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

The present work incorporates toxic arsenic-contaminated sludge (AsCS) obtained from ground-water filtration into a chemically durable borosilicate glass matrix to minimize arsenic contamination. 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, 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 and higher characteristic thermal properties (T_g, T_d,, 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.