Increasing concerns on global warming and climate change have led to numerous attempts and advanced technology developments to tackle the problem of excessive greenhouse gases emitted to the atmosphere. One of the technical strategies receiving great attention is the application of membrane technology for greenhouse gas separation/capture. Such technology exhibits significant advantages over other conventional methods in terms of removal efficiency, compactness, and environmental friendliness. Many state-of-the-art membrane developments as well as its applications to post-combustion treatment, which could be a promising approach for reducing CO 2 emission from point sources, are thoroughly reviewed. Furthermore, a comprehensive survey on the future perspective of membrane technologies as a potential solution for CO 2 removal and utilization is provided.

BACKGROUND Biogas is an alternative renewable energy produced by anaerobic digestion of various organic wastes mainly from agriculture, households and biomass and food industries. Typically, raw biogas consists of 50–70% methane (CH4), 30–50% carbon dioxide (CO2), and small amounts of hydrogen sulfide (H2S) and water vapour. Purifying biogas by removing CO2 and other trace impurities is required in order to achieve higher calorific value, safe operation and to meet fuel standards. As CO2 is the second largest component of biogas, this study focused on its removal from CH4. RESULTS Composite membranes of blended PEG 400/Pebax 1657 polymer and graphene oxide (GO) were developed for CO2/CH4 gas separation. The effects of GO loading and PEG 400 addition on CO2/CH4 separation performance were investigated. Optimal loadings of 0.25 wt% GO and 50 wt% PEG 400 obtained the best membrane performance with 12.4 GPU of CO2 permeance and 14 of CO2/CH4 separation factor. CONCLUSION Incorporating GO to the polymer membrane enhanced CO2/CH4 separation, whereas PEG 400 addition increased CO2 permeance. The advantages from each component led to an enhancement of CO2 permeance and CO2/CH4 separation. © 2019 Society of Chemical Industry