Evonik Degussa Research Articles

One-Pot Synthesis of TiO2/Hectorite Composite and Its Photocatalytic Degradation of Methylene Blue

TiO2/hectorite composite photocatalysts with different molar ratios of lithium, magnesium, and silicon were synthesized by a one-pot hydrothermal method. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption isotherms, and ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS). When the molar ratio of lithium, magnesium, and silicon was 1.32:5.34:8 (TH-2), the composite showed the highest UV photocatalytic degradation of methylene blue (MB). The apparent rate constant of TH-2 was 0.04361 min−1, which was about 3.12 times that of EVONIK Degussa commercial TiO2 of AEROXIDE P25. The improvement of photocatalytic efficiency of the composite was mainly due to its high specific surface area, light trapping ability, and effective separation of electrons (e−) and holes (h+). At the same time, the F element of hectorite is beneficial to the formation of Ti3+ in TiO2, thus enhancing the photocatalytic activity. After five cycles, the removal rate of MB with TH-2 still reached 87.9%, indicating its excellent reusability.

UV/Vis Light Induced Degradation of Oxytetracycline Hydrochloride Mediated byCo-TiO2 Nanoparticles.

Pharmaceuticals, especially antibiotics, constitute an important group of aquatic contaminants given their environmental impact. Specifically, tetracycline antibiotics (TCs) are produced in great amounts for the treatment of bacterial infections in both human and veterinary medicine. Several studies have shown that, among all antibiotics, oxytetracycline hydrochloride (OTC HCl) is one of the most frequently detected TCs in soil and surface water. The results of the photocatalytic degradation of OTC HCL in aqueous suspensions (30 mg·L−1) of 0.5 wt.% cobalt-doped TiO2 catalysts are reported in this study. The heterogeneous Co-TiO2 photocatalysts were synthesized by two different solvothermal methods. Evonik Degussa Aevoxide P25 and self-prepared TiO2 modified by the same methods were used for comparison. The synthesized photocatalysts were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), UV/vis diffuse reflectance spectroscopy (DRS), and N2 adsorption (BET) for specific surface area determination. The XRD and Raman results suggest that Ti4+ was substituted by Co2+ in the TiO2 crystal structure. Uv/visible spectroscopy of Co-TiO2-R showed a substantial redshift in comparison with bare TiO2-R. The photocatalytic performance of the prepared photocatalysts in OTC HCL degradation was investigated employing Uv/vis spectroscopy and high-performance liquid chromatography (HPLC). The observed initial reaction rate over Co-TiO2-R was higher compared with that of Co-TiO2-HT, self-prepared TiO2, and the commercial P25. The enhanced photocatalytic activity was attributed to the high surface area (153 m2·g−1) along with the impurity levels within the band gap (2.93 eV), promoting the charge separation and improving the charge transfer ability. From these experimental results, it can be concluded that Co-doping under reflux demonstrates better photocatalytic performances than with the hydrothermal treatment.

Ytterbium Doped TiO2 Nanofibers on Activated Carbon Fibers Enhances Adsorption and Photocatalytic Activities for Toluene Removal

AbstractThe combination of activated carbon fiber (ACF) adsorbents and ytterbium‐doped TiO2 (Yb‐TiO2) photocatalysts is a promising strategy for toluene removal. Herein, we firstly constructed Yb‐TiO2/ACF porous materials (Yb‐TiACFs) by the treatment of TiO2/ACF porous materials (TiACFs) with Yb(NO3)3 solutions. The ultralong Yb‐TiO2 nanofibers that were composed of many nanocrystals along [101] direction twisted around ACFs. The synergetic effects of Yb‐TiO2 and ACFs promoted toluene adsorption, and the adsorption trends matched well with pseudo‐second‐order kinetics model. It was firstly found that ACFs and Yb3+ dopants improved TiO2 quantum efficiency by driving electron‐hole separation and enhancing light adsorption activity. Yb‐TiACFs promoted the photocatalytic oxidation of toluene, and the photocatalytic activity was better than TiO2 nanocrystals (P25, Evonik Degussa). The toluene photodegradation trend on Yb‐TiACFs was fit well with apparent first‐order reaction kinetics model. The interesting findings demonstrated that Yb‐TiACFs were a promising platform for toluene removal via adsorption and photocatalysis synergetic effects.

Electron transport in surface modified TiO2 nanoparticles

Surface modified nanoparticles of P25 Evonik Degussa TiO2 with silane coupling agent 3-(2-aminoethylamino) propyltrimethoxysilane (AAPTMS) were prepared at low temperature conditions. The samples were characterized using the BET technique. Their temperature dependent dc electrical conductivity was investigated in the temperature range 195–440 K. In order to investigate the influence of the environment, measurements were conducted in vacuum and in air. A change of conductivity with the molar ratio of AAPTMS/P25 is shown. Moreover, a decrease of conductivity is exhibited when compared to that of P25 nanopowder, attributed to the presence of silica in AAPTMS. The modified samples show a significant decrease of conductivity in air. In addition, the conductivity dependence on temperature differs from that in vacuum, suggesting the competition between the adsorption of oxygen and water from the surrounding atmosphere. It was demonstrated that the electrical conduction was controlled by the grain boundaries and the small polaron hopping at the high and intermediate temperatures whereas Mott's variable range hopping was the main conduction mechanism at the lower temperature regime.

Preparation of mesoporous titania xerogels under controlled synthesis conditions. Effects of processing in the textural, adsorption and photocatalytic properties

A straightforward and potentially scalable procedure based in the Evaporation-Induced Self-Assembly (EISA) method has been used in order to synthesize mesoporous titania (TiO2) xerogels. The structural, textural and photocatalytic properties of the synthesized materials were determined. The variation of synthesis parameters relative humidity (RH) and temperature, allowed controlling the textural properties of materials that exhibited mesopores with controllable pore and neck diameter distributions in the range of 3–12nm, large surface area (125–161m2g−1) and pore volume values between 0.17 and 0.38cm3g−1. Selected area electron diffraction (SAED) and X-ray diffraction (XRD) patterns indicated the presence of anatase phase. The uptake of gallic acid (GA) on these mesoporous powders and Evonik Degussa P25 was measured using Fourier Transform IR (FTIR) spectroscopy. The photocatalytic degradation rates of GA adsorbed on TiO2 were measured and followed by FTIR. The mesoporous materials showed interesting features including efficient trapping of the adsorbate and good photolytic response. The catalysts were exposed to successive cycles of adsorption/photolysis of GA and a very good performance was observed for the mesoporous anatase samples, leading to efficient, recoverable and reusable photocatalysts.

Evonik Degussa v Commission: Hearing Officer’s Review of Confidentiality Claims on Leniency Information in Public Versions of European Commission Cartel Decision

When deciding on the disclosure or publication of leniency information in public versions of Commission decisions, the hearing officer is obliged to examine any ground based on rules of EU law raised by the company concerned in order to justify the confidentiality of the contested information. Public versions of Commission decisions may not contain quotes from corporate statements of leniency applicants; however, they may contain quotes from other documents submitted in support of a leniency application subject to compliance with professional secrecy and the protection owed to business secrets and other confidential information.

Mechanistic Characteristics of Surface Modified Organic Semiconductor g-C₃N₄ Nanotubes Alloyed with Titania.

The visible-light-driven photocatalytic degradation of Bisphenol A (BPA) was investigated using the binary composite of alkaline treated g-C3N4 (HT-g-C3N4) deposited over commercial TiO2 (Evonik Degussa GmbH, Essen, Germany). The existence and contribution of both TiO2 and g-C3N4/HT-g-C3N4 in the composite was confirmed through various analytical techniques including powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectra (UV-vis-DRS), and photoluminescence (PL) analysis. The results showed that the titania in the binary composite exhibited both pure rutile and anatase phases. The morphological analysis indicated that the spongy “morel-like” structure of g-C3N4 turned to nanotube form after alkaline hydrothermal treatment and thereby decreased the specific surface area of HT-g-C3N4. The low surface area of HT-g-C3N4 dominates its promising optical property and effective charge transfer, resulting in a deprived degradation efficiency of BPA two times lower than pure g-C3N4. The binary composite of HT-g-C3N4/TiO2 exhibited excellent degradation efficiency of BPA with 2.16 times higher than the pure HT-g-C3N4. The enhanced photocatalytic activity was mainly due to the promising optical band gap structure with heterojunction interface, favorable specific surface area, and good charge separation.

Peculiarities of coagulation of the pseudohydrophilic colloids: Aggregate stability of the positively charged γ-Al2O3 hydrosol in NaCl solutions

The results of the turbidimetric and dynamic light scattering study of colloid stability and coagulation kinetics of the polydisperse γ-Al2O3 hydrosol, prepared on the base of alumina nanopowder (Aeroxide Alu C, Evonik Degussa GmbH), in sodium chloride solutions (3×10−2M–2М) at рН 4.2 are discussed within the extended Derjaguin–Landau–Verwey–Overbeek theory. We have revealed that the γ-Al2O3 dispersion possess an anomalous stability, i.e. unusually high salt concentration is required to cause coagulation, and can be viewed as a pseudohydrophilic system. The observed aggregate sol stability has been attributed to both the structural component of the particle interaction energy and the interaction of the solvate layers formed due to the secondary hydration of the surface. In order to adjust the agreement of the experimental and theoretical results, we have determined the optimal structural component parameters and the effective Hamaker constants for aggregates containing in initial sol along with primary nanoparticles. By analyzing the calculated particle interaction energy profiles and stability factor values, we have concluded that coagulation mainly proceeds via the barrierless mechanism in the long-range potential minimum.

Eco-efficient TiO2 modification for air pollutants oxidation

In the present work, the surface of P25 Evonik Degussa TiO2 nanoparticles was modified with silane coupling agent 3-(2-aminoethylamino) propyltrimethoxy-silane (AAPTMS) at low temperature conditions to increase the hydrophilicity and De-NOx ability of the photocatalyst. The modified nanoparticles showed excellent stability in water. Their hydrodynamic diameter and polydisperse index were reduced in comparison with P25 and negatively charged surface was observed. The FTIR spectra revealed -NH2 groups deformation which suggests interaction between surfactant’s amino groups (–NH2) with surface hydroxyl groups of TiO2. The thermal analysis depicted combustion of the attached modifier in an elevated temperature range (300–800°C). The AAPTMS-TiO2 particles exhibited higher activity in NOx oxidation in comparison with the bare P25 and remarkable NOx removal ability that was attributed to the surface modification of the nanoparticles with hydrophilic AAPTMS groups.

Antimicrobial properties of highly efficient photocatalytic TiO2 nanotubes

A rapid chlorine-based electrochemical anodization method resulted in the production of free-standing bundles of titania (TiO2) nanotubes with high-aspect ratio (up to 100μm long and about 20nm in diameter). XRD and Raman spectroscopy revealed the presence of partially crystalline amorphous titania nanostructures modified with surface hydroxyl groups. Photocatalytic antimicrobial properties of these nanotubes have been investigated using Escherichia coli and Staphylococcus aureus and compared with a commercial reference sample, Evonic-Degussa P25. Titania nanotubes were found to be highly efficient in inactivating both E. coli (97.53%) and S. aureus (99.94%) in under 24h of UV irradiation. On the other hand, commercial Evonik Degussa P-25 titania nanoparticles and control samples did not reveal antimicrobial properties for the same amount of time under either light or dark conditions. These results indicate that along with material properties, the high-aspect ratio nanotube architecture, surface hydroxyls, physicochemical properties of TiO2 nanotubes as well as experimental conditions of the biological investigations play a significant role in the antibacterial activity.

Photocatalytic degradation of β-blockers by using immobilized titania/silica on glass slides

Abstract Photocatalytic degradation of five β-blockers (acebutolol, atenolol, metoprolol, nadolol and propranolol) was investigated in aqueous media using immobilized TiO2 as a photocatalyst. The analyzed parameters were pharmaceutical removal and non purgeable organic carbon. Two different types of photocatalyst incorporated in sol–gel matrix were compared; P25 exhibited a higher photocatalytic activity compared to P90 (both from Evonik Degussa). Besides, optimal photocatalyst concentration and light intensity were determined. According to the results obtained, after 120 min of treatment a complete removal was achieved for all compounds (initial concentration 25 mg/L) using P25. After 240 min of irradiation a mineralization degree ranged from 75% for acebutolol to 92% for propranolol. A longer illumination time was needed for complete removal of β-blockers in river water. Main intermediate compounds were identified by high performance liquid chromatography coupled to mass spectrometry (HPLC–MS/MS) technique.

N-modified TiO2 photocatalytic activity towards diphenhydramine degradation and Escherichia coli inactivation in aqueous solutions

Nitrogen modified TiO2 samples were prepared by grinding the benchmark TiO2 photocatalyst (P25, Evonik Degussa Corporation) with different amounts of urea and applying calcination temperatures between 340 and 420°C. Several characterization techniques, including X-ray photoelectron spectroscopy (XPS), N2 porosimetry, X-ray diffraction (XRD), scanning electronic microscopy (SEM), and diffuse reflectance UV–vis spectroscopy (UV-DRS), were used to obtain information about the morphology, crystalline phases of TiO2 and chemical binding of nitrogen. Nitrogen modification did not affect the crystalline phase of TiO2 as far as XRD analysis concerns; on the other hand the modified materials developed an absorption in the visible part of the electromagnetic spectrum. The material with a urea:TiO2 weight ratio of 1:2, calcined at 380°C, exhibited the highest photocatalytic activity under visible light illumination (λ>430nm), towards degradation of diphenhydramine, an emerging water pollutant of pharmaceutical origin. The measured band gap energy of the material was 2.99eV, which is in-line with observed optical absorption properties. In addition, this photocatalyst was also the most efficient for complete inactivation of Escherichia coli in aqueous solution when ultraviolet radiation (λ=365nm) was used. From the XPS analysis on the chemical states of this photocatalyst it is concluded that nitrogen is interstitial to the TiO2 structure.

Photocatalytic degradation of endocrine disruptor compounds under simulated solar light

Nanostructured titanium materials with high UV-visible activity were synthesized in the collaborative project Clean Water FP7. In this study, the efficiency of some of these catalysts to degrade endocrine disruptor compounds, using bisphenol A as the model compound, was evaluated. Titanium dioxide P25 (AEROXIDE® TiO2, Evonik Degussa) was used as the reference. The photocatalytic degradation was carried out under the UV part of a simulated solar light (280–400 nm) and under the full spectrum of a simulated solar light (200 nm-30 μm). Catalytic efficiency was assessed using several indicators such as the conversion yield, the mineralization yield, by-product formation and the endocrine disruption effect of by-products. The new synthesized catalysts exhibited a significant degradation of bisphenol A, with the so-called ECT-1023t being the most efficient. The intermediates formed during photocatalytic degradation experiments with ECT-1023t as catalyst were monitored and identified. The estrogenic effect of the intermediates was also evaluated in vivo using a ChgH-GFP transgenic medaka line. The results obtained show that the formation of intermediates is related to the nature of the catalyst and depends on the experimental conditions. Moreover, under simulated UV, in contrast with the results obtained using P25, the by-products formed with ECT-1023t as catalyst do not present an estrogenic effect.

The impact of ZnO load, stability and morphology on the kinetics of the photocatalytic degradation of caffeine and resazurin

Zinc oxide (ZnO) powders with diverse morphologies were synthesized with various solvothermal techniques. Water, 1-butanole and ethylene glycol were used as the solvents, while the temperature of the solvothermal synthesis was varied from 90°C to 120°C. Resazurin and caffeine were used for the evaluation of the photocatalytic activity of all the prepared samples, and in particular to compare ZnO with commercial titanium dioxide photocatalytic material (P25 Evonik Degussa) using UV–vis spectroscopy. The composition, crystallinity, and morphology of the prepared materials were investigated with FTIR, XRD, TEM and FEG-SEM techniques. The band gaps of the obtained semiconductors were measured because the band gap of hydrozincite, determined in this study to be 4.1eV, has not been reported previously. The specific surface area (BET) and the porosity of the prepared particles were estimated. The crystal size in one dimension was estimated and was found to play an important role in the photocatalytic activity, which increased with a smaller size. A higher degree of aggregation caused the opposite effect. Thus, a more aggregated material with a larger surface area than a less aggregated one exhibited a lower photocatalytic activity. The particle morphology strongly influenced the photocatalytic process, while the degree of crystallinity was not comparably significant. The external mass-transfer (diffusion to the catalytic surface) resistance was negligible, and consequently the first-order, second-order, and Langmuir–Hinshelwood mechanism kinetics of the photocatalysis were examined.

Photocatalytic degradation of Reactive Black 5 with TiO2-coated magnetic nanoparticles

A core–shell TiO2-coated magnetic nanomaterial, Fe3O4@SiO2@TiO2, was prepared, characterized and tested as photocatalyst in the degradation of Reactive Black 5 (RB5) dye by a UV-photocatalytic path. For comparison, two reference materials were also evaluated as photocatalysts in the same reaction: as-prepared non-magnetic TiO2 and TiO2 from Evonik Degussa Company (P25). TEM characterization confirmed the core–shell structure of the Fe3O4@SiO2@TiO2 nanocomposite, while SEM micrographs revealed that the particles presented a spherical morphology with sizes ranging from 140 to 160nm. FTIR and XRD data confirmed the presence of magnetite (Fe3O4) cores, silica and anatase in the magnetic nanomaterial.The Fe3O4@SiO2@TiO2 photocatalyst in combination with UV irradiation led to a RB5 degradation of 91% after 60min, which was very similar to the values achieved with the as-prepared TiO2 (93%) and with P25 (97%). Furthermore, the magnetic nanocatalyst was efficiently separated from the reaction medium by magnetic decantation and could be reused three times with no decrease of the photocatalytic performance.

Bio‐based production of organic acids with Corynebacterium glutamicum

The shortage of oil resources, the steadily rising oil prices and the impact of its use on the environment evokes an increasing political, industrial and technical interest for development of safe and efficient processes for the production of chemicals from renewable biomass. Thus, microbial fermentation of renewable feedstocks found its way in white biotechnology, complementing more and more traditional crude oil-based chemical processes. Rational strain design of appropriate microorganisms has become possible due to steadily increasing knowledge on metabolism and pathway regulation of industrially relevant organisms and, aside from process engineering and optimization, has an outstanding impact on improving the performance of such hosts. Corynebacterium glutamicum is well known as workhorse for the industrial production of numerous amino acids. However, recent studies also explored the usefulness of this organism for the production of several organic acids and great efforts have been made for improvement of the performance. This review summarizes the current knowledge and recent achievements on metabolic engineering approaches to tailor C. glutamicum for the bio-based production of organic acids. We focus here on the fermentative production of pyruvate, l-and d-lactate, 2-ketoisovalerate, 2-ketoglutarate, and succinate. These organic acids represent a class of compounds with manifold application ranges, e.g. in pharmaceutical and cosmetics industry, as food additives, and economically very interesting, as precursors for a variety of bulk chemicals and commercially important polymers.Funding Information Work in the laboratories of the authors was supported by the Fachagentur Nachwachsende Rohstoffe (FNR) of the Bundesministerium für Ernährung, Landwirtschaft und Verbraucherschutz (BMELV; FNR Grants 220-095-08A and 220-095-08D; Bio-ProChemBB project, ERA-IB programme), by the Deutsche Bundesstiftung Umwelt (DBU Grant AZ13040/05) and the Evonik Degussa AG.

TiO2, surface modified TiO2 and graphene oxide-TiO2 photocatalysts for degradation of water pollutants under near-UV/Vis and visible light

In this work the photocatalytic activity between a TiO2 catalyst synthesized by a modified sol–gel method (ECT), TiO2 nanoparticles surface modified with organic shell layer (m-TiO2) and a graphene oxide-TiO2 composite (GOT-3.3) was compared. Diphenhydramine (DP) pharmaceutical and methyl orange (MO) azo-dye were used as model water pollutants under both near-UV/Vis and visible light irradiation. The TiO2 photocatalyst from Evonik Degussa Corporation (P25) was used as reference material and the pseudo-first order rate constants (k) and total organic carbon (TOC) removal were determined.Under near-UV/Vis irradiation, the results show that ECT and GOT-3.3 are highly active photocatalysts for the degradation of DP (k=64.5×10−3 and 62×10−3min−1, respectively) and mineralization (TOC removal of 55% and 50%, respectively) being the overall performance comparable to that obtained with P25 (k=56×10−3min−1 and 48% of TOC removal). The composite GOT-3.3 presents a markedly higher activity for conversion of the MO dye (k=126×10−3, 52×10−3, 49×10−3, 18.1×10−3min−1 for GOT-3.3, P25, ECT and m-TiO2, respectively) as well as for its mineralization, with TOC removals tailoring the same order. Under visible light illumination, P25 is practically inactive and GOT-3.3 (for DP) and m-TiO2 (for MO) are the photocatalysts with better properties than P25, or even than ECT.Scavenger agents were used as a diagnostic tool for the analysis of the photocatalytic mechanism, being defined three ratios to understand the relevance of each step in this mechanism. Regarding DP, it was concluded that direct oxidation by photogenerated holes is more important for the modified TiO2 materials (m-TiO2 and GOT-3.3) than for ECT and P25 which present higher availability to generate radical species from photoinduced holes. A photoreduction mechanism on the surface of the photocatalysts was observed for MO, the addition of EDTA (electron donor) greatly enhancing the rate of MO photoreduction.

Physicochemical Properties of Phytopharmaceutical Preparations as Affected by Drying Methods and Carriers

This article reports a study of the effects of the drying methods and drying carriers on system performance and physicochemical properties of spray- and spouted bed–dried phytopharmaceutical preparations from Bidens pilosa L. Colloidal silicon dioxide, β-cyclodextrin, maltodextrin dextrose equivalent (DE) 10, and microcrystalline cellulose were used as drying carriers. The dried product was characterized by the particle size and morphology, total flavonoid content, solubility, flowability, and water activity. High-performance liquid chromatography (HPLC) was used to detect four marker compounds previously reported for this plant. Spray and spouted bed drying systems were compared through energetic efficiency, product recovery, elutriation, and product accumulation. The crystalline state of the powders was assessed by X-ray diffraction. Results showed high degradation rates for total flavonoid content and marker compounds during spouted bed drying. Depending on the drying carrier added to extractive solutions, different degrees of protection from degradation were conferred, and the physical characteristics of the product were changed accordingly. The lowest flavonoid degradation (8.6%) and the higher concentration of marker compounds were obtained using β-cyclodextrin as the drying carrier. Particle size was higher when a blend of Aerosil (Evonik Degussa, Hanau, Germany) and cellulose was employed as the drying carrier. A maximum product recovery of 86.9% was achieved by spray drying and 72.9% by spouted bed drying with the Aerosil : cellulose composition.

A comparison of digestible amino acid databases: Relationship between amino acid concentration and digestibility

SUMMARY Databases compiling the amino acid (AA) digestibility values of 20 common poultry feed ingredients from 2 commercial companies, Evonik Degussa (Burr Ridge, IL; chick assays) and Ajinomoto Heartland (Chicago, IL; rooster assays), were used to investigate the influence of AA concentration on observed digestibility values. Casual observation of the rooster assay database suggested that AA digestibility may be related to AA concentration. Ideally, digestibility should be a property of the feed ingredient and should not be related to the concentration at which an ingredient is fed. If the AA concentration during an assay has a large effect on its digestibility, then the results may not be valid at different levels of feed ingredients or when the AA concentration in the test situation is different from actual feeding levels in a diet. Differences in digestibility values in the Evonik Degussa and Ajinomoto Heartland databases were compared. Multiple regression techniques were then used to test the hypothesis that the results of the AA digestibility assays were related to the AA concentration in the feed ingredient being tested. Total AA concentration and digestible AA averaged 6 and 14% higher in the rooster database than in the chick database, respectively. Differences in assay type were quantitative because slopes of digestible AA = f(total AA concentration) were positive for 19 of 20 ingredients in each database. However, when all data were included in 1 model, the influence of concentration on digestibility was very unlikely to have been due to chance (P < 0.0006), as evidenced by the interaction of concentration × assay type. Removing the lowest (Trp) or highest (Ile) AA was not critical to the conclusions. The effect of AA concentration on its digestibility was quantitatively the same for each AA (P < 0.50) except Cys (P < 0.05). We confirmed, based on data from the 3 selected articles, that this relationship was not due only to the different samples in the different databases. Therefore, to best predict the digestibility of any AA in any ingredient, its intended concentration in the diet should be known.

Degradation of diphenhydramine pharmaceutical in aqueous solutions by using two highly active TiO2 photocatalysts: Operating parameters and photocatalytic mechanism

In the present work the efficiency of a new TiO2 catalyst (ECT), synthesized by means of an optimized sol–gel method, is studied for degradation of an important pharmaceutical water pollutant, diphenhydramine (DP). Its activity is compared to P25, the benchmark catalyst, produced by Evonik Degussa Corporation, under different catalyst loadings (up to 2.00gL−1) and initial solution pH (3.0–11.0). The results show that DP is very stable under non-catalytic conditions but complete degradation and considerable mineralization (ca. 60–70%) under near UV to visible irradiation (∼50mWcm−2) can be achieved in 60min by selecting the appropriate TiO2 loading. ECT is significantly more active than the benchmark catalyst for loadings higher than 1.00gL−1 while the pseudo-first order rate constant increased with the initial solution pH from 3.0 to 11.0. The highest rate constant was obtained with ECT at pH 11 (173×10−3min−1 against 116×10−3min−1 for P25). Scavenger agents were used as a diagnostic tool for the analysis of the photocatalytic mechanism and it was possible to prove that holes were crucial active species participating in the photocatalytic mechanism as well as that ECT has a higher availability than P25 to generate reactive radicals, such as hydroxyl (HO•) and hydroperoxyl (HOO•) radicals.