A new and low-cost surface-functionalized corn straw adsorbent for adsorptive removal of sodium dodecylbenzene sulfonate: Adsorbent preparation and adsorption performance

Utilization of greywater can relieve the pressure of water scarcity. However, the widespread presence of anionic surfactants in greywater poses threats to the environment and the health of the human and ecosystem. In this study, bioinspired polyethyleneimine-tannic acid (PEI-TA) complexes were innovatively used for coating of corn straw (CS) and the as-prepared PEI-TA modified CS (PEI-TA@CS) was applied for adsorptive removal of the commonly found sodium dodecylbenzene sulfonate (SDBS) in greywater. The adsorption performance of the modified CS was maximized under the following optimized preparation conditions: 5 g/L of PEI concentration with molecular weight of 3000 Da, 0.5 g/L of TA concentration and 3 h of modification time. Investigation of the adsorption conditions showed that adsorption of SDBS on the adsorbent were pH-independent at pH <= 7 and the adsorption process reached equilibrium in about 3 h. The pseudo-second-order model and Freundlich model fit well the kinetic and isotherms data, respectively, and the nature of the adsorption was exothermic and spon-taneous. Mechanism analysis showed that the adsorption of SDBS was dominated by hydrophobic interactions. With a dosage of 100 mg, PEI-TA@CS could satisfactorily remove 94.95 % of SDBS from its aqueous solution (50 mg/L). Even in the complex synthetic greywater, the removal of SDBS still reached as high as 81.99 %. The overall results indicated that PEI-TA@CS has promising applications in the removal of anionic surfactants from greywater.