Applications of ash, clay, foundry sand, and pumice based-metal oxide semiconductors for photodegradation of pollutants^a.

Photocatalyst	Pollutant	Degradation efficiency (%)	Operating conditions				Ref.
			Pollutant concentration (ppm)	Catalyst dosage (mg)	Reaction time (min)	Light source
TiO2 supported VA	Methylene blue	100	20	2400	30	UV	93
Fe2O3–TiO2/FACs	Methylene blue	86.81	2	100	60	Visible	112
ZnO/FA	Methylene blue	100	10	15	180	UV	113
Fe/TiO2–FACs	Methyl blue	50	20	1800	—	Visible	84
Zn/TiO2–RHA	Rhodamine B	95	0.47	25	100	Visible	90
TiO2–FA	Reactive red 45	90	30	100	90	UV	114
TiO2 pillared montmorillonite	Methylene blue	98	30	50	90	UV	115
Cu(ii)-grafted TiO2–imogolite	Acetaldehyde	100	200	50	1500	Visible	116
Halloysite:palygorskite–TiO2	NOx gas	98	1	40	—	UV	117
ZnO/clay	2-Chlorophenol	88	20	200	60	Solar light	118
ZnO/kaolinite	2-Chlorophenol	100	20	200	60	Solar light	119
TiO2/kaolinite	Acid red G	∼98	50	150	60	UV	120
TiO2/kaolinite	4-Nitrophenol	90	10	100	240	UV	120
Fe–TiO2/FA–FS	Pentoxifylline	88	50	—	120	Solar light	121
TiO2/FE–FS	Metronidazole	85	25	—	45	Solar light	122
FS/FA/TiO2	Cephalexin	89	50	—	240	UV	123
FS/FA/TiO2	Cephalexin	94	50	—	210	Solar light	123
N–Ag–TiO2/FS–FA	Cephalexin	77	50	—	60	Solar light	124
TiO2/FS	Phenazone	96	50	—	240	Solar light	125
TiO2–pumice	Methylene blue	100	0.355	1600	2880	UV	126
Fe3O4/ZnO@pumice	Methylene blue	85.5	10	50	60	LED light	127
ZnO/pumice	Dye	90.17	3.01	600	45.04	Solar light	128
PDMS–SiO2–TiO2–pumice	Methylene blue	59	5	—	1800	Visible	129

^aVA: volcanic ashes, FA: fly ash, FACs: fly ash cenospheres, RHA: rice husk ash, FS: foundry sand, FE: fuller's earth, PDMS: polydimethylsiloxane.