Process optimization of electrospun polycaprolactone and nanohydroxyapatite composite nanofibers using response surface methodology.

Electrospinning is a process that produces continuous polymer fibers in the sub-micron range through the action of an external electric field imposed on a polymer solution or melt. In this study the effects of process parameters on the mean diameter of electrospun polycaprolactone and nanohydroxyapatite (nHA) composite nanofibers were investigated. The fiber morphology and mean fiber diameter of prepared nanofibers were investigated by scanning electron microscopy. Response surface methodology (RSM) was utilized to design the experiments at the settings of nHA concentration, applied voltage, spinning distance and the flow rate of polymer solution. It also used to find and evaluate a quantitative relationship between electrospinning parameters and average fiber diameters. Mean fiber diameter was correlated to these variables using a third order polynomial function. Value of R-square for the model was 0.96, which indicates that 96% of the variability in the dependent variable could be explained and only 4% of the total variations cannot be explained by the model. It was found that nHA concentration, applied voltage and spinning distance were the most effective parameters and the sole effect of flow rate was not important. The predicted fiber diameters were in good agreement with the experimental results.

Optimization of the removal of phenol by soybean seed coats using response surface methodology.

Peroxidase from soybean seed coats catalyzes the oxidation and polymerization of aromatic compounds in the presence of H(2)O(2). The present study investigated the optimization of the phenol removal from wastewaters by direct using of soybean seed coats that can be extended to large scale, as a cost-effective option in comparison to pure enzyme. A central composite design was used to evaluate the effect of the following factors on the phenol removal: H(2)O(2) concentration (1-40 mmol/L), polyethylene glycol (PEG) concentration (0-1 g/L) and the amount of soybean seed coats (10-60 g/L). The results showed that PEG concentration had no significant effect on phenol conversion. Additionally, by increasing the amount of soybean seed coats, the extent of phenol conversion was increased and a higher concentration of H(2)O(2) was required to reach the maximum phenol conversion. Under optimum conditions for 1 mmol/L initial phenol, 50 g/L soybean seed coats, 14 mmol/L H(2)O(2) and 0.8 g/L PEG, the phenol conversion after 30 min was 78%. After 2 h, the catalyzed process was capable of achieving 90-92% removal of the total phenol from synthetic wastewater. A cubic model was also developed that was verified by predicting some independent experimental results.