Investigation of Nonisothermal Combustion Kinetics of Isolated Lignocellulosic Biomass: A Case Study of Cellulose from Date Palm Biomass Waste

The efficient and high yielding acid-base and Organosolv methods were studied for cellulose isolation from date palm lignocellulose waste biomass and thereafter analyzed for nonisothermal kinetic and thermodynamic parameter determination using model-free methods. The structural and chemical characterization of the isolated celluloses revealed structures and functional groups characteristics of cellulose. Thermal decomposition analysis revealed one major peak with average mass loss of 72.51 ± 0.7% and 55.82 ± 1.1% for the acid-base and Organosolv method, respectively. This occurred in the temperature region between 250 and 350°C associated with cellulose degradation and contrasted with the three peaks detected in the original biomass. The kinetic and thermodynamic results revealed a strong relationship between the average activation energy and average change in enthalpy with a difference of 5.23 and 147.07 kJmol−1 for Organosolv and acid-base methods, respectively. The Gibbs’s free energy results revealed that Organosolv cellulose pyrolysis would reach equilibrium faster in KAS, Starink and FWO models with average ΔG values of 115.80 ± 36.62, 115.89 ± 36.65, and 119.45 ± 37.98 kJmol−1, respectively. The acid-base method for FWO model gave negative entropy values. The Malek method revealed the acid-base and Organoslv cellulose pyrolysis mechanism as (gα=−ln1−α14) and (gα=−ln1−α13), characterized by random nucleation and growth, respectively

A Review of Enzymatic Transesterification of Microalgal Oil-Based Biodiesel Using Supercritical Technology

Biodiesel is considered a promising replacement to petroleum-derived diesel. Using oils extracted from agricultural crops competes with their use as food and cannot realistically satisfy the global demand of diesel-fuel requirements. On the other hand, microalgae, which have a much higher oil yield per hectare, compared to oil crops, appear to be a source that has the potential to completely replace fossil diesel. Microalgae oil extraction is a major step in the overall biodiesel production process. Recently, supercritical carbon dioxide (SC-CO2) has been proposed to replace conventional solvent extraction techniques because it is nontoxic, nonhazardous, chemically stable, and inexpensive. It uses environmentally acceptable solvent, which can easily be separated from the products. In addition, the use of SC-CO2 as a reaction media has also been proposed to eliminate the inhibition limitations that encounter biodiesel production reaction using immobilized enzyme as a catalyst. Furthermore, using SC-CO2 allows easy separation of the product. In this paper, conventional biodiesel production with first generation feedstock, using chemical catalysts and solvent-extraction, is compared to new technologies with an emphasis on using microalgae, immobilized lipase, and SC-CO2 as an extraction solvent and reaction media

A new process for the recovery of ammonia from ammoniated high-salinity brine

This paper describes a new method for the recovery of high-concentration ammonia from water in the form of ammonium chloride, ammonium hydroxide and ammonium carbonate. The method was applied to the Solvay process, in which sodium bicarbonate is produced through the reaction of ammoniated brine and CO2 gas. The Solvay effluent contains ammonia in the form of soluble ammonium chloride. The proposed method is based on the recovery of ammonia using a high-alkalinity reactant, calcium oxide (CaO), in a closed electrocoagulation cell operating at a specific current density. The recovered ammonia is collected as a gas within a closed cell containing deionized (DI) water at room temperature. Afterwards, the collected solution (DI water-NH3 gas) is concentrated through a separate process, and is then reused in the Solvay process and other applications. The electrocoagulation process is applied to the treatment cell using aluminum electrodes and a current density of 5-15 mA/cm2 . After 7 h of treatment using the electrocoagulation cell, a high reduction of the ammonia concentration-99%-was realized after ~9 h of the electrochemical treatment. The initial ammonia concentration in a Solvay effluent of 13,700 mg/L N was decreased to 190 mg/L N. Furthermore, an ammonia recovery of 77.1% in the form of ammonium hydroxide was achieved. Generally, this process, which starts at room temperature, can result in an energy reduction of 80%-from 7.8 to 2.3 kWh/kg NH3-compared to conventional processes, which entail heating the Solvay effluents to 160?C. The proposed system and method were found to be suitable for the recovery of ammonia from ammoniated water, and can be utilized for the treatment of landfill leachate, and municipal and industrial wastewater.Funding: This research was funded by United Arab Emirates University, grant number G00002622.Scopu

CO2 capture and ions removal through reaction with potassium hydroxide in desalination reject brine: Statistical optimization

Previous studies have investigated the overall performance of the modified Solvay process based on a new alkaline compound, namely, KOH. Preliminary results have confirmed its high reactivity and effectiveness in capturing CO2 and managing reject brine. In this study, parametric sensitivity analysis has been carried out to optimize the operating conditions and thereby maximize CO2 capture and ions removal from high-salinity brines. Response surface methodology (RSM) analysis using the central composite design (CCD) approach was implemented to statistically determine the impact of important operating conditions, including KOH concentration (30–110 g/l), CO2 gas flow rate (400–1600 ml/min), gauge pressure (1–3 barg), and temperature (10–50 °C) on key response process output variables, such as CO2 uptake and ions reduction. The importance of these parameters and their interactions were confirmed by employing analysis of variance (ANOVA) approach at a confidence level of 95% (p < 0.05). These analyses demonstrated that under the optimized conditions of a temperature of 10 °C, gauge pressure of 2.1 barg, CO2 gas flow rate of 848.5 ml/min, KOH concentration of 110 g/l, and an inert mixing particle volume fraction of 15%, a maximum CO2 uptake value of 0.58 g/g KOH, maximum sodium (Na+) removal of 44.1%, chloride (Cl−) removal of 40.1%, calcium (Ca2+) removal of 100%, and magnesium (Mg2+) removal of 99.8% were achieved. The characterization of the collected solid products at optimum conditions revealed the production of valuable and useful products, particularly sodium and potassium bicarbonates, in addition to KCl.Open Access funding is provided by the Qatar National Library.Scopu

Klason Method: An Effective Method for Isolation of Lignin Fractions from Date Palm Biomass Waste

Klason lignin extraction method is one of the robust techniques for isolation of lignin from lignocellulosic palm biomass waste for future production of High Value Chemicals (HVCs). To elucidate the mechanism of hemicellulose and cellulose glycosidic bond distraction, lignocellulos

Estimating Combustion Kinetics of UAE Date Palm tree Biomass using Thermogravimetric Analysis

Palm tree consists of different parts among which are the leaflet, rachis and fibers. All these parts constitute lignocellulose biomass components capable of producing value added end products. A kinetic study of thermal decomposition of UAE date palm tree of phoenix dicteylifera species was carried out using thermal gravimetric analysis (TGA) at heating rates 10 oC/min, 15 oC/min and 20 oC/min. Most of the lignocellulose material decomposed between 300 oC and 650 oC at each heating rate. The rachis decomposed in three phases while the leaflet and fibers decomposed in two phases. The apparent activation energies increased from 54 to 476 kJ/mol, 55 to 458 kJ/mol and 84 to 329 kJ/mol for leaflet, rachis and fibers, respectively for conversion ranging from 10-% to 80-%. Results from this study are fundamental in optimizing operational conditions of a reactor for production of furfural, levulunic acid, dihydroeugenol, DHE and 2,6-dimethoxy-4-propyl phenol, DMPP as high value chemicals. Key words: UAE Palm tree biomass, Thermogravimetric analysis, Combustion kinetics, Activation energ

Comprehensive optimization of the dispersion of mixing particles in an inert-particle spouted-bed reactor (Ipsbr) system

Effective gas dispersion and liquid mixing are significant parameters in the design of an inert-particle spouted-bed reactor (IPSBR) system. Solid particles can be used to ensure good mixing and an efficient rate of mass and heat transfer between the gas and liquid. In this study, computational fluid dynamics (CFD) coupled with the discrete phase model (DPM) were developed to investigate the effect of the feed gas velocity (0.5-1.5 m/s), orifice diameter (0.001-0.005 m), gas head (0.15-0.35 m), particle diameter (0.009-0.0225 m), and mixing-particle-to-reactor-volume fraction (2.0-10.0 vol.%) on the solid mass concentration, average solid velocity, and average solid volume fraction in the upper, middle, and conical regions of the reactor. Statistical analysis was performed using a second-order response surface methodology (RSM) with central composite design (CCD) to obtain the optimal operating conditions. Selected parameters were optimized to maximize the responses in the middle and upper regions, and minimize them in the conical region. Such conditions produced a high interfacial area and fewer dead zones owing to good particle dispersion. The optimal process variables were feed gas velocity of 1.5 m/s, orifice diameter of 0.001 m, gas head of 0.2025 m, a particle diameter of 0.01 m, and a particle load of 0.02 kg. The minimum average air velocity and maximum air volume fraction were observed under the same operating conditions. This confirmed the novelty of the reactor, which could work at a high feed gas velocity while maintaining a high residence time and gas volume fraction.This research was funded by the ADNOC Refining Research Center, Abu Dhabi, United Arab Emirates, grant number 21N224, https://dx.doi.org/10.13039/501100002672 (accessed on 20 September 2021). The authors would like to express their sincere gratitude to Jawad Mustafa from Chemical Engineering Department at the UAE University for his valuable help and assistance.Scopu

Computational fluid dynamics simulation of an Inert Particles Spouted Bed Reactor (IPSBR) system

A novel system for contacting gases and liquids, suitable for many applications involving gas-liquid contact such as CO2 capture and brine desalination, has been simulated and experimentally validated. The system comprises a vertical vessel with gas and liquid ports and inert particles that enhance mixing and provide a high gas-liquid interfacial area. A low gas flow rate was statistically demonstrated and experimentally verified to be the optimum condition for CO2 capture and brine desalination; however, the gas velocity can have a considerable effect on the motion of inert particles inside the reactor. Uniform particles motion ensures good mixing within the reactor and hence efficient absorption and stripping process. A computational fluid dynamics (CFD) model, namely Eulerian model, presented in this paper, will help demonstrate the effect of mixing particles at specific conditions on the gas and liquid velocities inside the reactor, gas and liquid volume distribution through reactor, and eddy viscosities stresses of the mixing particles. A mesh-independent study was conducted to demonstrate the independency of mesh structure and size on the output responses. A quasi-steady state was attained to ensure the stability and feasibility of the selected model. The assembled model exhibits remarkable applicability in determining the optimum mixing particles densities, volume ratios, and sizes to ensure best velocity distribution and gas spreading inside the reactor and accordingly enhance the associated chemical reactions.Research funding: Abu Dhabi National Oil Company, Refining Research Center, Abu Dhabi, UAE (Grant no. 21N224). https://dx.doi.org/10.13039/501100002672 .Scopu