Surfactant Anions Intercalated Titanium-Based Layered Double Hydroxides And Their Adsorption-Desorption Properties For Pentachlorophenol

In present thesis, cyanic acid, dodecylbenzensulfate and dodecylsulfate surfactant anions intercalated titanium-based layered double hydroxides (LDH) were prepared by using coprecipitation method. The structures and physicochemical properties of the synthesized materials were systematically investigated. The adsorption and desorption properties of a hydrophobic ionizable oranic compounds(HIOCs) pentachlorophenol over the as-prepared materials were studied. The novelty and major content of the thesis were detailed as follows:Organic dodecylbenzensulfate (DBS) and dodecylsulfate (DS) surfactant anions intercalated titanium-based LDH were synthesized by coprecipitation method for the first time. The as-synthesized samples have been characterized by XRD,FT-IR,TG-MS,ICP and BET measurements. The effects of the interlayer anions, as well as the layer charge densities and the metal within the layers on the crystal structure and the surface properties of the as-synthesized materials were systematically investigated. XRD and FT-IR characterizations revealed the well-organized layered structures of the prepared materials. The contact angle measurement indicates the evident hydrophobic properties of the prepared materials, and DBS-LDH possesses stronger hydrophobic properties than DS-LDH. Based on the characterization results, the interlamellar arrangement of surfactant molecules was proposed that the surfactant anions was two-layer interlaced in the layer decision.Adsorptions and desorptions of a pentachlorophenol on the as-synthesized materials were investigated by batch equilibration techniques, pH effects on the distribution coefficients (k_d) were also sdudied. The experimental results indicate that Linear equation is fit for the adsorption of pentachlorophenol on dodecylbenzensulfate and dodecylsulfate surfactant anions intercalated titanium-based LDH. The amount of absorbed pentachlorophenol can be increased due to the interlayer hydrophobic areas of surfactant anions intercalated LDH, which can be reached 30.8mg/g. However, the amount of absorbed pentachlorophenolthe on cyanic acid anions intercalated LDH was only 1.3mg/g. The amount of absorbed pentachlorophenol on surfactant anions intercalated LDH was 23.7 times than cyanic acid anions intercalated LDH. The highly linear adsorption isotherms suggestes that the adsorption of pesticides on surfactant anions intercalated LDH conforms to partition retention mechanism. The interaction between the surfactant anions intercalated LDH and pentachlorophenol includes hydrophobic interaction, hydrogen force and the van der Waals' force. Desorption experimental results indicate the desorption of pentachlorophenol on surfactant anions intercalated titanium-based LDH is an irreversible process, While, that inorganic- intercalated titanium-based LDH presents a reversible process. The present results imply that the surfactant anions intercalated titanium-based LDH may be an alternative effective adsorbent in adsorption retention of HIOCs in environment.