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Synchronic and diachronic studies were carried out in order to examine the change of certain soil parameters with time after applying organic (green waste and sugarcane composts) and inorganic (gypsum at two rates) amendments on three soils with different salinity levels using ryegrass as the test crop during a 180-day incubation. The diachronic analysis involved the evaluation of the electrical conductivity dynamics over time. Maximum level of salinization has been observed when applying gypsum (both rates) for the non-saline soil, low gypsum rate (3.8 mg.g−1) for the saline soil, and sugarcane compost for the extremely saline soil. The maximum decrease in salinity was recorded at 120 days for non-saline soil and at 20 days for both saline and extremely saline soils. The synchronic study evaluated at the end of the incubation, showed a relative increase in electrical conductivity (EC) when applying gypsum (all rates) for non-saline soil, after applying green waste compost for the saline soil, and by applying high gypsum rate for extremely saline soil. This analysis also showed an increase in alkalinity and a decrease in organic matter, calcium, and magnesium. However, gypsum application showed, with regard to the other treatments, its effectiveness as a good mineralizer, pH neutralizer, and reservoir of Ca2+ when measured overtime. Maximum potassium uptake by ryegrass at the expense of sodium was obtained at day 60 of incubation, whereas, the highest absorption was not related as expected to the lowest EC whilst, optimum uptake levels were reached in the non-amended soil in the case of non-saline soil, high rate gypsum-amended soil for saline soil and low rate gypsum-amended soil for extremely saline soil.

A study is undertaken of the effect of fluorinating two TiO catalysts, both with the same surface area but one composed only of pure anatase phase (SA) and the other of mixed anatase and rutile phases (P25), on the degradation of phenol, formic acid and aniline. The catalysts were characterised by FTIR, BET, EDAXs, SEM, XRD and DRS-UV–vis studies. The method used for synthesis of the F-P25 and F-SA resulted in fluorinated catalysts with properties different to those of other fluorinated catalysts reported in the bibliography. The results obtained show that, unlike other studies in which the formation of free hydroxyl radicals ([rad]OH) was enhanced with the fluorinated catalysts, in the F-P25 and F-SA catalysts it was the formation of surface hydroxyl radicals ([rad]OH) which was significantly enhanced. In this way, the F-P25 and F-SA catalysts gave rise to higher degradation rate constants of phenol (k), aniline (k) and formic acid (k) than the P25 and SA catalysts., We are grateful for the financial support of the Spanish Ministry of Economy and Competitiveness through the projects CTQ2015-64664-C2-1-P and the Spanish Ministry of Science and Innovation for the UNLP10-3E-726 infrastructure, co-financed with ERDF funds. D. Garzón Sousa would like to thank the University of La Palmas de Gran Canaria for its funding through its PhD Grant Program and Wiâm El-Alami would also like to thank the UNetBA Erasmus Program for its funding through a mobility grant.

TiO2 deactivation processes during gas-phase degradation of ethanol were studied. To force the deactivation processes, various cycles were performed, avoiding the degradation of acetates. It was observed that acetates adsorbed on the anatase phase of catalysts provoke the transference of electrons to surface traps which modify the electron states of the semiconductor. The same deactivation studies were also performed with fluorinated TiO2. It was noted that the electrons present in the surface traps, as a consequence of the Ti-F interaction, react with the holes during irradiation and provoke a change in the electron states of the semiconductor.

The inhibition of mild steel corrosion in 1.0 M HCl by some hydrazine derivatives namely: (1E,2E)-1,2-bis(thiophen-2-ylmethylene)hydrazine (PP2) and (1E,2E)-1,2-bis(1H-pyrrol-2-ylmethylene)hydrazine (PP3) has been investigated using weight loss, electrochemical studies, SEM and quantum chemical calculations. The results showed that PP3 is the best corrosion inhibitor among the three compounds studied and the inhibition efficiency increases with increase in concentration for all the inhibitors. The adsorption of inhibitor molecules on mild steel surface was found to be spontaneous and obeyed the Langmuir adsorption isotherm. Potentiodynamic polarization investigations indicated that the studied inhibitors were mixed type inhibitors. Electrochemical Impedance Spectroscopic measurements show that the inhibitors form an adsorptive layer on the metallic surface. Some of the inhibitors' quantum chemical parameters are calculated with the DFT method at the B3LYP/6-31G(d,p) level of theory. Among the calculated parameters, the LUMO energy, energy gap between the HOMO and LUMO, dipole moments (μ), global chemical hardness (η), softness (σ), and the fraction of electrons transferred from the inhibitor to the iron surface (ΔN) could well describe the experimental observations.

The potential of a novel triazole derivative namely 4,5-diethyl 1-[(4-ethyl-2-phenyl-4,5-dihydro-1,3-oxazol-4-yl)methyl]-4,5-dihydro-1H-1,2,3-triazole-4,5-dicarboxylate (OxTDC) as anticorrosion agent for mild steel (MS) in 1 mol/L HCl solution was investigated using gravimetric and electrochemical techniques. The OxTDC was tested at various concentrations (0.001-1 mM) and four temperatures (308, 318, 328 and 338 K) to determine the optimal concentration and temperature range for the best corrosion inhibiting effect. The synthesized inhibitor showed inhibition efficiency reach to 94.8% at temperature 298 K. Corrosion current density decreased from 1071.9 µA cm−2 (blank) to 67.1 µA cm−2 at 1 mM OxTDC. This derivative acts as mixed type inhibitor and the adsorption mode conforms to Langmuir isotherm in acidic environment. Furthermore, the results elucidated from molecular simulations (DFT linked with molecular dynamics) evidenced the adsorption of OxTDC compound on the iron surface. The quantum mechanics computations clarified the electronic interactions of OxTDC molecules with metal atoms.

In the present paper, the practical elimination of pesticides from water by photocatalysis has been studied by using two commercial titania photocatalysts (Degussa P25 (50 m2/g) and Millennium PC500 (340 m2/g)) and by choosing diuron as a model molecule. These two catalysts have been tested and compared in suspension in a slurry reactor. Their activities have been based on the rates of diuron disappearance diuron. In particular, comparisons have been made on their initial activities, which is independent of the influence of intermediates formed. Under identical conditions, Degussa P25 appeared substantially more active than Millennium PC500. However, since the final filtration of titania powders in suspension for the release of cleaned water and the recovery of the catalysts is a tedious process, titania has been successfully deposited on flexible photo-inert supports to be easily removed and recycled. The binding agent was an amorphous silica, transparent to UV. Depending on the nature of the industrial paper support used, both industrial titania photocatalysts behaved oppositely: for the same quantity of deposited titania samples, Degussa P25 was as active as in suspension when deposited on paper KN47 and substantially (20%) less active when deposited on NW10 whereas Millennium PC-500 behaved oppositely.

The photodegradation of imazaquin, [2-(4,5-dihydro-4-methyl-4-(methylethyl)-5-oxo-1-imidazol-2-yl]-3-quinolinecarboxylic acid (CAS RN: [1] , [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] , an herbicide belonging to the family of imidazolinone, was investigated using steady-state irradiation in aqueous solutions at different pH values, different wavelengths and different oxygen concentrations. Using spectrometry techniques (UV–vis and fluorescence), p K a values for the ground state, p K a ( S 0 ) , and for the lowest excited singlet state p K a ( S 1 ) , were found to be 3.6 and 7.5, respectively. The degradation of imazaquin appeared to be more effective at pH > p K a ( S 0 ) and in the absence of oxygen. The use of laser flash photolysis has shown the presence of a triplet state in the region from 320 to 550 nm with a maximum centred at 380 nm. By comparing the quenching rate constant, k q , obtained from the quenching of the triplet state by molecular oxygen ( k q = 9.31 × 10 8 mol −1 L s −1 ) and from the Stern–Volmer relation ( k q = 1.13 × 10 8 mol −1 L s −1 ), we deduced that the singlet state also seems to play a role in the photodegradation process. According to the experimental results, it has been found that imazaquin is a rather stable molecule in the dark or at low pH. In pure water, imazaquin degrades slowly and the photodegradation leads to the formation of four photoproducts. Three photoproducts were tentatively identified by HPLC–MS analyses and another one was proposed by taking into account the literature.

Imazethapyr herbicide [5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl) nicotinic acid] is widely used on agricultural field crops in Morocco. It is reported that soil properties largely enhance the sorption of the herbicide in soils, however understanding their impact in soils of Morocco is needed. The present article investigates the sorption behavior of imazethapyr herbicide toward six agricultural soils from Morocco in batch equilibrium experiments at pH 5 and evaluates the effect of the organic matter, the clay content, and the cation exchange capacity (CEC) on the sorption by applying simple and multiple linear regressions. Freundlich isotherm model described well the dynamic of imazethapyr sorption in all studied soils under the experimental conditions. The linear regressions showed significant differences between the soil properties and their impact on the sorption. While simple regression revealed strong positive correlations between the sorption and both the soil clay content ( R 2 = 0.91) and CEC ( R 2 = 0.92), the multiple regression revealed a noteworthy influence of soil organic matter when combined with clays. Our findings showed a weak adsorption of imazethapyr on the selected Moroccan soils, in addition to a potential role of clay minerals and CEC in the retention of the herbicide compared to the organic matter. The low adsorptive capacity of the Moroccan soils urges the necessity of minimizing herbicide application rates in agricultural regions to prevent environmental detrimental impacts.