Assessment of the synthesis method of Fe3O4 nanocatalysts and its effectiveness in viscosity reduction and heavy oil upgrading.

In this research, Fe3O4 nanocatalysts were synthesized systematically microwave-assisted. The effectiveness of the synthesized nanocatalysts in reducing viscosity and upgrading heavy oil was evaluated. The nanocatalysts were investigated for their magnetic and electromagnetic properties. The impact of microwave radiation's time and power on the size and purity of nanocatalysts was investigated. The purities in the crystal network of Fe3O4 nanocatalysts expanded as a result of reducing microwave radiation time and power due to less heat production. Increased temperature leads to dope NH4Cl into the Fe3O4 nanocatalysts crystal network. At: 1 min and power of 400 watts the most satisfactory results in the size and purity of nanocatalysts. The electromagnetic properties, size, and effectiveness of the synthesized Fe3O4 nanocatalysts have been examined to determine the effect of the synthesis method. The performance of Fe3O4 nanocatalysts synthesized by co-precipitation and microwave-assisted viscosity reduction and heavy oil upgrading was evaluated and compared. The crystallite size of the Fe3O4 nanocatalysts synthesized by microwave-assisted was smaller than that synthesized using co-precipitation. Fe3O4 nanocatalysts synthesized by microwave-assisted and the co-precipitation method decreased viscosity by 28% and 23%, respectively. Moreover, Fe3O4 nanocatalysts synthesized by microwave-assisted reduced the sulfoxide index and aromatic index considerably more than the co-precipitation synthesized Fe3O4 (90% against. 48% and 13% vs. 7%, respectively).

Facile fabrication, characterization and catalytic activity of a NiMo/Al2O3 nanocatalyst via a solution combustion method used in a low temperature hydrodesulfurization process: the effect of fuel to oxidant ratio.

Novel bimetallic NiMo/Al2O3 nanocatalysts were fabricated via a solution combustion method to evaluate the role of fuel to oxidant molar ratios on their structural properties and hydrodesulfurization activity. The citric acid/oxidant ratios of 0.5, 1, 2 and 4 were selected to address the optimum ratio. Characterization results demonstrated that the content of citric acid considerably influenced the morphological and textural properties of the nanocatalysts. Such morphology modification is attributed to the consequent difference of the effluent exhaust gas during combustion. We show that with our method a relatively homogeneous distribution of the active material over the support can be achieved. The obtained data from N2 adsorption-desorption analysis illustrated that at a fuel/oxidant ratio of 4 the external and surface area were ca. 2.1 and 1.5 times more than the corresponding one in the fuel/oxidant ratio of 0.5, respectively. Furthermore, a higher amount of fuel can improve the catalyst reducibility by decreasing the interaction of metal active phase with the support surface. The catalytic performance of sulfided nanocatalysts is evaluated in a slurry reactor, operated at ambient pressure using high thiophene contamination as a model fuel. The solution combustion synthesis method was able to remove 100% of the sulfur compound in the reaction medium.

Influence of phosphorus content on properties and performance of NiW nanocatalyst supported on activated red mud in atmospheric diesel hydrodesulfurization.

The influence of phosphorus promoter addition on structural properties and hydrodesulfurization activity of NiW nanocatalysts supported on activated red mud, called NiW/P-ARM, was studied at atmospheric pressure. Before red mud usage, it was treated by Pratt and Christoverson technique and then NiW/P-ARM nanocatalysts with different phosphorus loadings were prepared by impregnation technique. The prepared samples were characterized by XRF, XRD, FESEM, BET, FTIR and H2-TPR analyses. Base on the obtained results, XRF analysis indicated that activation process remarkably decreased Ca and Na content in the red mud. XRD results indicated the high dispersion of the tungstate, nickel and active phase (NiWO4) species on the surface of activated red mud support. FESEM analysis illustrated that all particles of NiW/P-ARM were less than 100 nm. TPR measurements revealed that phosphorus-promoted nanocatalysts had higher reduction potentials than nanocatalyst without promoter. The catalytic ability of synthesized nanocatalysts was investigated in a fixed bed reactor at atmospheric pressure and 380 °C using Iso diesel and light diesel as the reaction feeds. It was found that NiW/P-ARM with 1.5 wt.% prompter showed higher activity for hydrodesulfurization process and further addition of P promoter decreased the catalytic activity that may be due to the decrease in surface area or agglomeration particles.

Screening and characterization of marine actinomycetes from the northern Oman Sea sediments for cytotoxic and antimicrobial activity

A total of 168 actinomycete colonies were isolated from 14 sediment samples of the northern parts of the Oman Sea and were screened for cytotoxic and antimicrobial activity. Among four media and two treatments, the glucose arginine agar medium (18%) and heat treatment (28.3%) showed maximum isolation rate of actinomycetes. Preliminary characterization revealed that the members of Streptomycetaceae were widely distributed (66%) in the most of the sampling stations followed by Micromonosporaceae (14%), Nocardiaceae (6%), and Pseudonocardiaceae (4%), respectively. Approximately, 23.8% of the isolates inhibited the growth of at least one of the microbial test strains, while the majority of them belonged to the Streptomycetaceae family. Minimum inhibitory concentrations of the ethyl acetate culture extracts of the five most putative isolates varied from 64 μg/mL against Micrococcus luteus and Candida albicans to 1 mg/mL against Aspergillus niger. These extracts showed significant cytotoxic activity at18.74-193.5 μg/mL on the human breast (MCF7), colon (HCT 116), and liver (HepG2) tumor cell lines while exhibited less or no cytotoxicity on the normal cell line (HUVEC). Interestingly, IFSRI 193 extract selectively inhibited the growth of HCT 116 cell line and gram-positive bacteria. 16S rRNA gene sequencing revealed that the potent isolates have 97 to 99% similarity with S. chartreusis, S. cacaoi, S. sampsonii, S. qinglanensis, and S. diastaticus. These results suggested that the five Streptomyces strains could be considered candidates for discovering the antitumor antibiotics

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Screening and characterization of marine actinomycetes from the northern Oman Sea sediments for cytotoxic and antimicrobial activity.

A total of 168 actinomycete colonies were isolated from 14 sediment samples of the northern parts of the Oman Sea and were screened for cytotoxic and antimicrobial activity. Among four media and two treatments, the glucose arginine agar medium (18%) and heat treatment (28.3%) showed maximum isolation rate of actinomycetes. Preliminary characterization revealed that the members of Streptomycetaceae were widely distributed (66%) in the most of the sampling stations followed by Micromonosporaceae (14%), Nocardiaceae (6%), and Pseudonocardiaceae (4%), respectively. Approximately, 23.8% of the isolates inhibited the growth of at least one of the microbial test strains, while the majority of them belonged to the Streptomycetaceae family. Minimum inhibitory concentrations of the ethyl acetate culture extracts of the five most putative isolates varied from 64 µg/mL against Micrococcus luteus and Candida albicans to 1 mg/mL against Aspergillus niger. These extracts showed significant cytotoxic activity at18.74-193.5 µg/mL on the human breast (MCF7), colon (HCT 116), and liver (HepG2) tumor cell lines while exhibited less or no cytotoxicity on the normal cell line (HUVEC). Interestingly, IFSRI 193 extract selectively inhibited the growth of HCT 116 cell line and gram-positive bacteria. 16S rRNA gene sequencing revealed that the potent isolates have 97 to 99% similarity with S. chartreusis, S. cacaoi, S. sampsonii, S. qinglanensis, and S. diastaticus. These results suggested that the five Streptomyces strains could be considered candidates for discovering the antitumor antibiotics.

Beneficial use of ultrasound irradiation in synthesis of beta-clinoptilolite composite used in heavy oil upgrading process.

A novel beta-clinoptilolite composite was prepared from beta zeolite and alkaline treated clinoptilolite by employing conventional and sonicated mixing procedures. Parent and prepared catalysts were characterized by XRD, FE-SEM, N2 adsorption-desorption and NH3-TPD analyses. Prepared composite of beta zeolite and treated clinoptilolite exhibited improved structural properties especially upon sonicated mixing procedure. Employing ultrasound irradiation notably improved beta distribution in the composite and increased mesoporous volume and specific surface area from 0.245 cm3 g-1 and 171.3 m2 g-1 in conventionally mixed composite to 0.353 cm3 g-1 and 232.9 m2 g-1 in sonicated sample. Catalytic performance of prepared composite was evaluated in heavy oil upgrading process in a continuous fixed bed apparatus. Liquid product was specified by conducting SIMDIS-GC and GC/MS analyses. Spent catalysts were characterized by TGA, FTIR and XRD. Beta-clinoptilolite composite containing only 30 wt% of beta zeolite, exhibited similar performance to beta zeolite catalyst by resulting 75.3% viscosity reduction while producing lower amount of coke. Amount of light hydrocarbons produced over beta-clinoptilolite composite was 33.51 wt% while beta zeolite catalyst produced 35.58 wt% light hydrocarbons in upgrading process. Ultrasound irradiated composite showed more stable structure in catalytic cracking procedure compared to conventionally mixed composite. After 5 h time on stream, relative crystallinity of clinoptilolite phase in the conventionally mixed composite was reduced by 34.5% while sonicated sample remarkably preserved its structure during the reaction and only 1% reduction occurred for this sample.

Organic contaminants removal from industrial wastewater by CTAB treated synthetic zeolite Y.

Due to environmental issues, wastewater treatment is a main concern for most industries and providing access to clean and affordable water is one of the big challenges. Besides, industrial wastewater contains many pollutants, one of the most toxic contaminants is organics. Currently, zeolites are widely used as an adsorbent to remove such pollutants. This study examines a surfactant modified zeolite Y (SMZY), as an applicable solution, to get over this problem. Here, zeolite Y, synthesized from bentonite, is used as an adsorbent basis. Then, it is characterized by XRD, FTIR, BET, SEM, and TGA. Next, it is modified by hexadecyltrimethyl ammonium bromide (CTAB) surfactant in different concentrations. These SMZYs are used to adsorb organic contaminants of an olefin plant wastewater. Based on adsorption capacity evaluated by several isotherms, such as Langmuir, Freundlich, Sips and Dubinin-Radushkevich, total organic carbon (TOC) content of wastewater reduced up to 89%. The optimum modification method and possible mechanism for obtaining this result is presented in the current research. Furthermore, to understand the nature of adsorption process, Van der Waals, hydrophobic, and electrostatic interactions are determined. The results indicate that adsorption process depends on both hydrophobic and electrostatic interactions.

Statistical media optimization for growth and PHB production from methanol by a methylotrophic bacterium.

Media components were optimized by statistical design for cell growth and PHB production of Methylobacterium extorquens DSMZ 1340. Four important components of growth media were optimized by central composite design. The growth increased from an OD=1.35 for Choi medium as control to an OD=2.15 for optimal medium. Then media components for PHB production were optimized. Optimization of five important factors was conducted by response surface method. The optimal composition of PHB production medium was found to be at 7.8 (g/L) Na2HPO4 x 12H2O, and surprisingly at zero concentration of (NH4)2SO4, KH2PO4, MgSO4 and MnSO4. The PHB production was found to be 2.95 (g/L) at this medium. RSM results indicated that a deficiency of nitrogen and magnesium is crucial for PHB accumulation in this microorganism. Also, PHB production was carried out in a 5 L fermentor at the optimum condition which resulted in 9.5 g/L PHB and 15.4 g/L cell dry weight with 62.3% polymer content.