Effective removal of Cr(VI) ions from synthetic solution using mixed biomasses: Kinetic, equilibrium and thermodynamic study

Abstract Heavy metals are the prominent toxic pollutant extensively present in the industrial waste. Due to its toxicity in nature it should be removed from the industrial waste. In this research, raw and pyrolysis assisted dragon fruit peel along with fungal biomass (Fusarium subglutinans) was utilized as a mixed adsorbent for the removal of Cr(VI) ions from the aqueous phase. FTIR, SEM, and EDX analyses were used to characterize the synthesized mixed biomasses (Fusarium subglutinans – RDFP and Fusarium subglutinans - PADFP). Batch adsorption tests reveal that optimum conditions for the effective removal of Cr(VI) ions onto mixed biomasses (pH = 4.0; biomass dosage =6.0 g/L for Fusarium subglutinans – RDFP, 3.5 g/L for Fusarium subglutinans – PADFP; temperature =30 °C; Cr(VI) ion concentration =25 mg/L; equilibrium time =60 min). The adsorption equilibrium data and contact time data were best fitted with Langmiur and Pseudo-first-order model, respectively. The monolayer adsorption capacities were found to be 11.0 mg/g for Fusarium subglutinans – RDFP and 16.52 mg/g for Fusarium subglutinans – PADFP. Thermodynamic parameters demonstrated that the adsorption was favorable at low temperatures and exothermic process. Overall results exposed that present mixed biomasses had superior adsorption capacity for the removal of Cr(VI) ions from the water/wastewater.