Arsenic-contaminated sludge remediation induced generation of coloured glass using conventional and microwave heating

Abstract

Abstract The present work incorporates toxic arsenic-contaminated sludge (AsCS) obtained from groundwater filtration into a chemically durable borosilicate glass matrix to overcome the environmental exposure's arsenic (As) toxicity. Upto 25 wt% of AsCS loaded borosilicate system found X-ray amorphous that ensures the successful glass formation. The optical absorption spectra reveal the utilization of AsCS to develop heat absorption property (NIR absorption ~ 1000 nm) into the borosilicate matrix. 3–5 wt% of AsCS was found suitable for developing a green colour glass for various purposes. Furthermore, green colour in glass can be turned yellow with the adoption of novel microwave heating (MW), which reduces energy demand. From a structural viewpoint, the presence of tetrahedral boron (B4) and tetrahedral Fe3+ within the silicate glassy network collectively help to maintain a low thermal expansion coefficient (CTE) and higher characteristic thermal properties (Tg, Td, etc.)Further, the structural integration of iron (major component in AsCS) as bridging network helps to maintain the thermal and chemical durability of the system. Significantly lower leaching rate (7.47 *10− 7 g.cm− 2.h− 1in 42 days) followed by a successful immobilization of toxic As, the glass becomes an alternative and most attractive material for AsCS immobilizing material.