جستجوی مقالات مرتبط با کلیدواژه "روش سطح پاسخ" در نشریات گروه "جنگلداری"

Densification of biomass materials such as briquette improves the management properties of materials for transportation, storage, and so on. This study aimed to determine the optimal conditions of the briquette production process using a hydraulic press from the combination of bagasse and walnut shell using response surface methodology. The effects of independent variables including bagasse particle size (PS), process temperature (PT), bagasse moisture content (MC), and the composition ratio percentage of the walnut shell to bagasse (CR) were evaluated at three levels on the response variables of the density and tensile strength. The calorific value of the briquette was determined through validated linear and nonlinear equations of the high heat value using the proximate analysis of volatiles, fixed carbon, and ash. The results showed that by decreasing the moisture content of bagasse particles, the density and tensile strength of the briquette increased. Adding walnut shell particles to the briquette produced with the size of fine particles reduces tensile strength. The briquette production significantly reduced the percentage of volatile materials relative to their biomass and increased the percentage of fixed carbon. The calorific value of the raw material sample relative to the briquette produced increased from 16 to 22 MJ/kg. The optimal values of the density and tensile strength of briquettes were equal to 867.847 kg/m3 and 1.356 MPa, respectively at the CR of 5%, PS less than 1.18 mm, MC content of 7%, and PT of 360 °C. At this condition, the calorific value of 22 MJ/kg was obtained.

Recently, paper recycling has been significantly increased for several reasons such as environmental concerns and coast-saving. Ultrasound is used in the paper industry at various stages. Deinking has an important and determinant role in the recycling of newspapers. The aim of this study was to conduct the process of deinking in order to improve the optical properties of newspaper as a cellulosic material by using ultrasonic pretreatment combined with chemical method. The hydrogen peroxide, sodium hydroxide, sodium silicate, poly sorbent 80, and Diethylenetriaminepentaacetic acid were utilized for chemical deinking. Effect of important parameters of ultrasonic pretreatments such as ultrasonic bath temperature and sonication time on deinking efficiency was investigated by using response surface methodology based on central composite design. After chemical treatment of obtained recycled pulps, maximum and minimum efficiency of deinking for hand sheet papers with 60 gsm grammage according to standard T 205om-88 were calculated about 88 and 45% respectively. Surface and 3D curves were created to show the interactions of the independent variables with response one (deinking efficiency). Based on the ANOVA test, the quadratic model presented the best explanation of variables interaction. Ultrasonic pretreatments increased brightness and decreased opacity of obtained recycled newspaper compared to the control ones. According to the statistical analysis, the effect of each variable on deinking efficiency was significant and sonication time was introduced as the most effective factor. In addition, 47 oC ultrasonic bath temperature and 31 min sonication time were determined as the optimal conditions for maximum deinking efficiency (86.95%).

In this study, it was evaluated the effect of almond shell powder as extender on the mechanical properties of the medium density fiberboards manufactured from bagasse fibers. Almond shell powder/UF resin ratio at five level (0:100, 5:95, 10:90, 15:85 and 20:80), paraffin content at five levels (0, 0.5, 1, 1.5 and 2%), press temperature at five levels (140, 150, 160, 170 and 180 C) and press time at five levels (5, 6, 7, 8, 9 min) were selected as production variables. The mechanical properties (modulus of rupture (MOR), modulus of elasticity (MOE) and internal bonding strength (IB)) of panels were tested and the data was analyzed based on Response surface methodology (RSM). Results showed almond shell powder, significantly influenced the mechanical properties of panels. They in general decreased with increasing almond shell powder content. Although internal bonding of all panels showed a decrease with increasing the extender, but internal bonding strength of all panels were more than recommended standards (EN). Besides, results of this analysis showed during high press temperature, the extender was better efficiency. In general, wax had a negligible reducer effect on mechanical properties. According to RSM analyses, the best results were found on the panels that have been made at 160° C press temperature and 6 min pressing time.