Performance Evaluation of the Bio-char Heavy Metal Removal Produced from Tomato Factory Waste

Abstract

Bio-char is a carbon-enriched and porous material produced from a variety of biomass. When bio-char is produced from biomass, approximately 50 % of the carbon that the plants absorbed as CO₂ from the atmosphere is “fixed” in the charcoal. Bio-char is similar in its appearance to charcoal and activated carbon.

In this study tomato factory waste has been used for the production of the bio-char. Biomass with a mean particle size was carbonized at 623 K in a furnace. Biomass and bio-char were characterized by using elemental analyses, Fourier Transform Infrared Spectroscopy (FTIR), and scanning electron microscope (SEM) analysis.

The adsorption capacity of the bio-char produced with carbonization of tomato factory waste has been evaluated with the Co(II) ion removal to investigate the effects of pH, amount of adsorbent, initial concentration of the aqueous solution, adsorption time, and solution temperature. To describe the equilibrium isotherms Langmuir and Freundlich models were applied. Pseudo-first order and pseudo-second order kinetic models were used to find out the kinetic parameters and mechanism of adsorption process with increasing adsorbent dosage from 1 to 10 g/l in the batch mode. The final heavy metal concentrations have been reduced from 59 to 8 ppm and removal efficiencies have been increased from 60 to 82 % respectively.

Experimental results showed that, tomato factory waste char seems to be an effective and alternative adsorbent precursor for the removal of heavy metal ions from aqueous solutions due to its high adsorption capacity, low cost, and availability.

Nomenclature

b:

Langmuir coefficient related to adsorption energy, l/mg

C₁ :

Final metal concentration, mg/l

C_e :

Concentration of metal ions in solution at equilibrium, mg/l

C_o :

Initial metal concentration, mg/l

FTIR:

Fourier transform infrared spectroscopy

k₁ :

Rate constant of the pseudo-first-order, 1/min

k₂ :

Rate constant of the pseudo-second-order model, g/(mmol/min)

M:

Mass of the adsorbent, g

q_e :

Amount of metal ions at equilibrium in unit mass of adsorbent, mg/g

q_max :

Langmuir coefficient related to adsorption capacity

q_t :

Amounts of sorbed Co²⁺ at time t, mmol/g

R_L :

Dimensionless constant separation factor

SEM:

Scanning electron microscope analysis

t:

Contact time, min

V:

Solution volume, l