Recent Innovations in Chemical Engineering - Volume 9, Issue 2, 2016

Background: The bioconversion of renewable terrestrial and marine bioresources and agro-industrial wastes presents a very interesting research and development (R) subject to show how high added-value products could be obtained from inexpensive materials, and how this bioconversion could bring solutions to many serious problems like fuel shortage, pollution and waste disposal in a sustainable, yet profitable manner. Objective: Extensive research efforts were, and are being, pursued to develop new products from biomass or to optimize the production procedures of other valuable ones. Method: In this review article, we will present the use of various terrestrial and marine bioresources, by-products and wastes for the production of important and strategic supplies of liquid (bioethanol and biodiesel) and gaseous (biomethane) biofuels, and activated carbons. A special attention will be given to eco-friendly and cost-effective conversion procedures.

Background: The background of using the pour point depressant is that wax precipitation causes several challenges during oil extraction and pipeline transport of waxy crude oils, including wax deposition, plugging of the pipeline and damage to the oil drilling equipment, which, collectively, adversely impacts pipeline performance. Method: The method which used to solve the problem of paraffin deposit is adding chemical additive. The objective of adding pour point depressant is to improve the fluidity of crude oil. Addition of pour point depressants to the oil to improve the extract efficiency is an effective way to prevent the generation of waxy crystalline clusters. In this article, four mechanisms of the pour point depressants are introduced and the types of commonly used pour point depressants are classified. The effect of different functional groups and structures of pour point depressants on the wax crystal are summarized. Conclusion: In conclusion, the factors that influence polymeric efficacy include the degree of branching, molecular weight and carbon chain length. The prevention of the wax crystal formation and improvement of the low-temperature fluidity of crude oils occurs by five reaction mechanisms of the pour point depressant, including inserting, cutting off and by other means changing the manner of wax crystal growth. The wax crystal structure and doughty polar components of crude oil can adversely affect the pour point depressant action. Furthermore, this article also describes future research directions for pour point depressants as a possible guide for researchers.

Introduction: In recent years many investigations have been accomplished in the field of photocatalysis for decomposition of organic matters and other pollutants in order to achieve stringent discharge standards. Therefore, making an assessment on the wastewater treatment processes through photocatalytic reactors seems to be an interesting option. Objective: In this study, we discussed the various methods and patents used for the synthesis of photocatalyst, kinetics of reaction, and the effects of operative parameters. Method: Photocatalytic reactors, several type of photocatalysts, and synthesis method of nanoparticle photocatalysts have been explained. Result: Improving the photocatalytic efficiency by electrical current, advantage of mixing, doping of photocatalyst, photocatalytic process kinetics, and parameters affecting the photocatalytic process such as temperature, initial concentration of pollutants, catalyst concentration, pH, UV irradiation intensity, solution stirring intensity, as well as, addition of hydrogen peroxide have been reviewed. Conclusion: UV irradiation and visible light are necessary in photacatalytic process. In some cases, increase in stirring intensity caused great enhancement in photocatalytic process. Further, addition of H2O2 increases the rate of photocatalytic process. Kinetics of photodecomposition of organic pollutants usually is first order.

Mn0x particles were successfully in situ doped on activated carbon via a redox deposition process. The effects of calcination temperature on the surface characteristics and desulfurization performance were studied. Desulfurization activity was evaluated at a fixed bed reactor in simulated flue gas. A remarkable promotional effect was observed by supporting Mn0 particles on activated carbon surface. Results showed that the sulfur capacity of activated carbon loaded by Mn0 was 312.81 mg/g under optimal conditions, which was 61% higher than that of blank activated carbon. Physiochemical properties of the composites were studied by characterizing wit BET, XRD, XPS, SEM and TEM. Better desulfurization performance of the nanocomposites was mainly attributed to stronger basicity of carbon surface and oxidation effect of S02 by Mn0. The formation of manganese sulfate after desulfurization indicated that Mn0 could be involved in the desulfurization process.

Background: Palm oil mill effluent (POME) is dominant agroindustrial wastewater in Indonesia and Malaysia. Some kind of microalgae can utilize the wastewater as media of cultivation, and produce value-added compounds. However, the production of lipid and carbohydrate from microalgae cultivated on untreated POME medium were not clearly reported. Objective: to cultivate Chlorella vulgaris, Dunaliella salina, and Spirulina platensis on a media containing the different concentration of POME to produce lipid and carbohydrate by employing a microwave assisted method. Methods: microalgae were cultivated on different POME concentration (10-30% v/v) to replace synthetic medium at 13 days of cultivation. The microwave-irradiation was employed on lipid extraction, carbohydrate hydrolysis, and fatty acid methyl ester (FAME) formation. GC/MS was employed to analyze the fatty acid and hydrocarbon compound on the lipid. Chemical oxygen demand (COD) on the medium was analyzed before and after the cultivation. Results: Growth rate of the microalgae were decreased along with the increasing of POME addition except for C.vulgaris. The lipid and carbohydrate content were influenced by POME except for D. salina. The microwave-assisted method successfully enhanced carbohydrate yield in the hydrolysis process. The highest productivity was found on C.vulgaris with 12.60 mg/L/d lipid, and 11.22 mg/L/d carbohydrate, and remove 74% COD content. The highest FAME content was recorded from S. platensis. Conclusion: In summary, the microalgae can utilize POME wastewater in low concentration under mixotrophic condition. The microwave-assisted method seems promising in the integrated biorefinery process of producing value-added compound from microalgae.

Background: As a kind of hydrocarbon mixtures, diesel oil is mainly consisted of linear chain alkanes as a medium distillate of petroleum. The removal of diesel oil depends on several technologies not merely chemical or physical, but also biological methods, especially biodegradation. Method: Five microorganisms considered as the potential diesel oil-degrading bacteria were chosen for biodegradation experiment. Among these five microorganisms, D2 and D4 showed better removal efficiency of diesel oil with removal rate reached to 75.16% and 69.09%, respectively. Result: According to the test of 16S rDNA sequence, strain D2 and D4 were identified as Bacillus subtilis strain ATCC 13952 and Bacillus cereus AH676, respectively. After optimizing biodegradation condition of D2 mixed strains by using response surface methodology (RSM), the removal efficiency was promoted to 83.06%, with the optimal condition calculated as rotate speed 124 rpm, pH 7.1, temperature 37.0132;ƒ, and inoculum size 5.1% (v/v). Furthermore, immobilization technique was applied for improving the removal efficiency sequentially. Conclusion: Compared with free strains, the immobilized D2 mixed strains, embedded by the mixture of 4% (w/v) sodium alginate and 4% (w/v) polyvinyl alcohol (PVA), obtained a higher removal rate reached to 95.95% with no breakage and well permeability.

Background: The Hydrothermal liquefaction (HTL) of the biomass generates two phases, namely, liquid bio crude & an aqueous phase containing soluble hydrocarbons. Hydrothermal gasification converts aqueous hydrocarbons into fuel gas containing mainly CH4,H2 and CO2. Objective: Objective of the present study is to carry out thermodynamic analysis of sub and supercritical water gasification of aqueous fraction of HTL for hydrogen rich bio-gas production. Method: In this study, equilibrium composition calculations for sub and supercritical water gasification product performed using Gibbs method for aqueous HTL fraction & its constituent components. Results: Thermodynamic model was validated with experimental data at different operating conditions. Sensitivity study of critical process parameters (for individual constituents components of HTL aqueous fraction and their multicomponent mixture) conducted over broad range, namely, temperature (300-1000°C), pressure (190-340 bar) and feed concentration (1-30 wt%) to identify optimum process condition. Conclusions: Increase in reaction temperature shows the positive effect on hydrogen mole fraction in product gas mixture. However, increase in pressure leads to decrease in hydrogen mole fraction in product. Maximum hydrogen concentration in the range of 0.60-0.75 mole fraction (depending upon selected composition of organics in multicomponent aqueous fraction) was observed in the bio-gas at temperature of 705°C. Lower feedstock concentration of aqueous HTL organics is observed to lead to high hydrogen production.