permissable concentration of 500 μg/L from a complex matrix of natural water. Findings from this study demonstrate that PIMs can serve as a potential alternative method for the removal and recovery of pi- cloram and related herbicides from contaminated aqueous solutions.
Targeting of cationic organic pesticide residues using polymer inclusion membranes containing anacardic acid from cashew nut shell liquid as a green carrier
(Elsevier Ltd, 2021-07-21) Mwakalesi, Alinanuswe J.; Potter, Ian D.
Many emerging organic pollutants exist as cationic residues at environmentally relevant pH. This indicates a need to develop economically viable and robust methods to remove such residues from environmental waters. In this paper, we report using polymer inclusion membranes (PIMs) containing anacardic acid (AA), sourced from cashew nut shells, as an acidic carrier for the extraction and transport of 4-amino-2-chloropyridine (ACP), paraquat and diquat as representative target solutes of organic pesticide residues in aqueous solutions. Amounts of cellulose triacetate (CTA) as polymer, 2–nitrophenyl octyl ether (NPOE) as plasticiser, AA as carrier, and 1- dodecanol as modifier were used to prepare membranes. An optimal composition of 30 wt% CTA, 40 wt% NPOE, 10 wt% AA and 20 wt% dodecanol produced an initial flux of 364 (± 16) × 10 − 8 mol m − 2 s − 1 for transport of ACP. The extraction performance of AA was comparable to bis-(2-ethylhexyl) phosphoric acid, a widely used acidic carrier, in PIMs of similar composition. PIMs utilizing AA were also successfully applied to a sample of environmental water for the competitive recovery of ACP, paraquat and diquat, each at 500 μ g/L. Using chemicals from plants as active reagents was shown to be an effective strategy to enhance the green chemistry credentials associated with methods for water remediation.