Tianming Lv

Removal of methylene blue over low-cost mesoporous silica nanoparticles prepared with naturally occurring diatomite

AbstractThe low-cost mesoporous silica nanoparticles were successfully prepared from naturally occurring diatomite. The resultant samples were tested in the adsorption of methylene blue (MB) from aqueous solution. The effect of various adsorption parameters including initial pH, adsorbent dose and contact time was examined. The experimental data obtained with mesoporous silica were well fitted with both the pseudo-second-order kinetic and Langmuir models; and thermodynamic calculations showed that the removal of MB onto mesoporous silica was a spontaneous and exothermic process. The maximum adsorption amount of MB onto mesoporous silica reached 347.2 mg g−1. Moreover, mesoporous silica could be effectively regenerated by simple heating treatment and reused five cycling runs without significant loss of adsorption capacity. 27Al NMR results indicated aluminum was mainly incorporated into the framework. XPS studies also confirmed the presence of Fe2O3 in the adsorbent. Mesoporous silica prepared from inexpensive raw material was found to a potential adsorbent towards the removal of MB owing to its easy recovery and eco-friendliness. The low-cost mesoporous silica prepared from naturally occurring diatomite exhibited high adsorption capacity and fast adsorption kinetics for methylene blue.HighlightsThe low-cost mesoporous silica nanoparticles were successfully prepared from naturally occurring diatomite.The effects of solution pH, adsorbent dose, contact time were thoroughly investigated.The adsorption process was successfully fitted with the pseudo-second-order kinetic and Langmuir isotherm models.The reusability study showed that mesoporous silica was effectively recovered by simple heating treatment and still stable after five cycling runs.The maximum adsorption capacity of adsorbents obtained under optimum synthesis conditions reached 347.2 mg g−1 at 25 °C. The results indicated that the synthesized solid sorbent had a good potential for the removal of methylene blue due to its low-cost and eco-friendliness.