Problem to be solved: to provide an aqueous medium for hydroponic cultivation which realizes sterilization and purification of a culture medium while suppressing inactivation of an organic medium or an ionic substance in an aqueous medium while realizing an inefficient purification of an aqueous medium capable of sterilization, and suppressing the inactivation of the culture component in the culture medium.Porous particles andSupported by the porous particles；A metal compound having a metal atom and a hydrocarbon group is bonded to the surface through an oxygen atomAnd has absorption at 500 nm wavelength in visible absorption spectrumA photocatalytic particle consisting of a titanium based compound particle having an absorption peak at 2700 cm. Sup. - 1 to 3000 cm. Sup. - 1 in the infrared absorption spectrum andWater purifying particle or hydroponic medium particle having.Diagram【課題】水系媒体中の有機物又はイオンの不溶化を抑制しつつ、効率のよい水系媒体の殺菌浄化を実現する水質浄化粒子、及び培養液中の培養成分の不活性化を抑制しつつ、培養液の殺菌浄化を実現する水耕栽培用培地粒子を提供する。【解決手段】多孔質粒子と、前記多孔質粒子に担持され、金属原子及び炭化水素基を有する金属化合物が酸素原子を介して表面に結合し、かつ可視吸収スペクトルにおける波長５００ｎｍに吸収を持ち、赤外吸収スペクトルにおける２７００ｃｍ－１～３０００ｃｍ－１に吸収ピークを持つチタン系化合物粒子からなる光触媒粒子と、を有する水質浄化粒子又は水耕栽培用培地粒子。【選択図】図１
