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

Application of whole-cell biosensor for the impact of crude oil exploration on the environment of the Niger Delta

The discovery of crude oil in exportable quantities in Nigeria was greeted with overwhelming ovation and high expectations in terms of the wealth generation possibilities and economic growth for the region. However, 5 decades onwards, the Niger-delta terrain and its people have become disenchanted with the ills and aggravated impacts of crude-oil discovery as a result of unsustainable patterns of its exploitation in Nigeria. The inundation of oil spills, accompanying ecological disasters and human health risks served to undermine the benefits of huge petroleum resource revenues. Nigeria has recorded over 3,324,269.28 million barrels of crude oil spills from 12,854 spills incidents as captured since 1976-2011 and the polluting process persists as a result of exploration, drilling and production activities as well as flagrant disregard for best health, safety, security and Environmental practices (HSSE). Even though these spills have been blamed on various factors, the fact remains that the people and environment of the Niger-delta desperately need state, public and private intervention to stem the menace of environmental pollution engulfing the region. This research therefore proposes urgent rehabilitative measures expedited by the Bio-reporter approach, to enhance rapid detection, toxicity and management of spills impacted sites. The Bio-reporter method and its success is hinged on its advantages over the conventional method entailing rapid detection of genotoxicity, easy operations, inexpensiveness and more importantly it provides information about bioavailability. It is thus a complementary tool to the chemical analysis methods. The novel magnetic bio-reporter device developed with the magnetic nanoparticles (MNPs) functionalization and also the device on Simultaneous and online detection of crude oil contamination via biological- phase micro-extraction and bios-sensing (BPME-BS) in the Niger Delta environment have been applied with significantly positive results. Consequently, the novel magnetic nanoparticle-mediated isolation (MMI) technology was tested on Nigerian soils for the separation and characterization of functional alkane degraders from crude-oil-contaminated sites. Essentially, the new technique’s qualities of cost-effectiveness and zero risk of species invasion on the environment has become more apparent from extensive experimentation

A critical analysis of the Nigerian entrepreneurial ecosystem on transformational entrepreneurship

Previous research suggests that the entrepreneurial ecosystems (EEs) support factors are critical for the systemic development of micro, small. and medium enterprises (MSMEs). However, there is limited understanding of how MSME owner's/manager’s characteristics impact their perspectives of the EE support factors for business development. This study addresses this research gap to adopt a coherent approach to understand the EE in supporting MSMEs to achieve transformational entrepreneurship (TE), which builds sustainable businesses for long-term societal benefits. The MSMEs characteristics alongside the EE factors were tested with 576 MSMEs in Nigeria. The MSME owner's/manager’s characteristics were positively correlated to their perspective of EE support factors (access to finance, markets, resources, and policies and regulations), which were inadequate. The findings will assist theory and practice development to understand and focus on the EE discussed in the context of TE in Nigeria, offering potential insights for similar developing economies. </p

Pattern at Presentation of Extremity Gunshot Injuries in Warri, Nigeria

Background Gunshot injuries (GSI) in civilian populations are becoming more common worldwide. The  result is significant morbidity, mortality and disability particularly among the young active productive  males who are often the most frequently affected. The wide spread socioeconomic down turn and small  arms proliferation particularly in developing countries might be partly responsible for this. This study  aims to further highlight the pattern, including aetiology and the emerging significance of GSI in Warri pointing out the need for urgent and appropriate action by all concerned.Methodology A prospective study of consecutive gunshot injury patients who presented at the Central Hospital and two other private health facilities in Warri between l"t of January and 31"t of December, 2011. Relevant data were collected using previously prepared forms, collated and analysed with SPSS version 17.Results Eighty five patients presented with GSI during the study period. This consisted of 78 males and 7  females giving a male: female ratio of 11.1:1. The mean age of patients was 34.23+13.22years with the most frequently affected age group being that of 16-30 years. Most patients (51. 76%) were shot by  armed robbers, traders being the most frequently affected (28.2%). Ninety six m]uries were sustained by the 85 patients with 52 fractures. High velocity weapons were used more frequently.Conclusion Gunshot injuries are common in Warri. Armed robbery is frequently responsible. Practising trauma surgeons here need to be abreast with modern treatment modalities for GSI and our health  facilities should be equipped to meet the challenges. There is also need for improvement in the  socioeconomic conditions of the people, youth reorientation and empowerment programmes and more proactive measures towards addressing security challenges.Keywords: Gunshot injuries; Extremities; Fractures

Assessment of Tropospheric Radio Refractivity and its Variation with Climatic Variables in the Guinea Savannah Region of Nigeria

In studies involving terrestrial atmospheric electromagnetic propagation, such as point-to-point microwave communication, terrestrial radio, television radio, television broadcast, and mobile communication systems, radio refractivity—the bending of a radio signal as it propagates through media—is crucial. In this study, the seasonal tropospheric radio refractivity was estimated and its variations with other meteorological parameters and refractive index were investigated using the measured monthly climatic data of atmospheric pressure, relative humidity, and temperature obtained from the National Aeronautic and Space Administration (NASA) for Makurdi and Ibadan during the period of forty-two (42) years (1981 to 2022). The refractivity gradiant, effective earth radius, and percentage contribution of the dry and wet term radio refractivity were examined. The findings indicated that for the two locations, high values of radio refractivity were observed during the rainy season and low values during the dry season. The maximum and minimum average values of radio refractivity observed for Makurdi and Ibadan during the rainy and dry seasons are, respectively, 380.0641 N-units in the month of May, 331.9776 N-units in January, and 379.9479 N-units in the month of May, 352.2143 N-units in January. The dry term (Ndry) contributes 70.8764 % and 69.4504 % to the total value of radio refractivity, while the wet term (Nwet) contributes to the major variation with 29.1236 % and 30.5496 % for Makurdi and Ibadan, respectively. The study areas under investigation yielded average refractivity gradients of -43.8583 and -43.1480 N-units/km. Additionally, the average effective earth radius (k – factor) for Makurdi and Ibadan was found to be 1.3876 and 1.3790, respectively. These values align with the conditions of super refraction propagation.&nbsp

Crafts industry lifecycle strategies and entrepreneurial development in Ikot Ekpene Senatorial District of Akwa Ibom State

The study evaluates crafts industry life cycle strategies and entrepreneurial development in Ikot Ekpene Senatorial District of Akwa Ibom State. The survey research design was adopted and a sample size of 265 was determine for the study using the Taro Yamane formula. A total of 265 copies of questionnaire was administered on the sample craft producers in the ten LGAs that make up Ikot Ekpene Senatorial District of Akwa Ibom State.250 copies of the questionnaire was return and use for the study. Descriptive statistic was use for data analysis while multiple regression was used in test of hypotheses. It was discovered that industry life cycle analysis enables craft producers to identify the stages of their business development in the industry in order to take steps towards gaining market share and remain competitive. Other findings revealed that the adoption of strategies such as entry strategy, market penetration, cost leadership and diversification strategies at the various phases of the craft industry life cycle enhance development, growth and sustainability of craft businesses. It was therefore recommended that entrepreneurs, particularly craft producers should adopt strategies such as entry strategy, market penetration, cost leadership and diversification strategies at the different stages of the industry life cycle in order to enhance growth, profitability and sustainability of their business. Also, Akwa Ibom State government should provide access to funds and as well build entrepreneurship development centres in Ikot Ekpene Senatorial District in order to enhance the skills and knowledge of entrepreneurs particularly craft producers to enable them navigate their businesses in the different phases of the industry life cycle.Keywords: Industry Life Cycle; Entrepreneurial Development; Strategy Adoptio

Evaluation of the Air Quality of Two Cites in the Niger-Delta, Delta State Nigeria

The air quality of two cities in the Niger-Delta, Delta State, Nigeria was assessed via the Air Pollution Tolerance Indices (APTI) of plants. This is a bio-monitoring technique using the biochemical parameters of the plant species. Twenty plant species were taken from each city along the major highways in the cities. Standard methods of analysis were employed for leaf extract pH, leaf extract total chlorophyll, ascorbic acid content of leaf and the relative water content of leaf. The APTI were then computed of the different plant species according to standard procedure. The APTI values for the cities ranged from 3.18 – 8.27 for Abraka and 4.28 – 9.45 for Ughelli. The mean APTI value for Abraka was 5.69 ±0.35 and Ughelli, 7.28 ±0.32. The result showed that the air quality in Ughelli is more compromised when compared with that of Abraka. Using the students’t-test, there was a significant difference between the qualities of air in these cities. It is therefore recommended that tolerant plant species be planted in these areas to mitigate air pollution and improve the quality of air. Keywords: Ughelli, Abraka, APTI, Air Quality, Niger – Delt

Magnet bioreporter device for ecological toxicity assessment on heavy metal contamination of coal cinder sites

A novel magnet bioreporter device was developed in this research for soil toxicity assessment, via magnetic nanoparticles functionalized whole-cell bioreporters. The whole-cell bioreporter ADPWH-recA kept response capability to DNA damage after magnetic nanoparticles (MNPs) functionalization, and could be harvested from soil samples by permanent magnet to reduce the soil particle disturbance. Compared to conventional treatments applying bioreporter directly in soil-water mixture (SW-M treatment) or supernatant (SW-S treatment), MNPs functionalized bioreporter via the magnet device (MFB) treatment achieved high sensitivity to evaluate the toxicity and bioavailability of chromium contamination in soils from 10 mg/kg to 5000 mg/kg soil dry weight. The MNPs functionalized bioreporter also achieved high reproducibility with pH value from 5.0 to 9.0, salinity from 0% to 3% and temperature from 20 °C to 37 °C. A case study was carried out on the ecological toxicity assessment of heavy metal contamination at the coal cinder site via the magnet bioreporter device. The heavy metal toxicity declined with the increasing distance to the coal cinder point, and a significant accumulation of heavy metal toxicity was observed along the vertical distribution. No direct link was found between the pollution load index (PLI) and heavy metal toxicity, and the results suggested the bioreporter test monitored the toxicity of heavy metals in soils and was an important approach for ecological risk assessment. Magnet bioreporter device also offered the high throughput biological measurement and was feasible for in situ monitoring