Rheological evaluation of the fabrication parameters of cellulose acetate butyrate membrane on CO2/N2 separation performance

The rise in emission of greenhouse gases (GHGs) mainly carbon dioxide (CO2) in recent years due to rapid development of modern civilisation, has been listed as the primary contributor to global warming. To address this global issue, membrane technology was applied and developed intensively because of its superior performance in terms of efficiency and economic advantages. In this study, the cellulose acetate butyrate (CAB) polymer was selected as the polymer matrix material since it exhibited excellent film-forming properties. In addition, the wet-phase inversion technique was adopted to synthesise the membrane based on different casting conditions. The optimum outcomes of the fabrication conditions were then characterised with the scanning electron micrograph (SEM) to determine the best CAB membrane for CO2/N2 separation. The results showed that CAB-70000 fabricated with 4 wt% of CAB polymer concentration, casting thickness of 250 µm, solvent evaporation time of 5 minutes, and 30 minutes of solvent exchange for isopropyl alcohol and n-hexane, exhibited the best gas separation performance. Further, CAB-70000 showed an average selectivity of 6.12 ± 0.09 and permeance up to 227.95 ± 0.39 GPU for CO2 and 37.28 ± 0.54 GPU for N2, respectively. In summary, this study is expected to show a detailed outline of the future direction and perspective of the novel CAB polymeric membrane that is suitable to be applied in the industry, and serves as an insight for researchers and manufacturers working in the related field of gas separation

Chemical, physical, and morphological characteristics of nanomaterials for CO2 capture and conversion

The major cause of global warming and ocean acidification are due to the anthropogenic emissions of CO2 from industrial development. Till date, various mitigation strategies had been proposed for CO2 capture from different effluent sources. Presently, due to commercial impact and vast potential of nanotechnology, it had attracted various attention of research sectors nationwide. Nanotechnology is prominent in several fields such as health care, agriculture, industries, science and technology where intensive investigation, development, production, and processing of structure and materials had been done in the recent years to enhance the materials properties. However, viability of such materials became uncertain due to the irregularities and ambiguities in dimensions and chemical compositions. More concerns arise about the efficiency of mass transfer, transformation of nanomaterials and impacts towards the environment. In this regards, a comprehensive analysis of the present phase of knowledge concerning the morphology of nanomaterials properties has been discussed in depth. Several nanomaterials include carbon nanotubes, graphene-based nanomaterials, nanoclay composites, metal organic frameworks, nanostructured thin films with their applications were highlighted here. In addition, novel development, and breakthrough applications with nanomaterials in separation and purification processes are discussed in detail. Nonetheless, the distinctive characteristics and functions of nanomaterials together with the challenges for their applications and mass scale fabrication were also discussed. Some future perspective and possible areas of study are highlighted in the end of the chapter.Scopu

The Role of Solvent Mixture, Acetic Acid and Water in the Formation of CA Membrane for CO2/N2 Separation

The improvement of Carbon dioxide (CO2) separation efficiency from flue gases to reduce the total energy cost of sequestration technologies in coal-fired power plants has been identified as a high-priority research area. In the past three decades, membranes have attracted the attention of chemists and engineers due to their unique separation principles (i.e., selective transport and efficient separation compared to other unit operations). In this study, the formation of cellulose acetate (CA) membrane for CO2/nitrogen (N2) separation was investigated by wet phase inversion. In order to modify the CA membrane structure, different concentration ratio of solvent mixture (acetic acid:water), acetic acid and water were studied. The CA membranes were analyzed by Fourier transform infrared spectroscopy (FTIR). The separation results supported by the characterization, where the best formulate membrane with solvent mixture ratio of 70:30 (acetic acid:water), acetic acid concentration of 63 wt% and water concentration of 27 wt% had high CO2 permeance of 400.92 GPU and slightly better CO2/N2 separation performance at 32.92 as compared to others literature

Body mass index and complications following major gastrointestinal surgery: A prospective, international cohort study and meta-analysis

Aim Previous studies reported conflicting evidence on the effects of obesity on outcomes after gastrointestinal surgery. The aims of this study were to explore the relationship of obesity with major postoperative complications in an international cohort and to present a metaanalysis of all available prospective data. Methods This prospective, multicentre study included adults undergoing both elective and emergency gastrointestinal resection, reversal of stoma or formation of stoma. The primary end-point was 30-day major complications (Clavien–Dindo Grades III–V). A systematic search was undertaken for studies assessing the relationship between obesity and major complications after gastrointestinal surgery. Individual patient meta-analysis was used to analyse pooled results. Results This study included 2519 patients across 127 centres, of whom 560 (22.2%) were obese. Unadjusted major complication rates were lower in obese vs normal weight patients (13.0% vs 16.2%, respectively), but this did not reach statistical significance (P = 0.863) on multivariate analysis for patients having surgery for either malignant or benign conditions. Individual patient meta-analysis demonstrated that obese patients undergoing surgery formalignancy were at increased risk of major complications (OR 2.10, 95% CI 1.49–2.96, P < 0.001), whereas obese patients undergoing surgery for benign indications were at decreased risk (OR 0.59, 95% CI 0.46–0.75, P < 0.001) compared to normal weight patients. Conclusions In our international data, obesity was not found to be associated with major complications following gastrointestinal surgery. Meta-analysis of available prospective data made a novel finding of obesity being associated with different outcomes depending on whether patients were undergoing surgery for benign or malignant disease