One Step Synthesis Of Porous Polyurea And Its Adsorption Performance

In this work, a novel one-step protocol for facile preparation of porous polyurea material（PPU） bearing abundant amido was presented. The process was done through precipitationpolymerization of toluene diisocynate （TDI） as the sole monomer in water-acetone mixedsolvent, in which neither surfactant nor porogen during the polymerization was used. Theeffects of TDI amount, mechanical stirring, composition of the mixed solvent and TDIaddition rate on PPU structure were studied. The surface morphology and pore parameters ofPPU as prepared were characterized by scanning electron microscope （SEM） and Hg intrusionrespectively.The obtained PPU was used as adsorbent for anionic dye. Three anionic dyes namelyRemazol Brilliant Blue R （RBBR）, Acid Fuchsin （AF） and Congo Red （CR） were used foradsorption research. The effects of adsorption pH, adsorption time and initial concentration ofdyes on the adsorption process were studied. The maximum adsorption capacity of PPU forRBBR, AF and CR were of122.10mg·g^-1,108.61mg·g^-1and93.02mg·g^-1under theiroptimized conditions. Analysis of the adsorption results demonstrated that the adsorption ofdyes obeyed the pseudo-second-order kinetics and was better fit by Langmuir adsorptionequation compared to Freundlich adsorption. The negative free energy values and positiveΔH°values indicate the feasibility, spontaneous and endothermic nature of the process.Furthermore, the obtained PPU was used as adsorbent for cationic dyes adsorption in whichrhodamine-B （RB） and mmethylene blue （MB） were selected. The maximum adsorption ofRB and MB in neutral aqueous medium is of92.98mg·g^-1and86.96mg·g^-1, respectively.Analysis of the adsorption results demonstrated that the adsorption of dyes also obeyed thepseudo-second-order kinetics and was better fit by Langmuir adsorption equation compared toFreundlich adsorption. The negative free energy values and positive ΔH°values indicate thefeasibility, spontaneous and endothermic nature of the process. The results indicate that PPUmay be also an attractive candidate for removal of cationic dyes from the wastewaters.Finally, a novel porous iminodiacetic acid chelating resin （PACR） was obtained by thereaction of amino on PPU with chloroacetate in alkaline condition. The surface morphologyand pore parameters of PPU and PACR as prepared were characterized by SEM and Hg intrusion respectively. The effects of Pb²⁺adsorption pH, contact time and Pb²⁺initialconcentration on the adsorption process were studied. The maximum adsorption capacity ofPACR for Pb²⁺was of102.34mg·g^-1under optimized conditions. Analysis of the adsorptionresults demonstrated that the adsorption was better fit by Langmuir adsorption equationcompared to Freundlich adsorption. The results indicate that PACR may be an attractivecandidate for removal of metal ions from the wastewaters.