Silica materials recovered from photonic industrial waste powder: Its extraction, modification, characterization and application

Highlights: → Photonic industrial waste powder was recovered into NaF and silica precursor. → The extracted silica precursor was used for producing mesoporous MCM-41 material. → MCM-41 synthesized from photonic waste powder can be a cost-effective adsorbent for CO2 capture. -- Abstract: This study explored the possibility of recovering waste powder from photonic industry into two useful resources, sodium fluoride (NaF) and the silica precursor solution. An alkali fusion process was utilized to effectively separate silicate supernatant and the sediment. The obtained sediment contains purified NaF (>90%), which provides further reuse possibility since NaF is widely applied in chemical industry. The supernatant is a valuable silicate source for synthesizing mesoporous silica material such as MCM-41. The MCM-41 produced from the photonic waste powder (PWP), namely MCM-41(PWP), possessed high specific surface areas (1082 m2/g), narrow pore size distributions (2.95 nm) and large pore volumes (0.99 cm3/g). The amine-modified MCM-41(PWP) was further applied as an adsorbent for the capture of CO2 greenhouse gas. Breakthrough experiments demonstrated that the tetraethylenepentamine (TEPA) functionalized MCM-41(PWP) exhibited an adsorption capacity (82 mg CO2/g adsorbent) of only slightly less than that of the TEPA/MCM-41 manufactured from pure chemical (97 mg CO2/g adsorbent), and its capacity is higher than that of TEPA/ZSM-5 zeolite (43 mg CO2/g adsorbent). The results revealed both the high potential of resource recovery from the photonic solid waste and the cost-effective application of waste-derived mesoporous adsorbent for environmental protection.