In this study, Rice straw as an abundant and inexpensive raw material was selected to produce soda - anthraquinone pulp. Nano cellulose fiber from Rice straw, cationic starch and cationic ployacrylamide were added to improve the pulp strength. Cationized nano cellulose fibers suspension was mixed with Rice straw pulp at three levels (2, 5 and 10 percent) and mixed for five minutes. Starch and polyacrylamide as cationic chemicals were used to stabilize nano fiber cellulose at 1.5% and 0.2% (based on oven dried pulp) respectively. The result showed that there is a linear change between stock drainage time and paper strengths containing nano cellulose fiber. Tensile and burst strength indices were improved at 18.66% and 18.12% respectively by adding 10% of nano cellulose fiber to suspension treated with cationic polyacrylamide. Furthermore, the two indices increased by 19.35% and 19.24% by adding the maximum amount of nano cellulose fiber (10%) to pulp suspension cationized with cationic starch, respectively. The overall results indicated that nano cellulose fiber had a positive significant effect on the refined and unrefined pulp strengths of Rice straw.

CEHEP and HEP sequences were used for bleaching of Rice straw organosolv pulps and the effects of these sequences were investigated on optical (brightness and opacity) and mechanical (tear index, burst index and breaking length) properties of produced paper sheets. Despite of the significant reduction in mechanical properties, brightness was increased so that it was suitable for writing and printing paper. CEHEP sequence had more increment on brightness and more decrement on mechanical properties than the HEP sequence. The catalytic soda organosolv pulping was used for the pulp production (delignification) from Rice straw via batch process at high temperatures and high pressures. The catalytic pulping of Rice straw was performed in ethanol-water mixtures (50 and 65% w/w) at various cooking times (150 and 180 min). The ratio of cooking liquor to dry mass of Rice straw was 10:1 and the catalyst (soda) was 1(%) dry mass of Rice straw.

In this study, the effect of alkali treatment on the mechanical properties of Rice straw flour-polypropylene composite was investigated. Rice straw flour (40 mesh) was treated with hydroxide sodium 5 and 10% in two times, once for 45 and another time for90 min respectively. The composites were made from Rice straw flour as filler (30%), polypropylene (65%) as matrix and maleic anhydride (5%) as coupling agent. In order to blend the raw materials of internal mixer a Haake HBI system 90 machines and make standard samples testing an injection molding were applied. The results of this study suggest that treatment of Rice straw flour with alkali 5% concentration increases tensile modulus and impact strength which increase with time prolongation. However, treatment of Rice straw flour with alkali 10% concentration decreases these properties even with the increasing of time. Furthermore, the increasing of alkali concentration and treatment time resulted in an increase in the tensile strength of composites.

In this study chemical method of dissolution-precipitation was applied to produce amorphous silica nanoparticles from Rice straw ash (RSA), the waste material of Rice cultivation. The morphology, particle size, structure and area of specific surface of synthesized amorphous silica nanoparticles were evaluated using transmission electron microscopy (TEM), X-ray diffraction analysis (XRD) and analysis technique for the measurement of the specific surface area of materials (BET). In addition, chemical composition of RSA, used and the synthesized silica nanoparticles was studied by X-ray fluorescence (XRF) spectroscopy. The effects of sodium hydroxide concentration, precipitation reaction temperature and precipitation reaction duration on the area of a specific surface were determined through Design of Experiments (DOE) Technique. Results depicted that silica nanoparticles with particle size of 10-15 nanometers were successfully synthesized. Average area of a specific surface and purity were 327 m2/g and 99.5% respectively. The interactive influence of temperature and duration having the highest effect on the average area of the specific surface.

Annually huge amount of un-used Rice straw after Rice harvesting were burned due to no specific utilization. Whereas, based on the biorefinery concept there is possibility to use these agricultural residues for production of high value added products. So, this study was aimed to extract the silica from the Rice straw (Oryza Sativa var Indica) as one of the important agro-industrial residues in the country and its capabilities for production of silica nanostructures based on the mentioned concept. After washing, drying and grinding of Rice straw samples, some of them were separately leached with a hydrochloric acid and some ones with a sulphuric acid at concentration of 0. 5 M for 30 min with constant stirring. Afterwards, the silica content of acid-leached and un-leached Rice straw samples was measured in a muffle furnace with varying temperatures at 500, 600, 700, 800 and 900° C for 2 h. The results were obtained from Energy Dispersive X-ray (EDX) and X-ray Fluorescence (XRF) demonstrated the maximum presence of silica into the Rice straw ash. Two of aforementioned spectroscopy methods explored the higher content and purity of acid-leached Rice straw samples in comparison to un-leached Rice straw ones. The Field Emission Scanning Electron Microscopy (FESEM) images demonstrated that the prepared silica nanostructures had a spherical shape and their average particle sizes were 30 nanometer for un-leached Rice straw samples and less than 12 nanometer for acid-leached ones.

Rice straw is among the important lignocellulose residues in Iran and the world. In this research, Rice straw as renewable lignocellulosic materials were used to produce Nano-structural lignocellulosic aerogel. For this purpose, Rice straw powder was first pre-treated in sodium hydroxide aqueous solution and the resulting gel mixture was transformed into physically bonded lignocellulosic porous and ultra-lightweight aerogel through consecutive processes including freezing-thawing, solvent exchange and freeze-drying. The product properties including apparent density and total porosity were determined, and other physical and chemical properties were evaluated using SEM, FTIR, XRD, nitrogen absorption (BET) and DSC methods. The results showed that a significant portion of the Rice straw compounds were dissolved in aqueous alkali solution and removed during the subsequent stages of aerogel production. The resulting aerogel showed a nano dimensional structure composed of particles and interconnected nanofibers, which had a great chemical and physical difference from the original Rice straw.

In this study, composites were prepared from unsaturated polyester-Rice straw at different levels (5, 10, 15 % by wt.) and mechanical properties (tensile, bending and impact) were measured. The effects of silane as a coupling agent on mechanical properties of composites were investigated. The results show that a composite has better mechanical properties compared to polyester without Rice straw. Also, coupling agent has no effect on mechanical properties. The composite containing 15% Rice straw particles has better mechanical properties (tensile, bending and impact strength) than other composites. The composite containing 10% of Rice straw particles has better bending and tensile modulus than other composites. The density was decreased with increasing of Rice straw.

Dimethyl formamide (DMF) as an organic solvent with special properties (such as pulping at mild condition and high selectivity) was used for pulping of Rice straw. The most important role of DMF is inhibiting from degradation of cellulose chains during pulping process.Pulping was conducted following a central composite design using three level factorial plans (cooking temperature 190~210 oC, cooking time 120~180 min and DMF ratio 30~70%). Responses of pulping were analyzed using statistical software MINITAB and the models of each variable were developed the optimum values of the variables: pulping yield 65. 64%, holocellulose 75.19 %, beta cellulose 7.4 %, degree of freeness 363 ml and liquor suspended solids 2.47%. Results showed that acceptable properties of pulp could be achieved at 200oC, 150 min and 50 % DMF.