An electroanalytical approach for evaluation of biochar adsorption characteristics and its application for Lead and Cadmium determination

•New electrochemical procedure for evaluation of biochar’s proprieties adsorption.•Analytical application of biochar obtained under low temperature pyrolysis conditions.•Development of voltammetric sensor for determination of Pb2+ and Cd2+ using biochar.•Low limit of detection, excellent sensitivity and stability of the proposed electrode.•Analysis of simulated industrial waste water without any pretreatment of the sample. This work describes for first time the use of electroanalytical techniques for evaluation of adsorptive proprieties of biochar using it as electrode modifier and its application for preconcentration and determination of Lead(II) and Cadmium(II) under differential pulse adsorptive voltammetric conditions (DPAdSV). Samples of biochars were obtained from castor oil cake using a predefined set of experimental conditions varying the heating rate (V), final temperature (T) and warm-up period (P) and subsequently used for carbon paste modified electrode (CPME) preparation. The proposed method was applied for Lead(II) and Cadmium(II) determination in spiked simulated industrial effluents and the limit of detection obtained for both metals were adequated for determination of these evaluated ions taking into account the limits established by Brazilian legislation. For all samples analyzed, recoveries ranged from 95% to 104% were obtained and no significative interferences were observed for common cations in water samples.