Browsing by Author "Ukanwa, Kalu Samuel"

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    Approaches to maximise the utilisation of residues from thermal conversion of oil palm waste.
    (Cranfield University, 2020-12) Ukanwa, Kalu Samuel; Patchigolla, Kumar; Sakrabani, Ruben
    Palm oil processing generates enormous volume of waste, which can be used as a feedstock in thermal processing. Subsequently, these can be valuable in the production of activated carbon (AC) and soil amelioration. The production of AC often results in secondary contamination through activating agents. This prompts the necessity for a non-toxic activating agent for high quality production of high adsorptive AC. Therefore this research aims to assess and determine the optimum route for efficient utilisation of biowaste from thermal conversion process of palm oil residues in producing activated carbon and soil amelioration by evaluating the impact of the selected utilisation techniques. In the production process, energy demand and process duration have influence on the efficiency of AC; therefore, an appropriate design configurations and parameter selection are required to achieve an anticipated yield. AC was produced by microwave and conventional techniques through pyrolysis. The feedstock was also used in combustion and the thermal residues were applied in agricultural soil and crop yield relative to application rate was assessed on Habanero chili pepper. Therefore, the requisite to quantify the processes, which include appropriate assessment of the technology and economic performance. The accomplishment of the project overall aim was dependent on the design of a microwave system for efficient biomass pyrolysis. The process also evaluated the microwave interaction with reactors implemented to produce AC from mixed oil palm waste, using Trona ore as an activating agent. The AC was analysed to determine the effectiveness of Trona ore for activation using Fourier infrared spectrometry, Brunauer-Emmett-Teller (BET) analyser and scanning electron microscope. The oil palm waste ash was applied to the soil. The optimum outcome of the microwave assisted technique for combine palm waste (CPW) was obtained at 600 W, BET surface area (SBET) is 980 m²/g compared to 920 m²/g from a conventional technique; total volume (Vtotal) 0.865 cm³/g; mean pore diameter 2.2 nm and AC yield is 42%. Therefore, this study additionally identifies the need for an even distribution of electromagnetic waves within the reactor during activation to ensure uniformity of AC. It also proposes that the design of a composite reactor for an industrial production of AC is necessary to enable heterogeneous waste stream of the process. For ash application, the physiological development and crop yield were measured. The combine maximum yield for both sites were 49 t/ha/first season and 71.8 t/ha/second season, occurred at 8 t/ha treatment plot against the control plot with 1.3 t/ha/first season and 0.7 t/ha/second season. The interaction between oil palm waste ash and soil, improved agronomic efficiency of Habanero chilli pepper by 66-69% and Scoville value by 3.52%. These utilisation routes (AC production and ash to soil) were further integrated for economic and technological benefits using Aspen plus Economy. The processes have 16-17% return on investment for the 8-9 year payback period. This study therefore concluded that thermal residues of oil palm waste are useful in the production of high quality AC and also has rich effect on agricultural soil.
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    Energy and economic assessment of mixed palm residue utilisation for production of activated carbon and ash as fertiliser in agriculture
    (Taylor and Francis, 2021-10-16) Ukanwa, Kalu Samuel; Patchigolla, Kumar; Sakrabani, Ruben
    he resultant residues after thermal processes can be reused in the form of activated carbon (AC) production or used for soil amelioration. However, the economic and energy optimisation of the waste revaluation process is necessary for the prediction of technology requirements, investment boundaries and cost–benefit analysis. Mass, energy and cost estimation of the entire process were systematically executed relative to equipment sizing and type of product, as major factors in the evaluation. The economic analysis and process optimisation were quantified and evaluated with the Aspen Plus economy and an SPSS statistical tool for economic analysis. Simulation results were concomitant with economic analysis to determine the approximate annualised return on investment, profitability index and payback period, using optimised variables in the process. The four processes examined: process scenario 1–4 (pyrolysis, gasification, combustion and combined) have 16, 17, 14 and 17.2% return on investment for the 8.5, 8.2, 9.8 and 8-year payback period, respectively. The results provide a technology assessment and economic guide for investors and policymakers among others. This work is also useful for researchers in achieving the goal of efficient biomass utilisation. Palm waste ash as a potential alternative to chemical fertiliser, especially for the treatment of ultisol and acidic soils, were evaluated and it was confirmed that it is a good alternative to typical inorganic fertiliser. Finally, the results indicate that using such wastes in the AC market is a viable business option, though with high initial capital investment even though palm waste ash can be produced locally.
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    Preparation and characterisation of activated carbon from palm mixed waste treated with trona ore
    (MDPI, 2020-10-29) Ukanwa, Kalu Samuel; Patchigolla, Kumar; Sakrabani, Ruben; Anthony, Edward J.
    This study explores the use of a novel activating agent and demonstrates the production and characterisation of activated carbon (AC) from a combine palm waste (CPW) in 3:2:1 proportion by weight of empty fruit bunch, mesocarp fibre and palm kernel shell. The resulting biomass was processed by a microwave-assisted method using trona and compared with material produced by conventional routes. These results demonstrate the potential of trona ore as an activating agent and the effectiveness of using a combined palm waste for a single stream activation process. It also assesses the effectiveness of trona ore in the elimination of alcohol, acids and aldehydes; with a focus on increasing the hydrophilicity of the resultant AC. The optimum results for the conventional production technique at 800 °C yielded a material with SBET 920 m2/g, Vtotal 0.840 cm3/g, a mean pore diameter of 2.2 nm and an AC yield 40%. The optimum outcome of the microwave assisted technique for CPW was achieved at 600 W, SBET is 980 m2/g; Vtotal 0.865 cm3/g; a mean pore diameter 2.2 nm and an AC yield of 42%. Fourier transform infrared spectrometry analyses showed that palm waste can be combined to produce AC and that trona ore has the capacity to significantly enhance biomass activation.
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    A review of chemicals to produce activated carbon from agricultural waste biomass
    (MDPI, 2019-11-06) Ukanwa, Kalu Samuel; Patchigolla, Kumar; Sakrabani, Ruben; Anthony, Edward J.; Mandavgane, Sachin
    The choice of activating agent for the thermochemical production of high-grade activated carbon (AC) from agricultural residues and wastes, such as feedstock, requires innovative methods. Overcoming energy losses, and using the best techniques to minimise secondary contamination and improve adsorptivity, are critical. Here, we review the importance and influence of activating agents on agricultural waste: how they react and compare conventional and microwave processes. In particular, adsorbent pore characteristics, surface chemistry interactions and production modes were compared with traditional methods. It was concluded that there are no best activating agents; rather, each agent reacts uniquely with a precursor, and the optimum choice depends on the target adsorbent. Natural chemicals can also be as effective as inorganic activating agents, and offer the advantages that they are usually safe, and readily available. The use of a microwave, as an innovative pyrolysis approach, can enhance the activation process within a duration of 1–4 h and temperature of 500–1200 °C, after which the yield and efficiency decline rapidly due to molecular breakdown. This study also examines the biomass milling process requirements; the influence of the dielectric properties, along with the effect of washing; and experimental setup challenges. The microwave setup system, biomass feed rate, product delivery, inert gas flow rate, reactor design and recovery lines are all important factors in the microwave activation process, and contribute to the overall efficiency of AC preparation. However, a major issue is a lack of large-scale industrial demonstration units for microwave technology.