PREPARATION, APPLICATION, ORANGE PEEL DERIVED BIOCHAR
Loading...
Date
2016
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Biochar is a solid material obtained from thermo-chemical conversion of biomass through
pyrolysis, This can be used in achieving carbon sequestration and other beneficial effects on soils
and environmental properties for greenhouse gas (GHG) mitigation. The waste generated in foodprocessing
industry has the potential to supply feedstock for biochar production. Heavy metals are
found to be among the major environmental pollutants due to the direct discharge of industrial
wastewater into water bodies. Biochar is a very useful low cost product to be used as an adsorbent
for heavy metals immobilization in the environment. The current research is focused on the
preparation of orange peel derived biochar and its application for removal of heavy metals from
waste water and colour from the textile effluent as well as the moisture adsorption and desorption
ability of biochar. Dried peels were pyrolysed for biochar production and were used for heavy
metal removal from waste water using box-behnken method of response surface methodology
(RSM). The three independent variables were BD (biochar dose of 0.5, 1.5 and 2.5g/l), HMC
(heavy metal concentration of 10, 30 and 50ppm) and ET (exposure time of 24, 48 and 72h). The
plan consisted of 15 experimental runs with three experiments at centre point. The dependent
response of heavy metal removal was percentage reduction of heavy metal (Pb, Cd and Cr). The
experimental data were analyzed to develop response functions and the input variables were
optimized for best outputs. A complete second order polynomial model was fitted to the data of all
responses using multiple regression technique. The moisture adsorption and desorption study was
conducted to compare the ability of biochar with that of silica gel. The colour removal study was
done by collecting four colour samples (Blue, Purple, Yellow, Red) from the textile effluent.
100kg of orange fuits give rise to about 20kg peel and 80kg pulp along with seeds. 5.5kg
of dried peels were obtained after drying of peels. The yield of biochar from dried orange peels
was about 1kg (20% db) within a time period of 5min subjected to pyrolysis at 1000ᶱC. Using
multiple responses optimization technique for heavy metal removal a set of compromised process
variables i.e. BD, HMC and ET was found out to be 0.636, -0.454 and 0.696 (coded) and 2.2g/l,
21ppm and 65h (uncoded) respectively. Corresponding to these conditions, the values of response
i.e. %removal of Pb, Cd and Cr were 86.5, 84.4 and 69.7% respectively. The overall desirability
was 0.84. Adequacy of proposed second order models developed for percentage removal (Pb, Cd
and Cr) through regression analysis was confirmed by R2 close to 1(0.996 for PB, 0.995 for Cd and
0.995 for Cr). The results of regression analysis revealed that all the process variables (BD, HMC
and ET) had significant effect on % removal of Pb, Cd and Cr. The factors influencing each
response at linear, quadratic and interactive level have been analyzed thoroughly. In order to have
a better flexibility in the selection of operating range surface plots and superimposed contour plots
having common feasible zone have been plotted for all the responses as a function of two process
variables with the third one at optimum value. The moisture adsorption study indicated that the
orange peel derived biochar is more effective than silica gel. The saturation capacity of moisture
on the orange peel derived biochar is relatively higher (60%) than that of silica gel (50%). Further,
the amount of moisture desorbed during the regeneration was also higher (45%) in biochar as
compared to that of silica gel (30%). The colour removal study concludes that the orange peel
derived biochar could remove blue and purple dyes from textile effluent of more than 90% with a
dose of 5-10g/l at a contact time of 6 to 9days. However, the colour removal percentage for
Yellow and Red colour dyes is very less (< 5 and < 50%) respectively.