Numerical simulation of CO2 adsorption behaviour of polyaspartamide adsorbent for post-combustion CO2 capture

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. 10 February, 2017.Climate change due to the ever-increasing emission of anthropogenic greenhouse gases arising from the use of fossil fuels for power generation and most industrial processes is now a global challenge. It is therefore imperative to develop strategies or modern technologies that could mitigate the effect of global warming due to the emission of CO2. Carbon capture and storage (CCS) is a viable option that could ensure the sustainable use of cheap fossil fuels for energy generation with less CO2 emission. Amongst existing CCS technologies, absorption technology using monoethanolamine (MEA) is very mature and widely embraced globally. However, the absorption technology has a lot of challenges such as, low CO2 loading, high energy requirement for solvent regeneration, corrosive nature etc. On this note, the adsorption technology using solid sorbents is being considered for CO2 capture due to its competitive advantages such as flexibility, low energy requirement for sorbent regeneration, non-corrosive nature etc. On the other hand, adsorbents have a very vital role to play in adsorption technology and there is need to understand the behaviour of adsorbents for CO2 capture under different operating conditions in order to adapt them for wider applications. On this note, the study contained in this dissertation investigated the adsorption behaviour of a novel polymer-based adsorbent (polyaspartamide) during post-combustion CO2 capture using experimental study and mathematical modelling approach. Polyaspartamide is an amine-rich polymer widely used in drug delivery. In addition, its rich amine content increases its affinity for CO2. Its porosity, thermal stability and large surface area make it a promising material for CO2 capture. In view of this, polyaspartamide was used as the adsorbent for post-combustion CO2 capture in this study. This dissertation investigated the kinetic behaviour, the diffusion mechanism and rate limiting steps (mass transfer limitation) controlling the CO2 adsorption behaviour of this adsorbent. Furthermore, effect of impurities such as moisture and other operating variables such as temperature, pressure, inlet gas flow rate etc. on the CO2 adsorption behaviour of polyaspartamide was also investigated. Existing mathematical models were used to understand the kinetics and diffusion limitation of this adsorbent during CO2 capture. Popularly used gas-solid adsorption models namely; Bohart- Adams and Thomas model were applied in describing the breakthrough curves in order to ascertain the equilibrium concentration and breakthrough time for CO2 to be adsorbed onto polyaspartamide. Lagergren’s pseudo 1st and 2nd order models as well as the Avrami kinetic models were used to describe the kinetic behaviour of polyaspartamide during post-combustion CO2 capture. Parameter estimations needed for the design and optimization of a CO2 adsorption system using polyaspartamide were obtained and presented in this study. The Boyd’s film diffusion model comprising of the interparticle and intra-particle diffusion models were used to investigate the effect of mass transfer limitations during the adsorption of CO2 onto polyaspartamide. Data obtained from continuous CO2 adsorption experiments were used to validate the models in this study. The experiments were conducted using a laboratory-sized packed-bed adsorption column at isothermal conditions. The packed bed was attached to an ABB CO2 analyser (model: ABB-AO2020) where concentrations of CO2 at various operating conditions were obtained. The results obtained in this study show that temperature, pressure and gas flow rate had an effect on the adsorption behaviour of polyaspartamide (PAA) during CO2 capture. Polyaspartamide exhibited a CO2 capture efficiency of 97.62 % at the lowest temperature of 303 K and pressure of 2 bar. The amount of CO2 adsorbed on polyaspartamide increased as the operating pressure increased and a decrease in the adsorption temperature resulted in increased amount of CO2 adsorbed by polyaspartamide. The amounts of CO2 adsorbed on polyaspartamide were 5.9, 4.8 and 4.1 mol CO2/kg adsorbent for adsorption temperatures of 303, 318 and 333 K, respectively. The maximum amount of CO2 adsorbed by polyaspartamide at different flow rates of 1.0, 1.5 and 2.5 ml/s of the feed gas were 7.84, 6.5 and 5.9 mmol CO2/g of adsorbent. This shows that higher flow rates resulted in decreased amount of CO2 adsorbed by polyaspartamide because of low residence time which eventually resulted in poor mass transfer between the adsorbent and adsorbate. Under dry conditions, the adsorption capacity of polyaspartamide was 365.4 mg CO2/g adsorbent and 354.1 mgCO2/g adsorbent under wet conditions. Therefore, the presence of moisture had a negligible effect on the adsorption behaviour of polyaspartamide. This is very common with most amine-rich polymer-based adsorbents. This could be attributed to the fact that CO2 reacts with moisture to form carbonic acid, thereby enhancing the CO2 adsorption capacity of the material. In conclusion, this study confirmed that the adsorption of CO2 onto polyaspartamide is favoured at low temperatures and high operating pressures. The adsorption of CO2 onto polyaspartamide was governed by film diffusion according to the outcome of the Boyd’s film diffusion model. It was also confirmed that intra-particle diffusion was the rate-limiting step controlling the adsorption of CO2 onto polyaspartamide. According to the results from the kinetic study, it can be inferred that lower temperatures had an incremental effect on the kinetic behaviour of polyaspartamide, external mass transfer governed the CO2 adsorption process and the adsorption of CO2 onto polyaspartamide was confirmed to be a physicochemical process (both physisorption and chemisorption).MT201

Les Représentations De La Beauté Féminine: Une Lecture Des Fondements Socioculturels Du Teint Clair Chez Les Bété De Côte d’Ivoire

This study proposes an analysis of the representation of the female beauty whose clear complexion is one of the illustrations in the bété. In Côte d’Ivoire, the bété shows that there was a development of the beauty through the worship of the bagnon. However, in the representation of the male beauty through the bagnon, there is no fixed color complexion. It is not the same for the beauty of the woman whose clear complexion is of significant importance. This is why this study proposes the canons of the female beauty and to question the sociocultural bases which specifically underlie the preference of the clear complexion to the black complexion of the bété woman. However, this is in a bid to understand the cultural anchoring of the female depigmentation in bété country. From a field survey of people of all social categories, the study shows that the preference of the clear complexion is explained by the fact that it would carry virtues of rejuvenation and longevity for the man. In other words, the beauty of the woman aims at developing the man by rejuvenating him and by lengthening his life expectancy. These imaginations results to the depigmentation of the young girls and women bété in their search for beauty. This they do via the clear complexion to make them more attractive to men

Modifications structurales de deux sols ferrallitiques du nord-ouest de la Côte d'Ivoire sous l'effet du piétinement par l'homme

Etude des effets du piétinement par l'homme sur la structure des horizons de surface de deux sols ferrallitiques du nord-ouest de la Côte d'Ivoir

ANALISIS KUALITAS HAND SANITIZER DARI KOMBINASI VIRGIN COCONUT OIL (VCO) SEBAGAI PELEMBUT DAN ANTIBAKTERI DENGAN CAMPURAN ETANOL

Era pandemi Covid-19 dalam kehidupan masyarakat sangat dibutuhkan pelindung diri yang dapat menangkal virus korona, salah satu pelindung diri yang digunakan saat ini adalah hand sanitizer. Penelitian ini akan dibuat hand sanitizer dengan kombinasi Virgin Coconut Oil (VCO) dengan alkohol. Fungsi kedua bahan ini sebagai antibakteri memungkinkan paduan kedua bahan ini sangat efektif untuk dikombinasikan menjadi produk hand sanitizer.  Metode pengujian yang dilakukan dalam penelitian ini adalah uji organoleptic dan uji zona bening untuk mengetahu kualitas dari hand sanitizer. Hasil penelitian yang diperoleh melalui uji organoleptik dan uji zona bening dapat disimpulkan bahwa hand sanitizer yang terbaik berada pada konsentrasi VCO 25% karena sifat lembut di area telapak tangan dan kemampuan zona hambat yang sangat kuat terhadap bakteri yang berasal dari tangan manusia sebesar 20,05 mm. Pemanfaatan kelapa sebagai tanaman pesisir untuk dijadikan VCO dan bahan dasar pembuat hand sanitizer maka diharapkan dapat digunakan dengan mudah oleh masyarakat

Peningkatan Kadar Protein Pada Kulit Umbi Singkong (Manihot esculenta Crantz Sin M. Utilissima Pohl) Melalui Proses Fermentasi

Research has been conducted on increasing protein levels in cassava skin through the fermentation process. Cassava skin is an organic waste that if not handled well feared can cause environmental pollution. The purpose of the research to reduce waste, also make use of cassava skin to have a value. The phase of the research is the waste of cassava skin cleaned from the skin of Ari then washed and diced with a length of ± 1 cm. After that analyzed pH, moisture content, and protein content using micro method Kjehdhal. From the results of the analysis, obtained fermentation data is done with pH 6 and water content of 81.6%. Protein levels of fermentation from day 2 to 7th day. Obtained using microanalysis Kjehdhal participated 1.52%; 2.27%; 6.93%; 7.62%; 3.79%; 0.57%. From this research can be concluded that the fermentation of cassava skin can increase protein levels and can be used as feed additives.Telah dilakukan penelitian tentang peningkatan kadar protein pada kulit umbi singkong melalui proses fermentasi. Kulit umbi singkong adalah sampah organik yang bila tidak ditangani dengan baik dikhawatirkan dapat menyebabkan pencemaran lingkungan. Tujuan dari penelitian untuk mengurangi limbah, juga memanfaatkan kulit umbi singkong agar mempunyai nilai guna. Tahap pelaksanaan penelitian adalah limbah kulit umbi singkong dibersihkan dari kulit ari lalu dicuci dan dipotong dadu dengan panjang ± 1 cm. Setelah itu dianalisis pH, kadar air, dan kadar proteinnya menggunakan metode mikro Kjehdhal. Dari hasil analisis diperoleh data fermentasi dilakukan dengan pH 6 dan kadar air 81,6%. Kadar protein hasil fermentasi dari hari ke-2 sampai hari ke 7 yang didapat menggunakan analisis mikro Kjehdhal berturut – turut 1,52 %; 2,27 %; 6,93 %; 7,62 %; 3,79 %; 0,57%. Dari penelitian ini dapat disimpulkan bahwa fermentasi pada kulit umbi singkong dapat meningkatkan kadar protein dan dapat digunakan sebagai bahan tambahan  pakan