PARTNERS SEARCH
Research project on Removal of Toxic Metals from Aqueous Solutions by
Adsorption on Waste Materials Rich in Chitin.
ACTIVITY 6.3. ENVIRONMENTAL TECHNOLOGIES
Sub-activity 6.3.1. Environmental technologies for observation, simulation,
prevention, mitigation, adaptation, remediation and restoration of the natural and
man-made environment
ENV.2007.3.1.1.1. Innovative technologies and services for sustainable water use in
industries
Summary
Large quantities of chitin food wastes (crab, prawn and crayfish shells and squid pens)
are generated in several Portuguese seafood industries and can be reused as adsorbent
for toxic metals before final disposal. On the other hand, the waste material is cheaper
than other commercially available adsorbents (activated carbon, ion exchange resins,
etc.). The search of effective methods to remove these compounds is of global interest
in order to fulfil the discharge legislation.
Metal binding enhancement by submitting biomass to chemical (protonation and Cabiomass) and physical pre-treatments (granulation of the chitin food waste) will be
studied for a better implementation of the process scale-up. To elucidate the different
metal-binding mechanisms will be addressed as it opens the possibility of optimising
the uptake process, manipulating the adsorbent properties and improving the sorption
performance. So, a chemical equilibrium programme (MINEQL+) will be used to
calculate metal speciation in aqueous solution as a function of pH and ionic strength.
The uptake capacities of the chitin food wastes for Zn(II), Cd(II), Cr(III), Cr(VI) and
As(II) will be determined as well as the effect of some environmental factors (water
temperature, pH, ionic strength) on the sorption process. Adsorbent regeneration and
metal recovery will be also under study. Screening the most effective regeneration
solution is a key point. In multi-metal sorption systems, synergistic or antagonist effects
on the metal uptake will be investigated. Mathematical model combining equilibrium
data, mass transfer kinetics will be developed and validated in a sorption column
contactor. The applicability of the chitin food wastes adsorption process to metalplating, glass manufacturing and tanning industrials effluents will be evaluated and the
chemical composition of the treated effluent will be determined in order to check if it is
suitable for recycling as process water.
The main objective of the intended work is to optimize the application of chitin
processing food wastes in the adsorption of toxic metals in liquid effluents from metal
plating, glass manufacturing and leather tanning industries, using a biosorption process.
The specific objectives are as follows:
i. Characterization and granulation of the chitin wastes in a organic polymer, in
order to obtain rigid spherical particles;
ii. To evaluate the uptake capacities of Ni2+, Zn2+, Cr3+, Cr6+ and As3+ by the chitin
wastes;
iii. To define the mechanism and kinetics of biosorption;
iv. To study the effect of pH, temperature, ionic strength in the performance of the
adsorption process;
v. To study the biosorption simultaneous of two and three metal ions;
vi. To establish a adequate kinetic model that describes the global mass transfer
process in solution for mono and multi-component;
vii. To study the optimal desorption conditions of the different metal ions and the
desorption mechanism;
viii. To evaluate the biosorption efficiency in packed bed column system at different
conditions;
ix. To evaluate the possibility of the recuperation of the biosorbents and reutilization
in consecutive adsorption-desorption cycles;
x. To develop mathematic models capable of describe the global mass transfer
process for the saturation and regeneration of the biosorbents;
xi. To optimize the treatment of metal plating, glass manufacturing and leather
tanning effluents using a packed bed column at a pilot scale;
Contacts:
Dr. Rui Boaventura
LSRE – Laboratory of Separation and Reaction Engineering
Faculty of Engineering – University of Porto
Porto, Portugal
E-mail: bventura@fe.up.pt
Dr. Vítor Vilar
LSRE – Laboratory of Separation and Reaction Engineering
Faculty of Engineering – University of Porto
Porto, Portugal
E-mail: vilar@fe.up.pt