(642f) Biochar-Alginate Novel Composite Adsorbent: Synthesis Characterisation and Application in Water and Wastewater Treatment

Biochar-Alginate novel
composite adsorbent: synthesis characterization and application in water and
wastewater treatment

Subrata Biswas^a,b,
Tushar Kanti Sen^b, Bhim Charan Meikap^a,b

^aDepartment of Chemical Engineering, Indian
Institute of Technology, Kharagpur, W.B, India, 721302.

^bChemical Engineering,
Curtin University, GPO BOX U 1987, 6,845 WA, Australia.

Email:
b4subrata@gmail.com, T.Sen@curtin.edu.au,
bcmeikap@che.iitkgp.ernet.in

Abstract

Water
contamination is a serious risk and of great apprehension in today’s context
due to its harmful effects on the environment. Currently, large attention has
been made to industrial wastewater discharged into the land and water bodies.
Effluents from various process industries often contain various hazardous
metals, harmful gases, and several organic and inorganic toxic compounds. Contamination
of natural resources such as water & soil by heavy metals is of great
concern over the last few decades because of their toxicity, very low
degradability and carcinogenic nature to the living organisms. Over the last
few decades, various physio-chemical methods are in practice to minimize the
heavy metal ion contamination in wastewater. Among all the treatment process,
adsorption is one of the most effective processes for water and wastewater
treatment. Commercial activated carbon (CAC) is already used as an effective adsorbent
in water treatment. However, its use is costly because of its coal-based
synthesis and difficulties in regeneration. Therefore many researchers have
reported that cost-effective alternative adsorbents derived from natural
biomass, industrial solid waste, agricultural by-products, and biosorbent.
Biochar produced by pyrolysis from waste biomass was found a widespread
application in wastewater treatment. Biochar is very effective in removing
hydrocarbon and inorganic heavy metals from industrial wastewater. Along with
biochar use of algae in living and nonliving form is also very effective and
innovative alternative in heavy metal ions and organic pollutant removal.

In
this work, an attempt has been made to synthesize and characterize of a novel
Ca-alginate –biochar composite as adsorbent and tested its effectiveness in the
removal of aqueous phase Zn⁺² ions under various physiochemical
process conditions. Figure 1a, 1b& 1c represents the synthesized composite
beads and their morphological characteristics.  Physical characteristics like
FTIR, XRD is shown in Figure 2a & 2b which indicates promising properties
for this composite to be a good adsorbent. Percentage removal of Zn⁺²
with a variation of initial concentration and Langmuir isotherm plot has been presented
here in Figure 3a & 3b. The removal efficiency was studied
by varying with initial Zn⁺² ion concentration, adsorbent doses,
solution pH, contact time, temperature. Between two kinetic models namely
pseudo-first-order kinetic model and pseudo-second-order kinetic model, the
later resulted in a better fit with the experimental data for this system.
Mechanism of adsorption and Intra-particle-diffusion coefficient and boundary
layer thickness was determined by using Webber –Morris (Intra-particle-diffusion)
model. The nature of adsorption process is confirmed by activation energy
calculation as well as by diffusion coefficient value. Various thermodynamic
parameters such as Gibbs free energy change (DG⁰), enthalpy
change (DH) and entropy change (DS) for which graphical
representation is not present here, suggested that the adsorption process
becomes spontaneous, feasible, endothermic and irreversible in nature.  From
the performance analysis, it has been found that adsorbent like this is very
efficient compared to other reported Activated carbon from various sources.
Novel adsorbent like this can be a good alternative for large-scale application
in various process industries for removal of heavy metal from the process
effluent.

Fig
1. a) Synthesized Beads in water. b) outer and c) inner surface of beads

Fig.
2. a) FTIR spectra of treated and untreated composite adsorbent. b) X-ray
diffraction spectra of composite adsorbent

                                                                                                                                                
              Fig 3. a)Variation of Percentage removal of Zn⁺² with
initial concentration b) Langmuir isotherm plot

Keywords: Biochar
alginate composite, wastewater treatment, adsorbent characteristic.

Reference

S. Dawood, T.K.
Sen, C. Phan, Synthesis and characterization of novel-activated carbon from
waste biomass pine cone and its application in the removal of congo red dye
from aqueous solution by adsorption, Water. Air. Soil Pollut. 225 (2014). doi:10.1007/s11270-013-1818-4.