No abstract

No abstract

Detailed assessments of adsorption properties (isotherm, thermodynamics and kinetics) were carried out on chemically modified activated carbon (AC). Some pretreatment methods prior amination have been used to improve the CO 2 selective capture of AC in our previous works. Here, the inter-relationships among the adsorption properties were further investigated and reported. It was found that CO 2 molecules bind onto the heterogeneous surfaces of AC in a monolayer pattern as experimental data fit Freundlich isotherm rather than Langmuir. However, Redlich-Peterson, a 3-parameter model provided the best fit. The highest degree of precision of Chi-square analysis professed it as the most efficient error function for the isotherm study. Values of standard entropy showed to be the most significant thermodynamic limiting parameter in the adsorption process, as physisorption was found predominant for CO 2 collection at the interface. This observation was corroborated with temperature programmed desorption (TPD) analysis where ca. 86% of adsorbed CO 2 were desorbed below 500°C. The kinetic study indicated that CO 2 -AC interaction follows pseudo-second order while the higher R 2 of intraparticle diffusion over Elovich equation confirmed the deduction made from the thermodynamic study. Conclusively, the study of adsorption properties in this work provides useful information for designing proper adsorption reactor and subsequent regeneration of CO 2 -laden adsorbents at environmental levels.

Typical municipal solid waste (MSW) is composed mainly of biomass and polymers. In this study, the co-conversion of a feedstock obtained from a mixture of both constituent materials is investigated. The goal of this study was to determine the suitability of a low-temperature process for achieving biochar with properties that can make it amenable to multiple energy and environmental applications. Co-carbonization of oil palm (Elaeis guineensis) fiber (OPF) and low-density polyethylene (LDPE) was conducted at a peak temperature of 529 °C for 80 min in a top-lit updraft biomass conversion reactor using retort heating. The biochar yields for OPF and OPF-LDPE were 15.9 wt% and 62.7 wt%, respectively, with the higher yield of the latter attributed to a polymer effect. The OPF and OPF-LDPE biochars were mesoporous with relatively large specific surface areas of 352.9 and 391.4 m 2 g −1 , respectively. The addition of LDPE to the OPF feedstock was observed to be advantageous as it improved the biochar yield, carbon content, specific surface area, and pore volume. Consequently, the technology of choice for solid waste management offers key environment-friendly benefits such as no electrical power requirement, an excellent waste-to-wealth approach, and the capacity to be used globally (in remote locations).

No abstract

No abstract

The use of urea was investigated as an alternative to the poisonous and expensive NH3 gas, commonly used for amination of adsorbents. First, we fabricated activated carbon nanofibers (AnFs) by electrospinning of urea‐doped polyacrylonitrile solution (N‐AnF). By increasing the activation temperature, the average specific surface area (SBET) and micropore volume (Vmicro) of pristine nFs improved from 27.3 to 300 m2/g and 0.004 to 0.13 cm3/g, respectively. Upon urea doping, both properties were further enhanced to 542 m2/g and 0.22 cm3/g, respectively. However, with chemical investigation via X‐ray photoelectron spectroscopy, we observed that the urea‐doping incorporated more of less desired quaternary‐N, along with other more basic and desirable N‐functionalities (i.e., nitrile, pyridinic, pyrrolic N) tethered. Based on the eventual CO2 adsorption results, we realized that average pore diameter (davg) is a limiting factor with regard to CO2 adsorption by AnFs; the lower the davg, the better the adsorption. Further examination via adsorption isotherm model fitting showed that CO2 molecules were homogenously collected in a monolayer pattern. However, three‐parameter model Redlich–Peterson model best fits the experimental data, suggesting that the adsorption is concentration‐driven and that it tends toward Langmuir rather than Freundlich at elevated concentration of CO2. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45534.

No abstract