Comparison between two different pretreatment technologies of rice straw fibers prior to fiberboard manufacturing: Twin-screw extrusion and digestion plus defibration

The present work compares two different pretreatment technologies, i.e. twin-screw extrusion, and steaming digestion plus defibration, for producing a thermo-mechanical pulp from rice straw for fiberboard manufacturing. Five liquid/solid ratios from 0.43 to 1.02 were tested for twin-screw extrusion pretreatment, while liquid/solid ratios from 4 to 6 were used for digestion pretreatment. Energy consumption, and characteristics of the extrudates (twin-screw extrusion) and pulps (digestion) (including fiber morphology, chemical composition, thermal properties, apparent and tapped densities, as well as color) were the analyzed parameters for the resulting lignocellulosic fibers. The results showed that liquid/solid ratio had influence on energy consumption of the equipment for both defibrating methods For the twin-screw extrusion method, a lower liquid/solid ratio required more energy while for the digestion plus defibration the effect was the opposite. The corresponding total specific energy consumption ranged from 0.668 kW h/kg to 0.946 kW h/kg dry matter for twin-screw extrusion, and from 6.176 kW h/kg to 8.52 kW h/kg dry matter for digestion plus defibration. Thus, the pulping method consumed about nine times more energy than that of the twin-screw extrusion. In addition, for twin-screw extrusion, the liquid/solid ratio did not have a substantial effect on fiber characteristics with similar chemical compositions and thermal properties. For twin-screw extrusion, the energy consumption was 37% reduced when the liquid/solid ratio was increased from 0.43 to 1.02. Instead, for digestion plus defibration, the energy increase was 38% when the liquid/solid ratio increased from 4 to 6

Production of fiberboard from rice straw thermomechanical extrudates by thermopressing : influence of fiber morphology, water and lignin content

The objective of this study was to investigate the influence of fiber morphology and molding parameters on the mechanical and physical properties of fiberboards made from rice straw. The rice straw was thermomechanically treated with a twin-screw extruder. Three parameters were investigated: the amount of water added at molding (0–20%), lignin content (0–25%), and the liquid/solid ratio used for extrudate production (0.33–1.07). A Doehlert experimental design was used to evaluate the effects of these factors on fiberboard properties. A liquid/solid ratio of 0.4 at extrudate production, the addition of 5% water at molding, and a lignin content of 8.9% were found to be optimal for bending properties. The fiberboard produced in these conditions had a density of 1414 kg/m3 (i.e. the densest board). Maximum flexural strength and elastic modulus were 50.3 MPa and 8.6 GPa, respectively. A thickness swelling of 23.6% and 17.6% water absorption were observed. The statistical analysis suggested that a good compromise between density and flexural properties could be obtained with the addition of 0% water, a lignin content of 25% and a liquid/solid ratio of 0.33 at extrudate production. Polynomial models suggested that the fiberboards produced in such conditions would have a maximum flexural strength of 50 MPa, an elastic modulus of 6.0 GPa, a density of 1102 kg/m3, and a thickness swelling of 24%

Feasibility of incorporating treated lignin and cellulose nanofiber in fiberboards made from corn stalk and rice straw

Agricultural waste is of particularly interest due to abudant, cheap, widely available worldwide and renewable material. It represent a good option for wood sources substitution, containing similar in chemical and physical characteristics. The present Doctoral Thesis studies the possibility of substituting wood sources by crop residues and replacing synthetic binders by natural adhesives in fiberboard production. Corn and rice biomass were selected as raw materials, followed by thermo-mechanical pulping (TMP) pretreatment. Fiberboards made of TMP of both crop residues without any binder presented lower mechanical properties than commercial ones (which contained synthetic binder). In term of physical properties, lower water absorption and thickness swelling were found for the fiberboards made of crop residues than for the commercial one. Overall, the present study shows a more sustainable and effective way of producing cellulose-based fiberboards without aid of any synthetic binder, contributing thus to both technical and environmental aspects of fiberboard manufacturingEls residus agrícoles tenen un gran interès per ser un material abundant , barat, àmpliament disponible a tot el món i renovable. Es tracta d'una bona opció per substituir la fusta, i presenta característiques físiques i químiques similars a aquesta. La present tesi doctoral estudia la possibilitat de substituir la fusta i els aglutinants sintètics per residus de cultius i adhesius naturals respectivament en la producció panell de fibres. La biomassa de blat de moro i arròs sotmesa a un tractament termomecànic (TMP)es va seleccionar com a matèria primera. El panell de fibra resultant d'ambdós residus sense cap tipus d'aglutinant presentaven propietats mecàniques més baixes que els panells comercials (que contenien un lligant sintètic). Respecte a les propietats físiques, es va observar un augment de volum i espessor al absorbir aigua menors en el panell de fibres naturals que no pas en els comercials. En general, el present estudi mostra una forma més sostenible i efectiva de produir panells de fibra a base de cel·lulosa sense utilitzar aglutinant sintètic, fet que contribueix a la millora d’aspectes tècnics i ambientals en el procés de fabricació dels panells de fibr

Feasibility of incorporating treated lignin and cellulose nanofiber in fiberboards made from corn stalk and rice straw

Agricultural waste is of particularly interest due to abudant, cheap, widely available worldwide and renewable material. It represent a good option for wood sources substitution, containing similar in chemical and physical characteristics. The present Doctoral Thesis studies the possibility of substituting wood sources by crop residues and replacing synthetic binders by natural adhesives in fiberboard production. Corn and rice biomass were selected as raw materials, followed by thermo-mechanical pulping (TMP) pretreatment. Fiberboards made of TMP of both crop residues without any binder presented lower mechanical properties than commercial ones (which contained synthetic binder). In term of physical properties, lower water absorption and thickness swelling were found for the fiberboards made of crop residues than for the commercial one. Overall, the present study shows a more sustainable and effective way of producing cellulose-based fiberboards without aid of any synthetic binder, contributing thus to both technical and environmental aspects of fiberboard manufacturingEls residus agrícoles tenen un gran interès per ser un material abundant , barat, àmpliament disponible a tot el món i renovable. Es tracta d'una bona opció per substituir la fusta, i presenta característiques físiques i químiques similars a aquesta. La present tesi doctoral estudia la possibilitat de substituir la fusta i els aglutinants sintètics per residus de cultius i adhesius naturals respectivament en la producció panell de fibres. La biomassa de blat de moro i arròs sotmesa a un tractament termomecànic (TMP)es va seleccionar com a matèria primera. El panell de fibra resultant d'ambdós residus sense cap tipus d'aglutinant presentaven propietats mecàniques més baixes que els panells comercials (que contenien un lligant sintètic). Respecte a les propietats físiques, es va observar un augment de volum i espessor al absorbir aigua menors en el panell de fibres naturals que no pas en els comercials. En general, el present estudi mostra una forma més sostenible i efectiva de produir panells de fibra a base de cel·lulosa sense utilitzar aglutinant sintètic, fet que contribueix a la millora d’aspectes tècnics i ambientals en el procés de fabricació dels panells de fibr

Assessing Land Use and Land Cover (LULC) Change and Factors Affecting Agricultural Land: Case Study in Battambang Province, Cambodia

This study analyzed land use and land cover (LULC) change from 1998 to 2018 in Battambang, Cambodia, and determined factors and constraints affecting agricultural production. Landsat satellite images in 1998, 2008, and 2018 were used to identify the changes in LULC. In combination, a social survey was conducted in August 2021 using purposive sampling, selecting a total sample of 200 from two wealth classes: the poor (65) and the better off (135) based on the Cambodia poverty assessment by the World Bank, from uplands to lowlands of Battambang Province, Cambodia. Household characteristics, farm size, and constraints were compared between the classes. T-tests, the analysis of variance (ANOVA), and Likert scale analysis were adopted using the R Program and RStudio, while Pearson's correlation test was used to determine the factors affecting agricultural land. The results show that between 1998 and 2018, the forest cover decreased by 79%. In contrast, agricultural land expansion was the highest (54%). The average household size and age of the respondents were 5.0 persons/household and 50.1 years, respectively. Of all the interviewees, about 80% attended no higher than primary school. The total farm size of the better-off (7.0 ha/household) was larger than that of the poor (5.2 ha/household). The population growth, machinery use, and improved infrastructure were found to be positive and strongly related to agricultural land use. The highest constraints of the poor and the better-off households were the same: chemical fertilizer use. Then, drought and flooding were also challenges for all. In terms of land, credit, and labor, they were not the main constraints. Thus, it is recommended that the involvement of interdisciplinary stakeholders and policy frameworks is really important from both biophysical and social perspectives

Assessment of Land Use and Land Cover Changes on Soil Erosion Using Remote Sensing, GIS and RUSLE Model: A Case Study of Battambang Province, Cambodia

Soil erosion causes land degradation which negatively impacts not only natural resources but also livelihoods of people due to low agricultural productivity. Cambodia is prone to soil erosion due to poor agricultural practices. In this research we use Battambang province as a case study to quantify impact of land use and land cover change (LULC) on soil erosion. This study assessed the impact from LULC changes to soil erosion. LULC change maps were analyzed based on Landsat satellite imagery of 1998, 2008, and 2018, computed in QGIS 6.2.9, while the soil erosion loss was estimated by the integration of remote sensing, GIS tools, and Revised Universal Soil Loss Equation (RUSLE) model. The results showed that the area of agricultural land of Battambang province significantly increased from 44.50% in 1998 to 61.11% in 2008 and 68.40% in 2018. The forest cover significantly decreased from 29.82% in 1998 to 6.18% in 2018. Various soil erosion factors were estimated using LULC and slope. Based on that, the mean soil loss was 2.92 t/ha.yr in 1998, 4.20 t/ha.yr in 2008, and 4.98 t/ha.yr in 2018. Whereas the total annual soil loss was 3.49 million tons in 1998, 5.03 million tons in 2008, and 5.93 million tons in 2018. The annual soil loss at the agricultural land dramatically increased from 190,9347.9 tons (54%) in 1998 to 3,543,659 tons (70.43%) in 2008 and to 4,267,439 tons (71.91%) in 2018 due to agricultural land expansion and agricultural practices. These losses were directly correlated with LULC, especially agricultural land expansion and forest cover decline. Our results highlight the need to develop appropriate land use and crop management practices to decrease land degradation and soil erosion. These data are useful to bring about public awareness of land degradation and alert local citizens, researchers, policy makers, and actors towards land rehabilitation to bring the area of land back to a state which is safe for increasing biodiversity and agricultural productivity. Measures to reduce or prevent soil erosion and the use of conservation agriculture practices, along with water and soil conservation, management, agroforestry practices, vegetation cover restoration, the creation of slope terraces, and the use of direct sowing mulch-based cropping systems should be considered

Production of fiberboard from rice straw thermomechanical extrudates by thermopressing: influence of fiber morphology, water and lignin content

The objective of this study was to investigate the influence of fiber morphology and molding parameters on the mechanical and physical properties of fiberboards made from rice straw. The rice straw was thermomechanically treated with a twinscrew extruder. Three parameters were investigated: the amount of water added at molding (0-20%), lignin content (0-25%), and the liquid/solid ratio used for extrudate production (0.33-1.07). A Doehlert experimental design was used to evaluate the effects of these factors on fiberboard properties. A liquid/solid ratio of 0.4 at extrudate production, the addition of 5% water at molding, and a lignin content of 8.9% were found to be optimal for bending properties. The fiberboard produced in these conditions had a density of 1414 kg/m3 (i.e. the densest board). Maximum flexural strength and elastic modulus were 50.3 MPa and 8.6 GPa, respectively. A thickness swelling of 23.6% and 17.6% water absorption were observed. The statistical analysis suggested that a good compromise between density and flexural properties could be obtained with the addition of 0% water, a lignin content of 25% and a liquid/solid ratio of 0.33 at extrudate production. Polynomial models suggested that the fiberboards produced in such conditions would have a maximum flexural strength of 50 MPa, an elastic modulus of 6.0 GPa, a density of 1102 kg/m3 , and a thickness swelling of 24

Fiberboards Made from Corn Stalk Thermomechanical Pulp and Kraft Lignin as a Green Adhesive

The feasibility of incorporating purified kraft lignin, at different concentrations ranging from 5 to 29%, into fiberboards made from corn residues was studied. The lignin was obtained from black liquor, which is a residue of the paper industry. Corn stalk raw material and its thermomechanically produced fiber were characterized in terms of their chemical composition. The physical and mechanical properties of the resulting fiberboards were evaluated. The fiberboards produced following a wet process had good mechanical and water resistance properties that satisfied the requirements of the relevant standards. In addition, a Life Cycle Thinking (LCT) approach suggested that lignin-based fiberboards are environmentally preferable than those based on thermosetting resins

Fiberboards Made from Corn Stalk Thermomechanical Pulp and Kraft Lignin as a Green Adhesive

The feasibility of incorporating purified kraft lignin, at different concentrations ranging from 5 to 29%, into fiberboards made from corn residues was studied. The lignin was obtained from black liquor, which is a residue of the paper industry. Corn stalk raw material and its thermomechanically produced fiber were characterized in terms of their chemical composition. The physical and mechanical properties of the resulting fiberboards were evaluated. The fiberboards produced following a wet process had good mechanical and water resistance properties that satisfied the requirements of the relevant standards. In addition, a Life Cycle Thinking (LCT) approach suggested that lignin-based fiberboards are environmentally preferable than those based on thermosetting resin