A response surface for an eggshell model shows that for low
concentrations of catalyst, the conversion of methyl ester de-
creased graph is not showed. This shows that the significant factor
is
X
C
, which has a positive effect on transesterification at a confi-
dence level of 95%, as noted in the response surface plot. This is
due to the fact that the increase in catalyst concentration implies
a higher number of active basic sites in the reaction medium,
resulting in higher conversions to methyl esters. The transesterifi-
cation is a reaction that can be conducted by adding excess meth-
anol, which shifts the chemical equilibrium of the reaction toward
the formation of methyl esters, increasing the rate of conversion.
However, using high volumes of methyl alcohol complicates the
separation process due to the existence of gravity between the
phases formed and glycerin ester, increasing their miscibility and
promoting the displacement of the balance in the opposite direc-
tion toward the formation of mono-, di-, and triglycerides, thereby
decreasing the production of methyl esters. Based on the experi-
ments carried out, the best experimental conditions (coded and
dependent variables) for transesterification are as follows: 1:9
(
X
MR
) and 3 wt.% (
X
C
) on the mass of oil sunflower; tempera-
ture = 60
°
C; time = 3 h; stirring speed during reaction = 1000 rpm,
which is obtained after the conversion of triglycerides to methyl
esters (97.75 ± 0.02% wt.%).
The results showed that after calcination process, a mixed oxide
(CaO and CaCO
3
) has catalytic activity. The higher surface content
of Ca for calcined eggshell compared with that of calcined crab
waste (evaluated by XPS), associated to the high basicity character-
istics (evaluated by TPD-CO
2
) explains the better catalytic perfor-
mance of calcined eggshell
A response surface for an eggshell model shows that for lowconcentrations of catalyst, the conversion of methyl ester de-creased graph is not showed. This shows that the significant factorisXC, which has a positive effect on transesterification at a confi-dence level of 95%, as noted in the response surface plot. This isdue to the fact that the increase in catalyst concentration impliesa higher number of active basic sites in the reaction medium,resulting in higher conversions to methyl esters. The transesterifi-cation is a reaction that can be conducted by adding excess meth-anol, which shifts the chemical equilibrium of the reaction towardthe formation of methyl esters, increasing the rate of conversion.However, using high volumes of methyl alcohol complicates theseparation process due to the existence of gravity between thephases formed and glycerin ester, increasing their miscibility andpromoting the displacement of the balance in the opposite direc-tion toward the formation of mono-, di-, and triglycerides, therebydecreasing the production of methyl esters. Based on the experi-ments carried out, the best experimental conditions (coded anddependent variables) for transesterification are as follows: 1:9(XMR) and 3 wt.% (XC) on the mass of oil sunflower; tempera-ture = 60°C; time = 3 h; stirring speed during reaction = 1000 rpm,which is obtained after the conversion of triglycerides to methylesters (97.75 ± 0.02% wt.%).The results showed that after calcination process, a mixed oxide(CaO and CaCO3) has catalytic activity. The higher surface contentof Ca for calcined eggshell compared with that of calcined crabwaste (evaluated by XPS), associated to the high basicity character-istics (evaluated by TPD-CO2) explains the better catalytic perfor-mance of calcined eggshell
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