Fig. 3
Response surface plots showing the effects of initial pH, light intensity, and Mo concentration on hydrogen production rate (HPR). The interactive effect of light intensity and pH at a fixed the amount of Mo concentration of 0.44Â mg/L (a); the interactive effect of Mo concentration and pH at a fixed light intensity of 8.37 klux (b); the interactive effect of Mo concentration and light intensity at a fixed pH of 7.92 (c)