Measurement of trace metals in powder activated carbon (PAC) using proton induced x-ray emission (PIXE)

![CDATA[We have used proton-induced x-ray emission (PIXE) to quantify ppm level of arsenic adsorbed in powder activated carbon (PAC), during the exposure of PAC to arsenic solutions. To evaluate different aspects of adsorption mechanisms in PAC, we have carried out equilibrium and kinetic adsorption experiments. After the exposure, arsenic concentration in adsorbent was quantified by means of PIXE (with 1.0 mm diameter ion beam). The As concentrations determined using PIXE compared favourably to those determined from inductively coupled plasma (ICP) measurements. 1. Introduction: Quantification of trace metals in any adsorbent directly with high accuracy and sensitivity is a challenging task. A rapid, high-sensitivity, non-destructive, quantitative, multi-elemental analytical method is best suited to investigate the issues associated with detecting trace elements. Proton induced x-ray emission (PIXE) is such an analytical tool and it is suitable for simultaneously quantifying trace elements with sensitivity of at least parts per million (ppm) [1]. In this study, trace arsenic concentrations in drinking water were investigated by PIXE. Since activated carbon (AC) can effectively remove hazardous trace elements from the drinking or wastewater, it is commonly being used to treat wastewater [2, 3]. As such, activated carbon is an excellent adsorbent for the investigation of the analysis of trace arsenic concentrations in water by characterisation techniques such as PIXE. In this work, PAC has been used as an adsorbent to remove arsenic from drinking water. The amount of arsenic adsorbed was measured by PIXE. Various adsorption experiments were conducted to evaluate both the different aspects of adsorption mechanisms in PAC; and the detection limit and accuracy of PIXE measurements. The results are compared with those from inductively-coupled-plasma (ICP) measurements.]]