Abstract
A mesoporous hybrid silicate microsphere with superior adsorption performance has been successfully synthesized by employing an “all-into-one” strategy and a simple one-pot hydrothermal process using naturally abundant low-grade red palygorskite (PAL) clay as raw material in the presence of non-toxic SiO32− and Mg2+ ions. As is expected, both the PAL and associated minerals transformed into a new amorphous mesoporous hybrid silicate microsphere without using any additional pore-forming template. The mesoporous silicate microsphere shows a large pore size of 37.74 nm, high specific surface area of 489.81 m2/g (only 54.67 m2/g for raw PAL) and negative surface potential of −43.3 mV, and its maximum adsorption capabilities for Methylene bule (MB) and Crystal violet (CV) reach 407.95 mg/g and 397.22 mg/g, respectively. Meanwhile, 99.8% of MB (only 53% for raw PAL) and 99.7% of CV (only 43% for raw PAL) were sucessfully removed from 200 mg/L of initial dye solution by only using 1 g/L of the adsorbent. In addition, the spent adsorbent can be easily regenerated and repeatly reused for muptiple cycles. The study on adsorption mechanism revealed that electrostatic attraction, hydrogen bonding and chemical complexing interactions are the main factors contributed to the high dye adsorption.
Highlights
Carriers of catalyst and activated carbon[18,19,20]
It is well known that the primary factors limited the adsorption performance of low-grade PAL clay are: (i) the associated minerals in PAL clays show no adsorption activity; (ii) the low specific surface area (
The structure of the adsorbents was studied by Fourier transform Infrared spectra (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscope (SEM) and BET analysis, and the adsorption properties of the mesoporous adsorbent were evaluated using Methylene blue (MB) and Crystal violet (CV) as the model dyes
Summary
Carriers of catalyst and activated carbon[18,19,20]. Besides, PAL has been used as non-toxic, low cost and eco-friendly adsorbents for removal of dyes[21], heavy metal ions[22,23], and color matters[24]. At high pH value of 12.6, the PAL was rapidly evolved and crystallized to form bulk silicate aggregates (Fig. S2b, Supplementary Information).
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