Equilibrium kinetics studies on the biosorption of Cu (II) from aqueous solutions by a new adsorbent from a Eupatorium adenophorum Spreng/buckwheat straw mixture

Adsorbent was prepared by mixing Eupatorium adenophorum Spreng and buckwheat straw. The optimum carbonization conditions for time, temperature, and mixture ratio were determined by orthogonal test and extreme difference analysis. The adsorption character was studied by varying conditions of contact time, initial metal ion concentration, adsorbent dose, and pH. The optimum adsorption conditions for Cu (II) biosorption occurred at a temperature of 298 K, a pH of 3, and an adsorbent dosage of 0.25 g. Equilibrium and kinetics studies indicated that the adsorption process followed the Freundlich isotherm (R2 = 0.9896) adsorption model. The biosorption kinetics could be well described by the pseudo-second-order equation.