In terms of combined severity, the TRS and 5-HMF concentrations decreased linearly with increasing combined severity, whereas, the LA concentration was increased at a high combined severity factor.
Up to 161 mg/g xylose (93% theoretical) was achieved at moderate combined severity factors (CSF) of 1.0 1.6.
In this study, ethanol organosolv pretreatment was investigated and optimized for the pretreatment of empty palm fruit bunch using (1) response surface methodology based on three-variable central composite design and (2) the combined severity parameters.
combined severity factor.
Both the inhibitor formation and the hydrolysis of lignocellulose are a function of pretreatment severity, called the combined severity factor (CSF), which is influenced by the acid concentration, reaction temperature, and retention time.
WIS, water insoluble solid; Temp, temperature; and logR ' 0, combined severity factor.
There is a good correlation between the combined severity factor and xylan recovery of pretreated leaflets (R = 0.93) and rachis (R = 0.89), showing the potential of using combined severity factor as an index of xylan recovery in pretreatment process optimization.
Combined severity factors corresponding to each condition were calculated [ 25] (1) CS combined severity = log R o − pH = log t exp T − 100 14.75 − pH, where T is temperature, °C; t is time, min; R o is severity factor.
To quantify the effectiveness of pretreatment process, "combined severity (CS) factor" has been used in many studies.
The yield of monomeric glucose from cellulose during enzymatic hydrolysis slowly increased with increasing pretreatment combined severity (results not shown but are available in Additional file 1).
