Low-cost and effective phenol and basic dyes trapper derived from the porous silica coated with hydrotalcite gel

Novel low-cost and effective adsorbents of phenol and basic dyes were made by coating amorphous silica with hydrotalcite (HT) gel followed by soaking in alkaline solution, and the surface basic–acidic properties of resulting composites were evaluated by CO2-TPD, Hammett indicator method and NH3-TPD, respectively. Both BET surface area and microporous surface area of the composites were increased after they were soaked with alkaline solution; meanwhile the center of pore size distribution was changed from 9 to 3–4 nm. These composites efficiently captured phenol in gaseous and liquid phases, superior to mesoporous silica such as MCM-48 or SBA-15 and zeolite NaY, and the equilibrium data of gaseous adsorption could be well fitted to Freundlich model. These modified silicas also exhibited high adsorption capacity forward basic dyes such as crystal violet (CV) and leuco-crystal violet (LCV), reaching the adsorption equilibrium within 1 h and offering a new material for environment protection.

New bifunctional materials of the silica decorated with hydrotalcite gel, a good capturer towards phenol and basic dyes, greatly exceed mesoporous silica such as SBA-15 and MCM-48 and zeolite NaY.Figure optionsDownload high-quality image (66 K)Download as PowerPoint slideHighlights
► New bifunctional material was made by coating hydrotalcite (HT) gel on amorphous silica combined with alkaline soaking.
► This low-cost composite adsorbs more phenol than mesoporous silica SBA-15, MCM-48 and zeolite NaY.
► This composite can capture more crystal violet in aqueous solution than silica and HT.
► A clue is given for preparation of effective adsorbents from amorphous silica.