The effect of several prevalent cations (including Na+, K+, Mg2+, Ca2+, Al3+, and Fe3+) on the adsorption of monochlorobenzene (MCB) onto bentonite was investigated at the coexistence of nonionic surfactant Tween 80 (T80) in surfactant-enhanced remediation (SER). They are all favorable for MCB and T80 adsorption, especially Mg2+ and Ca2+. Adsorption of MCB is strongly depended on T80 micelles. When its concentration exceeds the solubility, MCB is easier to bind with T80 micelles and be adsorbed by bentonite. Acidic environment can facilitate MCB and T80 adsorption, but the effect of cations on the adsorption is most significant under alkaline conditions. Adsorption capacity of MCB increases first followed by a slight decrease with increasing cations concentrations. The maximum adsorption rate of MCB determined is about 68.4% in a solution containing Mg2+ in the isothermal adsorption of MCB, while it is only 6.8% in a cation -free solution. Various characterizations showed that cations mainly changed the repulsion between bentonite particles and T80 micelles and the agglomeration and structure of bentonite, thus affecting the adsorption of MCB and T80 micelles. Our research demonstrated the nonnegligible promotion of MCB adsorption on bentonite by cations and acidic environment, which will adversely affect SER efficiency.

There is interest in the role of ammonia on Saturn's moons Titan and Enceladus as the presence of water, methane, and ammonia under temperature and pressure conditions of the surface and interior make these moons rich environments for the study of phases formed by these materials. Ammonia is known to form solid hemi-, mono-, and dihydrate crystal phases under conditions consistent with the surface of Titan and Enceladus, but has also been assigned a role as water-ice antifreeze and methane hydrate inhibitor which is thought to contribute to the outgassing of methane clathrate hydrates into these moons' atmospheres. Here we show, through direct synthesis from solution and vapor deposition experiments under conditions consistent with extraterrestrial planetary atmospheres, that ammonia forms clathrate hydrates and participates synergistically in clathrate hydrate formation in the presence of methane gas at low temperatures. The binary structure II tetrahydrofuran + ammonia, structure I ammonia, and binary structure I ammonia + methane clathrate hydrate phases synthesized have been characterized by X-ray diffraction, molecular dynamics simulation, and Raman spectroscopy methods.