Rapid adsorption of benzotriazole onto oxidized carbon cloth as an easily separable adsorbent.

A commercial carbon cloth (CC) was oxidized by HNO3 acid and the features of the plain and oxidized CC were evaluated. The results of characterization illustrated that HNO3 oxidization duplicated the oxygen-containing functional groups and the surface area of the CC. The adsorption performance of the plain and oxidized CC (Oxi-CC) toward benzotriazole (BTR) was compared. The results disclosed that the uptake of BTR by oxidized CC was greater than the plain CC. Thence, the affinity of oxidized CC toward BTR was assessed at different conditions. It was found that the adsorption was quick, occurred at pH 9 and improved by adding NaCl or CaCl2 to the BTR solution. The kinetic and isotherm studies revealed that the surface of Oxi-CC is heterogeneous and the adsorption of BTR follows a physical process and forms multilayer over the Oxi-CC surface. The regenerability and reusability study illustrated that only deionized water can completely regenerate the Oxi-CC and that the Oxi-CC can be reused for five cycles without any loss of performance. The high maximum adsorption capacity of Dubinin-Radushkevich isotherm model (252 mg/g), ease of separation and regeneration, and maintaining the adsorption capacity for several cycles revealed the high efficiency and economical and environmental feasibility of Oxi-CC as an adsorbent for BTR.

Preparation and characterization of chemically cross-linked zwitterionic copolymer hydrogel for direct dye and toxic trace metal removal from aqueous medium.

In this work, a zwitterionic copolymer hydrogel with adsorption affinity toward anionic dye and cationic trace metal was prepared by a free radical copolymerization of cationic ([3-(methacryloylamino)propyl] trimethylammonium chloride (MPTC)) and anionic (sodium 4-vinylbenzenesulfonate (SVBS)) monomers. Bis[2-(methacryloyloxy)ethyl] phosphate was used as a cross-linker and its effect on the adsorption properties of the prepared hydrogel was evaluated. The prepared materials were characterized by FTIR, XRD, SEM, EDX, and N2 adsorption at 77 K analysis. FTIR and EDX analysis demonstrated the successful preparation of poly(MPTC-co-VBS). XRD and SEM analysis showed that the poly (MPTC-co-VBS) is amorphous and has quasi-honeycomb morphology with large pores. Increasing the amount of the cross-linker enhanced the adsorption of direct blue 71 dye (DB71) and Pb(II) ions. The highest removal of DB71 and Pb(II) was achieved after 2 h using 1.5 g/L of poly(MPTC-co-VBS); however, the optimum solution pH was 3 for DB71 and 5 for Pb(II). The kinetics and isotherm studies illustrated that the surface of poly(MPTC-co-VBS) is heterogenous with small-sized homogenous pitches and the DB71 and Pb(II) adsorption onto poly(MPTC-co-VBS) is favorable. Finally, poly(MPTC-co-VBS) is more efficient in removing DB71 and Pb(II) from aqueous solutions than many other reported adsorbents.

Simultaneous decolorization of anionic and cationic dyes by 3D metal-free easily separable visible light active photocatalyst.

To overcome the hard and costly post-treatment separation of ultrathin graphitic carbon nitride nanosheets (UGCN), it was supported on polyurethane foam (PUF). The ratio of PUF/UGCN was optimized for the removal of a mixture of methylene blue (MB) and methyl orange (MO) dyes. The characteristics of the composite photocatalyst and its photocatalytic performance were detailly studied. The X-ray diffraction and Fourier transform infrared results proved the successful preparation of UGCN and PUF and that the PUF/UGCN composite combines the features of both pure materials. The transmission electron microscopy illustrated the ultrathin nanosheet shape of the UGCN, while the scanning electron microscope showed the highly porous 3D-hierarchical structure of PUF. Compared to the pure components, the composite photocatalyst with PUF/UGCN mass ratio of 4 achieved better decolorization of MO and almost same decolorization of MB as UGCN. Neutral pH and 1 g/L of the composite photocatalyst were the optimum conditions for MB/MO mixture decolorization. The composite photocatalyst kept its efficiency for five successive cycles. Hydroxyl radicals were the dominant in the degradation of MB, while superoxide radicals were the most influencer in MO degradation. Conclusively, supporting UGCN onto PUF kept the photocatalytic efficiency of UGCN toward MB decolorization and improved its efficiency toward MO. Moreover, it enabled the reuse of the composite photocatalyst and facilitated the post-treatment separation process.

One-Step Room-Temperature Synthesis of Bimetallic Nanoscale Zero-Valent FeCo by Hydrazine Reduction: Effect of Metal Salts and Application in Contaminated Water Treatment.

The effect of initial salt composition on the formation of zero-valent bimetallic FeCo was investigated in this work. Pure crystalline zero-valent FeCo nanoparticles (NPs) were obtained using either chloride or nitrate salts of both metals. Smaller NPs can be obtained using nitrate salts. Comparing the features of the FeCo prepared at room temperature and the solvothermal method revealed that both materials are almost identical. However, the room-temperature method is simpler, quicker, and saves energy. Energy-dispersive X-ray (EDX) analysis of the FeCo NPs prepared using nitrate salts at room temperature demonstrated the absence of oxygen and the presence and uniform distribution of Fe and Co within the structure with the atomic ratio very close to the initially planned one. The particles were sphere-like with a mean particle size of 7 nm, saturation magnetization of 173.32 emu/g, and surface area of 30 m2/g. The removal of Cu2+ and reactive blue 5 (RB5) by FeCo in a single-component system was conformed to the pseudo-first-order and pseudo-second-order models, respectively. The isotherm study confirmed the ability of FeCo for the simultaneous removal of Cu2+ and RB5 with more selectivity toward Cu2+. The RB5 has a synergistic effect on Cu2+ removal, while Cu2+ has an antagonistic effect on RB5 removal.

Simultaneous removal of Pb2+ and direct red 31 dye from contaminated water using N-(2-hydroxyethyl)-2-oxo-2H-chromene-3-carboxamide loaded chitosan nanoparticles.

This study reports the preparation of a new material that can remove synthetic dyes and trace metals simultaneously. A new coumarin derivative was synthesized and its chemical structure was inferred from spectral data (FT-IR, 1H-NMR, 13C-NMR). Meanwhile, chitosan nanoparticles (CsNPs) were prepared then used as a carrier for two different concentrations of the coumarin derivative (C1@CsNPs and C2@CsNPs). The TEM, SEM and DLS findings illustrated that the prepared nanocomposites exhibited spherical shape and small size (less than 200 nm). The performance of the prepared material for the removal of an anionic dye (direct red 31, DR31) and cationic trace metal (Pb2+) was evaluated in unary and binary systems. The results revealed that complete removal of 10 mg L-1 of DR31 and Pb2+ in unary system was achieved at pHo 3.0 and 5.5 using 0.5 and 2.0 g L-1, respectively, of C2@CsNPs. The adsorption of DR31 and Pb2+ followed different mechanisms as deduced from the effect of pHo, kinetic, isotherm and binary adsorption studies. The adsorption of DR31 followed the Langmuir isotherm model and the pseudo-first-order kinetic model. While, the adsorption of Pb2+ followed Freundlich isotherm model and Elovich kinetic model. In the binary system, the co-presence of DR31 and Pb2+ did not affect the adsorption of each other's. Overall, the prepared material showed promising results for the removal of anionic dyes and cations trace metals from contaminated water.

A dual-functional sulfone biscompound containing 1,2,3-triazole moiety for decolorization and disinfection of contaminated water.

Water decontamination from toxic dyes and pathogenic microorganisms is critical for life on Earth. Herein, we report the synthesis of sulfone biscompound containing 1,2,3-triazole moiety and evaluation of its dye decolorization and biocidal and disinfection efficiencies. The decolorization efficiency was tested under different experimental conditions, while the biocidal action was examined against various types of waterborne pathogens, and the disinfection of some pathogenic microbes was executed in artificially contaminated water. The findindgs illustrated that the solution initial pH (pHi) affected the decolorization efficiency significantly. About complete removal of 10 mg/L malachite green (MG) dye was achieved after 10 min using 3 g/L of the sulfone biscompound at pHi 6. The pseudo-second-order equation suited the adsorption kinetics accurately, while the equilibrium data was suited by Langmuir isotherm model. Electrostatic, n-π, and π-π interactions brought about the adsorption of MG onto the sulfone biscompound. The biocidal results indicated that the sulfone biscompound had a powerful antibacterial potential against the tested bacterial species. Likewise, the distinction trail revealed that after 70-90 min of direct contact with an effective dose, the tested pathogens could be completely eliminated (6-log reduction). Overall, the newly synthesized sulfone biscompound can efficiently remove cationic dyes and disinfect contaminated water.

Multi-exposure human health risks assessment of trihalomethanes in drinking water of Egypt.

The present study aims to assess the probable lifetime cancer and non-cancer risks of exposure to the trihalomethanes in Egypt's drinking water through ingestion, dermal contact, and inhalation. A total of 1667 drinking water samples were collected from twenty-three Egyptian governorates over a three-years period. The concentrations of total trihalomethanes ranged between 29.07 and 86.01 µg/L and were always below the maximum contamination level recommended by the Egyptian standards (100 µg/L). Chloroform was the most prominent trihalomethanes species, while bromoform was rarely detected. The cancer risk study revealed that, among the investigated paths, inhalation poses the greatest risk. And bromodichloromethane had the highest impact to cancer (69%), followed by chlorodibromomethane (28%). Geographically, the highest cancer risk value was found in Matruh governorate (42.2 × 10-6) and the lowest was in Minya governorate (1.0 × 10-6). The cancer risk for the studied governorates, except Minya governorate, was higher than the level recommended by the USEPA (1.0 × 10-6). Hazard index (HI) study revealed that the ingestion pathway caused higher HI values than the dermal pathway and that chloroform had the highest contribution to HI value. However, the values of HI were below unity in all studied governorates demonstrating that there would be negligible non-cancer risk.

Multifunctional 3D cationic starch/nanofibrillated cellulose/silver nanoparticles nanocomposite cryogel: Synthesis, adsorption, and antibacterial characteristics.

We report a new 3D nanocomposite cryogel combines the advantages of cationic starch (Cs), nanofibrillated cellulose (NFC) and silver nanoparticles (Ag NPs). Cs was the main component of the cryogel while NFC was used as a filling agent to enhance the mechanical properties of the produced cryogel. Both Cs and NFC endow the cryogel with adsorption properties while Ag NPs enhances its antibacterial properties. Ag NPs was green synthesized with the aid of microwave radiation using NFC as reducing and stabilizing agent. The prepared Ag particles were free of impurities with sizes <10 nm and good stability in solution. Two different concentrations of the prepared Ag NPs were added to a mixture of Cs and NFC and subjected to freeze drying to get porous cryogel (3D microstructure). The Ag NPs free cryogel has highly porosity smooth surface with large surface area. Adding Ag NPs decreased these features and increased the 3D roughness. Optimum adsorption of reactive blue 49 was observed after 30 min of contact with 1.5 g/L of the cryogel at pH 1. The adsorption kinetics and isotherm were best described by the pseudo-first-order and Freundlich equations, respectively. All prepared cryogels have notable antibacterial properties that were significantly improved by adding Ag NPs. Overall, the new 3D composite cryogel can efficiently remove dyes and bacteria from wastewater.

Hazardous inorganic disinfection by-products in Egypt's tap drinking water: Occurrence and human health risks assessment studies.

This study is the first that monitored the presence and levels of chlorite, chlorate and bromate in tap drinking water of Egypt. Three hundred and eight samples were collected from 22 governorates across Egypt and were analyzed using a standardized ion chromatography method. Forty-seven samples were contaminated by one or more of the inorganic disinfection by-products (DBPs) and only 12 samples exceeded the admissible maximum contamination levels (MCLs). The ratio of samples detected, and exceeding the MCLs were low relative to the global literature. Chlorate was the most prevalent inorganic DBPs (40 samples; concentration <12-4082 µg/L) followed by bromate (12 samples; concentration <3-626 µg/L) then chlorite (5 samples; concentration <12-123 µg/L). Chlorite was always below the MCL and had no human health risk even for the worst-case scenario. Bromate is a real challenge as it poses a significant cancer risk even for the median concentrations. None of the inorganic DBPs was detected in the tap drinking water of Beheira, Cairo, Gharbia, Giza, Kafr El Sheikh, Luxor, Monufia, and Suez governorates. This study manifested the importance of routine monitoring, and implementing counter measures to control the levels of the hazardous inorganic DBPs in tap drinking water.

Bi2O3-BiFeO3 Glass-Ceramic: Controllable ß-/γ-Bi2O3 Transformation and Application as Magnetic Solar-Driven Photocatalyst for Water Decontamination.

Glass and glass-ceramic materials containing photoactive and magnetic crystalline phases were prepared from Fe2O3 and Bi2O3 using the conventional melt method. All samples were characterized in terms of formed phases, morphological analyses, optical properties, and magnetic properties. Formation of the photoactive tetragonal ß- and body-centered cubic γ-Bi2O3 phases along with the magnetic BiFeO3 and Fe3O4 phases was revealed. However, the crystalline structure relied on the composition and the applied heat-treatment time. ß-/γ-Bi2O3 transformation could be controlled by the heat-treatment time. The samples exhibited variable magnetic properties depending on their composition. All of the samples showed excellent absorbance in visible light with an optical band gap of 1.90-2.22 eV, making them ideal for solar-light-driven photocatalysis. The best performance was recorded for the sample containing equal amounts of Fe2O3 and Bi2O3 due to the formation of γ-Bi2O3/BiFeO3 heterojunction in this sample.

Bioremediation of potentially toxic metal and reactive dye-contaminated water by pristine and modified Chlorella vulgaris.

This is the first study on the biosorption of Cu2+ and reactive yellow 145 (RY145) dye by citric acid (CA), NaOH, and heat-treated Chlorella vulgaris (Cv). Influence of contact time, initial adsorptive concentration, and biomass dosage on the biosorption process was explored. The biosorption kinetics and isotherm were comprehensively investigated as well. The Fourier transform infrared analysis proved the successful insertion of carbonyl groups on Cv surface by CA modification and the intensification of all Cv functional groups by heat treatment. CA modified Cv was the best biosorbent for RY145, 0.5 g/L removes 97% of 10 mg/L solution (pHi 2) in 40 min. The biosorption was favorable, occurred via the formation of a monolayer of RY145 on the homogenous surface of CA-modified Cv and followed the pseudo-second-order kinetics. On the other hand, heat-treated Cv was the best biosorbent for Cu2+, 0.5 g/L removes 92% of 10 mg/L solution (pHi 5) in 5 min. The biosorption of Cu2+ on heat-treated Cv was complex and involves more than one mechanism. The Langmuir theoretical monolayer saturation capacity of RY145 on CA-modified Cv was comparable to other biosorbents, while that of Cu2+ on heat-treated Cv was drastically superior.

Removal of Hazardous Contaminants from Water by Natural and Zwitterionic Surfactant-modified Clay.

In this study, natural clay (NC) was collected from Saudi Arabia and modified by cocamidopropyl betaine (CAPB) at different conditions (CAPB concentration, reaction time, and reaction temperature). NC and modified clay (CAPB-NC) were characterized using X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, and N2 adsorption at 77 K. The adsorption efficiency of NC and CAPB-NC toward Pb2+ and reactive yellow 160 dye (RY160) was evaluated. The adsorption process was optimized in terms of solution initial pH and adsorbent dosage. Finally, the adsorption kinetics and isotherms were studied. The results indicated that NC consists of agglomerated nonporous particles composed of quartz and kaolinite. CAPB modification reduced the specific surface area and introduced new functional groups by adsorbing on the NC surface. The concentration of CAPB affects the adsorption of RY160 tremendously; the optimum concentration was 2 times the cation exchange capacity of NC. The equilibrium adsorption capacity of CAPB-NC toward RY160 was about 6 times that of NC and was similar for Pb2+. The adsorption process followed the pseudo-second-order kinetics for both adsorptive. RY160 adsorption on CAPB-NC occurs via multilayer formation while Pb2+ adsorption on NC occurs via monolayer formation..

The occurrence and risk assessment of phenolic endocrine-disrupting chemicals in Egypt's drinking and source water.

This is the first nationwide survey of bisphenol A (BPA), methylparaben, ethylparaben, propylparaben, butylparaben, and o-phenylphenol, in Egypt's water. Five hundred fifty-five water samples were collected from source water (SW, 109 samples) and drinking water (DW, 446 samples) of twenty-three Egyptian governorates. These chemicals were determined by direct ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis of a filtered aliquot of samples. The impacts of the measured concentrations on the aquatic organisms and human health were evaluated as well. BPA, methylparaben, propylparaben, and butylparaben were frequently detected in SW and DW, while ethylparaben and o-phenylphenol were not detected whatsoever. The most frequently detected endocrine-disrupting chemical (EDC) was BPA in SW and methylparaben in DW. The recorded highest concentrations of BPA and methylparaben in SW and BPA and methylparaben, propylparaben, and butylparaben in DW were the highest worldwide. Of the investigated twenty-three governorates, the SW and DW of Aswan, Red Sea, Cairo, Sharqia, and Damietta were free of the studied EDCs. Contrarily, BPA, MeP, PrP, and BuP were detected in Sohag's SW and DW. A detection ratio > 70% was recorded in SW of Faiyum, Dakahlia, and Ismailia, and > 90% in DW of Sohag, Port Said, Dakahlia, and Faiyum. The environmental risk assessment results excluded any human health risk even in the worst-case scenario and showed that BPA represents the highest risk to the aquatic organisms.

Synthesis, characterization and adsorption properties of microcrystalline cellulose based nanogel for dyes and heavy metals removal.

Recently, naturally occurring biopolymers have attracted the attention as potential adsorbents for the removal of water contaminants. In this work, we present the development of microcrystalline cellulose (MCC)-based nanogel grafted with acrylamide and acrylic acid in the presence of methylene bisacrylamide and potassium persulphate as a crosslinking agent and initiator, respectively. World-class facilities such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), surface analysis, field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and zeta sizer were used to characterize the synthesized MCC based nanogel. The prepared nanogel was applied to remove reactive red 195 (RR195) dye and Cd (II) from aqueous medium at different operational conditions. The adsorption experiments showed that the feed concentration of monomers has a significant effect on the removal of RR195 which peaked (93% removal) after 10min of contact time at pH2 and a dose of 1.5g/L. On contrary, the feed concentration has insignificant effect on the removal of Cd (II) which peaked (97% removal) after 30min of contact time at pH6 and a dose of 0.5g/L. The adsorption equilibrium data of RR195 and Cd (II) was best described by Freundlich and Langmuir, respectively. Conclusively, the prepared MCC based nanogels were proved as promising adsorbents for the removal of organic pollutants as well as heavy metals.

Impact of support characteristics and preparation method on photocatalytic activity of TiO2/ZSM-5/silica gel composite photocatalyst.

Titanium dioxide (Degussa P25) was supported onto two different aluminosilicate zeolites (ZSM-5) and anchored on three silica gels using two separate preparation methods to study the effect of the catalyst components and the preparation method on the photoactivity of composite catalysts. The photoactivity was investigated by tracking phenol disappearance in a batch UVA light-emitting diode reactor. An easily separable photocatalyst with higher photoactivity than commercial Degussa P25 was developed using Degussa P25, ZSM-5 (SiO2/Al2O3 = 280) and silica gel (particle size 0.2-0.5 mm and pore size 40 Å). The optimum composition was found to be P25:ZSM-5:silica gel = 0.3 : 0.5 : 0.5 g l-1. SEM photographs show that the distribution of the composite catalyst components prepared without a binder was better than that prepared with a binder. The efficiency of photocatalytic ozonation of sulfamethoxazole (SMX) using the new photocatalyst was assessed and compared to that of commercially available Degussa P25. It was found that photocatalytic ozonation promoted the SMX disappearance and mineralization. PZS was superior to Degussa P25 with respect to photocatalysis and photocatalytic ozonation. The enhancement was attributed to the synergetic effect between adsorption, ozonation and/or photocatalytic oxidation.

Photocatalytic ozonation of pesticides in a fixed bed flow through UVA-LED photoreactor.

In this study, a fixed bed flow through UVA-LED photoreactor was used to compare the efficiency of ozone, photocatalysis and photocatalysis-ozone degradation, and mineralization of two pure pesticides, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA), and a commercial one, Killex®. For the degradation of the parent compounds, ozone-based processes were more effective. While for mineralization, photocatalytic processes were more effective. Photocatalytic ozonation was the most efficient process for both the degradation and mineralization of the parent compounds. The degradation rates and mineralization by photocatalytic ozonation were higher than the summation of the corresponding rates by ozonation and photocatalysis, indicating a symbiotic relationship.Overall, the photocatalytic ozonation process with the fixed bed TiO2 reduces the time needed for the degradation and mineralization of the pesticides, reduces the costs of powder catalyst separation and overcomes the reduced efficiency of immobilized catalysts, which makes the process quite attractive for practical applications.

Preparation and characterization of humic acid-carbon hybrid materials as adsorbents for organic micro-pollutants.

The present work involves the preparation of novel adsorbent materials by the insolubilization and hybridization of humic acid (HA) with carbon. The prepared materials were characterized by N2 adsorption, elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, solid-state (13)C cross polarization magic angle spinning nuclear magnetic resonance, and low-field nuclear magnetic resonance (NMR) relaxometry on wetted samples. The water solubility of these materials and the lack of effect of oxidants were also confirmed. With this background, the adsorption capacities toward phenol, 2,4,6-tricholrophenol, and atrazine were evaluated, using these as model compounds for organic micropollutants of concern in water. Experimental results show that the prepared materials are mesoporous and have a higher surface area than humic acid and even than the porous carbon in the case of carbon coating. They retain the basic features of the starting materials with lowered functional group content. Moreover, there are interesting new features. NMR relaxometry shows that equilibration of water uptake is very fast, making use in water simple. They have higher adsorption capacities than the pure materials, and they can be applied under a wide range of environmental conditions.