pH Level Of Solution Research Articles

Development of Automated Nutrients Composition Control Fertigation System

Inefficient management of nutrient inputs has put a large constrainton the environment and human’s health. Indiscriminate use of nitrogen and phosphorus fertilizers has ledto ground water pollution. So the farmers has to pay close attention to nutrient management and incorporate the concept of balanced plant nutrition into their farming techniques. Thebalanced nutrition level to plantis provided by managing pH and Electrical conductivity level of fertilizer solution according to soil pH and electrical conductivity . Developed system comprises of two sensors to measure pH and EC of the fertilizer solution and soil. The output signals from the pH and EC electrode sensors are conditioned with the help signal conditioning cards and then interfaced to microcontroller through inbuilt ADC.Microcontroller will turnON and OFF particular solenoid valve to pore the fertilizer s into the mixing tank according to the pH and EC level in the mixing tank solution. LCD is used to display the computed results. pH and EC level of fertilizer solution is maintained on the basis of output readings of EC and pH sensor s.

A new medium for Caenorhabditis elegans toxicology and nanotoxicology studies designed to better reflect natural soil solution conditions

A new toxicity test medium for Caenorhabditis elegans is presented. The test solution is designed to provide a better representation of natural soil pore water conditions than currently available test media. The medium has a composition that can readily be modified to allow for studies of the influences of a range of environmentally relevant parameters on nematode biology and toxicology. Tests conducted in the new medium confirmed that nematodes' reproduction was possible at a range of solution pH levels, offering the potential to conduct toxicity studies under a variety of conditions. A test to establish silver nanoparticle and dissolved silver nitrate toxicity, a study type not feasible in M9 or agar media due to precipitation and nanoparticle agglomeration, indicated lower silver nanoparticle (median effective concentration [EC50] of 6.5 mg Ag/L) than silver nitrate (EC50 0.28 mg Ag/L) toxicity. Characterization identified stable nanoparticle behavior in the new test medium.

Removal of 4-chloro-2-methyl phenoxy acetic acid pesticide using coffee wastes from aqueous solution

The objective of this study is to investigate the use of coffee waste (CW) to remove the 4-chloro-2-methyl phenoxy acetic acid (MCPA) from aqueous solutions. To prepare CW, it was first washed and boiled to remove color and impurities then it was air dried at room temperature for 48h. Afterward the particle size distribution and zeta potential of the CW ground were determined. The porous texture of coffee was proved by scanning and transition electron microscopy. Batch adsorption tests were performed at 298K. The effects of contact time, MCPA concentration, and pH were investigated. It was observed that the adsorption of MCPA by using CW is independent of the solution pH level. The Langmuir isotherm provided the best correlation for MCPA adsorption onto CW, showing that the adsorption was favorable. The Langmuir adsorption capacity was found to be 0.34g/g. The second-order model provided the best description of MCPA adsorption onto CW when compared with the first order model. Infrared spectral studies revealed that acidic groups carboxyl and hydroxyl, are predominant contributors to MPCA adsorption by coffee.

PH dependence of chlordecone adsorption on activated carbons and role of adsorbent physico-chemical properties

From the 1960s to the 1990s, the large-scale production of banana in the French West Indies required an intensive use of chlorinated pesticides, such as chlordecone (Kepone), resulting in the diffuse contamination of soil and surface waters in the banana-producing areas. For this reason, drinking water plants were equipped with filters containing commercial activated carbons, being one of the challenges to find local adsorbents for the sustainable management of water treatment plants. In this paper, the adsorption of chlordecone (CLD) on activated carbons (ACs) prepared from sugar cane bagasse is studied, aiming to understand the mechanism of CLD adsorption on the AC surface. First, textural, acido-basic and chemical characteristics of the ACs were determined by thermal desorption, X-ray photoelectron and Boëhm studies. Adsorption isotherms of CLD show that the adsorption capacity increases with the amount of carbon and acidic groups at the AC surface whereas basic groups, hydroxyl and ether groups are detrimental to adsorption. The adsorption capacity is maximized at a solution pH level equal to the pHpzc of the considered AC. From temperature programmed desorption studies, it is proposed that chlordecone adsorption mechanism onto ACs is mainly governed by interaction with carboxylic groups. These results were correlated to molecular modeling studies of CLD interactions with surface functional groups of AC. The models of preferential positions, corresponding to minimal value of association energy, of interactions between CLD and AC functional groups were obtained.

Highly efficient and simultaneous removal of 2‐mercaptobenzothiazole and 2‐mercaptobenzoxazole from water samples by copper oxide nanoparticles

AbstractBACKGROUNDThis study introduces a method for simultaneous removal of 2‐mercaptobenzoxazole (2MBO) and 2‐mercaptobenzothiazole (2MBT) from water samples. The method uses a cartridge loaded with copper oxide nanoparticles as an efficient adsorbent to separate these hazardous mercaptans from aqueous solutions in a flow process.RESULTSThe effects of some important parameters such as amounts of adsorbent, pH, buffer type and its volume, electrolyte concentration, contact time, flow rate, tolerable volume of solution, reusability of cartridges and interfering ions on removal efficiency were studied. Data on adsorption were analyzed using linear and non‐linear forms of first‐ and second‐order kinetic equations and also Langmuir and Freundlich isotherm models and results showed that maximum adsorption amounts of 90.9 mg g−1 and 158.7 mg g−1, were obtained for 2MBO and 2MBT, respectively.CONCLUSIONThe proposed removal method is independent of pH level of the sample solution and is effective over a wide range of pH values. Using a copper oxide nanoparticle loaded cartridge (CONLC) has the advantage that there is no need to collect nanoparticles after the removal process and that CONLC can be reused for further removal processes (at least three times). This method was successfully applied to remove 2MBT (≥95% removal) from the cooling water of a 3000 MW power plant. © 2013 Society of Chemical Industry

Influence of pH on the transport of silver nanoparticles in saturated porous media: laboratory experiments and modeling

Given the ubiquity of silver nanoparticles (AgNPs) and their potential for toxic effects on both humans and the environment, it is important to understand their environmental fate and transport. The purpose of this study is to gain information on the transport properties of commercial AgNP suspensions in a glass bead-packed column under saturated flow conditions at different solution pH levels. Commercial AgNPs were characterized using high-resolution transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, ultraviolet visible spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. Transport data were collected at different pH levels (4, 6.5, 9, and 11) at fixed ionic strength. Capture of AgNPs increased as the pH of the solution increased from 4 to 6.5. Further increase in pH to 9 and 11 decreased the attachment of AgNPs to the glass beads. AgNP concentration versus time breakthrough data were simulated using an advection–dispersion model incorporating both irreversible and reversible attachment. In particular, a reversible attachment model is required to simulate breakthrough curve tailing at near neutral pH, when attachment is most significant. The laboratory and modeling study reveals that for natural groundwaters, AgNP transport in porous media may be retarded due to capture; but ultimately, most of the mass may be slowly released over time.

Randomized phase II study of mixing steroid to reduce venous pain in patients with colorectal cancer receiving oxaliplatin through peripheral vein (APOLLO study).

474 Background: Although theCapeOX (capecitabine+oxaliplatin) regimen obviates the need for a central venous port, administration of oxaliplatin through peripheral vein can cause venous pain. One of the reasons is pH. The pH level of oxaliplatin solution is about 4.8 and that of buffered by steroid is approximately 7.0. To test the hypothesis that adjusting the pH of oxaliplatin solution by mixing steroid can reduce venous pain, we have conducted the randomized control study to compare pH-adjusted oxaliplatin solution with unadjusted oxaliplatin solution. Methods: This was a single-blinded multicenter randomized phase II study. Colorectal cancer patients receiving oxaliplatin through peripheral vein were enrolled and randomly assigned to arm A (oxaliplatin 130 mg/m2 with dexamethasone (DEX) 2 mg) or arm B (the same, without DEX) (UMIN000004286. Venous pain was evaluated according to CTCAE criteria (ver. 4.0) and the verbal rating scale (VRS). Assessments were conducted every 3 weeks until cycle 4. Results: A total of 53 patients (38 men and 15 women; median age, 67 y.o.) were enrolled at 9 institutions in Japan. Of these, 47 evaluable patients were randomized to either arm A (n = 24) or arm B (n = 23). The incidence of venous pain (grade ≥ 2) was 33.3% in arm A and 60.9% in arm B (relative risk 0.55; p = 0.082). The venous pain (VRS score ≥ 3) was 12.5% in arm A and 26.1% in arm B (relative risk 0.48; p = 0.286). No difference was observed in response rate and safety. Conclusions: Adjusting the pH of oxaliplatin solution by addition of a low dose of DEX reduced severe venous pain without influence on response rate and safety. Clinical trial information: UMIN000004286. [Table: see text]

Influence of thermal treatment and combustible additives on properties of Latvian clay ceramics pellets

Porous ceramic pellets for possible environmental application were produced from different Latvian clays by sintering at different temperatures. Their characteristics and influence of additives were analysed using X-ray diffraction, mercury porosimetry and BET tests. The obtained ceramic pellets from calcareous clays after immersion in distilled water change its pH value, which affects their capability to adsorb ions or molecules on the surface. The sorption capabilities are dependent on the pH level of water solution, composition of clays, and used adsorbate. Porosity of the produced pellets is mostly within range from 15 to 25 % throughout all sintering temperatures with a slight decrease at 1050 ?C. The specific surface area has a wide range up to 30 m2/g. The highest surface area has pellets sintered at lower temperatures. The adsorption capability of pellets was evaluated using water solutions with different ions. The most promising results were obtained with iodine sorption. For most pellets the sorption capacity was 12.7 mg/g, although for the pellets sintered at 1050 ?C it was lower.

Imazalil residue loading and green mould control on citrus fruit as affected by formulation, solution pH and exposure time in aqueous dip treatments

Green mould, caused by Penicillium digitatum, is responsible for major postharvest fruit losses on the South African fresh citrus export market. Some of these losses as well as fungicide resistance development can be attributed to sub-optimal imazalil (IMZ) residue loading on citrus fruit (<2μgg−1), which is commonly the case in South African packhouses. This will result in loss of control and sporulation inhibition on decayed fruit. IMZ formulation [IMZ sulphate and emulsifiable concentrate (EC)], solution pH (IMZ sulphate at 500μgmL−1 buffered with NaHCO3 or NaOH to pH 6 and 8) and exposure time (15–540s) were investigated in order to improve IMZ residue loading and the green mould control on Clementine mandarin, ‘Eureka’ lemon, and navel and Valencia orange fruit. Exposure time had no significant effect on residue loading in the unbuffered IMZ sulphate solution (pH 3). No differences were observed between the pH buffers used, but residue loading improved with increase in pH. The maximum residue limit (MRL) of 5.0μgg−1 was exceeded following dip treatment in the IMZ EC (after 75s exposure time), and IMZ sulphate at pH 8 using NaHCO3 (77s) or NaOH (89s) as buffer. The MRL was exceeded after 161s in IMZ sulphate solutions buffered at pH 6 with either NaHCO3 or NaOH. An IMZ residue-loading curve was prepared from which residue levels can be predicted for the control of IMZ-sensitive and IMZ-resistant isolates of P. digitatum. From this model the benchmark residue level for 95% control of an IMZ-sensitive isolate and of an IMZ-resistant isolate were predicted to be 0.81 and 2.64μgg−1, respectively. Residue loading can be improved by adjusting the pH level of an IMZ sulphate solution to 6 or by using the IMZ EC formulation, but exposure time should be restricted to 45s so as not to exceed the MRL. Conversely, sufficient exposure time of ≈90s in an unbuffered IMZ sulphate solution (pH 3) will result to improved green mould control, but with residue loading below 2μgg−1. The resistant isolate could not be controlled adequately with residue levels below the MRL, therewith indicating the practical relevance of IMZ resistance.

Removal of Reactive Blue 19 dye from Aqueous Solution Using Natural and Modified Orange Peel

Orange peel (OP) exhibits a sorption capacity towards anionic dyes such as reactive blue 19 (RB19). Cetyltrimethylammonium bromide (CTAB) as a cationic surfactant was used to modify the surface nature of OP to enhance its adsorption capacity for anionic dyes from an aqueous solution. Four adsorbents were investigated: the OP, sodium hydroxide-treated OP (SOP), CTAB-modified OP and CTAB-modified SOP. The physical and chemical properties of these sorbents were determined using nitrogen adsorption at 77 K and by scanning electron microscope and Fourier transform infrared spectroscopy techniques. The adsorption of the RB19 dye was assessed with these sorbents at different solution pH levels and temperatures. The effect of the contact time was considered to determine the order and rate constants of the adsorption process. The adsorption data were analyzed considering the Freundlich, Langmuir, Elovich and Tempkin models. The adsorption of RB19 by the assessed sorbents is of the chemisorption type following pseudo-first-order kinetics. CTAB modification brought about a significant increase in RB19 adsorption, which was ascribed to the grafting of the sorbent with a cationic surfactant.

Degradation of antibiotic norfloxacin in aqueous solution by visible-light-mediated C-TiO2 photocatalysis

A visible-light-mediated C-TiO2 photocatalytic process (Vis/C-TiO2) was employed to degrade antibiotic norfloxacin. The influences of catalyst dosage, initial probe compound concentration and solution pH levels on the decay performance and reaction kinetics were investigated and optimized. Based on the experimental results, an equation was established to predict the observed rate constant under neutral pH. In addition, the decay rate was accelerated under weak alkali in the presence of moderate OH− anions. Hydroxyl radical was confirmed to play a major role in the Vis/TiO2 process, where in the presence of OH quencher and electron acceptor, retardation and improvement were found respectively. Furthermore, an original schematic diagram describing the surface property of C-TiO2 was built and further verified, in which, NH4+ cations normally served as hole scavengers showed a negligible effect because the adsorbed OH− formed a barrier for NH4+ ions to approach the holes, and the F− anions presented a significant suppression on norfloxacin decay due to the formation of hydrogen bond (OH⋯F) around the C-TiO2 surface. Besides, the recycling and sedimentation tests justified that the Vis/C-TiO2 process is a cost-effective and feasible way for wastewater treatment.

Effect of nitrogen form and nutrient solution pH on growth and mineral composition of self-grafted and grafted tomatoes

Three greenhouse experiments were carried out to determine the effect of the nitrogen form and the nutrient solution pH on growth, yield, leaf gas exchange, carbohydrate, N-compound concentrations and mineral composition of tomato cv. Moneymaker (Solanum lycopersicum L.) self-grafted and grafted onto ‘Maxifort’ (S. lycopersicum L.×S. habrochaites S. Knapp and D. M. Spooner) grown in hydroponics. Exp. 1 included five pH levels in the nutrient solution (3.5, 4.5, 5.5, 6.5, and 7.5) while in the Exps. 2 and 3 four different ratios of NO3− to NH4+ (100:0, 70:30, 30:70, and 0:100) were used. The Exps. 1 and 2 were performed in a short period of time (about 20 days) while Exp. 3 was a long-term experiment. No significant differences among treatments were observed in shoot and root dry biomass of tomato in the pH experiment (Exp. 1), whereas shoot dry biomass, Ca and Mg concentrations decreased sharply when N was exclusively provided as NH4+ (Exp. 2). When averaged over the pH level of the nutrient solution, the highest Ca, Fe, Zn, and Cu concentrations were recorded in grafted than self-grafted plants (Exp. 1), whereas in Exp. 2 shoot and root biomass values recorded in grafted plants were significantly higher than those observed for self-grafted plants, by 20%, and 24%, respectively. In the long-term experiment, the plant growth and yield decreased in response to an increase of NH4+ in the nutrient solution. The decrease in marketable yield with decreasing NO3−:NH4+ ratio resulted mainly from the increase of blossom-end rot, which reduced the number of marketable fruits per plant. The adverse effects of an increased supply in NH4+ have been associated to a fall in Ca and Mg levels in plant tissues. The carbohydrate concentrations, amino acids and proteins increased under NH4+ in comparison to NO3− based nutrition. Moreover, NH4+ toxicity was associated with reduced rates of net photosynthesis. Our results also demonstrated that grafting ‘Moneymaker’ into ‘Maxifort’ did not mitigate the negative effects of ammonium nutrition on tomato productivity.

Synergy of sulfate and hydroxyl radicals in UV/S 2O 82−/H 2O 2 oxidation of iodinated X-ray contrast medium iopromide

The degradation of iodinated X-ray contrast medium, iopromide, by UV irradiation with the assistance of combined oxidants of S 2O 8 2− and H 2O 2 has been investigated. The effects of various parameters, including different wavelengths of UV irradiation, UV intensities, initial solution pH levels, dosages of oxidants, dosing sequence, and the presence of non-target organic matters, have been evaluated. The iopromide decay follows pseudo-first-order kinetics. The UV at 254 nm exhibits higher decay rate of iopromide than the others (300 and 350 nm) due to stronger photon energy of 254 nm and the relatively higher absorptivity of S 2O 8 2−, H 2O 2 and iopromide nearby this wavelength. Optimum pH level was determined to be around 4.34. The mechanism is complicated because of the involvement of the scavenging, recombination, self-decomposition and/or stability of the involved oxidant (S 2O 8 2− and H 2O 2) and radicals (SO 4 − and HO ) as discussed in the paper. Iopromide decay rate is linearly proportional to the [S 2O 8 2−], however a nonlinear-optimal rate was observed by varying [H 2O 2] due to the formation of weaker radicals via overdosing of H 2O 2. Additionally, the sequential addition of S 2O 8 2− to UV/H 2O 2 or H 2O 2 to UV/S 2O 8 2− was found no better than the UV/S 2O 8 2−/H 2O 2. This is because the quenching of already formed SO 4 − by newly added H 2O 2 (or vice versa the quenching of HO by S 2O 8 2−). The simultaneous addition of S 2O 8 2− and H 2O 2, however, will slightly delay the generation rates of SO 4 − and OH due to the competition of photons between S 2O 8 2− and H 2O 2, which can reduce both the radical-scavenging reactions and the peak radical concentration in the solution, thus maximizing the utilization of precious radicals. The presence of non-target organics, especially the humic acid, in the UV/S 2O 8 2−/H 2O 2 process will quench the radicals, a pre-treatment is recommended to lessen this problem in real application.

The effect of low pH on the glycitein–BSA conjugate interaction with specific antiserum: Competitive inhibition study using surface plasmon resonance technique

Competitive inhibition serological assay for detection of the phytoestrogen glycitein (Glyc) was developed using surface plasmon resonance (SPR) technique with protein conjugates and polyclonal antibodies initially designed for the enzyme-linked immunosorbent assays (ELISA). The efficiency of the approach to the quantification of the soy isoflavone glycitein in water was investigated using the competitive reaction of analyte (free Glyc)and immobilized Glyc–BSA-conjugate with polyclonal antibodies. It was shown that the efficiency to detect Glyc drastically depends on the pH level of the probe solution. With the decrease in pH from 7.4 to 4.0, (i) the affinity of the specific reaction increases and (ii) the level of unspecific sorption becomes saturated. Non-specific adsorption to a SPR sensor surface obscures the specific component and shaded specific response at higher pH (6.0–7.4) when used serum for the quantification of specific analytes. The standard curves obtained in acidic solutions (pH 4–5) indicate that the linear part of the dependence completely covers the range between detection limit (0.1 μg/ml) and Glyc solubility in water (0.9 μg/ml). The difference in SPR- and ELISA-based analytical protocols as well as the requirements for increasing the efficiency in quantitative SPR analysis using purified antibodies is discussed.

INTERACTION BETWEEN WATER ALKALINITY AND NUTRIENT SOLUTION PH ON THE VEGETATIVE GROWTH, CHLOROPHYLL FLUORESCENCE AND LEAF MAGNESIUM, IRON, MANGANESE, AND ZINC CONCENTRATIONS IN LETTUCE

Alkalinity of water is considered critical for plant growth. Interactions between water alkalinity and solution pH on lettuce were investigated. Seeds of romaine type lettuce were sown in pots containing perlite and irrigated with a high alkaline nutrient solution at four pH values (5, 6, 7, and 8). Considering the high amount of Fv/Fm at pH 5; higher shoot growth (at pH 5) could be due to the improvement of the efficiency of the photosynthesis apparatus of plants and consequently higher photochemical quantum yield. Although, magnesium (Mg) concentration in leaves increased with elevating pH up to 7 and then decreased at 8, but iron (Fe), manganese (Mn), and zinc (Zn) concentrations decreased at higher solution pH levels, constantly. In commercial lettuce production in which water with high pH and carbonate species is normally used, it is better to use safe acids to reduce the pH in nutrient solutions to 5.

The Nickel Micro-tubes Fabrication by Galvanic Displacement Method Using Macroporous Silicon as Template

The Nickel microtubes were fabricated using the macroporous silicon as template substrate. The metal microtubes were obtained after immersion of macroporus silicon layer into the ammonium fluoride media containing nickel ions. The results show that the efficiency of tubes formation is sensible to pH level of electrolyte solution. The best pH level was 6.5 since for other pH levels non-tubes formation was observed. These results were discussed in the sense of the galvanic displacement effect.

Mitigation of alkaline stress by arbuscular mycorrhiza in zucchini plants grown under mineral and organic fertilization

AbstractA greenhouse experiment was carried out during the spring–summer 2009 to test the hypotheses that: (1) arbuscular‐mycorrhizal (AM) inoculation with a biofertilizer containing Glomus intraradices gives an advantage to overcome alkalinity problems, (2) mineral fertilization is more detrimental to AM development than organic fertilization on an equivalent nutrient basis. Arbuscular mycorrhizal (AM) and non‐AM of zucchini (Cucurbita pepo L.) plants were grown in sand culture with two pH levels in the nutrient solution (6.0 or 8.1) and two fertilization regimes (organic or mineral). The high‐pH nutrient solution had the same basic composition as the low‐pH solution, plus an additional 10 mM NaHCO3 and 0.5 g L–1 CaCO3. Increasing the concentration of NaHCO3 from 0 to 10 mM in the nutrient solution significantly decreased yield, plant growth, SPAD index, net assimilation of CO2 (ACO2), N, P, Ca, Mg, Fe, Mn, and Zn concentration in leaf tissue. The +AM plants under alkaline conditions had higher total, marketable yield and total biomass compared to –AM plants. The higher yield and biomass production in +AM plants seems to be related to the capacity of maintaining higher SPAD index, net ACO2, and to a better nutritional status (high P, K, Fe, Mn, and Zn and low Na accumulation) in response to bicarbonate stress with respect to –AM plants. The percentage root colonization was significantly higher in organic‐fertilized (35.7%) than in mineral‐fertilized plants (11.7%). Even though the AM root colonization was higher in organic‐fertilized plants, the highest yield and biomass production were observed in mineral‐fertilized plants due to the better nutritional status (higher N, P, Ca, and Mg), higher leaf area, SPAD index, and ACO2.

Crayfish Carapace Micro-powder (CCM): A Novel and Efficient Adsorbent for Heavy Metal Ion Removal from Wastewater

Crayfish carapace, a plentiful waste in China, was applied to remove divalent heavy metal ions—copper (Cu), cadmium (Cd), zinc (Zn), and lead (Pb)—from wastewater. The adsorption capacities of crayfish carapace micro-powder (CCM) for heavy metal ions were studied with adsorbent dosages ranging from 0.5–2.5 g/L and with initial metal concentrations ranging from 50–250 mg/L. CCM particle size, initial solution pH (from 2.5–6.5), temperature (from 25–65 °C) and calcium level (from 3.5–21.5%) were also varied in batch mode. The results indicated that the adsorption capacity increases with both decreasing particle size and increasing calcium level of the crayfish carapace. The kinetic studies indicated that the adsorption could be complete within 2 h, and that the data correlated with the pseudo-second-order model. CCM recorded maximum uptakes of 200, 217.39, 80, and 322.58 mg/g for Cu, Cd, Zn, and Pb, respectively. The adsorption capacities and removal efficiencies of CCM for metal ions were three-times higher than those of chitin and chitosan extracted from the CCM.

Effect of platinum on the photocatalytic decomposition of 2‐chlorophenol in aqueous solution by UV/TiO2

Photocatalytic decomposition of 2‐chlorophenol in aqueous solutions with platinum‐coated TiO2 slurry under UV irradiation was examined, utilizing various solution pH levels, dissolved oxygen levels and UV light intensities. The atomic percentage of platinum deposited on the TiO2 surfaces were identified by X‐ray photoelectron spectroscopy (XPS) to be in the range of 0.12 and 0.99%. The decomposition of 2‐chlorophenol in acidic aqueous solutions by UV/TiO2 was enhanced to certain extents for experiments conducted with platinum‐coated TiO2 containing up to 0.82% platinum because of the formation of Schottky barrier between platinum and TiO2 to prevent the recombination of electric holes and electrons. However, for experiments conducted with TiO2 coated with higher platinum contents, the decomposition rate of 2‐chlorophenol was reduced markedly, possibly because of the depression of the light absorption of TiO2 by the shielding of coated platinum. The photocatalytic decomposition of 2‐chlorophenol in aqueous solution was inhibited for experiments conducted in neutral and alkaline solutions because the presence of platinum increases the repulsion between 2‐chlorophenol species and TiO2 to hinder the adsorption of 2‐chlorophenol species on TiO2. The decomposition rate of 2‐chlorophenol in aqueous solution by UV/TiO2 was found to be improved significantly with increasing UV light intensity.

Threshold chloride concentration for stainless steels activation in concrete pore solutions

The threshold chloride concentration for stainless steels activation in concrete environments depends not only on chemical composition of the steel and on pH level of concrete pore solution but is also considerably affected by the superficial state of the steel. The presence of scales leads to significant decrease of corrosion resistance. This study evaluates the corrosion resistance of various stainless steels exposed to pore solutions of fresh concrete by means of electrochemical methods. All tested materials with bare surface, except for martensitic chromium steel FeCr12, proved to be completely resistant to fresh concrete pore solution containing chlorides. If the surface is scaled, the identically high resistance cannot be expected even for the most alloyed stainless steels.