Absorption efficiency 1 Agricultural wastes 1 Diesel engines 1 Morphology 1 Natural sorbents 1 Oil absorption 1 Oil absorption efficiency 1 One-factor 1 One-factor-at-a-time 1 One-factor-at-a-time (OFAT) 1 Pollution 1 Response surface methodology 1 Response surface methodology (RSM) 1 Response-surface methodology 1 Rice straw 1 Rice straws 1 Scanning electron microscopy 1 Sorbents 1 Sorption 1 Sorption capacities 1 Sorption capacity Spectroscopic analysis 1 Surface morphology 1 Surface properties 1 bioremediation 1 concentration (composition) 1 detection method 1 experimental study 1 methodology 1 reflectance 1