Bioadsorvente derivado do carvão da casca da castanha de caju para remoção de contaminantes em água produzida
Produced water is an industrial effluent with a very complex composition and that its improper disposal generates damage to the environment. One of the methods of treatment of produced water is adsorption, however, the use of commercial activated carbon as adsorbent, in an industrial scale, makes...
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| Formato: | doctoralThesis |
| Idioma: | pt_BR |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/33206 |
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| Resumo: | Produced water is an industrial effluent with a very complex composition and that its
improper disposal generates damage to the environment. One of the methods of treatment of
produced water is adsorption, however, the use of commercial activated carbon as adsorbent, in
an industrial scale, makes the process costly. An alternative for the substitution of commercial
activated carbon is the use of biomass to produce bioadsorbents, which has been gaining emphasis
in the last decades, have high performance and a low production cost. The Northeast is the largest
producer of cashew nuts in Brazil, so the processing of cashew (Anarcadium accidentale L)
generates a lot of lignocellulosic residue, the cashew nut shell, which can be reused as a bioabsorbent. The objective of this work is to develop an efficient and low cost bioadsorber, reusing
the charcoal from the cashew nut shell (Anarcadium acidentale L) to remove metal ions (Cu2+
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Pb2+ and Cr3+) and oil and grease content (TOG). The bio-absorbent was pre-treated with NaOH
and characterized by scanning electron microscopy (SEM), Fourier transform infrared
spectroscopy (FTIR), the zero charge point (pHpcz) and the Boehm titration. The adsorption tests
involved experiments of kinetics and adsorption balance, in a batch system, using mono and
multi-element ionic solutions, and in a fixed bed column for the multi-element metallic solution
and semi-synthetic TOG solution. The characterization results obtained revealed the presence of
hydroxyl, carboxyl and carbonyl groups, as well as an irregular and heterogeneous structure,
which are favorable properties for the adsorption process. The kinetic models showed that the
chemisorption process occurred, as well as the isotherm models that best fit the experimental data
were Langmuir (Cu2+) and Redlich Peterson (Pb2+ and Cr3+). The rupture curves of the metal ions
showed that at a flow rate of 7 mL / min and a bed height of 5 cm, the break time for Cu2+ and
Pb2+ was 10.70 min and for Cr3+ was 8.56 min. The adsorption capacities of the metals in the
fixed bed column obtained the following order, Pb2+ < Cr3+ < Cu2+ being less than that obtained
in the batch system. The desorption of the metal ions, retained in the column, was sufficient using
1.0 mol / L HCl as eluent. The column regeneration tests showed that the bioadsorber can be used
for two cycles, following the studied parameters. The breaking point for TOG was approximately
25 min and the bed saturation was not reached in 171.34 min, the adsorption capacity in the 171
min column operating time was 4.85 mg / g. It is concluded that the bioabsorbent produced from
the cashew nut shell has a high potential for removing metals and TOG, besides being an abundant
product in nature, it is renewable and biodegradable and its reuse contributes to the reduction of
environmental pollution, the waste production and improves the local circular economy by
enhancing the by-product. |
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