Methylene blue adsorption in Pinus elliottii (pine) and Drepanostachyum falcatum (bamboo) sawdust

Müller, Laura Cecilia; Alves, Alcione Aparecida de Almeida; Mondardo, Renata Iza; Sens, Maurício Luiz

doi:10.1590/S1413-41522019160344

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Artigo Técnico • Eng. Sanit. Ambient. 24 (04) • Jul-Aug 2019 • https://doi.org/10.1590/S1413-41522019160344 copy

Methylene blue adsorption in Pinus elliottii (pine) and Drepanostachyum falcatum (bamboo) sawdust

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Kinetics, equilibrium and thermodynamic adsorption parameters were investigated for the adsorption of the methylene blue dye (MB) by means of the biosorbents Pinus elliottii (pinus) and Drepanostachyum falcatum (bamboo). The adsorption kinetics were described more precisely by the pseudo-second order model; the monocomponent equilibrium’s data were better represented by the Langmuir isotherm for the three temperatures studied (15, 25 and 35°C) and the thermodynamic parameters showed the adsorption process is exothermic, of a chemical nature and not spontaneous. The maximum adsorptive capacity of pinus was 47 mg L^-1 and 38 mg L^-1 bamboo for adsorption tests performed with MB (100 mg L^-1 at 35°C). Finally, the biosorbents were considered promising for the adsorbate MB removal in aqueous matrix under pH value close to neutrality (6.5).

Keywords:
adsorption; pine; bamboo; methylene blue

Adsorvente	Área superficial (m² g^-1)	Volume de poro (cm³ g^-1)	Diâmetro médio dos poros (Å)
Pinus	2,478	0,006	31,07
Bambu	1,514	0,005	36,68

Pinus
Temperatura	Langmuir				Freundlich
Temperatura	Q_máx (mg g^-1)	K_L (L mg^-1)	R²	R_L	n	K_f (L mg^-1)	R²
15°C	37	0,020	0,993	0,31	1,8	1,264	0,874
25°C	39	0,054	0,996	0,16	2,2	0,390	0,914
35°C	47	0,029	0,997	0,22	2,0	0,512	0,939
Bambu
Temperatura	Langmuir				Freundlich
Temperatura	Q_máx (mg g^-1)	K_L (L mg^-1)	R²	R_L	n	K_f (L mg^-1)	R²
15°C	26	0,036	0,991	0,19	2,4	0,477	0,957
25°C	22	0,108	0,994	0,07	2,6	0,366	0,906
35°C	38	0,041	0,990	0,16	2,4	0,316	0,906

Pinus
		Pseudoprimeira ordem			Pseudossegunda ordem
Temperatura	Q_{e experimental} (mg g^-1)	k₁ (min^-1)	Q_{e teórico} (mg g^-1)	R²	k₂ (g mg^-1 min^-1)	Q_{e teórico} (mg g^-1)	R²
15°C	14	0,028	9,95	0,946	0,008	14,27	0,995
25°C	16	0,023	9,58	0,907	0,010	16,98	0,998
35°C	15	0,022	5,23	0,258	0,088	15,85	0,995
Bambu
		Pseudoprimeira ordem			Pseudossegunda ordem
Temperatura	Q_{e experimental} (mg g^-1)	k₁ (min^-1)	Q_{e teórico} (mg g^-1)	R²	k₂ (g mg^-1 min^-1)	Q_{e teórico} (mg g^-1)	R²
15°C	18	0,029	13,60	0,985	0,005	18,87	0,991
25°C	16	0,027	8,90	0,659	0,039	16,18	0,994
35°C	17	0,017	7,10	0,608	0,023	17,45	0,997

Arrhenius
Adsorvente	E_a (kJ mol^-1)		A (s^-1)	R²
Pinus	88,91		1,25 . 10¹⁵	0,82
Bambu	54,24		9,17 . 10⁰⁸	0,52
Eyring
Adsorvente	ΔH* (kJ)	ΔS* (J K^-1)	ΔG* (J K^-1)	R²
Pinus	86,44	35,79	75,77	0,81
Bambu	51,76	-81,64	76,09	0,50

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