Zinc (II) removal using low-cost sorbents requires a proper process parametric study to determine its optimal performance characteristics. In this respect, the present study proposes a new modeling and simulation procedure for heavy metal removal system and is carried out to optimize input variables such as initial pH, adsorbent dosage, and contact time for biosorption of Zinc (II) by using bentonite. The proposed experimental system is cost-effective and requires less calculation for determining optimal values, i.e., input variables and their related removal capacity, Rem%. To optimize the adsorption process, cubic spline curve fitting and numerical differentiation techniques are used for required calculations. According to the proposed calculations, the removal capacity is calculated as 98.66%, while the optimal values are calculated as initial pH – 6.76, adsorbent dosage – 1.14 g L-1, contact time – 13 minutes. To evaluate the results, full factor experimental design and 3 way ANOVA test are used for comparison.
This paper presents a voltammetric segmented voltage sweep mode that can be used to identify and measure heavy metals' concentrations. The proposed sweep mode covers a set of voltage ranges that are centered around the redox potentials of the metals that are under analysis. The heavy metal measurement system can take advantage of the historical database of measurements to identify the metals with higher concentrations in a given geographical area, and perform a segmented sweep around predefined voltage ranges or, alternatively, the system can perform a fast linear voltage sweep to identify the voltammetric current peaks and then perform a segmented voltage sweep around the set of voltages that are associated with the voltammetric current peaks. The paper also includes the presentation of two auto-calibration modes that can be used to improve system's reliability and proposes the usage of a Gaussian curve fitting of voltammetric data to identify heavy metals and to evaluate their concentrations. Several simulation and experimental results, that validate the theoretical expectations, are also presented in the paper.