Column adsorption of Cr (VI) from dilute aqueous solution on tailored micro-mesoporous low-cost activated carbon: performance indicators and breakthrough modeling

Abstract

The adsorption technology based on low-cost adsorbents is of great interest for alternative sustainable abatement of toxic heavy metals from dilute industrial wastewaters. In this study, the performance of tailored low-cost activated carbon (AC) in column adsorption of Cr (VI) from dilute aqueous solution is evaluated using the rapid small scale column tests procedure. At solutions pH 2, the response of column performance indicators such as number of bed volumes, carbon usage rate, breakthrough capacity and column utilization for achieving effluent discharge limit of 0.5 mg L⁻¹ Cr (VI) to changes in flow rate and bed height are studied. At breakpoints, the low-cost AC showed number of bed volumes (38–259) and column utilization (10–72%) for empty bed contact time (0.8–6.13 min). The bed regeneration efficiency was low at 48%. Also, the low-cost AC exhibited total dynamic selectivity for Cr (VI) from simulated electroplating wastewater. The breakthrough data were correlated using a mass transfer model of Michael’s constant-pattern behavior. The results of this study demonstrate the possible application of the tailored low-cost AC for efficient column adsorption of Cr (VI) from dilute wastewaters.

Keywords:

• Breakthrough curve
• Column adsorption
• Dynamic selectivity
• Low-cost AC
• Performance indicators