Effect Of pH Changes Research Articles

SILAR Yöntemi İle Oda Sıcaklığında Üretilen CdO Filmlerinin Yapısal Morfolojik ve Optik Özelliklerine pH Değişimin Etkisi

Bu çalışmada oda sıcaklığında cam altlık üzerine SILAR tekniği ile büyütülen CdO ince filmlere pH etkisi araştırıldı. Elde edilen ince filmlerin yapısal, morfolojik ve optik özellikleri sırasıyla X-ışını difraksiyonu (XRD), taramalı elektron mikroskobu (SEM) ve UV vis spektrofotometre ölçümleri alınarak incelendi. XRD sonuçları, ince filmlerin pH 11.5 ve daha yüksek değerlerde farklı açı ve düzlemlere yönelim sergilediğini gösterdi. SEM görüntüleri, filmlerin yüzey morfolojisinin pH değeri değişimi ile önemli derecede değiştiğini gösterdi. Yapılan optik soğurma ölçümleri ise pH yükselmesine bağlı olarak band aralığının arttığını gösterdi.

Effect of pH on Rheological and Filtration Properties of Water-Based Drilling Fluid Based on Bentonite

The design of drilling fluids is very important for the drilling operation success. The rheological properties play a key role in the performance of the drilling fluid. Therefore, studying the mud rheological properties of the water-based drilling fluid based on bentonite is essential. The main objectives of this study are to address the effect of pH changes on the rheological and filtration properties of the water-based drilling fluid based on bentonite and to provide a recommended pH range for this drilling fluid for a safe and high-performance drilling operation. Different samples of the water-based drilling fluid based on bentonite with different pH values were prepared, and the rheological properties such as plastic viscosity, yield point, and gel strength were measured. After that, the filtration test was performed under 300 psi differential pressure and 200 °F. The pH for the water-based drilling fluid based on bentonite significantly affects the mud rheology. The shear stress and shear rate relation were varying with the change in the pH. Increasing the pH from 8 to 12 resulted in decreasing the plastic viscosity by 53% and the yield point by 82%, respectively. The ratio of yield point / plastic viscosity was 1.4 for pH of 8 while it decreased to 0.5 for a pH of 11 and 12. There was a significant decrease in the gel strength readings by increasing the pH. The filtrate volume and filter cake thickness increased by increasing pH. The filtration volume increased from 9.5 cm3 to 12.6 cm3 by increasing the pH from 9 to 12. The filter cake thickness was 2 mm at 9 pH, while it was increased to 3.6 mm for 12 pH. It is recommended from the results to keep the pH of water-based drilling fluid based on bentonite in the range of 9 to 10 as it provides the optimum mud rheological and filtration properties. The findings of this study illustrated that keeping the pH in the range of 9 to 10 will reduce the plastic viscosity that will help in increasing the rate of penetration and reducing the required pump pressure to circulate the mud to the surface which will help to sustain the drilling operation. In addition, reducing the filtrate volume will produce a thin filter cake which will help in avoiding the pipe sticking and protect the environment. In general, optimizing the pH of the water-based drilling fluid based on bentonite in the range of 9 to 10 will improve the drilling operation and minimize the total cost.

Deep eutectic solvent as an efficient modifier of low-cost adsorbent for the removal of pharmaceuticals and dye

Waste from biomass was used to prepare a low–cost biochar–clay hybrid adsorbent. The hybrid adsorbent was synthesised by combining Kaolin with biomass (Vitex doniana), thereafter, modified with Deep Eutectic Solvent (DES). The materials were characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), Thermal gravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET), also, pHpzc of the materials were studied. The resultant adsorbents were used for both column and batch adsorption of organic pollutants; dye (Acid Blue 74; AB74) and pharmaceuticals (ciprofloxacin; CIP and acetaminophen; ACTE). Column adsorption capacity, effect of pollutant concentration and effect of flow rate were studied, also, the column was modelled using Thomas, Yoon-Nelson and Adams-Bohart model. Furthermore, batch adsorption experiments were performed, effect of change in pH, time, dose and concentration were studied. Batch adsorption data were fitted with isotherm and kinetic models. The experiment showed tremendous increase in adsorption capacity when the hybrid adsorbent (HYD) was modified with DES (HYD–DES). Acid Blue 74 on HYD–DES has the highest column sorption capacity followed by ciprofloxacin and acetaminophen. Adsorption was favoured at pH range of 2–10 for both AB74 and ACTE as there is no significant changes in the % removal performance, while adsorption was best at pH 6 and above for CIP. AB74 and CIP are best described by Langmuir isotherm, whereas ACTE adsorption was best explained by Freundlich isotherm equilibrium. The DES modified HYD has shown it can be effectively utilised as possible adsorbent for adsorbing organic dyes and pharmaceuticals.

Effect of pH change on size and nanomechanical behavior of whey protein microgels

Microgels specific structural and functional features are attracting high research interest in several applications such as bioactives and drug delivery or functional food ingredients. Whey protein microgels (WPM) are obtained by heat treatment of whey protein isolate (WPI) in order to promote intramolecular cross-linking. In the present work, atomic force microscopy (AFM) was used in contact mode and in liquid to investigate WPM particles topography and mechanical properties at the nanoscale at native pH (6.5) and acid pH (5.5 and 3.0). Prior to AFM, WPM particles were captured on a gold substrate via low energy interactions by means of specific monoclonal antibodies. AFM images clearly showed an increase in the size of WPM particles induced by pH decrease. AFM in force spectroscopy mode was employed to monitor the elasticity of WPMs. The obtained effective Young’s modulus data showed a significant increase in stiffness at pH 5.5 and pH 3.0, over 15-fold compared to native pH. These findings indicate that the mechanical profile of the WPM network varied with the pH decrease. The WPM topographic and nanomechanical changes induced by acidification were most likely due to substantial changes in the shape and inner structure of WPM particles. Our results suggest that internally cross-linked structures, modified by acidification could display interesting functional properties when used as a food ingredient.

Effect of pH Change and water Temperature On Nickel Removal from Surface Water by Chemical Precipitation

The research aims to find relationship between indications, change of raw surface water which are: pH, temperature, and optimum doses of alum [Al2(SO4)3.14H2O] to develop a suitable mathematical equation. A series of experiments were performed under different conditions and on different seasonal circumstances to determine the effect of the previous indications on the coagulation efficiency, where we treat Qattinah lake water by Coagulation, Sedimentation then Filtration. We studied the impact of coagulant dose change with the change of pH water within the domain ( 6.5 to 8.5 ) and the percentage of nickel removal was 75 % at pH = 8 , and we studied the effect of coagulant dose change with raw water temperature change ( from 5 to 25) °C on reducing the nickel concentration where the percentage of nickel removed when the temperature 20 °C was up to 85%, and all that when the coagulant dose was 30 mg/l.

PH-Sensing Machinery of Excitation Energy Transfer in Diatom PSI–FCPI Complexes

Excitation energy-transfer processes in photosynthetic light-harvesting complexes are strongly affected by the surrounding environments of pigments. Here we report on the effects of pH changes on excitation energy dynamics in both diatom photosystem I-fucoxanthin chlorophyll a/ c-binding protein (PSI-FCPI) and PSI core complexes by means of fluorescence spectroscopies. The steady-state fluorescence spectra of the PSI-FCPI showed similar features among three samples at pH 5.0, 6.5, and 8.0. However, fluorescence decay-associated spectra of the pH 5.0- and 8.0-adapted PSI-FCPI within 100 ps exhibit peak shifts to longer and shorter wavelengths, respectively, than the peaks in the pH 6.5 spectra. Because such spectral changes hardly occur in the PSI complexes, the peak shifts at pH 5.0 and 8.0 in the PSI-FCPI can be ascribed to alterations of pigment-pigment and/or pigment-protein interactions around/within FCPI caused by the pH changes. These findings provide novel physical insights into the pH-sensing light-harvesting strategy in diatom PSI-FCPI.

Proteolysis of Reduced-Salt Cheddar Cheese as Affected by Casein to Fat Ratio, Rennet, and pH at Drainage

Effects of change in pH at drainage (6.2, 5.9, and 5.6), rennet concentration (0.1 and 0.3 mL rennet/L of milk) and casein to fat ratio (0.6, 0.7, and 0.8) on proteolytic characteristics of salt-reduced Cheddar cheese were investigated. Chemical composition, lactic acid bacteria and proteolysis were measured. At the same drainage pH, cheeses with C/F ratio 0.6 had significantly higher moisture and ash content compared other ratios. The pH decreased significantly from day 0 (right after pressing) to 120 day and then remained constant. Total LAB growth in cheeses made with 0.3 ml rennet /L was higher at the same C/F ratio and pH at drainage of 6.2. Total plate count at day 180 was significantly higher compared with day 0 (right after pressing). At the same drainage pH, C/F ratio and storage time, water soluble nitrogen contents in cheeses made with 0.3 ml/L rennet were higher compared with 0.1 ml/L. Total free amino acids and trichloroacetic acid-soluble nitrogen contents increased significantly during storage. More hydrophobic peaks appeared as the rennet concentration was increased from 0.1 to 0.3 ml/L. Extra-hydrophobic peptides % in cheese at day 0 and pH at drainage of 5.6, were higher compared to cheese where pH at drainage was 6.2. Increase in C/F ratio and rennet concentration, especially at low pH, showed similar proteolysis as cheese containing 2.5-3% salt.

Stress responses in Crassostrea gasar exposed to combined effects of acute pH changes and phenanthrene

Ocean acidification is a result of the decrease in the pH of marine water, caused mainly by the increase in CO2 released in the atmosphere and its consequent dissolution in seawater. These changes can be dramatic for marine organisms especially for oysters Crassostrea gasar if other stressors such as xenobiotics are present. The effect of pH changes (6.5, 7.0 and 8.2) was assessed on the transcript levels of biotransformation [cytochromes P450 (CYP2AU1, CYP2-like2) and glutathione S-transferase (GSTΩ-like)] and antioxidant [superoxide dismutase (SOD-like), catalase (CAT-like) and glutathione peroxidase (GPx-like)] genes, as well as enzyme activities [superoxide dismutase, (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferases transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH)] and lipid peroxidation (MDA) in the gills of Crassostrea gasar exposed to 100 μg·L−1 of phenanthrene (PHE) for 24 and 96 h. Likewise, the PHE burdens was evaluated in whole soft tissues of exposed oysters. The accumulation of PHE in oysters was independent of pH. However, acidification promoted a significant decrease in the transcript levels of some protective genes (24 h exposure: CYP2AU1 and GSTΩ-like; 96 h exposure: CAT-like and GPx-like), which was not observed in the presence of PHE. Activities of GST, CAT and SOD enzymes increased in the oysters exposed to PHE at the control pH (8.2), but at a lower pH values, this activation was suppressed, and no changes were observed in the G6PDH activity and MDA levels. Biotransformation genes showed better responses after 24 h, and antioxidant-coding genes after 96 h, along with the activities of antioxidant enzymes (SOD, CAT), probably because biotransformation of PHE increases the generation of reactive oxygen species. The lack of change in MDA levels suggests that antioxidant modulation efficiently prevented oxidative stress. The effect of pH on the responses to PHE exposure should be taken into account before using these and any other genes as potential molecular biomarkers for PHE exposure.

Uji Stabilitas Spironolakton Terhadap Perubahan pH dengan Menggunakan Kromatografi Cair Kinerja Tinggi (KCKT)

Spironolakton merupakan obat diuretic antagonis aldosterone untuk hipertensi. Pada prakteknya spironolakton terkadang digabungkan dengan obat-obat lain, dan pada pasien yang tidak sadarkan diri pemberian obat harus menggunakan feeding tube dan rentan akan ketidakstabilan.
 Objek dari penelitian ini adalah untuk melihat pengaruh perubahan pH pada spironolakton tablet yang digerus dan disuspensikan di dalam air. Metode pengukuran kadar spironolakton menggunakan Kromatografi Cair Kinerja Tinggi berdasarkan metode dalam United State Pharmacopeia. Suspensi spironolakton dibuat dalam pH 3, 5, 7, dan 9 dengan waktu pengambilan sampel pada menit ke 0, 15, 30, 45, dan 60.
 Hasil menunjukkan bahwa persen kadar spironolakton pada pH 3 adalah ≤ 40%, pH 5 adalah 74% - 100%. Pada pH 7 berada dikisaran 27% - 61%, dan pada pH 9 adalah 38% - 54%. Hal ini menjelaskan bahwa persen kadar spironolakton pada pH 3,7, dan 9 pada semua waktu pengambilan sampel sudah tidak sesuai dengan kadar terapi minimum dalam monograph. Hanya pada pH 5 kadar spironolakton masih sesuai dengan kadar yang ditentukan dalam monograph. Dalam penelitian ini dapat disimpulkan bahwa perubahan pH dapat menurunkan kadar spironolakton dalam suspensi secara signifikan.

Corrosion Performance of Valve Seat Hardfacing Materials in Amine Environment of Boiler Feed Water Service

As the valve seat hardfacing materials in boiler feed water service of coal power plants, the corrosion behavior of Stellite 6 alloy and 17-4PH stainless steel in amine solutions is studied using electrochemical test methods. Morpholine, cyclohexylamine, and sodium hydroxide (NaOH) solution with pH 9.5 are selected to be the corrosive media. The first solution is a typical amine medium, the second one is selected to examine if different amine media with the same pH can result in any change in the corrosion behavior of these materials. Sodium hydroxide is chosen to offset the effect of pH change. Polarization test is performed on Stellite 6 alloy and 17-4PH stainless steel under the low potential varying from –0.4 VSCE to 1.2 VSCE and is also conducted under a constant high potential (4 VSCE) in order to fail the sample surfaces. The polarization curves 17-4PH stainless steel from the low potential tests show an apparent passivation region indicating a protective oxide film formed on the sample surface, but Stellite 6 alloy only exhibits a tendency to passivate. The Stellite 6 alloy and 17-4PH stainless steel samples after the failure tests under the high potential (4 VSC) are analyzed using SEM/EDX. It is shown that the former is severely corroded in all the solutions while the latter is only corroded in morpholine solution and it is very corrosion-resistant in sodium hydroxide solution. The corrosion mechanisms of Stellite 6 alloy and 17-4PH stainless steel in amine solutions are discussed with assistance of the Pourbaix diagrams.

Experimental investigation of optical properties of oily sewage with different pH environment

Optical properties of oily sewage play an important role in detection of water quality index of oily sewage. The transmittance spectra of oily sewage were investigated and the optical properties of oily sewage were calculated. Transmittance spectra were measured by a TU-1900 spectrophotometer in the range of 190˜900nm in pH of 6.5˜11.8. The oily sewage optical properties were calculated by the double thickness method, and the optical properties of oily sewage with different pH were compared. The results show that the transmittance of different optical path all decreased with the increase of pH in the range of 8.7˜11.8, and the transmittance in acidic environment is much higher than that in alkaline. In the wavelength of 240˜350 nm and 650˜850 nm, the pH has obvious influence on the refractive index. With the increase of pH in range of 8.7˜11.8, the absorption index has a significant downward trend. When pH is 9.6 and wavelength range is 300˜700nm, the effect of pH change on the refractive index is greater than that of the absorption index.When the solution is neutral, the fitting of the optical properties of oily sewage is the best.

Effect of change in pH, heat treatment and diafiltration on properties of medium protein buffalo milk protein concentrate.

The demand of milk protein concentrate (MPC) powders is continuously increasing as high protein dairy ingredients. Presence of higher calcium and casein contents; heating, ultrafiltration (UF), diafiltration (DF) and spray drying of buffalo skim milk induces undesirable changes in milk proteins that causes problem of poor solubility in MPC powders. Therefore, this investigation was aimed to study the effect of change in pH (6.8-native, 7.0-neutral), heat treatments (74 ± 1°C/15s, 80 ± 1°C/5min, 85 ± 1°C/5min, 90 ± 1°C/5min) and DF on physicochemical, functional, reconstitution and rheological properties of medium protein buffalo milk protein concentrate (MP-BMPC) powder. Based on maximum ζ-potential and heat stability, UF retentate was selected, diafiltered and spray dried to obtain MP-BMPC powder. Despite having higher protein content, MP-BMPC powder exhibited markedly better functional (solubility, wettability, viscosity and emulsion stability) properties than buffalo milk protein concentrate 60. The interstitial air content, occluded air content, loose bulk density, packed bulk density, particle density and porosity values of MP-BMPC powder were 145.97 and 112.92mL 100g-1 of powder, 0.21gmL-1, 0.30gmL-1, 0.55gmL-1 and 65.09%. Further, its specific surface area; particle size distribution (d10, d50, d90); Sauter (D32) and DeBroukere (D43) mean values were 97.93m2 kg-1; 34.32, 104.42, 218.58µm; 61.27µm and 117.99µm. The storage modulus (G') and loss modulus (G″) crossover temperature of UF and DF retentates were ~ 57.16°C and 55.10°C, respectively. Rheological behaviour of UF, DF retentates and MP-BMPC solution were best explained by Herschel-Bulkley model. Fourier-transform infrared spectroscopy best described amide I, II and III regions in 1700-1400cm-1 and 1350-1200cm-1 wavenumber range.

Characterization and Iron Binding Dynamics of Haemophilus Influenzae Ferric Binding Protein

Iron is a fundamental metabolite for the survival of all biological systems because of its ability to function as both electron donor and acceptor. In unbound form, Fe+3 is not soluble in water whereas; Fe+2 is highly toxic in free form. Different organisms have developed specific mechanisms to transport iron. In humans transferrin is the responsible protein for carrying iron, whereas in bacteria Ferric Binding Protein (Fbp) performs this function. Pathogenic bacteria have evolved to sequester iron from human transferrin through an exceptional mechanism, where one of the two irons of transferrin is detached, transported through the periplasmic space and captured by Fbp. In this study, our main focus is to monitor conformational changes of Fbp from Haemophilus Influenzae, during iron release and binding in alternating environmental conditions. Fbp was expressed and purified by using recombinant DNA technology. Size Exclusion Chromatography (SEC), Dynamic Light Scattering (DLS), UV-Vis Absorption Spectroscopy (AS), Circular Dichroism (CD) and Small Angle X-ray Scattering (SAXS) are used for detecting structural changes. Additionally, features of the 480 nm ligand-to-metal charge transfer absorption peak of FBP-Iron complex was monitored during iron release/binding process for both Fe+3 and Fe+2 in different pH and ionic strength conditions. Our results confirm that Fbp changes its conformation to bind iron; hydrodynamic radius decreases when it captures the ligand because of the closing up of the metal-binding cleft. Effect of changes in pH, ionic strength and the state of iron on iron affinity are also investigated. We believe that the study on the dynamics of Fbp addresses us to further biosensor applications to determine elevated levels of iron in individual cells and targeted drug design practices.

Solution and Surface Properties of Metformin Hydrochloride in Aqueous Solution and Its Interaction with Amino Acids and Anionic Surfactant, Sodium Dodecyl Sulphate

This manuscript reports critical micelle concentration of metformin hydrochloride in aqueous solution which was determined by electrical conductivity, surface tension and refractive index measurements. From conductometric and surface tension data, different parameters were calculated which include surface excess concentration, area per molecule, dissociation constant and free energy of adsorption. Thermodynamic parameters like free energy of micellization, enthalpy of micellization and entropy of micellization were also calculated. The effect of change in pH on the CMC of drug was studied in pH range of 2–9. Three amino acids, i.e. glycine, tyrosine and tryptophane, were used to study their effect on CMC of drug. The interaction of this drug with two common surfactants, i.e. sodium dodecyl sulphate (SDS) and cetyl trimethylammonium bromide, was also studied with the help of UV–visible spectroscopy and conductivity measurements. Viscometric study was carried out to find the constants of Jones–Dole equation which are helpful to find the different types of interactions in solution. The results showed the spontaneous nature of adsorption of drug at air solution interface and spontaneous nature of micellization, becoming more spontaneous at elevated temperature. Strong interaction of drug with anionic surfactant SDS was observed. The increase in pH decreased CMC of drug, but higher CMC was found at pH of 7. The amino acids affect the CMC of the drug in different ways. Viscometric study showed the hydrophobic interaction of drugs with the solvent molecules.

Effects of Change in PH and Addition of Sucrose and NaCl on the Emulsifying Properties of Mucilage Obtained from Pereskia aculeata Miller

In this study, we evaluated the emulsifying properties of the hydrocolloids extracted from ora-pro-nobis (Pereskia aculeata Miller) (HOPN) in soy oil emulsions (20% w/w) in water after different processing conditions. These properties were evaluated in terms of index of creaming, activity and emulsifying stability, electrical conductivity, zeta potential, rheology, particle size distribution, and optical microscopy. A two-level factorial was used to evaluate the effects of changes in pH (4–7), sucrose concentration (0–15% w/w), and NaCl concentration (0–1% w/w) and different processing conditions. This study has important implications for the application of HOPN in the food industry, since it was found that the HOPN were efficient in forming emulsions with desirable characteristics under all conditions and that the presence of sucrose favored the characteristics of these emulsions. However, the presence of NaCl and acidic pH negatively influenced these characteristics leading to the conclusion that, under these conditions, the HOPN should be used in synergy with a stabilizing agent.

Effect of Change in pH of Flooded Water on Phosphate Release from Paddy Soils with High Water Content

Effect of Change in pH of Flooded Water on Phosphate Release from Paddy Soils with High Water Content

Adsorption Studies of Trimethoprim Antibiotic on Powdered and Granular Activated Carbon in Distilled and Natural Water

Contamination of drinking water sources by Pharmaceuticals and Personal Care Products (PPCPs) has raised concerns due to associated negative effects on the ecosystem, which include reproductive and hormonal malfunctions in some living organisms. In addition, occurrence of antibiotics in aquatic environment has been associated with development of antimicrobial resistance. However, the conventional water and wastewater treatment technologies are not effective at removing such organic micro-pollutants from the source waters, hence most of such contaminants find their way through the systems with minimal restrain. Hence accelerated effort to find technologies to enhance removal of recalcitrant organic micro-pollutants from the water and wastewater. The objective of this study was to investigate the removal of Trimethoprim (TMP) from natural water using Powdered Activated Carbon (PAC) and Granular Activated Carbon (GAC). Adsorption experiments were conducted following batch process using natural water and distilled water. We also investigated the effect of pH changes on adsorption of TMP from the water. We obtained better performance for PAC in the removal of TMP compared to GAC. The removal efficiency decreased as a function of TMP concentrations in the aqueous solution. The optimal pH for adsorption was found to be 7, whereas pH values below or above 7 exhibited decreased adsorption of the antibiotic. There was no significant difference in the adsorption of TMP in both natural water and distilled water, which was attributed to limited organic matter in the natural water that was used.

Graphene oxide grafted poly(acrylic acid) synthesized via surface initiated RAFT as a pH‐responsive additive for mixed matrix membrane

ABSTRACTIncorporation of nanostructured materials into the membrane matrix is a new strategy to improve mechanical and performance properties. Graphene oxide (GO) is one of the advantageous carbon‐based nanomaterials, which recently has been used extensively in this field. However, in the most cases, the surface modification of GO has been considered for the creation of new properties like a response to different stimuli such as temperature, pH, and pressure. In the present study, a well‐defined poly(acrylic acid) was grafted on GO using reversible addition–fragmentation chain transfer polymerization technique. This modified GO was incorporated into the mixed matrix membrane as a pH‐sensitive additive and its effect on the membrane performance was investigated. The membrane with 5 wt % of modified GO provides better hydrophilicity, flux, antifouling, and rejection properties and so the effect of pH change on the aforementioned characteristic properties was studied for this membrane. It is indicated that modified membrane shows different behaviors in acidic and alkaline conditions. In addition, excellent heavy metal separation was observed among rejection tests, especially for Hg ions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47213.

Evaluation of MEG reclamation and natural gas hydrate inhibition during corrosion control switchover

The breakthrough of formation water increases the risk not only of gas hydrate formation but also of corrosion. Switching between corrosion strategies may be necessary as formation water increases the risk of scale formation in the presence of methyl diethanolamine (MDEA), acetic acid, and cations. The switchover from pH stabilization with MDEA to a film-forming corrosion inhibitor (FFCI) was investigated when studying the effect of pH changes on the removal of MDEA, FFCI, acetic acid, and salts in the reclamation unit. The natural gas hydrate inhibitory performance (35 wt%) of the reclaimed monoethylene glycol (MEG) samples were also assessed. The study found that an optimum operating pH for the whole system was not achievable because of the contrasting pH requirements in the pretreatment and reclamation units. The study recommends operating the pretreatment unit at pH > 8 to precipitate out the divalent salts, and injecting acid before the regeneration unit, which allows for the volatile acetic acid to be removed via the reflux drum. We found that FFCI and MDEA accumulation in the reclamation unit resulted in a highly viscous residue (1430.53 mPa-s) and a discoloration (from brown to very dark brown). Further, new natural gas hydrate equilibria data for reclaimed MEG have been reported. The performance of reclaimed MEG varied compared with that of pure MEG, and was lower at the end of the experiment, whereas MDEA showed a hydrate-inhibiting effect.

PH level has a strong impact on population dynamics of the yeast Yarrowia lipolytica and oil micro-droplets in multiphasic bioreactor.

The oleaginous yeast Yarrowia lipolytica has the ability to use oils and fats as carbon source, making it a promising cell factory for the design of alternative bioprocesses based on renewable substrates. However, such a multiphasic bioreactor design is rather complex and leads to several constraints when considering emulsification of the oil-in-water mixture, foaming and cell growth/physiology on hydrophobic substrate. This study aims to shed light on the effect of pH changes on the physico-chemical properties of the cultivation medium and on cell physiology. It was indeed observed that at a pH value of 6, cell growth rate and intracellular lipid accumulation were optimized. Additionally, foaming was significantly reduced. In order to avoid over foaming in bioreactor, without impairing cell physiology, the use of alternative processes that can only act on the physical structure of culture medium, seems to be an effective alternative to usual chemical anti-foam agents.