Potential Application of Turnip Oil (Raphanus sativus L.) for Biodiesel Production: Physical–Chemical Properties of Neat Oil, Biofuels and their Blends with Ultra-Low Sulphur Diesel (ULSD)

Turnip oil (TO; Raphanus sativus L.) produces seeds that contain around 26 wt% of inedible base stock that are suitable as a potential feedstock for biodiesel production. A turnip oil methyl ester (TME) was prepared from acid-catalyzed pretreated TO in an effort to evaluate important fuel properties of turnip oil-based biodiesel, such as kinematic viscosity, cloud point, pour point (PP), cold filter plugging point, acid value, oxidative stability and lubricity. A comparison was made with soybean oil methyl esters (SME) as per biodiesel fuel standards such as ASTM D6751 and EN 14214. TME was characterized using FTIR, HPLC and ¹H NMR. Except PP property, SME displays superior fuel properties compared to TME. Blends (B5 and B20) of TME in ultra-low sulphur diesel fuel (ULSD) were also assessed for the aforesaid fuel properties and compared to an analogous set of blends of soybean oil methyl ester in ULSD as per petro diesel fuel standards such as ASTM D975 and D7467. TME B5 blends in ULSD displayed improved PP property in comparison to neat ULSD and blends of SME in ULSD. It was demonstrated that the B5 and B20 blends of TME in ULSD had acceptable fuel properties as per ASTM D975 (for B5 blend) and ASTM D7467 (for B20 blend). In summary, turnip oil has potential as an alternative, non-food feedstock for biodiesel production.     

Preparation and Evaluation of Jojoba Oil Methyl Esters as Biodiesel and as a Blend Component in Ultra-Low Sulfur Diesel Fuel

The jojoba plant (Simmondsia chinensis L.) produces seeds that contain around 50 to 60 wt.% of inedible long-chain wax esters that are suitable as a potential feedstock for biodiesel (BD) production. Jojoba oil methyl esters (JME) were prepared from acid-catalyzed pretreated jojoba oil in order to evaluate important fuel properties of jojoba-based BD, including kinematic viscosity, cloud point (CP), pour point (PP), cold filter plugging point (CFPP), acid value (AV), oxidative stability, and lubricity. A comparison was made with soybean oil methyl esters (SME) and relevant BD fuel standards such as ASTM D6751 and EN 14214. JME was characterized using Fourier transform infrared spectroscopy and ¹H and ¹³C nuclear magnetic resonance. The CP, PP, and CFPP of JME were ?13°C, ?16°C, and ?14°C, respectively, which were superior to SME. The kinematic viscosity (40°C) of JME was 6.67 mm²/s, which was higher than observed for SME. Blends (B5 and B20) of JME in ultra-low sulfur diesel fuel (ULSD) were also evaluated for the aforementioned fuel properties and compared to an analogous set of blends of SME in ULSD and relevant petro diesel fuel standards such as ASTM D975 and D7467. JME blends in ULSD displayed improved low-temperature properties in comparison to neat ULSD and blends of SME in ULSD. In summary, jojoba oil has potential as an alternative, nonfood feedstock for BD production.     

Sulphide production and corrosion in seawaters during exposure to FAME diesel

Experiments were designed to evaluate the corrosion-related consequences of storing/transporting fatty acid methyl ester (FAME) alternative diesel fuel in contact with natural seawater. Coastal Key West, FL (KW), and Persian Gulf (PG) seawaters, representing an oligotrophic and a more organic- and inorganic mineral-rich environment, respectively, were used in 60 day incubations with unprotected carbon steel. The original microflora of the two seawaters were similar with respect to major taxonomic groups but with markedly different species. After exposure to FAME diesel, the microflora of the waters changed substantially, with Clostridiales (Firmicutes) becoming dominant in both. Despite low numbers of sulphate-reducing bacteria in the original waters and after FAME diesel exposure, sulphide levels and corrosion increased markedly due to microbial sulphide production. Corrosion morphology was in the form of isolated pits surrounded by an intact, passive surface with the deepest pits associated with the fuel/seawater interface in the KW exposure. In the presence of FAME diesel, the highest corrosion rates measured by linear polarization occurred in the KW exposure correlating with significantly higher concentrations of sulphur and chlorine (presumed sulphide and chloride, respectively) in the corrosion products.     

Effects of oxygen on biodegradation of fuels in a corroding environment

The relationship between corrosion and biodegradation of bio- and petroleum-based fuels was evaluated using aerobic seawater, fuel and unprotected carbon steel coupons under stagnant conditions to simulate a potential fuel storage condition. Aerobic respiration and corrosion reactions consumed oxygen in the incubations in a short time. The transient oxygen influenced the microbial biodegradation of all fuels and resulted in a suite of characteristic metabolites, including catechols. The corrosion was believed to be the result of biogenic sulfide production and in all cases, the black corrosion products contained chlorine and sulfur (presumed chloride and sulfide) in addition to iron. There were few differences in electrochemically measured corrosion rates in incubations amended with any of the fuels or their blends. Clone library analysis demonstrated higher proportions of Firmicutes, Deltaproteobacteria (primarily sulfate-reducing bacteria), Chloroflexi, and Lentisphaerae in incubations exposed to fuels than the original seawater. Relative proportions of sequences affiliated with these bacterial groups varied with fuel. Methanogen sequences similar to those of Methanolobus were also found in multiple incubations. Despite the dominance of characteristically anaerobic taxa, sequences coding for an alkane monooxygenase from marine hydrocarbon-degrading genera and aerobically produced intermediates were observed, indicative that organisms with this metabolic potential were active at some point during the incubation. Aerobic oxidation of fuel components resulted in the formation of a series of intermediates that could be used by anaerobic seawater microbial communities to support metabolism, sulfide production, and carbon steel corrosion.     

Corrosion protection of reusable surgical instruments

To understand the corrosion properties of surgical scissors, 416 stainless steel disks and custom electrodes were used as simulated surfaces under various conditions. These simulated surfaces were exposed to tap water and 400-ppm synthetic hard water as Ca2CO3 under different conditions. The samples were evaluated by various techniques for corrosion potential and the impact of environmental conditions on the integrity of the passive film. The electrodes were used to monitor the corrosion behavior by potentiodynamic polarization technique in water both in the presence and absence of a cleaning product. The surface topography of the 416 stainless steel disks was characterized by visual observations and scanning electron microscopy (SEM), and the surface chemistry of the passive film on the surface of the scissors was characterized by x-ray photoelectron spectroscopy (XPS). The results suggest that surgical instruments made from 416 stainless steel are not susceptible to uniform corrosion; however, they do undergo localized corrosion. The use of suitable cleaning products can offer protection against localized corrosion during the cleaning step. More importantly, the use of potentiodynamic polarization techniques allowed for a quick and convenient approach to evaluate the corrosion properties of surgical instruments under a variety of simulated-use environmental conditions.     

Role of <Emphasis Type="Italic">Serratia marcescens</Emphasis> ACE2 on diesel degradation and its influence on corrosion

A facultative anaerobic species Serratia marcescens ACE2 isolated from the corrosion products of diesel transporting pipeline in North West, India was identified by 16S rDNA sequence analysis. The role of Serratia marcesens ACE2 on biodegradation of diesel and its influence on the corrosion of API 5LX steel has been elucidated. The degrading strain ACE2 is involved in the process of corrosion of steel API 5LX and also utilizes the diesel as an organic source. The quantitative biodegradation efficiency (BE) of diesel was 58%, calculated by gas-chromatography–mass spectrum analysis. On the basis of gas-chromatography–mass spectrum (GC–MS), Fourier Transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD), the involvement of Serratia marcescens on degradation and corrosion has been investigated. This basic study will be useful for the development of new approaches for detection, monitoring and control of microbial corrosion.     

Sulphide production and corrosion in seawaters during exposure to FAME diesel

Experiments were designed to evaluate the corrosion-related consequences of storing/transporting fatty acid methyl ester (FAME) alternative diesel fuel in contact with natural seawater. Coastal Key West, FL (KW), and Persian Gulf (PG) seawaters, representing an oligotrophic and a more organic- and inorganic mineral-rich environment, respectively, were used in 60?day incubations with unprotected carbon steel. The original microflora of the two seawaters were similar with respect to major taxonomic groups but with markedly different species. After exposure to FAME diesel, the microflora of the waters changed substantially, with Clostridiales (Firmicutes) becoming dominant in both. Despite low numbers of sulphate-reducing bacteria in the original waters and after FAME diesel exposure, sulphide levels and corrosion increased markedly due to microbial sulphide production. Corrosion morphology was in the form of isolated pits surrounded by an intact, passive surface with the deepest pits associated with the fuel/seawater interface in the KW exposure. In the presence of FAME diesel, the highest corrosion rates measured by linear polarization occurred in the KW exposure correlating with significantly higher concentrations of sulphur and chlorine (presumed sulphide and chloride, respectively) in the corrosion products.     

Wear Resistance and Non-Magnetic Layer Formation on 316L Implant Material with Plasma Nitriding

In this study, the applicability of plasma nitriding treatment in the production of non-magnetic and corrosion resistant layer on 316L stainless steel implant material was investigated. 316L stainless steel substrates were plasma nitrided at temperatures of 350 ℃, 375 ℃, 400 ℃, 425 ℃ and 450 ℃ for 2 h in a gas mixture of 50% N2-50% H2, respectively. It was determined that the treatment temperature is the most important factor on the properties of the corrosion resistant layer of 316L stainless steel. The results show that s-phase formed at the temperatures under 400 ℃, and at the temperatures above 400 ℃, instead of s-phase, CrN and y＇-Fe4N phases were observed in the modified layer. The electrical resistivity and surface roughness of the modified layer increase with treatment temperature. Under 400 ℃ the corrosion resistance increased with the temperature, above 400 ℃ it decreased with the increase in treatment temperature. It was analyzed that the electrical resistivity and the soft （ideal） ferro- magnetic properties of 316L stainless steel increased with treatment temperature during nitriding treatment. Also, plasma ni- triding at low temperatures provided magnetic behavior close to the ideal untreated 316L stainless steel.     

Extensive desulfurization of diesel by <Emphasis Type="Italic">Rhodococcus erythropolis</Emphasis>

The resting cells of a new isolate of Rhodococcus erythropolis FSD-2 were used to desulfurize diesel fuels. About 97% of the total sulfur content in the hydrodesulfurized diesel was removed by the two consecutive biodesulfurization (BDS) processes with the majority (∼94%) being removed in the first treatment, resulting in diesel with a sulfur content of 5.7 μg ml⁻¹.     

脱硫菌Fds-1的分离鉴定及其对柴油脱硫特性的研究

从含硫土壤中分离筛选出一株专一性脱硫菌Fds-1,经生理生化指标和16S rRNA序列分析鉴定其属于枯草芽孢杆菌(Bacillus subtilis)。用Gibb’s试剂显色和气相色谱-质谱联用分析表明,该菌株通过“4S”途径脱除有机硫。实验发现Fds-1的最佳脱硫活性在30℃,在此温度下72h内能脱除约0.5mmol/L DBT中的有机硫。Fds-1菌株对有机硫化合物的利用情况和柴油脱硫前后烃组分比较都进一步证明该菌株适合于柴油生物脱硫。利用休止细胞对不同组分柴油的脱硫研究表明,脱硫菌株Fds-1对精制柴油中的DBT类化合物的降解能力强。因此,该菌株对精制低硫柴油的深度脱硫具有应用意义。     

Impact of biodiesel on biodeterioration of stored Brazilian diesel oil

Alternative fuels are receiving considerable attention, especially biodiesel, which is recognized for its environmental benefits. One advantage is its biodegradability. However, biodegradability may allow the fuel to be more susceptible to microbial contamination, especially during storage. The susceptibility to biodeterioration of biodiesel, diesel, and diesel containing 5, 10, and 20% biodiesel was evaluated using fungi isolated from contaminated oil systems. Paecilomyces sp. produced the highest biomass in 20% and 100% biodiesel, while Aspergillus fumigatus grew best in pure biodiesel. Yeasts had the highest rates of degradation, especially Candida silvicola, with 100% degradation of all esters. Rhodotorula sp. showed greatest activity for C18:3 (linolenic acid), at 39.4%, followed by C18:1 (oleic acid) and C16 (palmitic acid), at 21% and 15%, respectively, after 7 days of incubation. The results are relevant for the resolution of the decade-long debate on the increase in diesel biodegradability due to the addition of biodiesel.     

Metal corrosion by aerobic bacteria isolated from stimulated corrosion systems: Effects of additional nitrate sources

Many microorganisms are reported to influence the corrosive behaviour of mild steel and stainless steel in different habitats. In this study, 40 bacterial strains were isolated from corroded mild steel and stainless steel coupons in the nitrate supplemented environments. The corrosion abilities of the isolates against the mild steel and stainless steel coupons were tested with or without additional nitrate sources. The presence of bacterial isolates alone stimulated the corrosion of mild steel coupons. Most of the bio-corrosion processes of mild steel coupons were mitigated by adding nitrate supplement with bacterial isolates. The effects of bacterial isolates and additional nitrogen sources on corrosion of stainless steels were varied. Not all bacterial isolates stimulated the corrosion on stainless steel during the study period. Unlike the effects on mild steel coupons, additional NaNO₃ might stimulate, retard the corrosion rate by the bacterial isolates or have limited effects. Similar results were obtained when NH₄NO₃ was used. Phylogenetic analysis demonstrated that all isolates were closely related. The majority of the bacterial isolates from corroded metal coupons were identified as Bacillus species. Others were identified as Pseudomonas sp., Marinobacter sp., and Halomonas species. The results prove that the isolated aerobic microorganisms do play a role in the corrosion process of stainless and mild steel. Adding additional nitrate sources might be a tool to mitigate corrosion of mild steel which was stimulated by the presence of bacteria. However, to prevent the corrosion of stainless steels, it might need a trial and errors approach in each case.     

Microbially influenced corrosion of galvanized steel pipes in aerobic water systems

Aims: To investigate the role of heterotrophic bacteria in the corrosion of galvanized steel in the presence of water. Methods and Results: Samples were taken from corroding galvanized steel pipes conveying water for specialist applications, and heterotrophic bacteria were isolated and cultured. The majority of bacteria were Gram‐negative aerobes and included Pseudomonas sp., Bacillus pumilus, Afipia spp. and Blastobacter denitrificans/Bradyrhizobium japonicum. Zinc tolerance was assessed through growth and zinc disc diffusion experiments. In general, zinc negatively influenced growth rates. An unidentified yeast also isolated from the system demonstrated a high tolerance to zinc at concentrations up to 4 g l^?1. Coupon experiments were performed to assess corrosion by the bacteria on galvanized steel and steel coupons. The majority of isolates as pure culture biofilms (69%) accelerated corrosion of galvanized coupons, assessed as zinc release, relative to sterile control coupons (P < 0·05). Pure culture biofilms did not increase the corrosion of steel, with four isolates demonstrating protective effects. Conclusions: Pure culture biofilms of heterotrophic bacteria isolated from a corroding galvanized pipe system were found to accelerate the corrosion of galvanized steel coupons. Significance and Impact of the Study: Microbially influenced corrosion is a potential contributor to sporadically occurring failures in galvanized steel systems containing water. Management strategies should consider microbial control as a means for corrosion prevention in these systems.     

Effects of diverse water pipe materials on bacterial communities and water quality in the annular reactor

To investigate the effects of pipe materials on biofilm accumulation and water quality, an annular reactor with the sample coupons of four pipe materials (steel, copper, stainless steel, and polyvinyl chloride) was operated under hydraulic conditions similar to a real plumbing system for 15 months. The bacterial concentrations were substantially increased in the steel and copper reactors with progression of corrosion, whereas those in stainless steel (STS) and polyvinyl chloride (PVC) reactors were affected mainly by water temperature. The heterotrophic plate count (HPC) of biofilms was about 100 times higher on steel pipe than other pipes throughout the experiment, with the STS pipe showing the lowest bacterial number at the end of the operation. Analysis of the 16S rDNA sequences of 176 cultivated isolates revealed that 66.5% was Proteobacteria and the others included unclassified bacteria, Actinobacteria, and Bacilli. Regardless of the pipe materials, Sphingomonas was the predominant species in all biofilms. PCR-DGGE analysis showed that steel pipe exhibited the highest bacterial diversity among the metallic pipes, and the DGGE profile of biofilm on PVC showed three additional bands not detected from the profiles of the metallic materials. Environmental scanning electron microscopy showed that corrosion level and biofilm accumulation were the least in the STS coupon. These results suggest that the STS pipe is the best material for plumbing systems in terms of the microbiological aspects of water quality.     

Microorganisms in Heat Supply Systems and Internal Corrosion of Steel Pipelines

In laboratory experiments with batch cultures of thermophilic microorganisms isolated from urban heat supply systems, the growth of sulfate-reducing, iron-oxidizing, and iron-reducing bacteria was found to accelerate the corrosion rate of the steel-3 plates used in pipelines. In the absence of bacteria and dissolved oxygen, minimal corrosion was determined. The aforementioned microorganisms, as well as sulfur-oxidizing bacteria, were found to be widespread in water and corrosion deposits in low-alloy steel pipelines (both delivery and return) of the Moscow heat networks, as well as in the corrosion deposits on the steel-3 plates in a testing unit supplied with the network water. The microorganisms were found in samples with a water pH ranging from 8.1 to 9.6 and a temperature lower than 90°C. Magnetite, lepidocrocite, goethite, and X-ray amorphous ferric oxide were the corrosion products identified on the steel-3 plates, as well as siderite, aragonite, and S⁰. The accumulation of corrosion deposits and variation in the total and local corrosion of the steel plates in a testing unit were considered in terms of the influence of microbial processes.     

Enhancement of bunker oil biodesulfurization by adding surfactant

Biodesulfurization (BDS) is a promising method to remove sulfur compounds from diesel and gasoline. However, the information on BDS of heavy oil is scanty, which might be due to their ??undesirable?? physical properties and more complicated sulfur diversities. In this study, the BDS of one kind of heavy oil, bunker oil MFO380 was investigated. The biocatalyst was obtained by the enrichment with oil sludge as the seed and using dibenzothiophene (DBT) as the sole sulfur source. The enriched biocatalyst (microbial mixed culture) could selectively remove sulfur from DBT and DBT was transformed into 2-hydroxybiphenyl, which indicates that the BDS process is beneficial to non-destructive carbon bonds and thus can maintain the calorific value. The bunker oil BDS results showed that after 7?days of incubation, the removal efficiency of sulfur in MFO380 was only 2.88?%, but this could be significantly improved by adding surfactants Triton X-100 or Tween 20. This effect could be attributed to greatly reduced viscosity of heavy oil and increased mass transfer of sulfur compounds in heavy oil into water. Adding Triton X-100 achieved the highest removal efficiency of sulfur, up to 51.7?% after 7?days of incubation. The optimal amount of Triton X-100 was 0.5?g/50?ml medium. When toluene was added as an organic solvent for MFO380, the BDS activity was improved, while lower than the effect of adding surfactants.     

Analysing the water and greenhouse gas effects of soya bean‐based biodiesel in five different regions

Bioenergy may have significant lower greenhouse gas (GHG) emission intensities compared to fossil alternatives, but concerns are raised that bioenergy would contribute to additional water scarcity. Therefore, the GHG intensity, water intensity and water‐related risks are analysed simultaneously for conventional diesel and soya bean‐based biodiesel from Argentina, Brazil, Unites States (U.S.), Thailand and Iran on a life cycle basis. The water‐related risks are estimated with a water scarcity—consumption matrix, which was recently developed. Results show that a significant share (9%‐38%) of the GHG emissions in all biodiesel cases is caused by soil N₂O emissions. In addition, the ranges in water consumption intensity for soya bean‐based biodiesel are considerably larger than for fossil fuels. However, whether this leads to high water‐related risks depends on the local water scarcity. Soya bean‐based biodiesel from Argentina has low water‐related risks to all nodes of the supply chain due to low local water stress combined with a low direct water consumption intensity (20 L/GJ_fuel). In addition, high GHG emission reduction (71%) and a low‐specific eutrophication potential (0.04 kg PO₄^3?/GJ_fuel) are achieved. The indirect water consumption intensity is estimated at 120–420 L/GJ for soya bean‐based biodiesel, which is significant if the soya beans are rainfed, like in Argentina and Brazil. If irrigation is required, indirect water consumption is dwarfed by irrigation water. Overall, it is concluded that soya bean‐based biodiesel can have significant lower GHG emission intensity than fossil diesel, without causing additional water stress in the supply chain if they are produced in water abundant areas and good agricultural practices are used. The used method shows disaggregated water‐related risks for the different nodes of the supply chain to acknowledge the regional nature of water scarcity and enables decision makers to identify “hot spots” and take targeted actions.     

Identification of key factors in Accelerated Low Water Corrosion through experimental simulation of tidal conditions: influence of stimulated indigenous microbiota

Biotic and abiotic factors favoring Accelerated Low Water Corrosion (ALWC) on harbor steel structures remain unclear warranting their study under controlled experimental tidal conditions. Initial stimulation of marine microbial consortia by a pulse of organic matter resulted in localized corrosion and the highest corrosion rates (up to 12-times higher than non-stimulated conditions) in the low water zone, persisting after nine months exposure to natural seawater. Correlations between corrosion severity and the abundance and composition of metabolically active sulfate-reducing bacteria (SRB) indicated the importance and persistence of specific bacterial populations in accelerated corrosion. One phylotype related to the electrogenic SRB Desulfopila corrodens appeared as the major causative agent of the accelerated corrosion. The similarity of bacterial populations related to sulfur and iron cycles, mineral and tuberculation with those identified in ALWC support the relevance of experimental simulation of tidal conditions in the management of steel corrosion exposed to harbor environments.     

Role of iron-reducing bacteria in corrosion and protection of carbon steel

The role of iron-reducing bacteria (IRB) in biocorrosion is under discussion. According to some reports, IRB are able to induce protection of carbon steel while others suggest an important enhancement of corrosion through the reduction and removal of passive films of ferric compounds on the metal surface. In this work, we review recent knowledge concerning microbial respiration, the ecology of IRB containing biofilms and the corrosive or protective effect of such biofilms on metal surfaces.     

Inhibiting mild steel corrosion from sulfate-reducing and iron-oxidizing bacteria using gramicidin-S-producing biofilms

A gramicidin-S-producing Bacillus brevis 18-3 biofilm was shown to reduce corrosion rates of mild steel by inhibiting both the sulfate-reducing bacterium Desulfosporosinus orientis and the iron-oxidizing bacterium Leptothrix discophora SP-6. When L. discophora SP-6 was introduced along with D. orientis to a non-antimicrobial-producing biofilm control, Paenibacillus polymyxa ATCC 10401, a corrosive synergy was created and mild steel coupons underwent more severe corrosion than when only D. orientis was present, showing a 2.3-fold increase via electrochemical impedance spectroscopy (EIS) and a 1.8-fold difference via mass-loss measurements. However, when a gramicidin-S-producing, protective B. brevis 18-3 biofilm was established on mild steel, the metal coupons were protected against the simultaneous attack of D. orientis and L. discophora SP-6. EIS data showed that the protective B. brevis 18-3 biofilm decreased the corrosion rate about 20-fold compared with the non-gramicidin-producing P. polymyxa ATCC 10401 biofilm control. The mass loss for the protected mild steel coupons was also significantly lower than that for the unprotected ones (4-fold decrease). Scanning electron microscope images corroborated the corrosion inhibition by the gramicidin-S-producing B. brevis biofilm on mild steel by showing that the metal surface remained untarnished, i.e., the polishing grooves were still visible after exposure to the simultaneous attack of the sulfate-reducing bacterium and the iron-oxidizing bacterium.