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Montmorillonite-based porous adsorbent prepared by gel casting method was used to adsorb Cr(III)-organic complexes in tanning wastewater with the initial concentration of 10 mg L−1. The as-porous adsorbent exhibited an excellent performance of separation. Meanwhile, its structural and morphology were characterized by TG, BET, XRD, SEM, EDS and XPS, showing that the porous adsorbent was complete hollow ball structure. And the adsorption results showed that the adsorption amount of porous adsorbent rapidly declined from 9.58 to 5.28, and only Cr(III) was adsorbed, when the molar ratio of Cr(III) and citrate was more than 1:5. Increased of pH was beneficial to the adsorption of Cr(III)-citrate in range from 2.46 to 7.12. Furthermore, the best removal efficiency of porous adsorbent for Cr(III)-organic complex used up to 97% and remaining above 84% after five cycles. Finally, the adsorption mechanism of Cr(III) on porous adsorbent is also provided. Therefore, a kind of easy separated porous adsorbent was prepared in this study so as to treat tanning wastewater containing Cr(III)-organic complex following alkali precipitation, as well as solving the problem of difficult recycle.

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