Enhanced removal of lead and zinc by a 3D aluminium sulphate-functionalised graphene aerogel as an effective adsorption system

Nicholas Yung Li Loh, Wan Ting Tee, Svenja Hanson, Wee Siong Chiu, Billie Yan Zhang Hiew, Poi Sim Khiew, Lai Yee Lee

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Abstract

The discharge of heavy metals into the environment has adversely affected the aquatic ecology due to their toxic and non-biodegradation nature. In this research, a three-dimensional graphene oxide/carboxymethylcellulose/aluminium sulphate (GOCAS) aerogel was synthesised and evaluated as a novel means for lead and zinc removal. The GOCAS aerogel was synthesised via ice-templating of graphene oxide with carboxymethylcellulose and aluminium sulphate as the crosslinking and functionalisation additives. Characterisation of the aerogel by various analytical techniques confirmed the successful integration of the substrates. The hydroxyl and sulphate groups in the aerogel were found to participate in the adsorption of both metals. The equilibrium of lead adsorption was found to correlate well to the Freundlich isotherm, while zinc adsorption better fitted to the Langmuir isotherm. The adsorption kinetic of both metals was found to be best described by the pseudo-second-order model. The interactive influences of concentration, temperature, contact time and dose on the metal elimination were explored by a central composite design, and the optimum adsorption capacity for lead was found to be 138.7 mg/g at a GOCAS dose of 20 mg, initial concentration of 100 mg/L, temperature of 50 °C and contact time of 45 min. The optimum adsorption capacity for zinc was 52.69 mg/g at 30 mg, 65 mg/L, 45 °C and 40 min. Furthermore, regeneration studies with hydrochloric acid eluant were successfully conducted for up to four adsorption-desorption cycles. Overall, this work demonstrates that GOCAS aerogel is a viable nanosorbent for the adsorption of lead and zinc from water systems.
Original languageEnglish
Article number142537
JournalChemosphere
Volume362
Early online date4 Jun 2024
DOIs
Publication statusE-pub ahead of print - 4 Jun 2024

Keywords

  • Adsorption
  • Central composite design
  • Graphene oxide
  • Lead
  • Zinc

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