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This paper describes studies of functionalized mesoporous silica employed as adsorbent for Mn(II) from aqueous solutions. The surface area of MCM-41 and diethylenetriamine functionalized-MCM-41 used in this study were 760 and 318 m(2) g(-1) (N2 adsorption). A strong dependence on pH in the Mn(II) adsorption capacity and best results were obtained at pH 6.5-7. The adsorption onto the diethylenetriamine functionalized-MCM-41 followed the pseudo-second-order kinetic model and the highest reaction rate 0.324 min(-1) was observed at low initial concentration 10 ppm. The equilibrium data showed excellent correlation with the Langmuir isotherm model and the maximum adsorption capacity of Mn(II) reached 88.9 mg/g for DETA-MCM-41 indicating that the adsorption occurs on a homogeneous surface by monolayer sorption without interaction between the adsorbed ions. These data contribute to the understanding of mechanisms involved in mesoporous silica and provide some practical clues to improve the adsorption efficiency (uptake capacity and kinetics) of Mn(II) ions.

Marine transportation still generates negative impacts on the marine environment, including releases of ballast water containing aquatic invasive species; historical use of antifoulants; oil and chemical spills; dry bulk cargo releases; garbage; underwater noise pollution; ship-strikes on marine megafauna; risk of ship grounding or sinkings; and widespread sediment contamination of ports during trans-shipment or ship breaking activities. Commercial vessels that do not conduct ballast water exchange, in accordance with International Convention Ballast Water Management, will endager the environment of ports. In this study, investigation of heavy metal (Cd, Cu, Fe, Mn, Pb and Zn) and nutrients (NO3, NO2, NH4, PO4 and SiO4) contents in ballast waters of three commercial ships entering the Tobruk port, along the Tobruk Gulf. High concentration levels were observed in all samples which were the main source of high heavey metals concentration of coastal waters of Tobruk Gulf. These results were confirmed by determination of nutrients concentration which were also found in high concentrations levels compared with reference sample. Results showed that in a long term the ballast water has the potential to change the chemical quality in marine environments, and it should treated before discharge in coastal areas, as well as the unpolluted of ballast waters should be loaded.

Mercury is recognized internationally as an important pollutant since mercury and its compounds are persistent, bioaccumulative and toxic, and pose human and ecosystem risks. A critical aspect of mercury cycling is its bioaccumulation, mainly as methylmercury, along the contaminated water with mercury resulting in high risk of human. Adsorption of mercury from water samples on mesoporous silica, mercaptopropyl functionalysed-SBA-15 (MP-SBA-15) and diethylenetriamine functionalysed-SBA-15 (DETA-SBA-15) has been studied. SBA-15 was prepared by using Pluronic P123, PEO20PPO70PEO20 and tetraethylorthosilicate. Surface modification of SBA-15 was carried out by MP-TMS or DETA-TMS to produce MP-SBA-15 or DETA-SBA-15, respectively. SBA-15 and functionalised SBA-15 materials were characterised for BET surface area, pore size and pore volume. The adsorption kinetics and adsorption isotherms of functionalised SBA-15 for mercury were investigated. Results revealed that the adsorption kinetics were fitted by a pseudo-second-order reaction model and the adsorption thermodynamic parameters ΔH°, ΔS° and ΔE° were 42.08 kJ/mol, 210.3 J/mol.K and 7.20 kJ/mol, respectively for DETA-SBA-15; 101.85 kJ/mol, 397.7 J/mol.K and 23.28 kJ/mol, respectively for MP-SBA-15. Langmuir and Freundlich isotherm models were also applied to analyse the experimental data and to predict the relevant isotherm parameters. The best interpretation for the experimental data was given by the Langmuir isotherm equation. The results indicate that the structure of the materials affects the adsorption behavior. These materials show a potential for the application as effective and selective adsorbents for Hg(II) removal from water.

The equilibrium dissociation constant (KD) is the basic parameter to evaluate the binding property of the chemical structure of compounds. Thus, a variety of analytical methods have been established to determine the KD values, including radioligand binding assay, surface plasmon resonance method, fluorescence energy resonance transfer method, affinity chromatography, and isothermal titration calorimetry. Here we present a detailed overview of the dissociation equilibria of Eberconazole nitrate (EBZ) in homogeneous and heterogeneous systems, focusing primarily on methods that are based on spectrophotometrically of the dissociation reaction. The Dissociation equilibria of Eberconazole nitrate (EBZ) in homogeneous and heterogeneous systems were studied spectrophotometrically in Britton-Robinson’s (BR) buffer at 25°C. Acidity constant of EBZ in BR buffer was found to be 9.5. The effect of anionic, cationic and non-ionic surfactants applied in the concentration exceeding critical micellar concentration (cmc) on acid – base properties of EBZ were also examined. The results revealed a shift of pKa values in micellar media comparing to the values obtained in BR buffer. These shifts in pKa values are more in cationic and anionic micellar media compared with that of non-ionic. The observed differences in pKa values between micellar media and BR buffer solution ranged between -6.0 to -2.0 units. The micellar-mediated pKa shifts can be attributed to the differences between the mean intrinsic solvent properties of the interfacial and bulk phases, with an additional contribution from the electrostatic micellar surface potential in the case of the charged aqueous micellar solutions.

Adsorbents were synthesized to obtain novel silica nanoparticles with a broad pore-size distribution (herein referred to as USG-41). The material demonstrated fast adsorption rates with highest adsorption capacities following Langmuir adsorption. Kinetic data best fit the intraparticle diffusion model demonstrating a two-step, surface and pore, adsorption process with pore diffusion being the rate determining step. This data provides key evidence of internal pore chelation of dichromate ions by USG-41. In contrast silica adsorbents (SBA-15 and MCM-41) prepared with similar average pore sizes to USG-41, but with narrow pore-size distributions, had lower adsorption capacities and their kinetic date best fit pseudo-second order diffusion models indicating a one-step, surface only, adsorption process. This study clearly demonstrated that pores size distribution, not the surface area or the average pore size, was central to ensure optimum adsorbent performance for removal of Cr (VI) from contaminated water.

This work consists of assessing the degree of pollution caused by wastewater, Power station discharge pipe and petroleum port in the gulf of Tobruk-Libya. This study is based on the analysis of the physicochemical parameters, the parameters indicating pollution and the determination of pH, DO, BOD, OOM, phenol, Salinity, nutrients (PO4, SiO3, NO2, NO3 and NH3), sodium and potassium on seawater samples taken from the site. The sampling was carried out during the April of year 2015. The results obtained show significant values in physicochemical parameters, pollution indicator parameters. The results of the pollution indicator parameters show the presence of important pollution at the site studied. It is clear from the determination of physicochemical parameters that the site under investigation shows a high contamination of seawater according to pollution caused by wastewater, Power station discharge pipe and petroleum port near the gulf of Tobruk-Libya. The absence of treatment and the long-term exposure to these discharges will lead to dangerous levels which maybe lead to destruction of marine life may affect people living near the port.

Silica sorbents, based on mesoporous crystalline material-41 (MCM-41), were functionalised using mercaptopropyl (MP) or diethylenetriamine (DETA) to extract mercury (II) ions from water. MP-MCM-41 is an extremely efficient and selective sorbent for the removal of mercury (II) from samples of distilled water doped with heavy metal ions and additionally from more complex matrices including tap and river water. In contrast DETA-MCM-41 preferentially removes hard metal ions (chromium, manganese, lead and zinc) over soft metal ions such as mercury. During extraction, the influence of pH on adsorption capacity was examined; a maximum adsorption capacity of 1245 μmol g(-1) was achieved for MP-MCM-41 even at pH values as low as 3. Significantly, a method has been developed for the first time to remove Hg (II) from loaded MP-MCM-41 allowing this analyte to be selectively recovered from water contaminated with a wide range of heavy metal ions. The regeneration method does not disrupt the chelating agent which remains on the surface of the silica permitting reuse of the sorbent in further extractions.

A room temperature method to create large pore size and pore volume ordered mesoporous silica (MCM-41) is demonstrated. Template removal was achieved with a microwave digestion procedure using a solution of nitric acid and hydrogen peroxide. The silica product exhibited an ordered hexagonal mesostructure, large pore volume (up to 0.99 cm(3)/g), and large pore size (up to 6.74 nm) indicating its potential as a high capacity adsorbent. Surface modification, to enhance the ability of the material to extract potentially toxic metals (PTMs) from water was performed using different amino- and mercapto-functional groups. This paper reports on the extraction of lead ions from aqueous solution to demonstrate the material's significant improvement in adsorption capacity (up to 1000 μmol g(-1) for lead). Moreover, methods have been developed to regenerate the sorbent allowing 100% recovery of Pb and reuse of the sorbent material in subsequent extractions. The performance of the material was also demonstrated for environmental samples containing relatively high concentrations (ppmv) of mixed metal ions reducing them to lower values (

Indoor air can become polluted with VOCs, and understanding the factors which affect adsorption of VOCs from indoor air is important for: (i) the accurate measurement of VOCs, and (ii) to apply mitigation strategies when high analyte concentrations are measured. In this study four VOCs (toluene, ethylbenzene, cumene and dichlorobenzene) were generated as a constant and controlled polluted air stream of VOCs from a dynamic atmospheric chamber. The effects of relative humidity, and sampling flow rate, on adsorption onto Tenax TA and the relatively new silica adsorbents SBA-15 or MCM-41 were studied. Air samples were collected and analyzed by thermal desorption followed by GC/MS. All sorbents were shown to be affected by changing the RH conditions from 25 to 80% RH, and sampling flow rates from 25 to 200 cm3 min−1, even when pollutant concentrations and sampled air volumes remained consistent. Although further work is required to examine the effect of the full RH range on scavenging potential, in this study Tenax TA was shown to provide best performance in high RH conditions whereas silica sorbents were more effective at low RH. Moreover it was shown that to provide accurate measurements in the field (e.g., when humidity conditions are fixed) it is suggested that Tenax TA is the preferred sorbent of choice as the masses of VOCs collected were less affected by changing the sampling flow rates.