Table 3: Coded and actual levels of variables with corresponding responses (initial sulfur concentration = 250 ppmw).

Experiment no.Coded level of variablesActual level of variablesResponses
S removal (%)S (ppm)

1−1−10250209512.5
21−102850201000
3−1102150208537.5
411028150201000
5−10−1210029122.5
610−12810021000
7−1012100389317.5
810128100381000
90−1−115502985
1001−1151502977.5
110−11155038992.5
1201115150381000
1300015100201000
1400015100201000
1500015100201000