b9-sialon powder was synthesised using kaolin of different chemical compositions by carbothermal reduction-nitridation. The products were analysed by X-ray diffraction (XRD) and differential thermal analysis (DTA). The results show that when the ratio m(SiO 2 )/m(Al 2 O 3 ) is large, the Z value is small, and when the ratio m(SiO 2 )/m(Al 2 O 3 ) decreases, the Z value tends to increase. Single crystal phase b9-sialon powder was obtained when the m(SiO 2 )/m(Al 2 O 3 ) ratio in kaolin was around 1 . 55.b9-sialon powder was synthesised using kaolin of different chemical compositions by carbothermal reduction-nitridation. The products were analysed by X-ray diffraction (XRD) and differential thermal analysis (DTA). The results show that when the ratio m(SiO 2 )/m(Al 2 O 3 ) is large, the Z value is small, and when the ratio m(SiO 2 )/m(Al 2 O 3 ) decreases, the Z value tends to increase. Single crystal phase b9-sialon powder was obtained when the m(SiO 2 )/m(Al 2 O 3 ) ratio in kaolin was around 1 . 55.

10 and 20 mg L−1 ZnO NPs damaged the integrity of cell membranes and the microbial community and affected phosphorus removal.