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Biocarbon adsorption and TiO

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Biocarbon adsorption and TiO

2

/solar photodecomposition of binary and tertiary antibiotics systems

LIMA, G.N.S.

1

; MORAIS. G

1

; MACEDO, M.V.

1

; AYOUB, J.M.S

2

; ORTIZ, N.

1

*

1

Center of Environmental Chemistry – CQMA

2

Fuel Cell and Hydrogen Center - CCCH Institute of Nuclear and Energy Research – IPEN Av. Lineu Prestes, 2242 – USP São Paulo - Brazil

* [email protected]

The occurrence of pharmaceutical residues in a polluted environment includes the exposition to a

contaminant mixture including antibiotics rather than individual toxic compounds. Some published

results confirm the detection of a variety of antibiotics in soil and water environment as binary and

tertiary systems which highlight the importance of antibiotics removal study of from a binary and

tertiary mixture. Experimentaly the antibiotic mixture was preheating before adding TiO

2

and kept in

a solar radiation chamber with constant temperature and pH values. The collection of the suspension

aliquots allows the photodecomposition control followed by the addition of micronized biocarbon

(diameter < 500 mesh) agitation and centrifugation. The supernatants measurements used

spectrophotometer UV-Vis at λ = 273nm, 261nm, and 373nm to amoxicillin, cephalexin, and

oxytetracycline, respectively. All results indicate the TiO

2

/solar photodecomposition followed by

biocarbon adsorption have better agreement with pseudo-second-order kinetics. The comparison

between the antibiotics photodecomposition removal percentages of the binary mixtures indicates

higher decomposition for amoxicillin (57,38%), followed by cephalexin (48,04%) and considering

the tertiary antibiotic systems the oxytetracycline (14,63 %). Such removal difference is a result of

the antibiotics chemical structure and bounding energy broken by the hydroxy radicals of the

solar/TiO

2

photodecomposition reaction. For amoxicillin, the results refer to break the weak

thiophene sulfur bond, for the cephalexin and oxytetracycline they have to break the strong hydrogen

bonding of amide (amino carbonyls group) and the benzamide bond.The use of the biocarbon

adsorption in the water treatment is final stage ensure the water quality polishing results.

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