Advanced Materials Research Vols. 236-238

Abstract: A instant air dissolution flotation method was used to harvest microalgal cells from culture to evaluate its feasibility. Effects of microalgae cell density, coagulant dosage, flocculant dosage, surfactant dosage and duration of air dissolution on recovery rate were studied by orthogonal experiment. The results show that the optimal recovery rate reaches 89.57% under one of the test combination conditions. The factors can be ordered by coagulant dosage, cell density, flocculant dosage, air dissolution duration and surfactant dosage according to their effect degree on recovery rate, and coagulant dosage, cell density were the marked factors when confidence level was given as 90%. Under test conditions, recovery rate rides up when the coagulant dosage increase, and the optimal dose of flocculant appears at 20 mg·L^-1. As seawater medium contains salts which own the similar fuction like surfactant, surfactant do not affect the recovery rate significantly. The time of air dissolution should not be too long, a 2-second duration is enough to providing dissolved air, and the recovery rate may reduce because of the disturbance induced by the redundant air.

Abstract: The micro-emulsion fuels were prepared with complex surfactant, and the effects of temperature on the stability of these fuels were investigated. The engine performance and the emissions were studied when the engine was fueled with diesel and micro-emulsion diesel respectively. Results showed that when the engine was fueled with micro-emulsion diesel, the NO_X and smoke emissions were decreased obviously and HC and CO emissions were increased slightly. Discounting of surfactant and water, the specific fuel consumption of micro-emulsion diesel was lower than those of diesel under any load at the speed of 2900r/min.

Abstract: In this study, Biosorption of hexavalent chromium ions from aqueous solution by using biomass of Aspergillus niger was investigated. Different parameters such as initial pH, biosorbent amount, contact time and temperature were explored. The biosorption of Cr (VI) ions was highly pH dependent and the optimum pH for biosorption of Cr (VI) ions was found to be 2.0. Biosorption capacity of Cr (VI) ions decreased with increased biosorbent dosage. The biosorption equilibrium was established in about 120min of contact time. Equilibrium uptake of Cr (VI) ions onto biomass increased from 12.57 mg/g at 20°C to 19.48 mg/g at 40 °C for 20mg/L Cr (VI) ions concentration. The biosorption process followed the pseudo-second order kinetic model and the correlation coefficients from the pseudo-second order model were all higher than 0.997 in all studied temperatures. These results suggest that the biomass of Aspergillus niger is a promising biosorbent for removal of chromium (VI) ions from the wastewater.

Abstract: The volatility has been studied since it influences the ignition quality of the fuels in a compression ignition engine. The chemical composition of -10# petrodiesel (-10PD) and rapeseed biodiesel (RME) was analyzed by gas chromatography-mass spectrometry (GC-MS). Volatility of -10PD and RME was studied by thermogravimetry (TG) and liquid volatile theory. Volatile index V was put forward for describing -10PD/RME volatility. A good correlation model was proposed for calculate the -10PD/RME volatility by RME blending ratio. The study showed that -10PD was mainly composed of alkanes: C8-C26. RME was mainly composed of saturated fatty acid methyl esters (SFAME): C14:0-C24:0, unsaturated fatty acid methyl esters (UFAME): C16:1-C22:1, C18:2 and C18:3. The mass fraction of SFAME and UFAME was 14.69% and 83.40%, respectively. RME is considerably more volatile in comparison to -10PD. The -10PD/RME volatility has relation to RME blending ratio. The volatility of B0-B20 is very close to -10PD. The volatility of B20-B100 is better with increasing the RME blending ratio.

Abstract: The chemical compositions of biodiesel derived from palm (PME) were analyzed by gas chromatography-mass spectrometry (GC-MS). The cold flow properties of PME were studied by multifunctional low temperature tester, differential scanning calorimetry (DSC) and solution crystallization theory. Three approaches for improving cold flow properties of PME were put forward: crystallization fractionation, blending with winter petrodiesel and treating with cold flow improver (CFI) additives. A good correlation model was proposed for prediction cold filter plugging point (CFPP) by winter petrodiesel blending ratio. The study shows that the PME was mainly composed of saturated fatty acid methyl esters (SFAME): C14:0-C24:0 and unsaturated fatty acid methyl esters (UFAME): C16:1-C22:1, C18:2 and C18:3. The mass fraction of SFAME and UFAME was 35.86% and 62.83%, respectively. The CFPP of PME was 8°C. Crystallization fractionation and blending with -10 petrodiesel (-10PD) decreased the CFPP to 0 and -12°C, respectively. Treating with CFI additives (volume fraction ≤ 1.5%) decreased the CFPP of PME and PME/-10PD to 2 and -26°C, respectively. This study has effectively improved cold flow properties of PME and provided theoretical support for using PME during cold weather.

Abstract: In this study we used 1-allyl-3-methyl imidazole formate ([Amim][HCOO]) as ionic liquid to pre-treat the cellulose and determined the rate of polymerization and enzymatic hydrolysis. The results showed that pretreatment with ([Amim][HCOO]) significantly decreased the cellulose polymerization. As the pretreatment temperature went up, the enzymatic hydrolysis rate was first increased and then decreased. The maximal enzymatic hydrolysis rate was achieved when the pretreatment temperature was 90°C. Under the ultrasonic condition, the initial rate of enzymatic hydrolysis for the ionic liquid-treated cellulose was up to 11.10 gL^-1h^-1, which was 33% increase compared to the untreated cellulose. Scanning Electronic Microscopy (SEM) and Fourier Transform Infrared-Raman Spectroscop (FT-IR) analysis showed that ionic liquid- treated cellulose started to depolymerize. In addition, the crystallinity of the cellulose was significantly decreased after pretreatment with ionic liquid.

Abstract: This study demonstrates sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) for robust bioconversion of corn stalks. With only about 3% sodium bisulfite charge on corn stalks and 30 min pretreatment at temperature 180°C, SPORL can achieve near complete cellulose conversion to glucose in 48h enzymatic hydrolysis. Sulfuric acid charge has great effect on SPORL pretreatment. Enzymatic cellulose conversion of substrate increased with the increase in acid charge under the studied conditions. Bisulfite with different counter-ions can be used in the SPORL. Magnesium as counter ion was found to be more effective on enzymatic hydrolysis of substrate than sodium or ammonium.

Abstract: A self-designed constant temperature fermenter was manufactured and used for this study. Dry anaerobic fermentation experiments were conducted with sugarcane leaf residue as raw material. With the C/N ratio being 25:1, various total solids concentrations (TS), inoculum sizes and fermentation temperatures were selected to study biogas production characteristics. The experiment results showed that biogas yield increased rapidly during the initial stage of reaction, decreased quickly after reaching the peak, and the decrease slowed down at some level. Orthogonal experiment results showed that both fermentation temperature and solids concentration showed significant effects on gas production yield. Fermentation temperature showed the most significant effect, while the effect of inoculum size was not significant on gas yield. The optimum fermentation performance was obtained at 20% solid content, 35°C fermentation temperature, and 30% inoculum size.

Abstract: The ectomycorrhizal fungi resource of Pinus massoniana and Chinese Fir forest had been investigated in the places of Hunan and YunNan Province. There were 17 species belong to 6 families and 9 genera. All the collected ectomycorrhizal fungi were separated by tissue isolation method, and 12 strains were obtained, which belong to 7 genera of 4 families. The preliminary selection results showed that there were 6 strains presented the better culture characteristics, which were Seleroderma polyrhizum Pers., Scleroderma cepa Pers., Calvatia craniiformis(Schw.)Fr., Lactarius hatsudake Tanaka, Lactarius deliciosus(Fr)Gray., Russula puellaris Fr.. Then these 6 strains were cultivated between every two among them, the results showed that the group of LS3/RHG1 was the optimal combination, the next were the groups of LGD-2/La-HZ3 and LS3/La-HZ3. The groups of A3/ La8 showed antagonism to each other, so it was not suitable to be combined for inoculation. These research results will provide the important technical support for expanding propagation of ECM fungi and mycorrhizal technology application in Pinus massoniana and Chinese Fir plantation.

Abstract: Maiz’s short sequential extraction procedure was used to extract the heavy metals in the carbon residues made from sewage sludge by co-pyrolysis with corn straw. The content of heavy metals in the residues was determined by ICP-MS to study the fraction distribution changes of heavy metals. It is concluded that the content of mobile and mobilization heavy metals exsisted in the residue decrease and the content of residual heavy metals increase due to the co-pyrolysis. The co-pyrolysis temperature has great effect on the fraction distribution changes of heavy metals. The content of residual fraction for Cr, Ni, Pb is up to the top at 700°C and for Cd、Cu、Zn is at 500°C. The carbon residues are unhazardous and safe.