Synthesis of boron nitride nanorod and its performance as a metalfree catalyst for oxidative desulfurization of diesel fuel

In order to reduce the sulfur compounds in diesel fuel,boron nitride(BN)has been used as a novel metal-free catalyst in the present research.This nanocatalyst was synthesized via template-free approach followed by heating treatment at 900℃ in nitrogen atmosphere that the characteristics of the sample were identified by the X-ray diffraction,Fourier-transform infrared spectroscopy,Raman spectroscopy,field emission scanning electron microscopy,transmission electron microscopy,atomic force microscopy,and N2 adsorption-desorption isotherms.The results of structural and morphological analysis represented that BN has been successfully synthesized.The efficacy of the main operating parameters on the process was studied by using response surface methodology based on the Box-Behnken design method.The prepared catalyst showed high efficiency in oxidative desulfurization of diesel fuel with initial sulfur content of 8040 mg·kg^(-1)S.From statistical analysis,a significant quadratic model was obtained to predict the sulfur removal as a function of efficient parameters.The maximum efficiency of 72.4%was achieved under optimized conditions at oxidant/sulfur molar ratio of 10.2,temperature of 71℃,reaction time of 113 min,and catalyst dosage of 0.36 g.Also,the reusability of the BN was studied,and the result showed little reduction in activity of the catalyst after 10 times regeneration.Moreover,a plausible mechanism was proposed for oxidation of sulfur compounds on the surface of the catalyst.The present study shows that BN materials can be selected as promising metal-free catalysts for desulfurization process.

Biomass pyrolysis: A review of the process development and challenges from initial researches up to the commercialisation stage

Lignocellulosic biomass can be convert to a condensable liquid named bio-oil,a solid product named as char and a mixture of gaseous products comprising CO2,CO,H2,CH4,etc.In recent years,much effort has been made on the investigation of conversion of biomass through pyrolysis.However,commercialisation of the biomass pyrolysis technology is still challenging due to various issues such as the deleterious properties of bio-oil including the low heating value and the high instability at elevated temperatures.To overcome such issues,many processes,reactors and catalysts have been developed for pyrolysis and catalytic pyrolysis of biomass.A state to the art of pyrolysis or catalytic pyrolysis of biomass need to be summarised to have an overall evaluation of the technologies,in order to provide a useful reference for the further development of pyrolysis technology.This study reviews the various pyrolysis process,especially focus on the effects of essential parameters,the process design,the reactors and the catalysts on the pyrolysis process.In addition,progress in commercialisation of pyrolysis technology was also reviewed and the remaining issues in the process of commercialisation were discussed.

Enhanced removal of nitrate and phosphate from wastewater by Chlorella vulgaris: Multi-objective optimization and CFD simulation

To enhance the efficiency of wastewater biotreatment with microalgae, the effects of physical parameters need to be investigated and optimized. In this regard, the individual and interactive effects of temperature, p H and aeration rate on the performance of biological removal of nitrate and phosphate by Chlorella vulgaris were studied by response surface methodology(RSM). Furthermore, a multi-objective optimization technique was applied to the response equations to simultaneously find optimal combinations of input parameters capable of removing the highest possible amount of nitrate and phosphate. The optimal calculated values were temperature of 26.3 °C, pH of 8 and aeration rate of 4.7 L·min^(-1). Interestingly, under the optimum condition, approximately 85% of total nitrate and 77% of whole phosphate were removed after 48 h and 24 h, respectively, which were in excellent agreement with the predicted values. Finally, the effect of baffle on mixing performance and, as a result, on bioremoval efficiency was investigated in Stirred Tank Photobioreactor(STP) by means of Computational Fluid Dynamics(CFD). Flow behavior indicated substantial enhancement in mixing performance when the baffle was inserted into the tank. Obtained simulation results were validated experimentally. Under the optimum condition, due to proper mixing in baffled STP, nitrate and phosphate removal increased up to 93% and 86%,respectively, compared to unbaffled one.

The effect of membrane pores wettability on CO_2 removal from CO_2/CH_4 gaseous mixture using NaOH, MEA and TEA liquid absorbents in hollow fiber membrane contactor

The present paper renders a modeling and a 2D numerical simulation for the removal of CO_2from CO_2/CH_4gaseous stream utilizing sodium hydroxide(NaOH),monoethanolamine(MEA)and triethanolamine(TEA)liquid absorbents inside the hollow fiber membrane contactor.Counter-current arrangement of absorbing agents and CO_2/CH_4gaseous mixture flows are implemented in the modeling and numerical simulation.Non-wetting and partial wetting modes of operation are considered where in the partial wetting mode,CO_2/CH_4gaseous mixture and liquid absorbents fill the membrane pores.The deteriorated removal of CO_2in the partial wetting mode of operation is mainly due to the mass transfer resistance imposed by the liquid in the pores of membrane.The validation of numerical simulation is done based on the comparison of simulation results of CO_2removal using Na OH and experimental data under non-wetting mode of operation.The comparison illustrates a desirable agreement with an average deviation of less than 5%.According to the results,MEA provides higher efficiency for CO_2removal in comparison with the other liquid absorbents.The order for CO_2removal performance is MEAN Na OHN TEA.The influence of non-wetting and partial wetting modes of operation on CO_2removal are evaluated in this article as one of the novelties.Besides,the percentage of CO_2sequestration as a function of gas velocity for various percentages of membrane pores wetting ranging from 0(non-wetting mode of operation)to 100%(complete wetting mode of operation)is studied in this research paper,which can be proposed as the other novelty.The results indicate that increase in some operational parameters such as module length,membrane porosity and absorbents concentration encourage the removal percentage of CO_2from CO_2/CH_4gaseous mixture while increasing in membrane tortuosity,gas velocity and initial CO_2concentration has unfavorable influence on the separation efficiency of CO_2.

Hydrothermal carbonization pretreatment makes a remarkable difference in activation of rice and lettuce in food waste

Cooked rice and the vegetables like lettuce are common kitchen waste,which are carbonaceous materials and have the potential as feedstock for the production of activated carbon.Cooking is similar to hydrothermal treatment(HTC),which might impact the subsequent activation of kitchen waste.In this study,the HTC of lettuce,rice,or their mixture and the activation of the resulting hydrochars were conducted.The results indicated that cross-polymerization between the N-containing organics from lettuce and the sugar derivatives from rice took place in their co-HTC,which significantly increased the hydrochar yield.Activation of the hydrochar from the coHTC generated the AC with a yield of 2 times that from direct activation of mixed lettuce/rice.However,the coHTC facilitated aromatization,reducing reactivity with K2C2O4in activation and producing the AC with main micropores and low specific surface area.Activation of the hydrochar from HTC of rice followed the above trend,while that from lettuce was the opposite.The organics in lettuce were thermally unstable and could not undergo sufficient aromatization.The activation of hydrochar from HTC of lettuce thus generated the AC with the lowest yield,but the highest specific surface area(1684.9 m2/g),abundant mesopores,and superior capability for adsorption of tetracycline.However,the environmental impacts and energy consumption for the production of AC from the hydrochar of lettuce were higher than that from hydrochar of co-HTC.

Facile Preparation of Fe-N-C Oxygen Reduction Electrocatalysts from Metal Organic Frameworks for Zn-Air Battery

It is critical to study efficient,stable oxygen reduction reaction(ORR)electrocatalysts due to insufficient stability and expensive price of Pt/C catalysts for Zn-air batteries.Fe–N–C electrocatalysts was synthesized by a facile solvent-green method and the efficiency of Fe–N–C optimized was studied as potential ORR electrocatalysts under alkaline condition.Results indicated that it had excellent ORR activity with E_(1/2)of 0.93 V,which was competitive to that of Pt/C-JM under the same conditions.Moreover,the assembled Zn-air battery exhibited discharge potential and charge potential of 1.2 V,2.32 V at 5 mA cm^(−2)with high stability,respectively.Overall,all results illustrated that Fe–N–C is an excellent ORR electrocatalyst in the field of metal air battery.Additionally,this work opens a good way to synthesize highly efficient electrocatalysts from metal organic framework and to investigate ORR mechanism of efficient chemical energy to electricity conversion.

Real-world and bottom-up methodology for emission inventory development and scenario design in medium-sized cities

Efficient management of air quality requires a comprehensive emission inventory to support decision-making on air quality improvement.This article presents a comprehensive framework for detailed emission inventory development in cities with low-quality basic data,which examines the emission of primary criteria pollutants(CO,NO_(x),SO_(2),PM_(2.5),PM_(10),and VOC)from mobile sources,residential,commercial,and public services,fuel stations,transport terminals,energy conversion sections,and industries.This research was applied to Tabriz in Northwest Iran,one of the polluted medium-sized cities with a population of 1.77 million.Results show the city daily emission per capita is 569.8 g of CO,68.6 g of NO_(x),38.6 g of VOC,17.6 g of SO_(x),and 3.7 g of PM.Vehicular emissions accounted for 98%of CO,91%of VOCs,61%of NO_(x),and 56%of PM;meaning alternative policy strategies in vehicles would reduce emissions rapidly.Fifteen applicable and effective scenarios in transport and one concerning stationary sourceswere proposed and reduction potential of themwas evaluated.Effectiveness of the public transport improvement and replacement of old passenger cars were founded the key scenarios.These two alternatives decrease 14 and 2 tons of SO_(2) and 6797 and 2394 tons of NO_(x) annually with the cost of$99.5 MM and$366.5 MM,respectively.The findings of this study provides the choice of travel method by each citizen is a function of cost,speed,comfort and safety of travel;therefore,all the requirements of any scenarios must be fully considered in the implementation step.

Biodegradation of high density polyethylene using Streptomyces species

Objective: To investigate the biodegradation of high density polyethylene (HDPE) by Streptomyces species isolated from the soil of East Azerbaijan, Iran. Methods: Powders of HDPE samples were prepared by grinding in different particle sizes of 212, 300, 420, and 500 microns. Each time 50 mg of a sample was poured to a liquid medium containing species. Samples were incubated for 18 days at 28 °C in a shaker-incubator and their degradation percentage was measured by weighting method. Produced metabolite at 18th day was analyzed by gas chromatography-mass spectrometry. Also a film of HDPE was subjected to biodegradation and after one month was analyzed by scanning electron microscope which showed degradation on the surface of the film. Results: The results showed that Streptomyces species degraded 50 mg of HDPE sample with the size of 212 μm about 18.26%, 300 and 420 μm about 14.4%, and 500 μm about 13%. Kinetic modeling of biodegradation process showed that the reaction rate was first order with respect to concentration of HDPE. Based on gas chromatography-mass spectrometry results, no high toxic material was produced during biodegradation of HDPE. Conclusions: The research showed that isolated Streptomyces sp. are capable of degradation of HDPE polymer with high degradation efficiency.