Angjian Wu

Synthesis and characterization of a plasma carbon aerosol coated sponge for recyclable and efficient separation and adsorption

A plasma-generated carbon aerosol, with the merits of high surface area, abundant porosity and high crystallinity, is a mass synthesized by-product from direct methane conversion in the production of syngas or hydrogen. In the present work, a carbon aerosol produced by rotating gliding arc (RGA) plasma was firstly incorporated with a commercial sponge to fabricate a highly selective and hydrophobic adsorption material. The properties of the carbon aerosol and its derived sponge were comprehensively characterized. By a simple dip-coating method, the wettability of the pristine sponge was altered, which was attributed to the plasma coating of the carbon aerosol. The modified sponge demonstrated an effective and selective adsorption ability for a wide range of oils and solvents, with the maximum adsorption capacity of up to 86 times its own weight. Moreover, the used sponge could be easily recovered by simple evaporation or manual squeezing, while maintaining approximately 100% of its starting adsorption capacity over 5 adsorption-recovery cycles. Such a plasma carbon aerosol coated sponge exhibits a great prospect as a cost-efficient, recyclable and scalable material in separation and adsorption for water treatment.

Upcycling Waste Lard Oil into Vertical Graphene Sheets by Inductively Coupled Plasma Assisted Chemical Vapor Deposition

Vertical graphene (VG) sheets were single-step synthesized via inductively coupled plasma (ICP)-enhanced chemical vapor deposition (PECVD) using waste lard oil as a sustainable and economical carbon source. Interweaved few-layer VG sheets, H2, and other hydrocarbon gases were obtained after the decomposition of waste lard oil. The influence of parameters such as temperature, gas proportion, ICP power was investigated to tune the nanostructures of obtained VG, which indicated that a proper temperature and H2 concentration was indispensable for the synthesis of VG sheets. Rich defects of VG were formed with a high ID/IG ratio (1.29), consistent with the dense edges structure observed in electron microscopy. Additionally, the morphologies, crystalline degree, and wettability of nanostructure carbon induced by PECVD and ICP separately were comparatively analyzed. The present work demonstrated the potential of our PECVD recipe to synthesize VG from abundant natural waste oil, which paved the way to upgrade the low-value hydrocarbons into advanced carbon material.

Formation pathways of PCDD/Fs during the Co-combustion of municipal solid waste and coal

The co-combustion of simulated municipal solid waste (SMSW) and the coal in a drop-tube furnace is studied in five test cases. The concentration and signature evolution of polychlorinated dibenzo-p-dioxins (PCDD) and -furans (PCDF) in both flue gases and fly ashes are monitored at the level of individual congeners, using statistical methods. Special attention is paid to chlorophenol (CP)-route congeners, 2,3,7,8-substitution, and 1,9-substitution, to reveal the formation pathways of PCDD/Fs and the interaction between SMSW and coal. It is identified that the increase of SMSW proportion alters the major formation pathways from CP-route to chlorophenols/chlorobenzenes condensation and de novo synthesis. The coal-induced carbon enhances the adsorption capacity of fly ash particles for PCDD/Fs, yet facilitates the generation of carbon matrixes and polycyclic aromatic hydrocarbons, both of which will significantly boost the de novo synthesis with the increase of SMSW-induced chlorine and catalytic metals. Further investigations about restricting the participation of chlorine in PCDD/Fs synthesis are essential to increase the treatment capacity of MSW and to reduce the PCDD/Fs emission.

Comparative investigation of waste rapseed oil derived carbon material fabricated by rotating gliding arc and aerosol fast pyrolysis

Green and facile recycling bio-waste rapeseed oil into carbon nanomaterial was comparatively investigated using two novel, catalyst free approaches; rotating gliding arc discharge and aerosol fast pyrolysis. V-I characteristics and dynamic motion of gliding arc in aerosol rapeseed oil were investigated by oscilloscope and high speed camera. Different properties in the morphologies, structures, order degree and chemical compositions of waste derived bio-carbon obtained from two reaction routes were revealed and analyzed by SEM, Raman spectroscopy and XPS, respectively. The carbon from both methods exhibited super hydrophobic characteristic with the contact angles measured above 130 degree. Reaction mechanisms from rotating gliding discharge plasma and fast pyrolysis were proposed. It was anticipated high valued bio-carbon could be fabricated by recycling waste rapeseed oil in the future.

Operation Patterns and Spectrum Characteristics of DC and AC Rotating Gliding Arc Plasma

Rotating gliding arc plasma reactor performs two operation modes according to supply power (dc and ac modes). According to the images of operating states and the emission spectrum of the two modes, the characteristics of dc mode and ac mode are well distinguished and investigated. The dc mode owns platform-type plasma region, high temperature, and energy consumption, suitable for fuel conversion field. The ac mode has a few advantages in gaseous organic pollutants treatment field, because of its relatively low gas atmosphere temperature, little by-products (NOx) production, and low energy consumption.