Composites of single-walled carbon nanotubes (SWNT) and polystyrene have been prepared using three different types of SWNT: HiPco, CoMoCat, and pulsed laser vaporization (PLV). Nanotubes were incorporated into the polystyrene matrix by two methods: (1) evaporation of chloroform solutions of SWNT noncovalently functionalized with poly[(m-phenylenevinylene)-co-(2,5-dioctoxy-p-phenylenevinylene)] (PmPV) and polystyrene; (2) coagulation in water of DMF solutions containing polystyrene and nitric acid oxidized SWNT. From measurements of the electrical conductivities of the composites over a range of concentration from 0.1 to 6 wt % SWNT, the percolation threshold of conductivity was 0.17-0.3% SWNT for the PmPV-coated materials and 0.4-0.5% for those made by coagulation. Of the three types of SWNT, composites made with HiPco tubes had the highest conductivity.
For the adsorption of sodium dodecylbenzenesulfonate (SDBS) in aqueous solution on reduced graphene oxide (rGO), it is demonstrated that the dual-site mechanism is strongly favored over the conventional single-site one. The dual-site adsorption isotherm is derived, and regression analysis is successfully applied to experimental UV−vis data (1 g L −1 rGO; 298−318 K; 100−900 mg L −1 SDBS; pH: 4−11), considering reparametrization to minimize the correlation between the parameter estimates (dual site: ΔH°= −37.1 ± 1.3 kJ mol −1 ; ΔS°= 35.5 ± 4.1 J mol −1 K −1 ; q ∞ = 546.9 ± 8.6 mg SDBS g rGO −1). A temperature of 298 K is identified as the optimal operating temperature with contact times of ca. 30 h (700 mg L −1 SDBS). An improved regression analysis strategy, carefully selecting only low contact times (maximal 10 h), allowed assessment of the dual-site adsorption and desorption coefficient as (1.2 ± 0.3) × 10 −4 L mg SDBS −1 h −1 and (2.8 ± 0.7) × 10 −3 h −1 . Moreover, by the additional presence of sodium chloride (1.2 × 10 4 mg L −1 ), a much lower contact time of ca. 10 h can be selected to ensure an as good as complete SDBS removal, highlighting the potential of the SDBS/rGO system for wastewater treatment.
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