Synthesis of biodiesel from waste cooking oil using immobilized lipase in fixed bed reactor

Waste cooking oil (WCO) is the residue from the kitchen, restaurants, food factories and even human and animal waste which not only harm people's health but also causes environmental pollution. The production of biodiesel from waste cooking oil to partially substitute petroleum diesel is one of the measures for solving the twin problems of environment pollution and energy shortage. In this project, synthesis of biodiesel was catalyzed by immobilized Candida lipase in a three-step fixed bed reactor. The reaction solution was a mixture of WCO, water, methanol and solvent (hexane). The main product was biodiesel consisted of fatty acid methyl ester (FAME), of which methyl oleate was the main component. Effects of lipase, solvent, water, and temperature and flow of the reaction mixture on the synthesis of biodiesel were analyzed. The results indicate that a 91.08% of FAME can be achieved in the end product under optimal conditions. Most of the chemical and physical characters of the biodiesel were superior to the standards for 0(#)diesel (GB/T 19147) and biodiesel (DIN V51606 and ASTM D-6751).

Vacuum pyrolysis of waste tires with basic additives

Granules of waste tires were pyrolyzed tinder vacuum (3.5-10 kPa) conditions, and the effects of temperature and basic additives (Na2CO3, NaOH) on the properties of pyrolysis were thoroughly investigated. It was obvious that with or without basic additives, pyrolysis oil yield increased gradually to a maximum and subsequently decreased with a temperature increase from 450 degrees C to 600 degrees C, irrespective of the addition of basic additives to the reactor. The addition of NaOH facilitated pyrolysis dramatically, as a maximal pyrolysis oil yield of about 48 wt% was achieved at 550 degrees C without the addition of basic additives, while a maximal pyrolysis oil yield of about 50 wt% was achieved at 480 degrees C by adding 3 wt% (w/w, powder/waste tire granules) of NaOH powder. The composition analysis of pyrolytic naphtha (i.b.p. (initial boiling point) similar to 205 degrees C) distilled from pyrolysis oil showed that more dl-limonene was obtained with basic additives and the maximal content of dl-limonene in pyrolysis oil was 12.39 wt% which is a valuable and widely-used fine chemical. However, no improvement in pyrolysis was observed with Na2CO3 addition. Pyrolysis gas was mainly composed of H-2, CO, CH4, CO2, C2H4 and C2H6. Pyrolytic char had a surface area comparable to commercial carbon black, but its proportion of ash (above 11.5 wt%) was much higher.

High-pressure sintering the novel light (W0.25Al0.75)C hard material without binder phase

A novel hard material of (W0.25Al75)C has been successfully prepared by the high-pressure sintering process without the addition of any binder phase. The high-pressure is a suitable and powerful technique for sintering the binderless hard material, the relative density of the hard material can reach 99.6% under high-pressure sintering. The density of the novel light hard material is only 6.2371 g cm(-3), which is much lighter than the normal hard material. The hardness of the light hard material can reach 18.89 GPa even the aluminum content get the astonished 75%.

Electrochemical characteristics of glucose oxidase adsorbed at carbon nanotubes modified electrode with ionic liquid as binder

Multiwall carbon nanotubes (CNTs)-modified electrode has been prepared by using ionic liquid (IL) as the binder. The as-prepared CNTs-IL composite modified electrode has good biocompatibility and is a suitable matrix to immobilize biomolecules. Glucose oxidase (GOx), containing flavin adenine dinucleotide as active site, stably adsorbed on modified electrode surface has resulted in the direct electron transfer. The electron transfer rate of 9.08 s(-1) obtained is much higher than that of GOx adsorbed on the CNTs papers (1.7 s(-1)), and the process is more reversible with small redox peak separation of 23 mV This may be due to the synergetic promotion of CNTs and IL to electron transfer of the protein, especially the IL as the binder, showing better electrochemical properties than that of chitosan and Nafion. Furthermore, GOx adsorbed at the modified electrode exhibits good stability and keeps good electrocatalytic activity to glucose with broad linear range up to 20 mM. Besides, the simple preparation procedure and easy renewability make the system a basis to investigate the electron transfer kinetics and biocatalytic performance of GOx and provide a promising platform for the development of biosensors.

High-pressure sintering study of a novel hard material (W0.5Al0.5)C-0.5 without binder metal

A novel hard material of (W0.5Al0.5)C-0.5 has been successfully sintered under high-pressure (4.5 GPa). The influence of sintering time and temperature on the microstructure, Vickers microhardness and density of the as-prepared specimens are well described. Interestingly, sintering temperature has an amazing influence on the hardness, density and microstructure of the specimen while the sintering time does not. It is found that the most suitable sintering condition from our work is 1600 degrees C and 10 min under pressure of 4.5 GPa. The hardness and relative density of the as-prepared sample can reach 2340 kg mm(-2) and 98.62%, respectively. The cell parameters of the sintered specimen is found to be little smaller than that of the powder, which we propose is related to the high pressure.