Adsorption performance of modified bentonite granular (MBG) on sediment phosphorus in all fractions in the West Lake, Hangzhou, China

- MBG was tested as novel sorbent for treating sediment P in all fractions.
- Optimal modification methods of bentonite was achieved.
- Adsorption mechanism of sediment P by MBG has been investigated.
- MBG could be further applied to treat internal P loading.

Modified bentonite granulars (MBGs) were prepared by acidification, natrification, calcination, and combined modification methods, and evaluated as effective in-situ adsorption materials to remove sediment phosphorus (P) in all fractions. The morphology and microstructure of MBG were characterized by scanning electron microscope (SEM), X-ray fluorescence (XRF), fourier transform infrared (FTIR) and X-ray diffraction (XRD). Results showed that the P removal capacity of CMBG-Na10-450 treated with 10% (g/g) Na2CO3 and calcined at 450 °C exhibited the highest P removal capacity. Under the optimal conditions of stirring tests, the removal rates of sediment TP, OP, IP, Fe/Al-P and Ca-P by CMBG-Na10-450 were 35.5%, 29.1%, 54.5%, 44.6% and 10.7%, respectively. The adsorption mechanism analysis found that MBG adsorbed sediment P mainly by anionic coordination exchange adsorption. These results indicated that modification enhanced the P adsorption capacity of bentonite, and the MBG can be further applied to control and reduce sediment P in eutrophication remediation.

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