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

Abstract

The present work incorporates toxic arsenic-contaminated sludge (AsCS) obtained from groundwater ltration 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 (B 4 ) and tetrahedral Fe 3+ within the silicate glassy network collectively help to maintain a low thermal expansion coe cient (CTE) 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. Signi cantly lower leaching rate (7.47 *10 − 7 g.cm − 2 .h − 1 in 42 days) followed by a successful immobilization of toxic As, the glass becomes an alternative and most attractive material for AsCS immobilizing material.