%T Synthesis of Black-TiO2 and manganese-doped TiO2 nanoparticles and their comparative performance evaluation for photocatalytic removal of phenolic compounds from agro-industrial effluent %A R. Nawaz %A C.F. Kait %A H.Y. Chia %A M.H. Isa %A L.W. Huei %A N.T. Sahrin %I Springer Science and Business Media B.V. %V 23 %K Effluents; Light; Light absorption; Manganese compounds; Palm oil; Particle size; Phenols; Photocatalytic activity; Rate constants; Sewage; Synthesis (chemical); TiO2 nanoparticles, Black-TiO2 nanoparticle; Comparative performance; Doped-TiO; Environmental remediation; Manganese-doped TiO2 nanoparticle; Palm oil mill effluents; Phenolic compound removal; TiO 2; Treated palm oil mill effluent; Visible light absorption, Titanium dioxide, black titanium dioxide nanoparticle; glycerol; manganese titanium dioxide nanoparticle; palm oil; permanganate potassium; phenol derivative; titanium dioxide; titanium dioxide nanoparticle; unclassified drug, adsorption; agro-industrial waste; Article; biodegradation; chemical structure; comparative study; controlled study; desorption; ecosystem restoration; irradiation; light absorption; particle size; photocatalysis; recycling; renewable resource; synthesis; waste component removal %X In this paper, the synthesis, characterization, and comparative performance of Black-TiO2 and manganese-doped TiO2 (Mn-TiO2) nanoparticles for photocatalytic removal of phenolic compounds from agro-industrial effluent known as treated palm oil mill effluent (TPOME) are reported. The Black-TiO2 nanoparticles were synthesized via a green synthesis approach using a renewable chemical, glycerol as a reducing agent. The Mn-TiO2 nanoparticles were synthesized via the wet impregnation method using potassium permanganate (KMnO4) as a precursor. Experimental results revealed that both types of TiO2 nanoparticles, Black-TiO2 and Mn-TiO2 nanoparticles were anatase phase with a particle size range from 30�80 nm, improved visible light absorption and narrow bandgap of 2.96 and 2.12 eV, respectively. The improved visible light absorption was ascribed to the presence of Ti3+ defect states in Black-TiO2 nanoparticles and the substation of Mn into TiO2 matrix in Mn-TiO2 nanoparticles. The improved visible light absorption led to the enhanced photocatalytic performance of Black-TiO2 and Mn-TiO2 nanoparticles. The former was able to remove 48.17 whereas the latter removed 39.11 of 224.85 mg/L of phenolic compounds from TPOME under 180 min of visible light irradiation. The Black-TiO2 and Mn-TiO2 nanoparticles showed 2.2-fold and 1.7-fold higher performance, respectively, than the Pure-TiO2 nanoparticles. The Black-TiO2 nanoparticles exhibited superior photocatalytic performance, and the highest reaction rate constant (Kapp = 0.31127) was achieved which is two-fold higher than the one obtained by Pure-TiO2 nanoparticles (Kapp = 0.14733). The recyclability test showed that Mn-TiO2 nanoparticles were more stable indicated by their negligible loss (1.55) of photoactivity after five repeated cycles. © 2021, The Author(s), under exclusive licence to Springer Nature B.V. %O cited By 6 %L scholars14169 %J Journal of Nanoparticle Research %D 2021 %R 10.1007/s11051-021-05373-4 %N 12