Effect Of pH Changes Research Articles

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.

Selectivity control of nitrite and nitrate with the reaction of S0 and achieved nitrite accumulation in the sulfur autotrophic denitrification process

The characteristics of reaction between S0 and NO2−-N or NO3−-N in the sulfur autotrophic denitrification (SADN) process were studied using S0 as an electron donor and NO2−-N and NO3−-N as electron acceptors. The effect of changes in pH and temperature on the processes of NO2−-N and NO3−-N reduction were also studied to identify the optimum control parameters for strengthening the preference of S0 on NO3−-N; thus, achieving the efficient accumulation of NO2−-N. The results showed that the affinity of S0 for NO3−-N was considerably higher than that for NO2−-N. The optimum pH values for the reductions of NO2−-N and NO3−-N were 7.0 and 8.5, respectively, and both optimum temperatures were 35 °C. By controlling different pH, the NO3−-N conversion efficiency reached 90%, at which time the accumulation of NO2−-N was more than 95%. Microbial community analysis showed that Thiobacillus, Sulfurimonas, and Thioahalobacter were the main genera in the S0-SADN process.

Effect of change in pH of skim milk and ultrafiltered/diafiltered retentates on milk protein concentrate (MPC70) powder properties

Poor solubility of milk protein concentrate (MPC) powders are attributed to their high protein and calcium contents. Concentration of skim milk in ultrafiltration (UF) and diafiltration (DF) increased total solids, protein and mineral contents and changed pH and ζ-potential values of the retentates that leads to milk proteins destabilization in 7× UF/DF retentates. Hence, this investigation was aimed to study the effect of change in pH of skim milk (no change; native pH maintained) and DF retentates (5.85 and 7.10) with KOH, NaOH and NaH2PO4∙2H2O on physicochemical, reconstitution, functional and rheological properties of fresh MPC70 powders. MPC70-7.10 powder had significantly higher (P < 0.05) solubility, but MPC70-NaOH and MPC70-5.85 showed significantly lower solubility than control. However, after two months storage at 25 ± 1°C, control powder had significantly lower solubility (27.78% decrease) than treated powders. These changes in pH, significantly decreased calcium content and specific surface area; significantly improved viscosity, water binding, oil binding, emulsifying, foaming and buffering capacities, L*, a*, flowability, pH (except MPC70-5.85) and packed bulk density (except MPC70-NaOH) of treated powders over control. However, rennet coagulation time of all reconstituted powder solutions was similar. Hershel Bulkley, a best fit model, efficiently explained the pseudoplastic rheological behavior of all reconstituted MPC70 powders. This investigation had established that change in pH could improve the functional properties of MPC70 powders and is a simple, cheap, compatible and easy to use approach. Treated MPC70 powders could replace control in several food formulations owing to their improved functional properties.

Effects of pH-Induced Changes in Soil Physical Characteristics on the Development of Soil Water Erosion

Soil water erosion is frequently reported as serious problem in soils in Southeast Asia with tropical climates, and the variations in pH affect the development of the erosion. This study investigated the effects of changes in pH on soil water erosion based on changes in the physical properties of the simulated soils with pH adjusted from 2.0 to 10.0 through artificial rainfall tests. The zeta potential was entirely shifted to positive direction at each pH condition due to Al, Ca, and Mg. In the pH range of 6.0 to 2.0, the aggregation of soil particles resulting from the release of Al3+ from clay minerals and/or molecular attraction between soil particles caused the plastic index (IP) of the soil to decrease. The decrease in IP led to the development of soil water erosion at the pH range. When the pH exceeded 6.0, the repulsive force generated by the negative charges on soil particles decreased IP, resulting in accelerated erosion by water. The results suggest that changes in pH causes physical properties of the soil to change through changes of the zeta potential in the clayey soil rich in Al, Ca, and Mg, leading to the development of soil water erosion.

Photochemical processes of 1,4-benzoquinones in aqueous medium

The photochemical reactions in the aqueous solutions of 1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2,6-dimethyl-1,4-benzoquinone, 2-chloro-1,4-benzoquinone, 2,5-dichloro-1,4-benzoquinone and 2,6-dichloro-1,4-benzoquinone were investigated using three independent monitoring techniques (spectrophotometric, spectrofluorimetric and pH-stat) and two different radiation sources, a LED with emission at 400 nm and an UV-A lamp emitting at 365 nm. The aqueous photoproducts were shown to be the corresponding substituted hydroxyl-quinones and hydroquinones for all the derivatives. Fully quantitative data treatment was used in all of the experiments based on fitting the entire kinetic curved obtained. From these fits, the quantum yield of product formation and reactant loss were determined in each case. In the pH-stat experiments, the effect of pH change was also investigated for some of the derivatives. Generally, aqueous photoreactivity is increased by the presence of electron withdrawing substituents and suppressed by electron donating ones. The pH did not have a very significant influence on the course of the photoreaction alone, but it affected the observations through different acid-base equilibria of the products hydroxyl-quinones and hydroquinones.

Microbial Sorption of Uranium Using Amycolatopsis sp. K47 Isolated from Uranium Deposits

The increasing contamination of soils, sediments, and water with heavy metals through natural and industrial processes is a worldwide problem. Mining processes produce tons of material contaminated with radionuclides such as U and different heavy metals such as Cd, Ni, and Pb. U(VI) adsorbs strongly on bacteria, exhibiting pH-dependent adsorption behavior that is caused by a range of uranyl surface complexes on bacteria cell walls. The Amycolatopsis sp. K47 was isolated from Manisa Koprubasi Kasar open-cast uranium mine and identified for the first time. Using the batch adsorption method, the biosorption potential of this microbe was investigated by studying the effects of changes in pH (1–10), biomass dose (0.1–5 g/l), initial uranium metal concentration (5–200 mg/l), contact time (5–180 min), and temperature (20–60 °C). Interpretation of FTIR data obtained for both the uranium loaded and unloaded Amycolatopsis sp. K47 biomass showed the presence of carboxylic acid, hydroxyl, and amide functional groups that could interact with uranium ions. Scanning electron microscopy images demonstrated that uranium was intensely adsorbed on the microbial biomass surface. The sorption isotherms were investigated by analysis of the Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) models. The Langmuir isotherm model was found to show the best fit for the experimental data obtained. Furthermore, thermodynamic parameters, such as ΔH°, ΔS°, and ΔG°, were calculated using adsorption equilibrium constant obtained from the Langmuir isotherm. The optimal experimental conditions were determined to be pH = 4, C0 = 40 ppm, t = 150 min, temp. = 40 °C, and abs. dose = 1 g/l, and the corresponding U(VI) removal efficiency was about 97 ± 2%.

Aggregation and metal-complexation behaviour of THPP porphyrin in ethanol/water solutions as function of pH

The effect of pH change on 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (THPP) with its aggregation as function of water-ethanol mixture was studied with UV–vis, fluorescence, Raman and computational analysis. In neutral pH, THPP was present as free-base and, increasing the water amount, aggregation occurred with the formation of H- and J-aggregates. The aggregation constant and the concentration of dimers were calculated, other information about the dimer aggregation were evaluated by computational study.In acidic pH, by the insertions of two hydrogens in the porphyrin rings, the porphyrin changed its geometry with a ring deformation confirmed by red-shifted spectrum and quenching in fluorescence; at this low pH, increasing the water amount, the acidic form (THPPH2)2+ resulted more stable due to a polar environment with stronger interaction by hydrogen bonding.In basic pH, reached by NH4OH, THPP porphyrin was able to react with alkali metals in order to form sitting-atop complex (M2THPP) confirmed by the typical absorption spectrum of metallo-porphyrin, Raman spectroscopy and by computational analysis.

The effect of changes in pH on the depression of talc by chitosan and the associated mechanisms

The depression effect of chitosan on talc as well as the associated mechanisms were investigated at different pH values. The flotation results showed that chitosan is a useful depressant for talc flotation and that its depression effect is independent of pH. The adsorption mechanisms of chitosan were different at pH3 and 9. X-ray photoelectron spectroscopy analysis indicated that at pH3 and pH9, the chitosan adsorbed on talc surfaces through physical interactions. At pH3, the adsorption changed the zeta potential of the talc from negative to positive and the adsorption was achieved via hydrogen bonding interaction. At pH9, in addition to adsorption due to hydrogen bonding, the water-insoluble chitosan also deposited on the talc surfaces and shifted the slip surface of the electric double layer outward, thus making the surface potential of the talc gradually approach zero. The adsorbed chitosan could be washed away from the surface. This phenomenon occurred more easily at pH3, because the deposited chitosan dissolved and entered the aqueous phase again. Flotation separation tests on the mineral mixtures indicated that the chitosan could only be used as a selective depressant for chalcopyrite and talc separation at pH3.

Behaviour of lactose with the presence of lactic acid and Ca as affected by pH.

Contradictory statements about the effects of pH change on crystallisation behaviour of lactose exist in the literature. Considering the importance of addressing the processability issue of acid whey, a systematic study is required to establish lactose crystallisation behaviour in the presence of LA and Ca at concentrations present in real acid whey waste streams emphasising impact of pH. Structural modifications of lactose were evident at elevated, more neutral pH in the presence of 1% w/w LA and 0·12% w/w Ca. These structural changes led to changes in the anomeric equilibrium of lactose, which manipulated the water-lactose behaviour and increased the crystallinity. Therefore, altering pH to 6·5 may be the solution to proper industrial processing of acid whey, enhancing the ability of lactose to crystallise properly.

Influence of the Culture Media and the Organic Matter in the Growth of Paxillus ammoniavirescens (Contu & Dessi)

The genus Paxillus is characterized by the difficulty of species identification, which results in reproducibility problems, as well as the need for large quantities of fungal inoculum. In particular, studies of Paxillus ammoniavirescens have reported divergent results in the in vitro growth while little is known of its capacity to degrade organic matter. For all the above, and assuming that this variability could be due to an inappropriate culture media, the aim of this study was to analyse growth in different culture media (MMN, MS, and 1/2 MS) and in the case of MMN in presence/absence of two types of organic matter (fresh litter and senescence litter) to probe the saprophytic ability of P. ammoniavirescens. We also evaluated the effects of pH changes in the culture media. Growth kinetics was assessed by weekly quantification of the area of growth in solid culture media over 5 wk, calculating the growth curves and inflection points of each culture media. In addition, final biomass after 5 wk in the different culture media was calculated. Results showed that best culture media are MS and 1/2 MS. Moreover, an improvement in growth in culture media containing decomposing fall litter was observed, leading to confirm differences in the culture media of this species with others of the same genus. Further, we established that all growth media suffered a significant acidification after fungal growth.

Effect of operating conditions on speciation and bioavailability of trace metals in submerged anaerobic membrane bioreactors

This study investigated the effect of changes in pH (7, 6.5 and 6), hydraulic retention time (HRT) (6h, 4h, and 2h), solids retention time (SRT) (100d and 25d) on the speciation of trace metals (TMs) in submerged anaerobic membrane bioreactors (SAMBRs). The results showed that the metal retention capacity of SAMBRs reduced when the pH, HRT and SRT were reduced i.e. up to 21.9%, 39.1%, and 17.1%, respectively, but it was also found that the speciation of these TMs generally shifted towards highly bioavailable fractions i.e. Soluble and Exchangeable. The degree of shifting in speciation depended on the affinity of the TMs for anaerobic sludge and their sensitivity to the changes. TMs with the most and the least significant changes in speciation were Fe and Mn, respectively.

Effect of pH Changes on Antioxidant Capacity and the Content of Betalain Pigments During the Heating of a Solution of Red Beet Betalains

Effect of pH Changes on Antioxidant Capacity and the Content of Betalain Pigments During the Heating of a Solution of Red Beet Betalains

Immobilized pH in culture reveals an optimal condition for somatic cell reprogramming and differentiation of pluripotent stem cells.

AimOne of the parameters that greatly affects homeostasis in the body is the pH. Regarding reproductive biology, germ cells, such as oocytes or sperm, are exposed to severe changes in pH, resulting in dramatic changes in their characteristics. To date, the effect of the pH has not been investigated regarding the reprogramming of somatic cells and the maintenance and differentiation of pluripotent stem cells.MethodsIn order to investigate the effects of the pH on cell culture, the methods to produce induced pluripotent stem cells (iPSCs) and to differentiate embryonic stem cells (ESCs) into mesendoderm and neuroectoderm were performed at each medium pH from 6.6 to 7.8. Using the cells of the Oct4‐GFP (green fluorescent protein) carrying mouse, the effects of pH changes were examined on the timing and colony formation at cell reprogramming and on the cell morphology and direction of the differentiation of the ESCs.ResultsThe colony formation rate and timing of the reprogramming of the somatic cells varied depending on the pH of the culture medium. In addition, mesendodermal differentiation of the mouse ESCs was enhanced at the high pH level of 7.8.ConclusionThese results suggest that the pH in the culture medium is one of the key factors in the induction of the reprogramming of somatic cells and in the differentiation of pluripotent stem cells.

Antibacterial activity of supernatant obtained from Weissella koreensis and Lactobacillus sakei on the growth of pathogenic bacteria

This study was carried out to obtain basic data for the industrial use of Weissella koreensis and Lactobacillus sakei. The antibacterial activity of supernatants obtained from W. koreensis and L. sakei were tested against pathogenic bacteria such as Escherichia coli KCCM 11234, Salmonella enteritidis KCCM 3313, Salmonella enteritidis KCCM 12021, Salmonella typhimurium KCCM 40253, and Salmonella typhimurium KCCM 15. The supernatant of L. sakei showed antibacterial activity against E. coli KCCM 11234, S. enteritidis KCCM 12021, and S. typhimurium KCCM 15, while the supernatant of W. koreensis showed antibacterial activity against E. coli KCCM 11234 and S. enteritidis KCCM 12021. The effect of pH changes and heat treatment on antibacterial activity of the supernatants was examined using the sensitive pathogenic bacteria (E. coli KCCM 11234, S. enteritidis KCCM 12021 and S. typhimurium KCCM 15). Antibacterial activity against sensitive pathogenic bacteria was maintained under heat treatment at all temperatures, but there was no antibacterial activity associated with pH modification. Furthermore, it was confirmed that the antibacterial activity of the supernatants obtained from W. koreensis and L. sakei was a result of organic acids including, lactic, acetic, phosphoric, succinic, pyroglutamic, citric, malic, and formic acids. Therefore, the present study showed that the organic acids produced by L. sakei and W. koreensis exhibited a strong antibacterial activity against pathogenic bacteria. Moreover, in the food industry, these organic acids have the potential to inhibit the growth of pathogenic bacteria and improve the quality of stored food.

Effects of milk pH alteration on casein micelle size and gelation properties of milk

ABSTRACTThe effects of changes in pH above and below the natural pH of milk (ca 6.6) on the casein micelle size and the gelation properties of the pH adjusted and restored samples were investigated. The size of casein micelles increased at pH 7.0 and 7.5, then started to decrease above pH 8.5. It is postulated that at pH below 8.5 the casein micelles swell, while elevated pH causes their dissociation. Conversely, the size of casein micelles decreased on acidification to pH 5.5 and increased when the pH dropped below 5.5, due to the shrinkage of casein micelles at lower pH before their aggregation at pH below 5.5. In response to neutralising treated milk back to normal milk pH of 6.6, it was found that the casein micelle size of treated milk with a narrow range of pH change between 6.0 and 7.0 was reversible, while beyond this range the structure of casein micelles became irreversible. The restoration of casein micelle size was followed by the restoration of some parameters such as soluble calcium, ethanol stability, and milk whiteness. Acid-induced gelation did not change the elastic modulus, while rennet-induced gelation was affected by initial milk pH. In reference to the size of reversible range elastic modulus (G’) of acid or rennet gels made from restored milk, the sizes were similar to control milk after 6 h of gelation.

Effect of Ph Changes on the Corrosion Resistance of Anodizing Titanium Dental Implant with Cobalt Chromium Bar Attachment

Effect of Ph Changes on the Corrosion Resistance of Anodizing Titanium Dental Implant with Cobalt Chromium Bar Attachment

Release of selected chemical elements from shale drill cuttings to aqueous solutions of different pH

The effect of pH changes on leachability of light and heavy metals from shale drill cuttings generated from unconventional shale gas production was investigated. Cuttings, being the primary byproduct generated from drilling operations, belong to the potentially hazardous type of wastes due to presence of heavy and radioactive elements and remains of drilling fluid. In this regard, assessment of potentially dangerous components (PDCs) from rock waste materials was performed by application of batch leaching tests, which has provided information on the sensitivity of leaching under externally imposed changes in pH (natural or caused by treatment) in specific scenarios. The description of shale rocks mineralogical and chemical properties was performed by means of X-ray fluorescence spectroscopy, diffractometry as well as scintillation spectrometry. The concentrations of released constituents due to the leaching tests were measured by atomic absorption spectrophotometry. Results were compared and discussed accordingly with the waste acceptable criteria of elution limits.Analysis of the substrate revealed that the elemental composition was dominated by light elements, whereas heavy metals were present in trace amounts. However, noticeable release of barium (2.0–4.6%) was also recorded, which has originated from not only rock material but also drill mud. Minor mobility was observed for transition elements such as Cr, Co, Fe, Mn, Ni, Zn, Cu and Pb. Results revealed that drill cuttings follow the requirements for other than hazardous and municipal type of deposition, with exception for barium. Moreover, content of radioactive isotopes fulfill the requirements range of acceptable concentrations.