Simple Aminated Modified Zeolite 4A Synthesized Using Fly Ash and Its Remediation of Mercury Contamination: Characteristics and Mechanism

Abstract

In this study, through simple ammonia impregnation, more amine functional groups could be introduced into the zeolite 4A synthesized using fly ash, which efficiently improved the mercury ion removal capacity of modified zeolites. The impregnation-modification mechanism of NH3·H2O, ammonium chloride, and silane coupling agent (KH792) for zeolite 4A, and the Hg2+ ion removal-efficiency by aminated zeolites, were studied and compared. Through ion exchange and hydroxyl reactions, NH3·H2O impregnation introduced the same kinds of nitrogen-containing groups into zeolite as KH792 grafting, which was more than the NH4Cl modification. The Hg2+ ion adsorption capacity of NH3·H2O-zeolite was higher than those of KH792-zeolite and NH4Cl-zeolite through ion exchange and the complexation of nitrogen-containing groups. When coexisting with Pb2+, Cu2+, and Zn2+ ions, the Hg2+ ion removal rate of NH3·H2O-zeolite was still higher than 99%. After five adsorption and desorption cycles, the Hg2+ ion removal rate of NH3·H2O-zeolite was 72.03%. When NH3·H2O-zeolite was added to the leaching of mercury-contaminated soil, the content of soluble mercury significantly decreased. Therefore, we synthesized a potential cheap and safe adsorbent using fly ash as the main raw material through the simple NH3·H2O impregnation modification for the treatment of mercury-contaminated water and soil.

Nano-revolution in heavy metal removal: engineered nanomaterials for cleaner water

“…Wastewater treatment is undergoing a significant revolution with the application of nanomaterials. Researchers are exploring a diverse range of these materials, including zeolite, various forms of carbon, polymers, chitosan, ferrites, magnetic particles, metal oxides, bimetallic structures, and even pure metals (Aloulou et al, 2022;Amariei et al, 2022;Gao et al, 2022). These nanoparticles boast a remarkable property called adsorption.…”

“…Zeolite nanoparticles are utilized for eliminating hazardous metals from wastewater owing to their reactive surfaces and expansive area (Deravanesiyan et al, 2015). Both natural zeolites like clinoptilolite and synthetic variants such as zeolite 4A and zeolite X are commonly employed for heavy metal treatment (Gao et al, 2022). These zeolites assist in transmitting alkali and alkaline earth metals to balance the overall negative charge within the framework.…”