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Copper desorption from Gelidium algal biomass
Vítor J P Vilar1, Cidália M S Botelho, Rui A R Boaventura
1LSRE-Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Química, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
Water Research
|February 6, 2007
Summary
Marine algae and its waste effectively desorb copper ions using nitric acid or EDTA. Elution efficiency is high, especially at low pH with nitric acid, indicating efficient copper recovery from these biosorbents.
Area of Science:
- Environmental Science
- Materials Science
- Chemical Engineering
Background:
- Marine algae, specifically Gelidium sesquipedale, and its waste products from the agar industry are abundant biomass resources.
- These materials, along with a composite form (algal waste immobilized in polyacrylonitrile), were investigated for their potential in heavy metal remediation.
- Copper (divalent) was the target pollutant due to its prevalence and toxicity in marine environments.
Purpose of the Study:
- To investigate the desorption efficiency of copper ions from marine algae, algal waste, and a composite material.
- To evaluate the influence of desorption agents (nitric acid and Na(2)EDTA), pH, and concentration on copper recovery.
- To analyze the kinetics and mechanisms governing the copper desorption process.
Main Methods:
- A batch system was employed to study the desorption of pre-adsorbed copper ions.
- Desorption was performed using nitric acid (HNO(3)) and ethylenediaminetetraacetic acid (Na(2)EDTA) solutions.
- Elution efficiency, stoichiometric and selectivity coefficients, and desorption kinetics were determined under varying conditions (pH, concentration, solid-to-liquid ratio).
Main Results:
- Nitric acid elution efficiency increased with decreasing pH, achieving up to 97% at pH 1.
- EDTA elution efficiency increased with EDTA concentration, showing a 1:1 molar complexation with copper.
- Desorption kinetics were rapid for all biosorbents and well-described by a mass transfer model, with diffusion coefficients ranging from 1.0 x 10(-7) to 3.0 x 10(-7) cm(2)s(-1).
Conclusions:
- Marine algae, algal waste, and the composite material are effective biosorbents for copper removal and subsequent desorption.
- Nitric acid and EDTA are efficient agents for copper recovery, with nitric acid being particularly effective at low pH.
- The study demonstrates the potential of algal biomass waste as a sustainable material for heavy metal remediation and recovery.
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