Powdery photocatalyst has long been studied, yet its several disadvantages such as light-harvesting and recyclability in suspension system are the bottlenecks for practical application. The recent report on floating photocatalyst provided an alternative method to solve the above problem. In this paper, TiO2 nanoparticles were co-doped by samarium and nitrogen, and then supported onto natural porous mineral diatomite via sol-gel method. The composite powder was granulated to produce self-floating pellet catalyst (Sm/N co-doped TiO2/diatomite hybrid pellet), denoted as SN-TDHP. Its various physicochemical properties such as light absorbance, crystallinity, surface condition as well as morphology were systematically analyzed. The synergy between Sm and N dopants, as well as diatomite and TiO2 were studied. The photoactivity of SN-TDHP was investigated via the degradation towards an antibiotic tetracycline (TC) solution under visible light, and then the optimal co-doping amount and pellet dosage were determined. The optimal pellet catalyst presented its removal rate of TC as 87.2% within 150 min of reaction time. Moreover, self-floating SN-TDHP could simply be filtrated from the surface of water matrix, and presented good reusability after 5 repetitions. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.