Modified pineapple waste as low-cost biomass for removal of Co(II) from simulated and real treated wastewater in batch and continuous system

Abstract

Sustainable waste management practices embrace integrating renewable resources such as biomass production and utilisation as an alternative means of waste disposal. Cobalt was selected as a target heavy metal because it is anticipated to be a human carcinogen, which finds its way into surface waters via industrial applications such as mining, electroplating, paints, pigments and electronics and anticipated advanced oxidation processes using cobalt-catalysed peroxymonosulphate. In this study, we applied waste derived from pineapple in pristine (RPP) and modified form (carbonised, CPP; and chemically treated, CTPP) for removing Co(II) ions from the aqueous system. The biosorbents were characterised using FTIR, SEM and BET techniques. Results from batch studies were subjected to relevant kinetic and equilibrium modelling. Best performing CPP was applied to removing Co(II) from simulated and real wastewater in column studies. Kinetic and equilibrium data were better described with the pseudo-second-order and Freundlich isotherm, respectively. Column data shows a saturation value (ts = 22.90 mg/g) that agreed with Langmuir's predicted qmax (qe = 22.31 mg/g) and was best fitted with the Yoon Nelson model. The expected breakpoint and saturation point were directly related to column mass and inversely related to flow rate and feed concentration. Thomas's model described the behaviour of CPP when applied to remove Co(II) from real wastewater (Ci = 16.34 mg/L, tb = 20 min, ts = 100 min).