Heavy metal ions and particulate pollutants can be effectively removed by a gravity-driven ceramic foam filter optimized by carbon nanotube implantation

It is of great significance to develop a new gravity-driven filter to remove water pollutants, but it is still challenging. Here, a novel and simple strategy is demonstrated to manufacture fly ash (FA) ceramic foams showing a three-dimensional interconnected porous structure, with multiwalled carbon nanotubes (MWCNTs) implanted by combining carbamate grafting and polydimethylsiloxane coating. The polydimethylsiloxane formed a physical coating on the carbamate group, generating an effective thermal insulating layer on the outer side of the entire MWCNT. The FA foam, which shows a sufficient adsorption capacity for Pb(II) (51.67 +/- 1.17 mg g-1) and Cd(II) (30.12 +/- 0.37 mg g-1) at pH = 5, T = 25 degrees C, has a 96.33%, 95.12%, 89.50% removal efficiency for Cd(II), Pb(II), and particulate pollutants, and exhibits excellent recycling performance. This paper provides new opportunities to fabricate gravity-driven filters with low energy consumption for wastewater treatment.

Automated summary

A novel method for manufacturing fly ash ceramic foams with a porous structure and multiwalled carbon nanotubes has been demonstrated in this study. The foam shows a high adsorption capacity for lead and cadmium, with excellent removal efficiency and recycling performance. This paper opens up new opportunities for developing low-energy gravity-driven filters for wastewater treatment.