Quantitative X-Ray Diffraction Technique for Waste Beneficial Use Opportunities

Abstract

The ability to control, manipulate, and design marketable products derived from the waste streams to simultaneously prevent the pollution of our environment and also beneficially use them as material resources is a major challenge in the twenty-first century. Conventional material designs are often assisted by the X-ray diffraction (XRD) technique to identify the mineral phases in the products via matching the observed diffraction peak positions with those of standard mineral phases. This qualitative function is important as the types of crystalline phases in the products directly lead to the performance and safety of the products. Moreover, further advancement in the quantitative capability of XRD technique is now available to further contribute to the accurate control of product quality. In this study, we will demonstrate the successful applications of quantitative X-ray diffraction (QXRD) on stabilizing the hazardous metals in ceramic products and on extracting metallic lead from waste electronics. The feasibility of stabilizing metal-laden waste sludge and ash materials by a wide variety of aluminum- and iron-rich ceramic precursors is reflected by the high metal transformation efficiency and the significant reduction of intrinsic metal leachability. The work of recovering metallic lead from waste cathode ray tube (CRT) glass also serves as a good example to reflect how the quantitative phase composition analysis can assist the development of new resource recovery technologies. A method of reductively transforming the lead in CRT glass into its metallic form through the reactive sintering with the zero-valent iron was invented and optimized by the QXRD technique. With the rapid progress in materials science and characterization techniques, substantial new technological developments in the beneficial uses of waste materials are now spearheaded by the interdisciplinary environmental materials research.