A comprehensive study on removal and recovery of copper(II) from aqueous solutions by NaOH-pretreated Marrubium globosum ssp. globosum leaves powder: Potential for utilizing the copper(II) condensed desorption solutions in agricultural applications

This paper reports on removal and recovery of copper(II) ions from aqueous solutions under batch experimental conditions using NaOH-pretreated powdered leaves of Marrubium globosum ssp. globosum plant. Experimental results showed that pH was optimized at the value of 5.5 by 16.23 mg/g. The increasing metal concentration and temperature caused an increase in biosorption capacity and the process reached its equilibrium in 60 min. The result obtained from kinetic and isotherm studies resulted in better agreement with pseudo second-order kinetic and Langmuir isotherm models. Thermodynamic parameters revealed that the Cu2+ biosorption by the biomass was an endothermic process. The higher desorption efficiency above 90% was obtained in case of using Na2EDTA, K4O7P2, HNO3, HCl, and (NH4)2C2O4 · H2O solutions, individually. Reusability of the biomass was examined under consecutive biosorption–desorption cycles repeating five times. The most interesting finding of the study is the idea of utilizing the EDTA–Cu complex, which can be qualified as a residual from desorption processes, as a liquid chemical fertilizer in agricultural applications.