This study was conducted to examine a new method for determining feedstuff dry matter degradation kinetics. For this purpose, an assembly of a one-liter volumetric flask, pH meter, gas output valve, buffer solution buffer and shaker in a water bath was employed. For each trial, 800ml of unfiltered rumen fluid was collected. Comparisons were made between the new method, in situ and in vitro data. In nylon bag technique, feed samples consisting of alfalfa, wheat straw and a mixture of both in different ratios were incubated for 0, 24, 48 and 72h in the rumen of four cannulated varamini rams as well as in the artificial rumen. Dry matter degradability parameters were estimated through Naway program. The new method's results were compared with in situ and in vitro results. in situ-in vitro results were different from in situ and there were significant differences between in vitro results (P<0.05). But in situ-in vitro feedstuff degradation means were close to in situ, rather than in vitro results (r2=0.94vs. r2=0.91).The newly proposed procedure can be recommended for estimating feedstuff dry matter degradation kinetics.

Kinetics of thermal degradation of polylactic acid (PLA), a biodegradable and bioabsorbable polyester, under atmosphere of inert gas has been investigated. Isothermal and dynamic heating techniques of thermogravimetry have been used in this study. The weight loss data versus time were recorded at the temperatures of 180, 200, 220, 240, 260 and 280° C, in the isothermal heating experiments. Also, the weight loss data versus temperature were collected in dynamic heating runs conducted with the heating rates of 10, 15, 20 and 25 °C/min. Two kinetic models, one for isothermal and the other for dynamic heating experiments were utilized to fit the data. It is elucidated that the thermal degradation of PLA is a single stage process within the range 0-30% of weight loss, having activation energy of 21-23 kJ/mol.

Considering the application of phenolic resins in ablative heat shields, studying the thermal degradation kinetics and effective parameters on their degradation mechanism is very important. In this work, thermal degradation of two grades of phenolic resins was investigated. The effects of resin type, experimental environment and heating rate on degradation mechanism have been investigated by thermal gravimetry analysis (TGA). The experimental results indicate that the modification of phenolic resin structure increases its char performance in ablation process. Presence of oxygen in environment increases thermal oxidation and causing oxidation of char residue of thermal degradation of resin. The results of multi-heating rate experiments show that the calculated maximum thermal decomposition temperatures at the heating rate of 3000°C/min will occur at 469°C. Kinetics parameters of thermal degradation reaction of resin (A, E and n) are determined by Ozawa model and they are in the order 1.5, 72kJ/mol and 2.1 x 106/min, respectively. Results of theoretical thermal degradation model, which was determined by these parameters, show the good agreement with the experimental results.

The potential of various organisms to metabolize organic compounds has been observed to be a potentially effective means in disposing of hazardous and toxic wastes. Phenols and their compounds have long been recognized as one of the most recalcitrant and persistent organic chemicals in the environment. The bioremediation potential of an indigenous Pseudomonas fluorescence was studied in batch culture using synthetic phenol in water in the concentration range of (100 –500) mg/L as a model limiting substrate. The effect of initial phenol concentration on the degradation process was investigated. Phenol was completely degraded at different cultivation times for the different initial phenol concentrations. Increasing the initial phenol concentration from 100 mg/L to 500 mg/L increased the lag phase from 0 to 66 h and correspondingly prolonged the degradation process from 84 h to 354 h. There was decrease in biodegradation rate as initial phenol concentration increased. Fitting data into Monod kinetic model showed the inhibition effect of phenol The kinetic parameters have been estimated up to initial phenol concentration of 500 mg/L. The rsmax decreased and Ks increased with higher concentration of phenol. The rsmax has been found to be a strong function of initial phenol concentration. The culture followed substrate inhibition kinetics and the specific phenol consumption rates were fitted to Haldane, Yano and Koga, Aiba et al., Teissier and Webb models. Between the five inhibition models, the Haldane model was found to give the best fit. Therefore, the biokinetic constants estimated using these models showed good potential of the Pseudomonas fluorescence and the possibility of using it in bioremediation of phenol waste effluents.

The current research was done to investigate the removal of Alizarin in the heat-activated sulfate radical-based advanced oxidation process in the batch system. The removal efficiency was evaluated based on the change in operating parameters, including pH (3-10), process temperature (50-80 °C), oxidant/pollutant molar ratio (20/1-80/1), and initial pollutant concentration (25-150 mg/L). From the results, the Alizarin oxidation was almost pH independent and the final removal rate was about 90% in all experiment pHs. The maximum decolorization efficiency of about 95% was achieved when the process temperature reached 80 °C, along with the activation energy of +134. 7 kJ/mol, which indicated the endothermic oxidation process. Moreover, the Alizarin removal was 94% at an initial concentration of 25 mg/L and a maximum oxidant per pollutant molar ratio of 80, and it fell to 24% as the initial concentration rose to 150 mg/L. Density Functional Theory (DFT) calculation was employed to identify the degradation mechanism of Alizarin, which revealed that the molecule has a high electron-accepting ability with significant reactivity. The effect of different oxidants was investigated, and the results show that more COD removal was observed when persulfate was used as an oxidant compared to hydrogen peroxide.