Pre-treatment of exopolymeric substances from Bacillus cereus for metal removal as a novel strategy to enhance metal biosorption

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Abstract

This study investigated several pre-treatments as strategies to increase the efficacy of the removal of metals when using exopolymeric substances (EPS) produced by Bacillus cereus. The pre-treatments used include heat (autoclaving, boiling) and chemical agents (sulphuric acid, sodium hydroxide, and methanol). Pre-treated EPS was subsequently used for metal removal in single-metal systems (Cu, Pb, Zn, Cd, Cr) and characterized for functional groups via Fourier transform infrared spectroscopy (FTIR). Results revealed that pre-treatment significantly improved metal removal efficacy of EPS compared to EPS without pre-treatment (removal of Cu: 29.48%, Pb: 73.44%, Zn: 39.27%, Cd: 35.64%, Cr: 56.13%). Pre-treatment using autoclaving (removal of Cu: 40.29%, Pb: 91.18%, Zn: 52.65%, Cd: 45.41%, Cr: 73.33%) and methanol (removal of Cu: 48.41%, Pb: 93.31%, Zn: 58.15%, Cd: 56.49%, Cr: 84.95%) was the most effective heat and chemical pre-treatment, respectively. The combination of autoclaving + methanol further improved metal removal efficacy of the treated EPS with removal of Cu, Pb, Zn, Cd, and Cr at 60.86%, 98.44%, 70.56%, 64.46%, and 91.85%, respectively. The improved biosorption by pre-treated EPS was attributed to the effect of pre-treatments liberating and increasing the number of functional groups present. EPS pre-treated by autoclaving + methanol were detected with a significantly higher number of hydroxyl groups compared to non-treated EPS. This study suggests that pre-treatment using a combination of autoclaving + methanol successfully improved the quality of EPS as a more superior biosorbent for feasible adoption in wastewater treatment.

Original languageEnglish
Article number121
Number of pages11
JournalWater, Air, and Soil Pollution
Volume234
Issue number2
DOIs
Publication statusPublished - Feb 2023

Keywords

  • Biosorption
  • Exopolymeric substances
  • Pre-treatment
  • Wastewater treatment

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