Mustapha Danlami Garba

An investigation was carried out to study the feasibility of using synthesized acid-bearing carbonaceous catalyst (SO₃H–C and PO₄H₂–C) derived from cassava peel for biodiesel production from waste cooking oil (WCO). The catalyst activity was tested using an autoclave type reactor and three different oil to alcohol ratios (1 : 3, 1 : 5 and 1 : 7) at four different temperatures (50–80°C) for 4 h. Two types of alcohol (i.e. methanol (CH₃OH) and ethanol (C₂H₅OH) were used to understand the efficiency of using alcohol in the process. The study indicates that reaction using high ratio of alcohol (1 : 7) generally produced high yield of the biodiesel compared to other ratios. The yield of the biodiesel also increased with increasing temperature over all the reaction systems. The carbon modified with sulphuric acid catalyst showed the highest yield of ~ 90%, which was obtained at 80°C using a 1 : 7 ratio of WCO : alcohol. It was also observed that reaction with methanol produced better yields compared to ethanol reactions where significant differences were observed across both temperature and ratio. The catalysts were characterized using Fourier transform infrared spectroscopy, X-ray powder diffraction, surface area and pore volume analyses. The catalyst is of interest because it is green, non-toxic and synthesized using cassava peel waste.

Изучена возможность использования катализатора (SO₃H–C, PO₄H₂–C) на основе кислоты и углерода, приготовленного из кожуры маниоки, для получения биодизельного топлива из отработанного растительного масла. Активность катализатора тестировали в автоклаве с использованием масла и спирта, взятых в трех разных соотношениях (1 : 3, 1 : 5 и 1 : 7) при четырех различных температурах (в диапазоне 50–80°C) в течение 4 ч. Для выяснения эффективности применения спирта использовали метанол (CH₃OH) и этанол (C₂H₅OH). Показано, что большее количество спирта (масло : спирт = 1 : 7) обеспечивало, как правило, более высокий выход биодизельного топлива по сравнению с другими соотношениями реагентов. Выход биодизельного топлива во всех реакционных системах увеличивался также с повышением температуры. Катализатор на основе углерода, модифицированного серной кислотой, показал самый высокий выход ~ 90 %, который был достигнут при 80 °C с использованием масла и спирта в соотношении 1 : 7. Реакции с метанолом давали лучшие выходы, чем реакции с этанолом, где наблюдались значительные различия как по температуре, так и по соотношениям реагентов. Катализаторы были охарактеризованы с помощью инфракрасной Фурье-спектроскопии, порошковой рентгеновской дифракции, определения площади поверхности и объема пор. Полученный катализатор представляет интерес, поскольку он экологически чистый, нетоксичный и синтезирован с использованием отходов кожуры маниоки.

Electrochemical CO₂ reduction reaction (CO₂RR) provides a promising approach to curbing harmful emissions contributing to global warming. However, several challenges hinder the commercialization of this technology, including high overpotentials, electrode instability, and low Faradic efficiencies of desirable products. Several materials have been developed to overcome these challenges. This mini-review discusses the recent performance of various cobalt (Co) electrocatalysts, including Co-single atom, Co-multi metals, Co-complexes, Co-based metal–organic frameworks (MOFs), Co-based covalent organic frameworks (COFs), Co-nitrides, and Co-oxides. These materials are reviewed with respect to their stability of facilitating CO₂ conversion to valuable products, and a summary of the current literature is highlighted, along with future perspectives for the development of efficient CO₂RR.

Setting a conventional cement plug is nearly unsuccessful when there is any wellbore flow especially for the zechstein formations. As such, the used of sodium silicate remain the common option. The silicate polymerization and gelation has been used in well formation to plug holes and reduce the catastrophic flow which cause a lot of production loses. This is usually encountered during drilling rocks zone producing large amount of water or brine. This could result in large volume of the drilling fluid lost into the formation and consequently reduce the effectiveness of the drilling operations. The total successfulness of sodium silicate/cement squeeze depends strongly on whether the cement placed in the desired place without any contamination. Contamination from Oil Base Mud (OBM), Brine influx in the formation can affect the properties of the cement and lead to the failure of it is placement. Other factors include too low concentration of the silicate and or fresh water dilution may also contribute to some extent as tentatively drawn from a bottle test. The thesis focuses on the laboratory evaluation of the likelihood of this contaminant resulted in the sodium silicate/cement squeeze failure in Swift well. The chemistry of their interaction with the cement slurry is discussed. The zechstein brine is prepared using a programmed spread-sheet provided by Shell UK Company based on typical Molln formation as produced from a well in Germany Compressive strength, thickening time and consistency of the source contaminant were measured varying the volume of the contaminant to see their influences comparing to the neat cement and to see how the extent of these contaminations affected the cement properties. Conclusions were made base on the change of these properties observed on what potentially contribute to it is failure