Modified Chitosan Hydrogels and Nano Hydrogels for Congo Red Removal from Aqueous System

In the present work, sulfonamide chitosan derivatives were prepared via the reaction of chitosan (Cs) with diphenyl ether – 4, 4`- disulfonylchloride (DPE) in absence and/or presence of glutaraldehyde (G) to form the hydrogel (DPE-I) and (DPE-II) respectively. The nanogels (DPE-III) and (DPE-IV) were prepared via ionotropic gelation method in presence of sodium tri polyphosphate (TPP) under the same reaction conditions. The hydrogels (DPE-I, DPE-II, DPE-III, and DPE- IV) were characterized by different tools as: Elemental analysis, Fourier Transform Infra-Red spectrometer (FT-IR), Proton Nuclear Magnetic Resonance (1HNMR), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The adsorption efficiency of the prepared hydrogels for removal of congo red dye (CR) from aqueous solution under different parameters such as (time, pH, and concentration) was evaluated. The adsorption capacity of CR by the prepared hydrogels increased with time, adsorbent dosage and the initial concentration of CR. The optimum adsorption capacity for CR dye by the prepared hydrogels was at pH 7. Hydrogels (DPE-III and DPE-IV) showed the highest efficiency for adsorption of (CR) dye

New modified chitosan composites and nanocomposites for different applications

The present work focuses on the preparation of chitosan composite and chitosan nanocomposite derivatives for different applications. Chitosan was modified with bentonite or nano-bentonite to give chitosan composite and nanocomposite derivatives hydrogels I and II respectively, however chemical modification of chitosan with isonicotinic aldehyde via Schiff base formation in presence of bentonite or nanobentonite yielded chitosan composite and nanocomposite derivative hydrogels In and IIn respectively. The prepared hydrogels were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (X-Ray), Thermogravimetric analysis (TGA), Differential Scanning Calorimetry (DSC), Scanning electron microscopy (SEM), and swelling behavior. Adsorption studies for removal of heavy metal ions from aqueous media and the biological activity for the new hydrogels were studied. Results of evaluation of the prepared chitosan derivatives hydrogel for metal ions uptake showed that the maximum adsorption capacity amounted to 68 and 22 mg/l and the highest efficiency for adsorption of cobalt and mercuric ions from aqueous solution by hydrogel IIn at 10 h (93.2%) and (97.8%) respectively, whereas the adsorption capacity of hydrogel IIn increased with the increase of the initial concentration of heavy metals ions ranging from 0.4 to 1 g/l. However, modified chitosan derivative hydrogels In and IIn showed remarkable MIC and MBC towards Gram-positive (B. subtilis) (19.5, 38) μg/ml compared to the standard antibiotic Ciprofloxacin (19, 38) μg/ml respectively

Consideration of the bioavailability of metal/metalloid species in freshwaters: experiences regarding the implementation of biotic ligand model-based approaches in risk assessment frameworks

After the scientific development of Biotic Ligand Models (BLMs) in recent decades these models are now considered suitable for implementation in regulatory risk assessment of metals in freshwater bodies. The approach has been developed over several years and has been described in many peer-reviewed publications. The original complex BLMs have been applied in prospective risk assessment reports for metals and metal compounds and are also recommended as suitable concepts for the evaluation of monitoring data in the context of the European Water Framework Directive. Currently, several user-friendly BLM-based bioavailability software tools are available for assessing the aquatic toxicity of a limited number of metals (mainly copper, nickel, and zinc). These tools need only a basic set of water parameters as input (e.g., pH, hardness, dissolved organic matter and dissolved metal concentration). Such tools seem appropriate to foster the implementation in routine water quality assessments. This work aims to review the existing bioavailability-based regulatory approaches and the application of available BLM-based bioavailability tools for this purpose. Advantages and possible drawbacks of these tools (e.g., feasibility, boundaries of validity) are discussed, and recommendations for further implementation are given

Synthesis of new Schiff bases bearing 1,2,4-triazole, thiazolidine and chloroazetidine moieties and their pharmacological evaluation

New compounds based on oxindole moiety were synthesized via the reaction of 5-substitued isatins 1a–e with different nucleophiles such as benzidine, 3,3′-dimethoxybenzidine 2a,b and 2,6-diaminopyridine 3 to afford three different classes of bis-Schiff bases 4a–e, 5a–e and 6a–e, respectively. The structures of the new compounds were elucidated on the basis of their FTIR, 1H NMR, 13C NMR, GC/MS spectral data and elemental analysis. The in vitro antimicrobial activity of the new compounds was evaluated using a broth dilution technique in terms of minimal inhibitory concentration (MIC) against four bacterial and two fungal pathogens and anticancer activities against HELA cervix. The revealed data showed that compound 9d has excellent activity against Gram + ve and Gram –ve bacteria, and compounds 11b presented promising anticancer activity against HELA cervix

Synthesis and Antimicrobial Activity of Some New Pyrazole, Fused Pyrazolo[3,4-d]-pyrimidine and Pyrazolo[4,3-e][1,2,4]- triazolo[1,5-c]pyrimidine Derivatives

Hydrazonyl bromides 2a,b reacted with active methylene compounds (dibenzoylmethane, acetylacetone, ethyl acetoacetate, phenacyl cyanide, acetoacetanilide, ethyl cyanoacetate, cyanoacetamide and malononitrile) to afford the corresponding 1,3,4,5- tetrasubstituted pyrazole derivatives 5-12a,b. Reaction of 12a,b with formamide, formic acid and triethyl orthoformate give the pyrazolo[3,4-d]pyrimidine, pyrazolo[3,4- d]pyrimidin-4(3H)one and 5-ethoxymethylene-aminopyrazole-4-carbo-nitrile derivatives 13-15a,b, respectively. Compounds 15a,b reacted with benzhydrazide and hydrazine hydrate to afford pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine and [4-iminopyrazolo- [3,4-d]pyrimidin-5-yl]amine derivatives 16a,b and 17a,b. Reactions of compounds 17a,b with triethyl orthoformate and carbon disulfide give the corresponding pyrazolo[4,3-e]- [1,2,4]triazolo[1,5-c]pyrimidine derivatives 18a,b and 19a,b, respectively

Solvent

Neat ethylacetoacetate (EAA) and its mixtures with a co-solvent and an anti-solvent have been studied for refining of heavy wax distillate fraction to produce substantially non-carcinogenic base oil. The co-solvent and anti-solvent used are dipropylene glycol (DPG) and ethylene glycol (EG) respectively. The solubility characteristics of the main solvent and its mixed solvent systems were studied. Selection of the optimum solvent mixture and extraction variables has been studied. The effect of co-solvent and anti-solvent addition on the carcinogenic potential and raffinate quality has been determined under clearly comparable conditions

Synthesis and evaluation of some amine compounds having surface active properties as H2S scavenger

In this work three H2S scavengers were prepared by reacting monoethanolamine with formaldehyde in different ratios (1:1, 2:1 and 2:3) to give MF1, MF2 and MF3, respectively. The chemical structures of the prepared scavengers were confirmed by FT-IR spectroscopy. The effect of reaction time (the time required for completing the reaction between the scavenger and the H2S gas) has been studied for the three prepared scavengers. The effects of concentration and temperature have been studied on the scavenging efficiency of H2S using three prepared products and two commercial products EPRI-710 and EPRI-730. The surface and thermodynamic parameters of the prepared scavengers were determined at 25 °C including, surface tension (γ), and effectiveness, maximum surface excess (Γmax) and minimum surface area (Amin). Also, the standard free energy of micellization and adsorption was recorded. The results show that the efficiency of scavengers increased with increasing reaction time up to 50 min. Also, as concentration of scavengers and temperature increased, the removal efficiency of the scavengers increased. By comparing the efficiency of the prepared products with the commercial products EPRI-710 and EPRI 730, it was found that, MF3 exhibited a similar efficiency comparing with the commercial scavenger EPRI 730 (currently used in the field) at different concentrations and temperatures

Synthesis and evaluation of some new demulsifiers based on bisphenols for treating water-in-crude oil emulsions

The present paper endeavors to synthesize nine types of demulsifiers based on bisphenols (bisphenol A (BA), bisphenol AC (BAC) and bisphenol CH (BCH)) having different ethylene oxide units (n = 27, 34, 45) namely; E (x + y) (where E represents BA, BCH or BAC and (x + y) which represents the ethylene oxide units (27, 34, 45)). The chemical structures of the prepared demulsifier were elucidated using FT-IR and 1H NMR spectra. Effect of the chemical structure (hydrophobic and ethoxylated degree of hydrophilic parts) and the mechanism of demulsification process was investigated. The data were discussed on the light of the chemical structure of the demulsifiers and the factors, effecting the demulsification process. The efficiency of these demulsifiers was tested on water-in-oil emulsions (w/o) at different concentrations (100, 200 and 300 ppm), 7.4% asphaltene content and 30%, 50% and 70% water content. From the obtained data the best demulsifier was E(34)BA which shows 100% demulsification after 58 min at 30% water content and 300 ppm of the demulsifier

New sustainable chemically modified chitosan derivatives for different applications: Synthesis and characterization

The functionalization of chitosan (CS) by terephthaloyl chloride (TPC), glutaraldehyde (GA), and 4(4-(ethyl carbamoyl) benzoyl chloride) benzene sulfonamide was performed under different reaction conditions to yield the new hydrogels (I, II, III) respectively. However, hydrogel (I-NPs) was prepared from reaction of chitosan with (TPC) via ionic gelation technique using sodium tripolyphosphate (TPP) as a cross-linker. Moreover, hydrogel (I) was loaded (Au, Ag and ZnO) nanoparticles to give the nanoformulations (I-Au NPs, I-Ag NPs and I-ZnO NPs) respectively. Structural and morphological analysis of the new chitosan derivatives hydrogels and NPs formulations were characterized by FTIR, elemental analysis, TGA, DSC, XRD, SEM and TEM. From swelling study, chitosan derivatives hydrogels revealed higher swelling degree compared to (CS) with increasing time, temperature and pH values which reached maximum at pH 7 then decreased at pH 10. In addition, the maximum sorption capacities of Congo Red (CR) in aqueous solution were in the range 81–88%. Moreover, adsorption equilibrium isotherm results displayed favorable Langmuir model than Freundlich model. Furthermore, chitosan derivatives hydrogels showed broad spectrum antimicrobial activities against Gram-negative bacteria, Gram-positive bacteria and fungi with the inhibition zone diameter ranged from 13 to 25 mm compared to (CS) hydrogel which revealed inhibition zone diameter ranged from 11 to 16 mm, especially the nano formulation hydrogel (I-Ag NPs) showed the highest antimicrobial activity. The results were promising suggesting that the new modified chitosan derivatives could be potential for dye removal and as antimicrobial agents