Adsorption of hydrocarbons on modified nanoclays

Fast and Efficient Adsorption of Ag Nanoparticles by Sodium Montmorillonite Nanoclay from Aqueous Systems

Silver nanoparticles (AgNPs) are, due to their antimicrobial properties, the most widely used nanoparticles in commercial products. AgNPs are incorporated into medical products such as bandages, as well as in textiles and household items. Besides its antimicrobial effect, exposure to soluble silver compounds produce toxic effects on all living organisms. In this work, the removal of Ag nanoparticles (AgNPs) using aqueous sodium montmorillonite nanoclay in the presence of a cationic surfactant stabiliser was investigated. The effects of experimental parameters on the adsorption process, such as pH, surfactant concentration, adsorbent dosage, initial AgNPs concentration and contact time, were studied. The Langmuir and Freundlich isotherm models were applied and the Langmuir model was found to best fit the equilibrium isotherm data. Langmuir adsorption capacity was found to be 71.4 mg g−1 of AgNPs at pH 7. The results indicate that sodium montmorillonite nanoclay can be used for the fast and efficient removal of AgNPs from aqueous solutions.

A self-assembled superhydrophobic electrospun carbon-silica nanofiber sponge for selective removal and recovery of oils and organic solvents

An oil spill needs timely cleanup before it spreads and poses serious environmental threat to the polluted area. This always requires the cleanup techniques to be efficient and cost-effective. In this work, a lightweight and compressible sponge made of carbon-silica nanofibers is derived from electrospinning nanotechnology that is low-cost, versatile, and readily scalable. The fabricated sponge has high porosity (>99 %) and displays ultra-hydrophobicity and superoleophilicity, thus making it a suitable material as an oil adsorbent. Owing to its high porosity and low density, the sponge is capable of adsorbing oil up to 140 times its own weight with its sorption rate showing solution viscosity dependence. Furthermore, sponge regeneration and oil recovery are feasible by using either cyclic distillation or mechanical squeezing.

Multi-Component Adsorption of Benzene, Toluene, Ethylbenzene, and Xylene from Aqueous Solutions by Montmorillonite Modified with Tetradecyl Trimethyl Ammonium Bromide

Multicomponent adsorption of benzene, toluene, ethylbenzene, and xylene (BTEX) was assessed in aqueous solutions by montmorillonite modified with tetradecyl trimethyl ammonium bromide (TTAB-Mt). Batch experiments were conducted to determine the influences of parameters including loading rates of surfactant, contact time, pH, adsorbate concentration, and temperature on the adsorption efficiency. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were used to determine the adsorbent properties. Results showed that the modification of the adsorbent via the surfactant causes structural changes of the adsorbent. It was found that the optimum adsorption condition achieves with the surfactant loading rate of 200% of the cation exchange capacity (CEC) of the adsorbent for a period of 24 h. The sorption of BTEX by TTAB-Mt was in the order ofB<T<E<X. The experimental data were fitted by many kinetic and isotherm models. The results also showed that the pseudo-second-order kinetic model and Freundlich isotherm model could, respectively, be fitted to the experimental data better than other available kinetic and isotherm models. The thermodynamic study indicated that the sorption of BTEX with TTAB-Mt was achieved spontaneously and the adsorption process was endothermic as well as physical in nature. The regeneration results of the adsorbent also showed that the adsorption capacity of adsorbent after one use was 51% to 70% of original TTAB-Mt.