Production of a halotolerant lipase from Halomonas sp. strain C2SS100: Optimization by response-surface methodology and application in detergent formulations

The aim of this work was to optimize the production of a new lipase by a halotolerant bacterial strain Halomonas sp. C2SS100, by means of the response-surface methodology (RSM). The process parameters having the most significant effect on lipase production were identified using the Plackett–Burman screening design-of-experiments. Then, Box–Behnken design was applied to optimize lipase activity and the quadratic regression model of the lipase production was built. Indeed, the lipase yield was increased, and the value obtained experimentally (39 ± 2 U/ml) was very close to the rate predicted by the model (40.3 U/ml). Likewise, optimization of parameters by RSM resulted in 2.78-fold increase in lipase activity. These findings provide the first report on lipase production and optimization by a halotolerant bacterial strain belonging to Halomonas genus. Afterward, the biochemical properties of the produced lipase were studied for apply in oil stains removal. The crude lipase showed a maximum activity at 60°C and at pH ranging from 7 to 10. It displayed an important stability at high temperature, pH, and NaCl. Interestingly, this bacterial lipase exhibited a prominent stability toward some commercial solid and liquid detergents after 30 min of incubation at 50°C. The capability of the crude lipase to eliminate stain was ascertained on polycotton fabric pieces stained with lubricating oil. Whether with the addition of hot water alone or of a commercially available detergent, lipase is able to considerably boost the elimination of oil stains. The actual findings highlight the capacity of Halomonas sp. lipase for energy-efficient biocatalytic application.     

Enhancement effect of zero-valent iron nanoparticle and iron oxide nanoparticles on dark fermentative hydrogen production from molasses-based distillery wastewater

This study investigates the effect of two different iron compounds (zero-valent iron nanoparticle: nZVI and iron oxide nanoparticles: nIO) and pH on fermentative biohydrogen production from molasses-based distillery wastewater. The nZVI and nIO of optimum particle sizes of 50 nm and 55 nm respectively were synthesized and applied for fermentative hydrogen (H₂) production. The addition of nIO & nZVI at (0.7 g/L, pH: 6) resulted in the highest H₂ yield, H₂ production rate, H₂ content and COD reduction. Moreover, the kinetic parameters of H₂ production potential (P) and H₂ production rate (R_m) increased to 387 mL, and 22.2 mL/h, respectively for nZVI, these values were 363 mL and 21.8 mL/h for nIO. The results obtained indicated the positive effect of nZVI and nIO addition on enhanced fermentative H₂ production. The addition of nZVI & nIO resulted in 71% and 69.4% enhancement in biohydrogen production respectively.     

Influence of Different Additives on the Interaction of Quinolone Antibiotic Drug with Surfactant: Conductivity and Cloud Point Measurement Study

Conductometric and cloud point (CP) measurement studies have been performed to investigate the interaction of tetradecyltrimethylammonium bromide (TTAB) and Triton® X-100 (TX-100) with ciprofloxacin hydrochloride (CFH) in different solvents over the temperature range of 295.15–315.15 K. CFH is used for the treatment of various bacterial infections. The observed critical micelle concentration (CMC) values of TTAB were found to be reduced in the presence of electrolytes (Na₂SO₄/Na₃PO₄), and this reduction proceeds with the elevation of salt concentration. The order of the CMC of TTAB follows the trend: > >. The observed CMC values of TTAB were found to increase with increasing temperature and decrease with increasing concentration of CFH in aqueous medium. The values of Gibbs free energy of micellization () for the TTAB/TTAB + CFH mixture were found to be negative, implying spontaneous micellization. The estimated CP of TX-100 decreases with increasing concentration of TX-100 in aqueous medium. The CP values first decrease with increasing concentration of CFH and then increase at higher concentration of CFH almost in all cases investigated. The values of free energy of clouding were found to be positive in all cases studied implying that phase separation of TX-100 was nonspontaneous. The other thermodynamic parameters associated with the micellization of TTAB and the phase separation of TX-100 were estimated and explained.     

A comparison study into low leak rate buoyant gas dispersion in a small fuel cell enclosure using plain and louvre vent passive ventilation schemes

Hydrogen, producing electricity in fuel cells, is a versatile energy source, but with risks associated with flammability. Fuel cells use enclosures for protection which need ventilating to remove hydrogen emitted during normal operation or from supply system leaks. Passive ventilation, using buoyancy driven flow is preferred to mechanical systems. Performance depends upon vent design, size, shape, position and number. Vents are usually plain rectangular openings, but environmentally situated enclosures use louvres for protection. The effect of louvres on passive ventilation is not clear and has therefore been examined in this paper. Comparison ‘same opening area’ louvre and plain vent tests were undertaken using a 0.144 m³ enclosure with opposing upper and lower vents and helium leaking from a 4 mm nozzle on the base at rates from 1 to 10 lpm, simulating a hydrogen leak. Louvres increased stratified level helium concentrations by typically in excess of 15%. The empirical data obtained was also used in a validation exercise with a SolidWorks: Flow Simulation CFD model, which provided a good qualitative representation of flow behaviour and close empirical data correlations.     

Evaluation of particle recovery from microalgae

Coccoliths are micro-structured biomineral particles found in cell protective covering layers of coccolithophore species. They are mainly composed of CaCO₃ and their individual crystal entities are arranged in such a way that they construct complex and unique structures. This complexity is found down to the individual particle level and appears to have promising properties to offer. This study focuses on the essential step prior to any kind of implementation, which is the recovery of the material. It summarizes cleaning protocols found in literature, compares them for the first time for the same freshly cultivated material and addresses challenges that still need to be overcome. Further, it highlight the advantages and disadvantages of the best cleaning protocols, suggests optimizations with promising results and uses size distribution measurements to analyse the recovery efficiency. To that end, further characterization techniques, new for coccoliths, are introduced and used to improve our current knowledge of the particles behaviour.     

Steel slag waste combined with melamine pyrophosphate as a flame retardant for rigid polyurethane foams

To explore the potential application of industrial waste, steel slag powder in combination with melamine pyrophosphate (MPP) was adopted to improve the flame retardancy of rigid polyurethane foam (RPUF). The incorporation of steel slag slightly reduced the thermal conductivity of the resulting flame-retardant RPUF samples. The addition of MPP and/or steel slag did not significantly alter the thermal stability in terms of T_-10% and T_max but did obviously increase the T_-50% value, suggesting the improved thermal resistance of the residues. The coaddition of MPP and steel slag into RPUF resulted in higher LOI values and lower peak heat release rates than the samples incorporating either MPP or steel slag alone. The superior flame retardancy could be attributed to MPP promoting char formation, which then acted as a barrier at the beginning of RPUF thermal decomposition; simultaneously, the thermally stable inorganics in the steel slag powder strengthened the thermal resistance of this char layer.     

Optimizing 100%‐renewable grids through shifting residential water‐heater load

A low‐carbon electricity supply for Australia was simulated, and the installed capacity of the electrical grid was optimized by shifting the electricity demand of residential electric water heaters (EWHs). The load‐shifting potential of Australia was estimated for each hour of the simulation period using a nationwide aggregate EWH load model on a 90 × 110 raster grid. The electricity demand of water heaters was shifted from periods of low renewable resource and high demand to periods of high renewable resource and low demand, enabling us to effectively reduce the installed capacity requirements of a 100%‐renewable electricity grid. It was found that by shifting the EWH load by just 1 hour, the electricity demand of Australia could be met using purely renewable electricity at an installed capacity of 145 GW with a capacity factor of 30%, an electricity spillage of 20%, and a generation cost of 15.2 ¢/kWh. A breakdown of the primary energy sources used in our scenario is as follows: 43% wind, 29% concentrated solar thermal power, and 20% utility photovoltaic. Sensitivity analysis suggested that further reduction in installed capacity is possible by increasing the load‐shifting duration as well as the volume and insulation level of the EWH tank.     

Materials aspects associated with the addition of up to 20 mol% hydrogen into an existing natural gas distribution network

The introduction of hydrogen into the UK natural gas main has been reviewed in terms of how materials within the gas distribution network may be affected by contact with up to 80% Natural Gas (NG)/20 mol% hydrogen blend at up to 2 barg. A range of metallic, polymeric and elastomeric materials in the gas distribution network (GDN) were assessed via a combination of literature review and targeted practical test programmes.The work considered:? The effect of hydrogen on metallic materials identified in the network.? The effect of hydrogen on polymeric materials identified in the network.? The effect of hydrogen exposure on polyethylene pipeline joining and repair techniques (squeeze-off, and socket and saddle electrofusion joints)The experimental work involved soaking materials, under pressure conditions representative of the network, in 100% hydrogen, 20% hydrogen in methane, and 100% methane. For the metal samples, the test programme involved the assessment of hydrogen uptake on the tensile properties. For the polyethylene samples, the test programme looked at the assessment of possible hydrogen absorption/desorption and its effect on electrofusion jointing.The trials concluded that the majority of metallic materials showed no significant deterioration in mechanical (tensile) properties when stored in hydrogen environments compared to those stored in analogous methane or blended gas atmospheres up to 2 barg. Polymeric materials showed no deterioration to efficiency of squeeze-off or collar electrofusion in socket or shoulder orientations following soaking in hydrogen, methane or hydrogen blends.     

Use of micellar extraction and cloud point preconcentration for valorization of saponins from sisal (Agave sisalana) waste

Sisal (Agave sisalana) is the main hard fiber produced worldwide, with an estimated generation of 400 thousands t in 2011. From its leaves, only the hard fibers, which represent 3–5% of their weight, are removed. The remaining 95–97% is referred to as sisal waste and contains steroidal saponins that can be potentially used in foods, cosmetics and pharmaceuticals formulations, as well as for soil bioremediation. The present work aimed at to evaluate strategies for the extraction and concentration of saponins from sisal waste, focused on the use of clean solvents, such as water and ethanol. For this purpose, it was firstly performed a central composite rotatable design for the optimization of the extraction conditions followed by a comparison of this strategy with other methods (Soxhlet, ultrasound-assisted extraction and micellar extraction). Cloud point preconcentration was then tested, using several types and concentrations of salts. The use of orbital shaker extraction (200 rpm) with an ethanolic solution (30%, v/v) at 50 °C, a mass/volume ratio sisal/solvent of 0.17 (g/mL) for 4 h allowed a recovery of 38.6% of the saponins. When a micellar extraction strategy using 7.5% (v/v) of Triton X-100, under the above-mentioned conditions was performed, saponins recovery raised to 98.4%. In a subsequent step, the addition of 20% (m/v) sodium carbonate led to a preconcentration factor of 20.3. The best adsorbent for Triton removal from the preconcentrated solution was Amberlite FPX-66. The process strategy proposed in the present study showed to be efficient for saponins extraction and preconcentration from a low-cost, highly available agricultural waste.