Abstract

A renewable, green activated carbon made from sucrose (sugar) was compared with traditional bituminous coal-based granular activated carbon (GAC). Single and multi-component competitive adsorption of nitrate and phosphate from water was investigated. Langmuir and Freundlich isotherm models were fitted to data obtained from the nitrate and phosphate adsorption experiments. Nitrate adsorption fits closely to either Freundlich or Langmuir model for sucrose activated carbon (SAC) and GAC with a Langmuir adsorption capacity of 7.98 and 6.38 mg/g, respectively. However, phosphate adsorption on SAC and GAC demonstrated a selective fit with the Langmuir model with an adsorption capacity of 1.71 and 2.07 mg/g, respectively. Kinetic analysis demonstrated that adsorption of nitrate and phosphate follow pseudo-second-order kinetics with rate constant values of 0.061 and 0.063 g/(mg h), respectively. Competitive studies between nitrate and phosphate were demonstrated in preferential nitrate removal with GAC and preferential phosphate removal with SAC. Furthermore, nitrate and phosphate removals decreased from approximately 75% removal to 35% removal when subject to multi-component solutions and highlight the need for adsorption analysis in complex systems. Overall, SAC proved to be competitive with GAC in the removal of inorganic contaminants and may represent a green alternative to coal-based activated carbon.

Highlights

  • Nitrate and phosphate were similarly removed by the produced green adsorbent compared to a typical GAC.

  • Competitive adsorption decreased removals of nitrate and phosphate by 50%.

  • Iodine number for the green adsorbent was found to be 1,191 mg/g.

  • Kinetic data followed pseudo-second-order kinetics.

  • The green adsorbent was determined to be competitively comparable to coal-based GAC.

Graphical Abstract

Graphical Abstract
Graphical Abstract
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