احمد غضنفری مقدم

Water transfer in plant tissues is a complex phenomenon. The cell wall and plasma membrane are permeable to water and the amount of water exchange among cells and the intercellular space mainly depends on the amount of intracellular water pressure and the viability of the cell membrane. The movement of water within the plant tissues includes simultaneous heat and mass transfer and therefore the thermophysical properties of the plant tissue plays an important role in this transition. Capillary pressure, intrinsic permeability, relative permeability, effective moisture diffusivity, and thermal conductivity are the key thermal and transport properties needed for comprehensive investigation of moisture transfer mechanism in plant tissue. The plant material can be considered as a porous medium in a non-steady state, which contains about 10 - 80% water. Molecular diffusion for gases (water vapor and air), capillary influence for the liquid (water) and advection mechanisms (Darcy flow) are used in the drying model in porous media. Thus, multiphase models can be used to study the water movement in plant tissues. In multiphase models of transmission mechanism, transfer of water into two types of liquid and gas is investigated simultaneously under the influence of temperature and other properties of plant tissue. In this article, the plant tissue is considered as a porous medium and the factors affecting the moisture transfer in these tissues are discussed.

Biodiesl is a renewable fuel that can be used alone or combined with diesel fuel in diesel engines. In this research biodiesel was synthesized using Persian lilac oil seeds. Biodiesel was purified by washing it with water and some of its physical properties was measured. Then it was mixed at 10, 20 and 30% proportion with regular diesel fuel and was tested in a four-cylinder diesel engine. The exhaust pollutants including CO, CO2, unburned carbohydrates (HC), NOx and the temperature of the exhaust gases were determined at three engine loadings of 200, 250, and 300 N.m and at six engine speeds ranging from 1300 to 1800 rpm. The measured pollutants were compared with those obtained from a regular diesel fuel. The results indicate that with increase in the percentage of biodiesel the emission of CO and HC and the temperature of the exhaust gases decreased but the CO2 and NOx emissions increased. By increasing the speed of the engine the emission of CO, CO2, HC and the temperature of the exhaust gases increased but the amount of NOx deceased.  Increase in the engine loading caused a decrease in NOx emission but other measured pollutant and the temperature of the exhaust gases increased.

Discrete element method has been identified as a suitable method for studying the flow of granular materials. In this research, the motion of Persian lilac fruit was initially investigated experimentally in a slopped hopper and then it was simulated using discrete element method. The experiments were carried out on the basis of factorial design with two factors of height and discharge area, each at four levels. The ANOVA tests indicated that the height of the fruits in the hopper and the surface area of the discharge and their interaction had a significant effect on the outflow of the fruits. The developed regression equation between the mass flow rate and discharge area and the interaction of discharge area and height was linear (R2 = 0.99), however, height of the fruits in the hopper had a negative impact on the discharge rate. The simulation results indicated that and the outlet size, the discharge flow and the output velocity increase, but they did not exactly follow the fluid flow relationships. The effect of fruits friction showed that the discharge rate increased with decreasing internal friction. In general, comparing the simulation results with laboratory tests showed that the discrete element method was well able to simulate the flow of particles within and through the hopper.

Knowledge of mechanical and viscoelastic properties of agricultural material will be helpful in the transportation and processing of these materials. Giant reed grass, also known as wild cane, is a tall, perennial, bamboo-like, grass that grows in wet areas.  The giant reed grass can flourish in a wide variety of soils, including coarse sands, gravelly soil, heavy clay, and river sediment.  This grass attains heights of 7 m and once established the stems can reach a thickness close to 3 cm.  The stems of giant reed grass are used for different purposes. Traditionally the stems are used in the villages for fencing, roofing, and producing handcrafts. The modern uses of the giant reed stems include plywood, composites panels and paper production. The giant reed stems are not uniform and are made from many nodes. The number of nodes and the distance between nodes can affect the mechanical properties of the stems. In order to attain a suitable use of the stems in various industries, the physical and mechanical properties of the stems must be determined. Knowledge of mechanical and viscoelastic properties of agricultural material will be helpful in transportation and processing of these materials. The purpose of this research was to determine some relevant mechanical properties of the stems of giant reed grass with different nodes and moisture contents.

In this research, different mechanical and viscoelastic tests were performed on the stems of cane at various levels of moisture and number of nodes. The Burger-Voigt model with different number of elements was also used to model the creep behaviors of the stems. The cane stems were cut and divided to three groups of two, four, and six-node stems. The moisture contents of the stems were adjusted to three levels of 30, 40 and 50% (w.b.). After preparing the stems the mechanical tests were performed using an Instron testing machine with a three-point support. The creep tests were done by hanging a 10 kg weight at the middle of each stem. The experiments were done using factorial tests based on completely randomized design. The Young module, toughness, and the yield points of the stems were measured by the three-point method. These parameters were obtained from the stress-strain curves of the three-point compression bending tests. The results showed that the Young module was affected by both moisture and the number of nodes, but there were no interaction effects. The creeps of the stems under 10 kg loading were modeled using 3 to 5 elements Burger-Voigt models. In these models a combination of springs and dashpots are used to represent the stems. The curve fitting was performed using the MATLAB software and the goodness of fitness was verified using the fitted curves and calculating the coefficient of determinations.

The results by investigating the graphs and the ANOVA tests showed that the Young module was significantly affected by both moisture and the number of nodes. The obtained Young module for cane stem ranged from 572-1268 MPa. Both yield point and toughness were affected by both moisture and the number of nodes and their values were 65-250 N and 0.016-0.132 J.m-3, respectively. The creep test results indicated that the maximum deformation and maximum time for of the interaction of the two factors was insignificant. The maximum deformations ranged from 2.1-42.5 mm, and the maximum time for reaching the final deformation was 12.5-75 minutes for various moistures and the number of nodes combinations and showed that the 5-element Burger was best for explaining the viscoelastic behavior of cane stems (R2>0.97).

In this research, some mechanical properties of the giant reed grass stems were measured and the creep behavior of the stem was modeled using 3-5 elements Burger-Voigt models. The results indicated a decrease in the Young module of the stems with increase with moisture content and increase in the Young module with increase in the number of nodes. On the other hand, the elongation of the stems increased with both number of the nodes and the level of moisture. The 5-element Burger-Voigt model was best fitted to the creep data.

Wild safflower is a plant resistant to dry climate and the seeds are used for producing edible or industrial oils. The objective of this research was to investigate the factors affecting solvent oil extraction from wild safflower seeds. The effect of 5 factors including solvent temperature (50 and 70°C), time of extraction (4 and 6 h), volume of solvent (200 and 300 ml), mass of the seeds (20 and 30 g) and size of the ground seeds (1.0 and 1.5 mm) on extracting oil by Soxhlet extractor was investigated using fractional factorial experiments based on completely randomized design (α=0.01 and α=0.05). After determining the significant factors, the value of the factors were optimized using response surface methodology based on the central composite design method. The experiments performed by fractional factorial experiments showed that extraction time (α=0.01), size of seed particles (α=0.01) and solvent volume (α=0.05) had meaningful effects on the oil extraction yield. The experiment performed based on central composite design indicated that particle size (α=0.01), extraction time (α=0.01), volume of solvent (α=0.05), and the interaction of time and solvent volume (α=0.01) had significant impact on the oil extraction yield. From the 5 investigated factors, time of extraction and the size of ground seeds (α=0.01) and the volume of solvent (α=0.05) had significant effects on the oil extraction yield. The optimized values for extraction time, volume of solvent and the size of the ground seeds were 6:40 h, 335 ml and 1.1 mm, respectively. The maximum oil extraction yield at the optimum conditions was 36.6%.

Moringa is a tree that grows in hot and humid regions and produces oil seeds that contain about 33% edible oil. The tree is native to the south-west regions of Asia and it is cultivated in Hormozgan and in Sistan and Bluchestan provinces of Iran. The oil extracted from these seeds is edible and has some various industrial applications. The extracted oil usually contains considerable amount of dissolved impurities which must be removed prior to industrial usages. Major part of impurities is removed by settling or filtering process. The fine impurities are removed through a degumming process using water, acids or enzymes. The degumming process affects the physco-chemical characteristics of the oil. In this research, various physco-chemical and heating properties of Moringa oil was measured and the stability of the oil under elevated temperatures were investigated
Material and The Moringa seeds were collected from the wild trees that grow in Hormazgan province. The seeds were manually cleaned and ground to mean diameter of less than 1 mm and then were placed in an oven at 65°C for 24 h to reduce their moisture. Samples of 50 g ground seeds were placed insoxhelt and n-hexane was used as the solvent. The oil extraction experiments were conducted at 60°C for 7 h retention time. The raw obtained oil was divided into two parts and one part was degummed. The degumming of the oil was performed by adding distilled water to it and raising the temperature to 80°C. Then, phosphoric acid was added to the mixture and stirred for 20 min at the same temperature and the mixture was centrifuged and the oil was separated from water and wax. Some characteristics of the raw and the degummed oils including: fatty acids, ion value, peroxide value, chemical, color, saponification value, ignition and clouding points, density and viscosity were measured and compared. The stabilities of the viscosity of the two oils were investigated under different temperatures ranging from 3 to 120°C. The oxidative stability of oils was determined against temperature, light and air exposure. In these experiments temperature ranged from 20 to 120°C, light and air exposure time were 10 days, each. High temperature stability of the oils was also verified using a Rancimat instrument.
The results of fatty acids analysis indicated that the Moringa oil is generally unsaturated oil containing a total of 76% pulmonic and oleic acids. The major saturated oil content of Moringa oil was plasmatic acids which accounted for 14.3% of the total fatty acids. High amount of unsaturated acids indicates that this oil is good for cooking purposes. The degumming process caused a significant decrease in peroxide value, saponification number and total fatty acids but the viscosity and the pH of the oil increased which all indicates that the degummed oil should be more stable than the raw oil. All heating properties of the degummed oil such as melting, combustion, pour, and cloudy points of the degummed oil increased which indicates that the degummed oil is more suitable for heating foods. In investigating the stability of the oil, the viscosity of the Moringa oil was decreased as the temperature of the oil was increased however, the viscosity increased with the holding time. The increase of the viscosity was more significant at higher temperatures due to the oxidation and degradation of the oil. Generally, increase in the viscosity of the degummed oil occurred at with lower rates. The peroxide value of the raw and the degummed oil was increased as the temperature of them was increased. The increase had higher rates when temperature of the oil exceeded 60C. The peroxide value was also increased with the holding time. The change was not significant for the first four days but it rapidly increased after that. The peroxide value of the oil that kept away from the sunlight remained unchanged for the 10 days test period. The value of peroxide was also affected by aerating the oil. Degradation was initiated immediately as aeration was started but a steep increase was noticed after the second day. The highest peak was reached on the sixth days and after that the oil was completely degraded. A Racncimat test on the raw and degummed oil indicated that with increase in the oil temperature the stability of the oil decreased and when temperature was at 110°C the stability of the raw and the degummed oils were 19 and 31 hours. In general, all the tests indicted that the degummed Moringa oil had higher stability than the raw oil.

The lignocelluloses materials have high potential for producing various types of biofuels. These materials include various parts of plants, especially leaves and stems that are left without a specific usage after annual pruning. These residues can be used through slow or fast pyrolysis process for production of liquid and gaseous biofuels. The slow pyrolysis is taking place at temperatures below 500°C while fast pyrolysis process takes place at a temperature above 700°C. Various studies on production of biofuels from plant residues have shown that the temperature, heating rate and the resident time of pyrolysis process are the main factors that affect the final product quality. At present time, in Iran, there are more than 360 thousands hectares of pistachio growing fields which annually produce over 215 thousands metric tons residues which are mainly leaves and stems. The main objective of this study was to measure the heating properties of the powders prepared from the leaves and the stem of pistachio trees. These properties include higher heating value (HHV), lower heating value (LHV) and thermal gravimetric analysis (TGA) of the powders. Then the powders were separately pyrolysed and the kinetic of the pyrolysis process for producing charcoal from them was investigated.
In this research, leaves and stems of pistachio trees were initially analyzed to determine their chemical constituents including moisture content, volatile compounds, carbon (C), hydrogen (H), nitrogen (N), sulfur (S) and oxygen (O) content. Using these constituents the height heating value and low heating value for the leaves and the stems were determined. The thermal gravimetric analysis (TGA) of the powders was made to select a proper heating temperature for pyrolysis of the powders. In each experiment about 10 g of powder powders were pyrolyzed to produce char. Based on TGA results, the pyrolysis experiments were performed at 350, 400, 450 and 500°C with 30 minutes residence time. The instantaneous amount (in decimal) of the produced gas (M) and char (Ms) as a function of time (t) was modeled using the following equations: For each experiment B is a constant value and is represented by: Where Ea is the activation energy, R is universal gas constant, T is the temperature of the experiment and A is the pre-exponential constant. By having M or Ms at different times (t), the parameters of A, B and Ea were estimated using the curve fitting tool box of the MATLAB® software.
Results and Discussion The results of chemical analysis indicated that the leaves powders contained 1.5% N, 42.1% C, 5.5% H, 0.4% S and 48.3% O while the stem samples contained 0.5% N, 46.5% C, 6.1% H, 0.2% S and 44.6% O. Higher amount of carbon and hydrogen in the stem leaves indicates that the stem should have higher energy content. In fact, the calculated high and low heating values for leaves were 17.23 and 16.03 MJ.kg-1, and for the stems were 18.91 and 17.59 MJ.kg-1, respectively which comply with the predicted results from chemical analysis of the powders. The TGA test results indicated that the initial weight loss took place up to 270°C for the stems powder and up to 220°C for leaves powders. This weight loss was due to loss of moisture and volatile compounds. The actual degradation temperature for the stem powders ranged from 300 to 500°C while for the leaves was from 350 to 600°C. The results of pyrolysis experiments indicated that the pyrolysis of stems took place faster than leaves. The pyrolysis time was 10 to 15 min for leaves and 5 to 10 min for stems. The resulting char for pyrolysis of stem was 30% and for stems were 40% of the original materials. The kinetic of pyrolysis was modeled using one-step global model for production of char and gas. The experimental data were fitted to the used model with high degrees of accuracy (R2>0.99). The model parameters, namely activation energy and frequency factors were 10.70 kJ.mol-1, and 0.047 s-1 for stems and 21.72 kJ.mol-1 and 0.312 s-1, respectively.
Conclusions In general, both HHV and LHV of the stems were higher than those of leaves due to higher carbon content of the stems. The TG curves indicated the pyrolysis time of stems was shorter than that of leaves. The leaves yielded 40% char while the stem yielded 30%.

The gradual depletion of fossil fuels and the increase on their cost have made the researchers to look for renewable sources of energy. Biodiesel fuel has attracted many researchers due to its low environmental pollution and being a renewable fuel. In this research, biodiesel was prepared by transesrtification of Persian lilac seed oil. The prepared fuel was mixed with regular petro diesel in 0, 10, 20, 30 and 100% proportions (biodiesel/diesel). The moisture was tested using a diesel engine operating at 1300 to 1800 rpm with a variable load of 200, 250 and 300 Nm. The test results indicated that with increase in proportion of biodiesel/diesel the break specific fuel consumption (bsfc) increased and the break mean effective pressure (bmep) decreased. When pure biodiesel was used as fuel, in comparison with pure diesel fuel, bsfc increased up to 68.9% and bmep decreased up to 13.4%. The best performance for the blended fuel was achieved when using B10 or B20. With theseblends, the increase in bsfcwas 4.9 and 6.8%, respectively and thedecrease in bmep was3.6 and 4.3%, respectively.

In this research, unpeeled and peeled fruit from the Persian lilac were prepared and the flow properties, mean geometric diameter, sphericity coefficient, bulk density, coefficient of static friction and coefficient of internal static friction were determined. The flow patterns and discharge flow rates from a cubic hopper was investigated. The results indicate that the minimum discharge diameter for peeled fruit was 4.6 cm and for unpeeled was 6.3 cm. A comparison of discharge through a 5.5 cm diameter discharge outlet showed that the flow for the peeled and unpeeled fruits were 586 and 554 cm3/s, respectively. Three flow patterns were distinguished within the hopper: the increasing zone, the decreasing zone and the re-increasing zone. Exponential and two third-degree polynomial models were chosen and presented to predict the instantaneous horizontal and vertical positions and speed of the fruits within the hopper. The discharge rate was modeled using the Beverloo and Gregory models. Both models were well-fitted to the experimental data; however the Beverloo model resulted in a higher accuracy (R2 = 0.97).

Dill is one of the most important plants in the world because of its medicinal properties and it is widely used as a vegetable in the most parts of Iran. In the present study a new solar dryer with finny, perforated absorber plate collector was utilized to dry fresh dill. The dryer was comprised of a solar collector, a product container, a fan and a drying air temperature controller. The temperature controller was used as a control system to regulate the drying air temperature. Thermal performance of the dryer with finny, perforated solar collector was compared with that of a simple flat plate solar collector at different airflow rates. The effect of drying air temperature at three levels (45, 55 and 65 °C), the product size at three lengths (3, 5 and 7 cm) and two different modes of drying (mixed and indirect) on the dryer performance was investigated. The results showed that the finny, perforated absorber plate solar collector could improve the thermal efficiency about 11% in comparison with the flat plate collector and the highest thermal efficiency was achieved at the maximum airflow rate. Meanwhile, increasing the air temperature and decreasing the product size caused a significant reduction in energy consumption. Solar fraction reduced by increasing the air temperature. Finally a maximum dryer efficiency of 70% was observed at air temperature of 65 oC, product size of 3 cm with mixed mode drying.

In this study, possibility of substituting date palm fibers, as a growth medium, for coco peat was investigated. First, moisture absorption, retention and loosing rate in date palm fibers, coco peat, peat moss, perlite and soil were examined by completely randomized blocks design in two time periods (3 and 5 days), with two groups of materials (date palm fibers- peat moss- perlite and coco peat-peat moss-perlite) in 11 treatments and 3 replications. To find the best treatment in each group, the response surface methodology and desirability function were used, and finally the optimized treatments for capability of holding moisture in the medium were statistically compared to other treatments. Results indicated that potential of absorption and loosing rate of moisture in coco peat, peat moss, date palm fibers, perlite and soil was decreased, respectively. Maximum amount of water holding capacity occurred in date palm fibers’ group by combination of 65-20-15% in 3 days and 75-10-15% in 5 days and in coco peat group with combination of 75-20-5% in 5 days.

During the past two decades، the use of bioplastics as an alternative to regular plastics has received much attention in many different industries. The mechanical and degradable properties of bioplastic are important for their utilization. In this research cellulose of wheat straw and glycerol were mixed by different weight ratios and then reinforced by using date palm fibers. To prepare the bioplastic plates، the materials were poured in molds and pressed by means of a hydraulic press and simultaneously heating of the molds. The experiments were performed based on a 3×3 factorial design with three levels: 50%، 60% and 70% of wheat cellulose and three types of reinforcement methods، namely: no-reinforcement، network reinforcement and parallel string reinforcement. The effect of the two factors on tensile strength، tensile strain، bending strength، modulus of elasticity and modulus of bending were investigated. The results indicated that the two factors and their interactions had significant effects on the mentioned properties of bioplastics (at α=0. 05 level). The comparison of the means of the tests showed that the network reinforcement type with 50% cellulose had the highest tensile and bending strengths with 1992. 02 and 28. 71 MPa، respectively. The maximum modulus of elasticity and modulus bending were 40. 4 and 2. 3 MPa، respectively for parallel string arrangement and 70% of cellulose. The degradability tests of bioplastic using a fistulated sheep indicated that with increasing the percentage of cellulose، the degradability rate deceased. The maximum degradability rate، after 48 h holding in the sheep rumen، was 74% that belonged to bioplastics with 50% cellulose. The degradability data were well fitted to a mathematical model (R2=0. 97).

Rose water residues are by-products of rose water industries. These residues do not have any industrial usage and they are returned to soil as crop fertilizer. In this research, the effects of adding rose water distillation residues to soil in different particle sizes and weight proportion were investigated and changes in mechanical strength, and water holding capacity of soil and the growth of barley were determined. The experiments were performed using a 3 × 3 factorial design in which the weight proportions of the residues were in three levels of 4%, 8% and 12%. The second factor was the size of the residues in three sieves meshes of 6, 16 and 20. The results indicated that with increase in the weight level of residue more moisture was retained by the soil, and the size of the soil particles had lower effect on water holding capacity of the soils. The mechanical strength of the soil decreased with increase in both weight proportion and the particle size of the residues. The length of the stems and roots did not show any definite trend with the variations in factors. In this research, the change in moisture content of the soil was expressed as a linear function of time and residues weight proportionas well as the particle size. The resulting model was well fitted to the experimental data (R2>0.98).

The use of plant fibers in producing different industrial products has attracted the attention of many researchers. Plant fibers, in comparison with industrial ones, are degraded faster in nature and are more environments friendly. One of the major conventional uses of plant fibers is the production of traditional ropes which are subjected to tensile forces. However, the traditional ropes bear rough surfaces, working with which becomes a difficult task. By reducing the lignin content of the fibers and their coverage them with polymeric materials, their surface roughness will be moderated. In this research, mechanical properties of the ropes, prepared from either raw or polymeric treated fibers, including tensile strength, modulus of elasticity and strain under tensile loads were assessed. The distributions of stress and strain within the ropes were modeled in ANSYS using solid mechanical equations. The maximum tensile force supported by the ropes prepared from 10 single raw fibers was 172N which was increased to 400N by reducing their lignin content and while having them covered with PVA resin. Moduli of elasticity for these ropes were found out as 600 and 250 MPa, respectively. The distribution models for stress and strain within the ropes revealed that the rupture point occurred at a point with a distance of about 25% of the length of the rope, away from the fixed end of the rope. The practical tensile test indicated a verification of these findings too.

Active carbon is char derived from pyrolysis of organic materials. It has a high porosity level and is used to filter fluids. Many types of agricultural materials are used to produce active carbon. The trunk of the date palm, with its low density and high porosity, has great potential for producing active carbon. In this research, the bark was pyrolyzed at 450°C for 60 min to produce active carbon. The results indicated that 100 g of wood produced 30 g of active carbon. The density of the active carbon was 0.12 g/cm2 and its iodine number was 585 mg/g. The pyrolysis of the wood was studied using an analytical model and the coefficient of diffusion for volatile compounds leaving the wood was estimated to be 4.2 ×10-8 m2/s. The progress of the pyrolysis was modeled using the finite element method and showed the model was well fitted to the experimental data (R2 = 0.98). The finite element model was superior to the analytical model because it presented more details of the weight changes in the wood during pyrolysis.

During the past two decades the use of bioplastics, as a suitable alternative to petroleum-based plastics, has attracted researcher's attention to a great extent. In this study, the whole wheat flour and straw cellulose at different proportions were mixed with glycerol and bioplastics sheets were obtained by a press type molding machine. The mechanical properties of samples were examined on compositions prepared by whole wheat weight in three proportions of 70, 60 and 50% and the cellulose in three proportions 75, 70 and 65%. The tensile tests on the samples indicated that with lowering proportions of both flour and cellulose, the modulus of elasticity and tensile strength of the bioplastics dropped as well. The maximum modulus of elasticity achieved for the flour and cellulose compositions were 12.5,and 8.6 MPa, and the maximum tensile strengths were 878 and 202 kPa, respectively.The TGA tests indicated that the bioplastics prepared from whole wheat flour showed higher temperatures of thermal degradation. The activation energies calculated for the flour and cellulose bioplastics, as estimated by Arrhenius type equation, were 133.0 and 63.8 kJ/mol, respectively.

During the past decade, the use of plant fibers for reinforcing biocomposite material has attracted many researchers. The lignin content of the fibers reduces the mechanical properties of the resulting biocomposites, thus the lignin content is reduced by chemical treatments. In this research, the effective factors in the process of lignin reduction, including hydrogen peroxide and sodium hydroxide content, and temperature of the medium and the retention time, were optimized to prepare fiber with lowest amount of lignin and with highest tensile strength. The experiments were performed based on "central composite rotatable design" using four independent factors, each at five levels. A second degree polynomial was used to define a function relating the dependent and independent variables. The experimental data and the predicted data by the models were highly correlated (R2 <0. 98). The optimization results indicated that the optimized level for hydrogen peroxide and sodium hydroxide were 4. 5% and 5. 7%، wt. The optimum medium temperature and retention time were 41. 9ºC and 16. 8 h, respectively. At the optimized values of the independent variables, the lignin content and the tensile strength of the fibers were 10. 23% ww and 220. 08 MPa, respectively.

To study the potential of production of biogas, utilizing the wastes of rose distillation process, the wastes were mixed with cow manure at manure proportions of 5, 10, 15 and 20% and in temperatures at two levels of 35 and 45 °C. The treatments were carried out using a 2×4 factorial design (?=0.05). The volumes of produced gas and generated methane were recorded daily and modeled as functions of time, using three mathematical models; namely: Gompertz, Logistic and Richards. The experimental results indicated that the treatment with 20% cow manure and at 45?C yielded the maximum cumulative gas production equal to 0.4268 m3/ (kg VS), while containing 72% methane. The mass reduction of available volatile compounds in this treatment was 81%. In general, the treatments mixed with higher proportions of cow manure reached their maximum level of daily gas productions in shorter periods of time. The results of mathematical modeling of the process indicated that Gompertz and Logistic models better fitted the experimental data with an R2 of over 94%.

The lignocelluloses fibers are produced in nature and by various agricultural activities. These materials are used in textile, paper and agricultural industries. The lignin content of these fibers causes browning and brittleness in the products made from them. In industries, the fibers are treated by various chemical treatments to reduce their lignin and hemicellulose content, as these are the main hydrophobic factors. In this research, the date palm fibers were treated using 1) sodium hydroxide and 2) sodium hydroxide and hydrogen peroxide. The physical, mechanical and chemical properties of the treated fibers were compared with untreated fibers. The results indicated that the color of the treated fibers were lighter than the untreated fibers. The static friction of the two groups of treated fibers reduced by 29 and 60%, respectively. The diameters of the treated fibers were also reduced by about 22%. The mean ultimate tensile strengths of the treated fibers were 75.1 and 91.2 MPa. The chemical and FTIR analysis of the fibers indicated a significant reduction in the hemicellulose and lignin content of the treated fibers. The TGA test on the fibers showed the treated fibers had higher temperatures both for starting and end of degradation.

Part of the process of feed preparation or oil extraction for date pits is to soak the pits inwater. Soaking softens the pits and reduces the required milling energy. In this research, the effects of water temperature at 25°, 35°, 55° and 65°C on water absorption and grinding of the date pits was investigated. The water absorption curves indicated that the rate of absorption and the final moisture content of the pits increased as the water temperature increased. The final moisture content of the pits for these temperatures were 59%, 62%, 71% and 73% w.b., respectively. Modeling water absorption using analytical, Page and exponential models indicated that the three models showed good fit with the experimental data (R2>0.95). The best results were obtained using the Page model with R2 = 0.99. The results of grinding the pits indicted that the average diameter of the ground particles decreased as soaking time and temperature of the water increased. A logarithmic model was defined to express the diameter of the particles as a function of grinding time. The presented model fit well with the experimental data (R2>0.98).

During the past two decades the use of lignocellouse fibers in reinforcingcomposites has attracted much research activities. In the present work,date palm fiber was used for production of composites compatible withliving environment. The fibers were pre-treated chemically to remove impurities. Inorder to verify and compare the effectiveness of the pretreatment methods, lignin,ash, moisture adsorption, diameter and tensile strength of the raw and treated fiberswere considered in all determinations. Some chemical contents of the treated fiberswere also estimated by FTIR method. The heating characteristics of the fibers wereevaluated using simultaneous thermal analysis (SAT) technique. The treated fiberswere mixed with HDPE by mass proportions of 10, 20 and 30% of the fibers in twotypes of fine and coarse sizes. Composite flower pots were prepared from the formulationsby extrusion process. The mechanical properties of the composites includingtensile strength, modulus of elasticity, strain, and impact strength were measuredby standard ASTM methods. Statistical analysis of the data revealed that the treatedfibers had smaller diameters containing lower levels of lignin and ash though havingsignificantly higher tensile strength, heat resistance and moisture adsorption. Theresults also indicated that by increase in fibre size the tensile strength, modulus ofelasticity and moisture adsorption of the composites are increased and their strainand impact resistance are decreased. The composites prepared using fine fibersshowed higher tensile strength, modulus of elasticity and impact strength but theirmoisture adsorption and elongation were significantly lower.

After harvesting, pistachio nuts are generally kept in storage before being exported. During handling, the nuts are exposed to external forces that cause mechanical damage to them. The increase of the mechanical damage is a function of storage conditions, especially temperature. This research investigated the effect of storage temperature (25, 5, -5, -15°C), on the mechanical properties of pistachio kernels. The kernels werekept at the four storage temperatures for three months. Durability, impact, compression and comminution tests were then performed on the kernels. The statistical analysis of the data indicated that the negative temperatures had lower durability damage, but caused the kernels to become brittle, which increased impact damage. In the compression test, the modulus of elasticity of the kernels at 25, 5, -5, -15°C were64.17, 63.11, 37.70 and 26.56 MPa, respectively. This also indicated that the power required to cause biological yield in the kernels increased as storage temperature increased. The comminution test showed little difference in the distribution of broken kernels on different sieves.

Date fruit, containing a substantial amount of carbohydrates is considered as an important agricultural product in Iran. In this research, the objective was the use date fruit wastes to produce bioethanol. For better understanding of the fermentation process the changes in sugar content, as well as the amount of produced bioethanol and carbon dioxide were periodically measured and modeled while using different mathematical models. To conduct the experiments, water was added to date syrup with 75°Bx to be diluted to 20°Bx. For proper initiation of fermentation, S.Cereviea inoculums along with different nutritional compounds were added to the syrup. The fermentation was done at 30±1°C. Results indicated that the rate of changes had an increasing trend during the first 5 days of the process, while decreasing sharply for the next following 15 days. At the end of the process, the brix of the syrup dropped to near 8.0°Bx. The bioethanol resulted from fermentation of the syrup was 72 g per liter. The produced carbon dioxide was figured out as 70 mL/L. A comparison of the applied models indicated that all the investigated models fitted well to the experimental data, but the decaying exponential model with an R2 =0.99 was the most fitted for sugar reduction modeling while the Gompertz model (R2 > 0.98) was found out as the most suitable the best for bioethanol and carbon dioxide production.

During the past two decades the use of lignocelluloses fiber for biocomposite production has been the focus of many investigations. In order to reduce the lignin and hemicelluloses of the crude fibers, the fibers are often treated with different chemicals. The chemical treatments should enhance the physical and mechanical properties of the fibers and increase the adhesive force between the matrix and the biofibers. In this research, NaOH, KOH, and HCl were used in different concentrations for purifying date tree fibers. The percentage of pure fiber, ash content, coefficient of friction, diameter, and the tensile strength of the fiber prepared by different treatments were determined and statistically compared. The Weibull distribution model was used to investigate the variation in tensile strength of the fibers. The results indicated that the purification methods decreased the lignin content between 20 to 50, the ash content from 37 to 75% and the diameter of the fibers between 37 to 62%. The tensile strength of the fibers increased between 15 to 60%. The Weibull analysis of the data indicated that the distribution of tensile strength in purified fibers was more uniform than the untreated fibers.