Increasing straw surface functionalities for enhanced adsorption property

[Display omitted] •Straw was modified by a promising low-temperature partial-oxidation process.•Free of secondary pollution, low energy consumption and high yield.•An optimal modification temperature was obtained at 180 °C.•Remarkable colour change, improved uptake and enhanced removal efficiency.•A strong correlation between acidic functional groups and adsorption property. A simple low-temperature partial-oxidation process was demonstrated as an effective technology for reed straw modification towards environmental remediation. At an optimal temperature of 180 °C, the straw materials exhibited a remarkable colour change from light yellow to dark brown, increased methylene blue (MB) uptake by 1.8 times, enhanced removal efficiency from 34.5% to 92.8%, and a high yield of 77.2%. Spectroscopic characterization and Boehm titration proved that the amount of surface oxygen (O)-containing functional groups significantly increased after modification. A strong linear correlation (R2 = 0.93) existed between total amounts of O-containing functional groups and MB uptake for modification temperatures below 180 °C, whereas blockage of the pore entrances and competition with metallic cations must be taken into account for samples generated from excess heating (>180 °C). These results provided insights into designing promising technologies for sustainable environmental management through reutilization of agricultural waste.