| Autor: |
Vaz, Marcelo, Pereira, Antonio, Fajardo, André, Azevedo, Antônio, Rodrigues, Francisco |
| Předmět: |
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| Zdroj: |
Water, Air & Soil Pollution; Jan2017, Vol. 228 Issue 1, p1-13, 13p |
| Abstrakt: |
A set of chitosan-g-poly(acrylic acid)/rice husk ash hydrogel composites was successfully employed as methylene blue (MB) adsorbent. Maximum MB adsorption capacity of 1952 mg/g of dried hydrogel was obtained with the composite at 5 wt% of rice husk ash (RHA) at pH ≥ 5. The adsorption capacity varied from 1450 to 1950 mg/g with increasing the initial MB concentration from 1500 to 2500 mg/L. The MB removal efficiency was higher than 90% for all samples. At pH ≥ 5, negatively charged groups (-COO) in the adsorbent were generated, which could strongly interact with the positive charges from MB, favoring adsorption. Adsorption kinetics followed the pseudo-second-order model, which is based on the chemisorption phenomenon, reaching saturation as fast as 1 h of experiments due to the formation of an adsorbed MB monolayer, as suggested by the Langmuir isotherm model (type I). Desorption experiments showed that 75% of loaded MB can be removed from the adsorbent by immersing it in a pH 1 solution. CHT-g-PAAc/RHA5% composite was submitted to five cycles of adsorption/desorption, maintaining its MB removal efficiency at 91%. Therefore, chitosan-g-poly(acrylic acid)/RHA hydrogel composites present outstanding capacity to be employed in the remediation of MB-contaminated wastewaters. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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