Electronic versions

DOI

  • James Bezzina
    Separations and Nuclear Chemical Engineering Research (SNUCER), Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United KingdomInstitute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, 01328, Dresden, Germany
  • Thomas Robshaw
    Nuclear Engineering Group, School of Chemical and Process Engineering, University of Leeds, Woodhouse, Leeds LS2 9JT, United KingdomSeparations and Nuclear Chemical Engineering Research (SNUCER), Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom
  • Adam Canner
    Separations and Nuclear Chemical Engineering Research (SNUCER), Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom
  • Robert Dawson
    Department of Chemistry, University of Sheffield, South Yorkshire S10 2TN, United Kingdom
  • Mark Ogden
Phosphate shortages and the ensuing pressures on food security have led to an interest in processed sewage sludge as a substitute for commercial fertilisers. The presence of heavy metals in this nutrient source causes concerns around environmental release and pollution. This work builds towards a resin-in-pulp sludge detoxification process. It showcases the kinetic and thermodynamic adsorption capabilities of the ion-exchange resins C107E (carboxylic acid functionality), MTS9301 (iminodiacetic acid) and TP214 (thiourea), with respect to Cu(II), Fe(II), Pb(II) and Zn(II), within a simulated sewage sludge weak acid (acetate) leachate. The isotherms produced in this complex system were quite different to those generated when single metals were investigated in isolation, with desorption of lower affinity species clearly observed at higher equilibrium concentration values. Mixed-metal isotherm data were fitted to common two-parameter isotherm models and also a novel modified Langmuir model, which better accounted for the effects of desorption and competition. Kinetic data were also fit to common two-parameter models; results suggesting the system was likely film diffusion-controlled and followed pseudo-2nd-order kinetics. C107E displayed rapid adsorption of lead (t1/2 = 26 ± 3min), and significant uptake of all metals. MTS9301 showed high affinity for copper ions, with concurrent desorption of all the other metals, and also displayed the fastest kinetics (t1/2 = 14.1 ± 0.9, 130 ± 20, 25 ± 5 and 49 ± 6 min for copper, iron(II), lead and zinc, respectively). C107E and MTS9301 showed far slower adsorption for iron(II) than the other three metals, which invited the possibility of kinetic separations. TP214 had reasonable effectiveness in removal of copper, but poor affinity for all other metals. The greatest difficulty in modelling the multi-metal system was the two-stage trends observed in equilibrium experiments, as metal-proton exchanges become metal-metal exchanges. While not having the highest capacity, MTS9301 was recommended as the most appropriate resin for rapid and efficient removal of Cu, Pb and Zn from the acetate medium.

Keywords

  • Resource recovery, Weak acid, Adsorption, Transition metals, Sewage sludge
Original languageEnglish
Pages (from-to)116279
Number of pages13
JournalJournal of Environmental Management
Volume324
Early online date25 Sept 2022
DOIs
Publication statusPublished - 15 Dec 2022
View graph of relations