Adsorption of Pb and Cd in rice husk and their immobilization in porous glass‐ceramic structures

Abstract

Rice husk, an agricultural waste, is abundantly available in many countries such as China, India, Brazil, US, and South East Asia. Despite the massive production of rice husk, it is mainly disposed to landfill. In this work, utilization of rice husk for a potential waste-water treatment is evaluated, along with subsequent encapsulation of the adsorbed heavy metals (Pb and Cd) inside a porous glass-ceramic. Vitrified bottom ash (another source of waste) was mixed with foaming agents in different weight ratios (40:60, 50:50, and 60:40) to prepare a glass matrix for encapsulation of Pb-/ Cd-loaded rice husk. It was shown that using 40 wt% vitrified bottom ash with 60 wt% foaming agents leads to a foam glass with the best pore size distribution. Therefore, this batch was further mixed with 70 volume% (5 wt%) heavy metal-loaded rice husk and was heat-treated at 750°C for 3 hours. The final glass-ceramic porous structure was char acterized using SEM, XRD, compression test, and it was shown that it is safe to be used as it passes the EN12457-2 leaching test.

A Systemic Design Approach Applied to Rice and Wine Value Chains. The Case of the InnovaEcoFood Project in Piedmont (Italy)

“…Production of jet fuel through fluidized-bed fast pyrolysis, hydro-processing and hydro-cracking/isomerization [125]. Utilization of rice husk for a potential waste-water treatment due to their adsorption potential across a variety of common drinking water contaminants [82,85]. Production of energy and fertilizer by using rice waste [77].…”

“…From combustion, 16% ash residue, rich in carbon and silica, is obtained and used in the production of refractory bricks, tyres and steelworks as thermal insulation and antioxidant in castings [78][79][80]. The adsorption potential of rice husk allows its use for the treatment and purification of drinking water [81][82][83].…”

Bulk Composition Effects on Vitrification of Mixed Fine Construction–Demolition and Inorganic Solid Waste

“…Waste treatments as alternatives to landfill confinement have thus attracted considerable research efforts, stimulated by the need to comply with EU regulations on waste. Moreover, among the different technologies for immobilizing polluting and/or toxic components in polymeric, cementitious, glass, or ceramic matrices, vitrification shows promise as a process which allows the confinement of environmentally hazardous elements into a stable amorphous structure, thus avoiding leaching ( [2][3][4] and references therein).…”