RESUMO
Spherical shaped nano-size aluminium oxide and its hybrids with indole and indole derivatives have been synthesized using sol-gel and post grafting methods coupled with sonication (Branson Digital SonifierS-250D; 20 kHz; 40%) for the remediation of toxic metals (lead and mercury). Different spectroscopic techniques (FTIR, SEM, BET, XRD, and XPS) have been applied to assess the properties of synthesized aluminium oxide and its hybrids. FTIR spectra showed the absorption bands of aluminium oxide (Al-O-Al) and aluminium hybrids (Al-O-C) at 800-400 cm-1 and 1650-1100 cm-1 region, respectively. SEM showed spherical shaped clusters of aluminium oxide which changed into the net-shape structure after the hybrid synthesis. It is worth noting that sonication energy increases the total surface area of aluminium oxide when it gets hybridized with indole and its derivatives from 82 m2/g to 167 m2/g; it also improved the product yield from 68% to 78%. Simultaneously, FTIR, SEM and BET analysis of non-sonicated aluminium oxide and its hybrids were also recorded for comparison. While XRD and XPS analysis were only conducted for sonicated aluminium oxide and its hybrids to manifest the structural and compositional properties. XRD patterns indexed as the cubic crystal system with an average 41 nm crystallite size of sonicated aluminium oxide which remains unaffected after hybrid synthesis. A survey scan under XPS confirmed the presence of all expected elements (aluminium, oxygen, carbon, nitrogen) and deconvolution of each recorded peak showed binding of element with its neighboring elements. The performance of aluminium oxide and its hybrids synthesize with and without sonication are also evaluated using a time-dependent batch adsorption protocol optimize for one hour. The maximum adsorption of lead (37%) and mercury (40%) are found onto sonicated aluminium oxide. The sonicated aluminium hybrids showed 43-63% of lead and 55-67% of mercury at pH 7. The fitness of experimental data using adsorption kinetics and isotherms revealed that adsorption follows Pseudo-second-order kinetic, Langmuir, and Freundlich isotherms.
RESUMO
Insecticide spray in fruit gardens is a very common practice in different districts of Pakistan. These toxic sprays not only deteriorate the taste of fruit but also due to wet deposition travel through soil, they reach groundwater via leaching process. In the present study, imidazolium-based ionic liquid ([C2im][C3H6NH2]Br-) and its cellulose acetate-supported membrane ([CA-C2im][C3H6NH2]Br-) was prepared and characterized using FTIR, XRD, and SEM. These materials are used as adsorbents for the removal of "Pirimicarb" (an insecticide from waste water). A closed batch at varying parameters, i.e., concentration and temperature as function of time, was conducted on UV-Vis spectrophotometer. Comparison of removal capacity exposed better (74%) adsorption trend by CA-IL membrane than ionic liquid (68%). Thermodynamic studies projected spontaneous process (-ΔG), favoring endothermic reaction (ΔH, ΔS). Kinetics supported pseudo-second order reaction while fitness of isothermic models (Langmuir, Freundlich, Temkin) proposed multistep intraparticle diffusion process.
