Pb(II) sorption by pyrolysed Pongamia pinnata pods carbon (PPPC)

Experiments employing pyrolysed Pongamia pinnata pods carbon (PPPC) to delineate the effects of environmental variables like pH, sorbent dosage, sorbate concentration, contact time and physicochemical pretreatments on Pb(II) sorption were conducted. Maximum adsorption capacity 170.6 mg g−1 was observed at pH 3.5. Pb(II) sorption data was fitted to Langmuir, Fruendlich, Dubnin–Radushkevich and Tempkin isotherms while time dependent study was well described by pseudo-second-order kinetic model. The equilibrium data suited well the Langmuir isotherm with qmax value of 370 mg g−1. FTIR spectroscopic analysis of PPPC revealed the existence of various alkane, aromatic CC and oxygen functionalities along with aromatic NO2 and surface SO2 complexes. The surface modification by various physicochemical approaches markedly influenced the chemical structure of PPPC. FTIR spectra confirmed that the basic pretreatment caused an increase in the hydroxyl group contents; acidic treatment increased the amount of single bonded oxygen functional groups along with bond cleavage while significant changes took place in the spectrum of boiled PPPC.