Chromium Removal Lab Report

CHAPTER 6
RESULTS AND DISCUSSION
6.1. INTRODUCTION
The experiment gave the knowledge about various things and various factors played their significance role in it. The experiment stated the Chromium removal and for that we had drawn a calibration curve (graph 6.1) between Absorbance on y axis and concentration on x axis through the table 6.1 as given below. To make calibration curve, we needed the absorbance of the Chromium solution which we got from atomic absorption spectrophotometer (AAS).

For calculating % of Chromium removal we have,
(C0 – C1) ÷ C0 × 100
Initial concentration (before adsorption) =C0
Final concentration (after adsorption) = C1
So the average efficiency or % Chromium removal = 52.575%

The factor analyses are –
1. Effect

After that with further increase in adsorbent dosage there are no significantly changes seen in percentage removal. Graph shown below represents the maximum percentage of removal of chromium when the initial concentration of chromium in aqueous solution is 30mg/l.

Graph 6.8: % removal of Chromium when initial Chromium(VI) concentration is 30mg/l

6.5 FINAL EQUILIBRIUM OPERATING CONDITIONS FOR MAXIMUM REMOVAL OF CHROMIUM(VI)

Table 6.4
PARAMETER Values investigated pH 2
Temeperature 32oC
Contact time 4hrs

6.6 ADSORPTION

To model the adsorption behavior two set of adsorption studies were studied and their correlation with the experimental data was assessed. This includes the Freundlich and Langmuir isotherms, which are the earliest and simplest known relationships describing the adsorption equation.
6.6.1 LANGMUIR ISOTHERM
Langmuir isotherm equation in linear form can be shown as
Ce/qe = 1/bqm +Ce/qm
Where ,b and qm are constants related to the apparent energy of adsorption and the adsorption capacity, respectively qe → the amount adsorbed per unit mass of the adsorbent (mg/g) with an equilibrium concentration of Ce (mg/ L ).
A plot of (Ce /qe) vs. Ce was linear (graph 6.9) and the constants qm and b were determined from the slope and intercept of the plot. The correlation coefficient obtained with the Langmuir equation was high, which indicated a good fit between the parameters. The dimensionless parameter (RL = 1/(1+bCo)), which is a measure of adsorption favorability, was found to be in the range of 0.03105<1) and confirmed that Chromium(VI) removal using besharam plant at pH 2 and 320c was a favorable adsorption process.
Table 6.5: Langmuir isotherm

S.no Ce Ce