Unary and binary adsorption of anionic dye and toxic metal from wastewater using 3-aminopropyltriethoxysilane functionalized porous cellulose acetate microspheres

Recent industrial development raised a great concern for human health and environmental protection due to the generation of toxic wastewater. The present study aims to prepare a new low-cost bio-based adsorbent for the effective simultaneous removal of anionic dye and toxic metal. Porous cellulose acetate (CA) microspheres were synthesized using a double emulsion (W/O/W)–solvents evaporation technique then modified using 3-aminopropyltriethoxysilane (APTES-CA). SEM, FTIR and XRD results emphasized the successful preparation of APTES-CA microspheres with average diameter size around 380–430 μm. Porosity analysis announced the mesoporous structure of the CA microspheres and the meso-microporous structure of APTES-CA microspheres. Also, EDX elemental analysis confirmed the presence of Si and N of APTES indicating the successful modification of CA surface. Further to this, the adsorption study showed that APTES modification improved the adsorption efficacy toward RB19 and Pb2+. Where, in unary solution, almost complete removal of 10 mg/L Pb2+ was achieved using 1.00 g/L of APTES-CA after 30 min at pHo 5. On the other hand, 91% of 20 mg/L RB19 preadjusted to pHo 2 can be removed by 1.00 g/L of APTES-CA after 90 min. The kinetic study indicated that APTES-CA adsorbs RB19 and Pb2+ via different mechanisms, specifically, chemisorption for RB19 and physisorption for Pb2+. The theoretical Langmuir monolayer saturation capacity (180 mg/g) manifested a good efficiency of APTES-CA towards Pb2+. In the binary solution, Pb2+ does not affect RB19 adsorption while RB19 retards Pb2+ adsorption. [Display omitted] •Mesoporous CA microspheres were prepared and functionalized with APTES.•Functionalization improved the adsorption of Pb2+ and RB19 significantly.•Unary and binary adsorption of Pb2+ and RB19 were studied using APTES-CA.•Binary system does not affect RB19 adsorption but reduces Pb2+ adsorption.•APTES-CA can efficiently and simultaneously adsorb RB19 and Pb2+.