All-Solid-State Piezocatalytic Destruction of Dibenzofuran via Atomic Hydrogen Abstraction and Mechano-Radicals in Hazardous Solid Matrices

Developing a facile and efficient method of dioxin removal from hazardous solid waste presents a compelling yet challenging avenue. Herein, an all-solid-state piezoelectric-mediated strategy is proposed for the piezocatalytic destruction of dioxins induced by ball milling (BM) under ambient and solvent-free conditions. Dioxin-like compounds of harmful solid substances including fly ash (FA), sediment, and soil can be effectively eliminated, filling the gap between dioxin-contaminated matrices purification and piezocatalytic technology. Using the dibenzofuran as a dioxin model pollutant, an optimized removal efficiency up to 100% (below the detection limit) in the FA of municipal waste incineration was obtained after stainless-steel BM with the rotary speed of 600 rpm. This process was affected by piezocatalyst species, moisture content, ball-sample mass ratio, and ball size. Under the initiation of ball collisions, a surface piezopotential of 200 mV on commercially tetragonal barium titanate with a piezoelectric coefficient of 195.3 pm/V appeared, enabling favorable charge transfer between the interface. A unique mechanism of combining mechanochemical activation, hydrogen-atom abstraction, and mechano-radicals attack is ascribed to the elimination of dibenzofuran in the all-solid-state system. Multiple reactions such as cleavage, hydrogenation, rearrangement, and mineralization/coupling were subsequently involved. This approach demonstrates a promising way of destructing dioxins in hazardous solid waste without the need of additional solvent, heating, or pressurization.