Sulfonated graphene oxide impregnated cellulose acetate floated beads for adsorption of methylene blue dye: optimization using response surface methodology.

New multi-featured adsorbent beads were fabricated through impregnation of sulfonated graphene (SGO) oxide into cellulose acetate (CA) beads for fast adsorption of cationic methylene blue (MB) dye. The formulated SGO@CA composite beads were thoroughly characterized by several tools including FTIR, TGA, SEM, XRD, XPS and zeta potential. The optimal levels of the most significant identified variables affecting the adsorption process were sequential determined by the response surface methodology (RSM) using Plackett-Burman and Box-Behnken designs. The gained results denoted that the surface of SGO@CA beads displayed the higher negative charges (- 42.2 mV) compared to - 35.7 and - 38.7 mV for pristine CA and SGO, respectively. In addition, the floated SGO@CA beads demonstrated excellent floating property, fast adsorption and easy separation. The adsorption performance was accomplished rapidly, since the adsorption equilibrium was closely gotten within 30 min. Furthermore, the adsorption capacity was greatly improved with increasing SGO content from 10 to 30%. The obtained data were followed the pseudo-second order kinetic model and agreed with Langmuir adsorption isotherm model with a maximum adsorption capacity reached 234.74 mg g-1. The thermodynamic studies designated the spontaneity and endothermic nature of MB dye adsorption. Besides, the floated beads exposed acceptable adsorption characteristics for six successive reuse cycles, in addition to their better adsorption selectivity towards MB dye compared to cationic crystal violet and anionic Congo red dyes. These findings assume that the formulated SGO@CA floated beads could be used effectively as highly efficient, easy separable and reusable adsorbents for the fast removal of toxic cationic dyes.

Floatable cellulose acetate beads embedded with flower-like zwitterionic binary MOF/PDA for efficient removal of tetracycline.

Removal of pharmaceutical wastes, especially antibiotics from aquatic systems is an imperative issue from both human-health and ecological perspectives. Herein, zwitterionic UiO-66/ZIF-8 binary MOF/polydopamine@cellulose acetate composite (UiO-66/ZIF-8/PDA@CA) were fabricated in the form of floated beads for the adsorptive removal of tetracycline (TC). The formulated composite beads were characterized by FTIR, XRD, SEM, BET, Zeta potential and XPS analysis tools. Under optimum adsorption conditions, the UiO-66/ZIF-8/PDA@CA composite beads demonstrated large specific surface area, good adsorption performance with a relatively short equilibrium time (60 min) and ease separation. Furthermore, the adsorption data fit Temkin > Langmuir > Freundlich with a maximal adsorption capacity of 290.69 mg/g at 25 °C, while the adsorption kinetics were well-described by pseudo-second order kinetics. The thermodynamics studies refereed that the adsorption process was endothermic and spontaneous. Besides, the floated UiO-66/ZIF-8/PDA@CA beads displayed better adsorption property for eight reuse cycles with a maximal removal (%) reached 67%, reflecting its promising applicability as reusable adsorbent for efficient removal of antibiotics from water bodies.

Formulation and Antibacterial Activity Evaluation of Quaternized Aminochitosan Membrane for Wound Dressing Applications.

Much attention has been paid to chitosan biopolymer for advanced wound dressing owing to its exceptional biological characteristics comprising biodegradability, biocompatibility and respectable antibacterial activity. This study intended to develop a new antibacterial membrane based on quaternized aminochitosan (QAMCS) derivative. Herein, aminochitosan (AMCS) derivative was quaternized by N-(2-Chloroethyl) dimethylamine hydrochloride with different ratios. The pre-fabricated membranes were characterized by several analysis tools. The results indicate that maximum surface potential of +42.2 mV was attained by QAMCS3 membrane compared with +33.6 mV for native AMCS membrane. Moreover, membranes displayed higher surface roughness (1.27 ± 0.24 µm) and higher water uptake value (237 ± 8%) for QAMCS3 compared with 0.81 ± 0.08 µm and 165 ± 6% for neat AMCS membranes. Furthermore, the antibacterial activities were evaluated against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus cereus. Superior antibacterial activities with maximum inhibition values of 80-98% were accomplished by QAMCS3 membranes compared with 57-72% for AMCS membrane. Minimum inhibition concentration (MIC) results denote that the antibacterial activities were significantly boosted with increasing of polymeric sample concentration from 25 to 250 µg/mL. Additionally, all membranes unveiled better biocompatibility and respectable biodegradability, suggesting their possible application for advanced wound dressing.

Titanium Dioxide/Phosphorous-Functionalized Cellulose Acetate Nanocomposite Membranes for DMFC Applications: Enhancing Properties and Performance.

This study intends to provide new TiO2/phosphorous-functionalized cellulose acetate (Ph-CA) nanocomposite membranes for direct methanol fuel cells (DMFCs). A series of TiO2/Ph-CA membranes were fabricated via solution casting technique using a systematic variation of TiO2 nanoparticle content. Chemical structure, morphological changes, and thermal properties of the as-fabricated nanocomposite membranes were investigated by FTIR, TGA, SEM, and AFM analysis tools. Further, membranes' performance, mechanical properties, water uptake, thermal-oxidative stability, and methanol permeability were also evaluated. The results clarified that the ion-exchange capacity (IEC) of the developed nanocomposite membranes improved and reached a maximum value of 1.13 and 2.01 meq/g at 25 and 80 °C, respectively, using TiO2 loading of 5 wt % compared to 0.6 and 0.81 meq/g for pristine Ph-CA membrane at the same temperature. Moreover, the TiO2/Ph-CA nanocomposite exhibited excellent thermal stability with appreciable mechanical properties (49.9 MPa). The developed membranes displayed a lower methanol permeability of 0.98 × 10-16 cm2 s-1 compared to 1.14 × 10-9 cm2 s-1 for Nafion 117. The obtained results suggested that the developed nanocomposite membranes could be potentially applied as promising polyelectrolyte membranes for possible use in DMFCs.

pH-Sensitive Alginate/Carboxymethyl Chitosan/Aminated Chitosan Microcapsules for Efficient Encapsulation and Delivery of Diclofenac Sodium.

To develop an effective pH-sensitive drug carrier, alginate (Alg), carboxymethyl chitosan (CMCs), and aminated chitosan (AmCs) derivatives were employed in this study. A simple ionic gelation technique was employed to formulate Alg-CMCs@AmCs dual polyelectrolyte complexes (PECs) microcapsules as a pH-sensitive carrier for efficient encapsulation and release of diclofenac sodium (DS) drug. The developed microcapsules were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analyzer (TGA), and scanning electron microscope (SEM). The results clarified that formation of dual PECs significantly protected Alg microcapsules from rapid disintegration at colon conditions (pH 7.4), and greatly reduced their porosity. In addition, the dual PECs microcapsules can effectively encapsulate 95.4% of DS-drug compared to 86.3 and 68.6% for Alg and Alg-CMCs microcapsules, respectively. Higher DS-release values were achieved in simulated colonic fluid [SCF; pH 7.4] compared to those obtained in simulated gastric fluid [SGF; pH 1.2]. Moreover, the drug burst release was prevented and a sustained DS-release was achieved as the AmCs concentration increased. The results confirmed also that the developed microcapsules were biodegradable in the presence of the lysozyme enzyme. These findings emphasize that the formulated pH-sensitive microcapsules could be applied for the delivery of diclofenac sodium.

Formulation of Quaternized Aminated Chitosan Nanoparticles for Efficient Encapsulation and Slow Release of Curcumin.

An effective drug nanocarrier was developed on the basis of a quaternized aminated chitosan (Q-AmCs) derivative for the efficient encapsulation and slow release of the curcumin (Cur)-drug. A simple ionic gelation method was conducted to formulate Q-AmCs nanoparticles (NPs), using different ratios of sodium tripolyphosphate (TPP) as an ionic crosslinker. Various characterization tools were employed to investigate the structure, surface morphology, and thermal properties of the formulated nanoparticles. The formulated Q-AmCs NPs displayed a smaller particle size of 162 ± 9.10 nm, and higher surface positive charges, with a maximum potential of +48.3 mV, compared to native aminated chitosan (AmCs) NPs (231 ± 7.14 nm, +32.8 mV). The Cur-drug encapsulation efficiency was greatly improved and reached a maximum value of 94.4 ± 0.91%, compared to 75.0 ± 1.13% for AmCs NPs. Moreover, the in vitro Cur-release profile was investigated under the conditions of simulated gastric fluid [SGF; pH 1.2] and simulated colon fluid [SCF; pH 7.4]. For Q-AmCs NPs, the Cur-release rate was meaningfully decreased, and recorded a cumulative release value of 54.0% at pH 7.4, compared to 73.0% for AmCs NPs. The formulated nanoparticles exhibited acceptable biocompatibility and biodegradability. These findings emphasize that Q-AmCs NPs have an outstanding potential for the delivery and slow release of anticancer drugs.

Fabrication of novel iminodiacetic acid-functionalized carboxymethyl cellulose microbeads for efficient removal of cationic crystal violet dye from aqueous solutions.

Novel anionic adsorbent microbeads were fabricated based on surface functionalization of p-benzoquinone-carboxymethyl cellulose (CMC-PBQ) activated microbeads with iminodiacetic acid (IDA). The developed IDA@CMC-PBQ microbeads were characterized by FT-IR, TGA, SEM, XPS and zeta potential analysis tools. Ion exchange capacity measurements proved the successful generation of extra carboxylic groups on the surface of IDA@CMC-PBQ microbeads with a maximum value reached 3.984 meq/g compared to 1.32 meq/g for neat CMC microbeads. The fabricated microbeads were tested for the removal of cationic crystal violet (CV) dye from aqueous solutions under various adsorption conditions. The results clarified that the removal percent of CV dye was augmented and reached a maximum value of 91.56% with increasing IDA concentration up to 0.15 M. Moreover, the experimental data were well-fitted both Langmuir and Freundlich isotherms with a maximum adsorption capacity of 107.52 mg/g. while the adsorption process was obeyed the pseudo-second order kinetic model. The developed adsorbent displayed respectable reusability after five sequential cycles and exhibited higher adsorption ability towards cationic CV dye compared to cationic methylene blue (MB) and anionic methyl orange (MO) dyes. Therefore, IDA@CMC-PBQ adsorbent could be effectually used as a convenient and reusable adsorbent for removing cationic dyes from their aqueous solutions.