Porous cellulose spheres: Preparation, modification and adsorption properties

Porous cellulose spheres (PCS) were fabricated by precipitating the spheres from a cellulose ionic liquid solution, followed by freezing, solvent exchange, and drying. PCS had low crystallinity and a large surface area that facilitated modification with trisodium trimetaphosphate (STMP) to introduce phosphate ester groups into the porous structure of the heterogeneous system. The STMP-modified PCS (SPCS) were used to remove heavy metal ions from aqueous solution. With increasing STMP dosage, the adsorption capacity of SPCS obviously improved due to chelation between Pb²⁺ and phosphate ester groups. The kinetic adsorption and isotherm data matched the pseudo-second order model and the Langmuir model well. The maximum adsorption capacity reached 150.6 mg g^-1 for SPCS. SPCS were competitive with other absorbents because the phosphate ester groups and porous structure contributed to Pb²⁺ adsorption. Moreover, SPCS can be regenerated with ethylenediamine tetraacetic acid disodium salt (EDTA) solution for repetitious adsorption of Pb²⁺.