Optimization of the Pretreatment of the Mixture of Cassava Peelings and Pineapple Fibers Using Response Surface Methodology and a Process Simulator for the Bioethanol Production

The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production of bioethanol remains a challenge given the crystallinity of cellulose and the presence of the complex. The pretreatment aimed to solubilize the lignin fraction and to make cellulose more accessible to the hydrolytic enzymes, was done using the organosolv process. A mathematical modeling was performed to point out the effect of the temperature on the kinetics of the release of the reducing sugars during the pretreatment. Two mathematical model was used, SAEMAN’s model and Response surface methodology. The first show that the kinetic parameters of the hydrolysis of the cellulose and reducing sugar are: 0.05089 min-1, 5358.1461 J·mol-1, 1383.03691 min-1, 51577.6100 J·mol-1 respectively. The second model was used. Temperature is the factor having the most positive influence whereas, ethanol concentration is not an essential factor. To release the maximum, an organosolv pre-treatment of this sub-strate should be carried out at 209.08°C for 47.60 min with an ethanol-water ratio of 24.02%. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure.

Composite Panels from the Combination of Rice Husk and Wood Chips with a Natural Resin Based on Tannins Reinforced with Sugar Cane Molasses Intended for Building Insulation: Physico-Mechanical and Thermal Properties

The objective of this work is to develop new biosourced insulating composites from rice husks and wood chips that can be used in the building sector. It appears from the properties of the precursors that rice chips and husks are materials which can have good thermal conductivity and therefore the combination of these precursors could make it possible to obtain panels with good insulating properties. With regard to environmental and climatic constraints, the composite panels formulated at various rates were tested and the physico-mechanical and thermal properties showed that it was essential to add a crosslinker in order to increase certain solicitation. an incorporation rate of 12% to 30% made it possible to obtain panels with low thermal conductivity, a low surface water absorption capacity and which gives the composite good thermal insulation and will find many applications in the construction and real estate sector. Finally, new solutions to improve the fire reaction of the insulation panels are tested which allows to identify suitable solutions for the developed composites. In view of the flame tests, the panels obtained are good and can effectively combat fire safety in public buildings.

Co-digestion of Waste Coffee and Cocoa Hulls: Modeling of Biogas Production by the Particle Swarm Method

Energy is a crucial material for the development of our economy.Access to sufficient energy remains a major concern for developing countries,particularly those in sub-Saharan Africa.The major challenge lies in access to clean,environmentally friendly,quality and low-cost energy in different households in our municipalities.To cope with this vast energy gap,many households are dependent on fossil fuels.In Cameroon,the consumption of wood for the supply of energy is increasing by 4%per year.Overall,approximately 80%of households in Cameroon depend on woody biomass as the sole main source of energy supply in Cameroon and demand is growing over time.In view of the climatic variations that our countries,particularly Cameroon,undergo through deforestation,the use of wood as a source of energy is expensive and harmful to the environment,hence the urgency of replacing wood with renewable energy.Biogas is one of the most versatile sources of renewable energy.On an industrial scale,it is important to automate the process control.The main objective of the present work is to model the anaerobic digestion of coffee and cocoa hulls using the particle swarm optimisation method.Pretreatment using the organosolv process was done.This resulted in 48%lignin removal and 22%cellulose increase.For the pretreated biomass,the maximum production rate was 21 NmLCH4 per day with a biomethane yield of 90 NmLCH4/gVS.This represents an enhancement of 117%in biomethane yield.A positive flammability test was recorded after the 10th day of retention time.Moreover,the data collected during anaerobic digestion allowed implementation of a two-phase mathematical model.The thirteen parameters of the model were estimated with particle swarm optimisation method in Matlab.The model was able to simulate the biomethane production kinetics and variation of volatile fatty acid concentration.

Structural Characterization of Bauxite Red Mud to Utilization in Ceramic Wall/Roofing Tile: Effect of Temperature on Mechanical Properties and Physic-Chemical Stability

This present research work is on the characterization of bauxite red mud (waste material) from Ngaoundal for the manufacture of ceramic products. After the extraction process, the raw material was characterized using Scanning Electron Microscopy (SEM). Morphology, mineral phases and chemical composition were determined by using energy-dispersive X-ray (EDX) analysis, X-ray diffractometer (XRD), X-ray fluorescence (XRF). Differential Scanning Calorimetry and Thermal Gravimetric Analysis (DSC-TGA), Infra-Red (IR), Particle size (PS) were also used. Results of red mud analysis show that major oxides were Fe2O3 (37.21%), Al2O3 (19.6%), SiO2 (7.68%), TiO2 (1.07%), Na2O (4.71%), and CaO (2.75%). These last oxides require low temperature to melt and act as binders which link particles of red mud during the sintering process. Presence of alkaline oxides is an appeal to reduce energy consumption during ceramic manufacture process and to protect our environment for sustainable development. Physical and mechanical properties of fired red mud showed that the firing shrinkage, bulk density, and flexural strength increase with firing temperature. Porosity and water absorption had the same pattern and they decreased with the increase of temperature. Chemical stability reveals that 10% material loss is obtained after 7 days of treatment under acid-base conditions.

Thermal and Physicochemical Characterization of Fibers from Coffee Hulls as Filler for Linear Low Density Polyethylene (LLDPE)

This work presents the thermal, physical and chemical characterization of Coffee canephora, from littoral region of Cameroon, for their use as reinforcement for polymeric materials. The infrared of coffee hulls shows the presence of a large peak intensity at 3299 cm-1 that can be attributed to O-H stretching group of alcohol (cellulose content in coffee pulp). The intensity 2926 cm-1 can be attributed to C-H stretching group of alkanes or the vibration of methoxy group of lignin. Thermo gravimetric analysis shows that around 440°C, the biomass has been completely consumed;the temperature profiles show a peak at 86°C that could correspond to the loss of water as evaporation at a percentage of 8%;the peak at 321°C is accompanied by a water loss of 64.50%; this temperature is assimilated to the degradation of hemicelluloses;the temperature range from 321°C to 401°C is accompanied by a loss of mass of 22.80%, which would be due to the degradation of cellulose. SEM images of the surface of raw coffee hulls, coffee hulls treated with caustic soda respectively clearly reveal gaps between the fibers. The results showed that the incorporation of coffee hulls fiber in LLDPE matrix might result in composites with suitable property application for various industrial fields;especially those that were mechanical features are crucial, such as the replacement of engineering plastics.

Low Density Linear Polyethylene Reinforced with Alkali and MAPE Treated Fibers from Coffee Pulp

In this work fibers derived from coffee, hulls have been incorporated into Linear Low Density Polyethylene (LLDPE). The influence of the filler content on the thermal and physicomechanical properties of the composites obtained was assessed. The results showed that the incorporation of fibers was able to improve the thermostability of LLDPE/Coffee hulls fibers;comparing the treated fiber composite with untreated fiber composites, the chemical treatment reduces by 58.3% the water absorption, while increasing the elongation and tensile strength by about 48% and 17% respectively. Moreover, due to better interfacial interaction induced by MAPE, the corresponding composite exhibited better properties compared to the untreated fiber composite. Results are indicative of the fact that both mercerization and MAPE (coupling agent) have significant positive effects on the fiber-matrix interaction in terms of adhesion, wetting and dispersion, this treatment produced a better fiber distribution and consequently a more uniform composite morphology without voids and gaps between the fibers and the matrix, allowing the possibility to use higher fiber contents (up to 30% wt.) with acceptable mechanical properties.

Influence of CRT Glass Quantity on the Properties of Red Mud-CRT Glass Ceramics Fired at Different Temperatures

This paper reports the production of ceramics using CRT(cathode ray tube)glass and red mud by varying the amount of waste glass and firing from 700-950℃.The raw materials were characterized using chemical composition,IR(infra-red spectroscopy),XRD(X-ray diffraction),DSC-TGA(differential scanning calorimetry-thermo gravimetric analyses)and SEM(scanning electron microscopy)analysis.The ceramic specimen was produced by mixing a constant quantity of red mud and 0%-40%of waste glass,then firing from 700-950℃.The linear shrinkage,water absorption,apparent porosity,bulk density,weight loss on ignition,flexural strength and chemical resistance test were used to evaluate the produced ceramics.Raw materials had good fluxing properties which were improved with firing.All the specimens produced had water absorption values below the maximum value of 20% specified by the norm for roofing tiles while specimens with 30%-40% CRT glass and fired at 850°C,and specimens with 20%-40% CRT glass and fired at 950℃ had water absorption values below 10%,which is the norm for ceramic tiles.For specimens 0%-40% CRT glass fired at 950℃,specimens 5%-40% CRT glass fired at 850℃,specimens 10%-40% CRT glass fired at 750℃ and specimen with 20%CRT glass fired at 700℃,water absorption values were all lower than 17% which is ASTM C62 specifications for bricks.The norm of flexural strength for floor tiles>25 MPa but all values were less than 25 MPa.The ceramic shows a maximum loss of 0.10%in HNO3 against 0.06%for NaOH.The two waste materials can effectively be used to produce ceramic materials with good properties.