Mechanism of dialkyl phthalates removal from aqueous solution using γ-cyclodextrin and starch based polyurethane polymer adsorbents

• Published in: Carbohydrate polymers 2014-12, Vol.114, p.440-449
• Main Authors: Okoli, Chukwunonso Peter, Adewuyi, Gregory Olufemi, Zhang, Qian, Diagboya, Paul N., Guo, Qingjun
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Applied sciences; Chemistry; Exact sciences and technology; gamma-Cyclodextrins - chemistry; General and physical chemistry; Organic polymers; Phthalates; Phthalic Acids - chemistry; Physicochemistry of polymers; Polymers - chemistry; Polyurethane polymer; Polyurethanes - chemistry; Properties and characterization; Special properties (catalyst, reagent or carrier); Starch; Starch - chemistry; Surface physical chemistry; γ-cyclodextrin
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2014.08.016

•γ-Cyclodextrin and starch based polyurethane polymers were applied for the removal of phthalates.•Adsorption capacity was controlled by chemical structural make-up of the polymers.•Adsorption mechanism was dominated by liquid film and intra-particle diffusion.•Adsorption occurred on both the interfacial and inclusion spaces as the active adsorption sites. Phthalate esters have been known as potent endocrine disruptors and carcinogens; and their removal from water have been of considerable concern recently. In the present study, γ-cyclodextrin polyurethane polymer (GPP), γ-cyclodextrin/starch polyurethane copolymer (GSP), and starch polyurethane polymer (SPP) have been synthesized and characterized. Their adsorption efficiencies for the removal of dimethyl phthalate (DMP) and diethyl phthalate (DEP) from aqueous solutions were investigated. The characterization results showed the success of the synthesis. The isotherms were L-type, and both the Langmuir and Freundlich adsorption isotherm gave good fittings to the adsorption data. Adsorption mechanisms suggested that these adsorbents spontaneously adsorb phthalate molecules driven mainly by enthalpy change, and the adsorption process was attributed to multiple adsorbent–adsorbate interactions such as hydrogen bonding, π–π stacking, and pore filling. The results showed that starch and γ-cyclodextrin polyurethane polymer adsorbents have excellent potential as adsorbent materials for the removal of phthalates from the contaminated water.