Heterogeneous porous biochar-supported nano NiFe2O4 for efficient removal of hazardous antibiotic from pharmaceutical wastewater.

Due to the dual issues of antibiotic resistance and bioaccumulation toxicity, antibiotics are ubiquitously present in aquatic environments, and this is causing serious concern. Herein, novel nickel ferrite (NiFe2O4) nanoparticles were successfully loaded onto activated biochar (BC) derived from banana peel (BP) to obtain magnetic nanocomposite (BC-NiFe2O4) as an effective biosorbent for the ciprofloxacin antibiotic (CIP) elimination from pharmaceutical effluent. A facile co-precipitation approach was utilized to construct the heterogeneous BC-NiFe2O4. The synthesized materials were systematically characterized using techniques such as XRD, FE-SEM, EDX, HR-TEM, BET, FTIR, and XPS. In addition, the magnetic measurements indicated the ferromagnetic behavior of the BC-NiFe2O4 sample. The influencing factors (i.e., pH, contact time, initial concentration, dose of adsorbent, ions interference, and solution temperature) of the adsorption process were also well studied. The adsorption capacity of the BC-NiFe2O4 heterostructure was 68.79 mg g-1 compared to the BC sample (35.71 mg g-1), confirming that the loading of magnetically NiFe2O4 nanoparticles onto the surface of porous biochar enhanced its stability and adsorption performance for CIP removal, wherein the metal-antibiotic complex has a significant effect for the removal of CIP. Moreover, the Langmuir adsorption isotherm and the pseudo-second-order model displayed a good fit for the experimental data. The values of △H° and △G° revealed that the adsorption process was endothermic and spontaneous. The coordination affinities, π-π stacking, and H-bonding interactions play a more critical role in the adsorption mechanism that confirmed by FTIR and XPS analysis. To study the stability of BC-NiFe2O4 nanocomposites, desorption and recycling studies were investigated. The results revealed that after three cycles, no significant loss in removal efficiency was detected, reflecting the stability and reusability of the prepared BC-NiFe2O4 nanocomposite.

Proton exchange membrane based on graphene oxide/polysulfone hybrid nano-composite for simultaneous generation of electricity and wastewater treatment.

Microbial fuel cell (MFC) is a combined technology for simultaneous generation of electricity and wastewater treatment. In MFC, the proton exchange membrane (PEM) is an essential component affecting electricity generation. In the current study, two proton exchange membranes, namely sulfonated polyethersulfone (SPES) and graphene oxide/sulfonated -polyethersulfone hybrid nanocomposite (GO-SPES), were prepared and characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The collected information confirmed the successful preparation of the membranes. Moreover, contact angle measurements, ion exchange capacity and degree of sulfonation of the prepared membranes were determined. The results showed that the introduction of GO nanoparticles into SPES membrane improved its proton exchange capability and resulted in better performance. The power density and the current generated from SPES membrane were 60 mW/m2 and 425 mA/m2, respectively. For GO-SPES, the obtained power density was 101.2 mW/m2 and the current was 613 mA/m2. Both membranes showed comparable chemical oxygen demand (COD) removal efficiency of about 80%; suggesting that the prepared membranes are working efficiently in wastewater treatment as PEMs in MFCs. As a final point, the performance of GO-SPES membrane was compared to the performance of the well-known Nafion® 117 membrane and the results were promising. To conclude, the GO-SPES membrane is an outstanding membrane for use as PEM in MFCs for simultaneous generation of electricity and wastewater treatment.

Reduction of sulfur oxides emissions via adsorptive desulfurization of transportation fuels using novel silica-based adsorbent.

Transportation fuels with high sulfur content are one of the primary contributors to air pollution because they emit massive quantities of sulfur oxides upon combustion. The emitted sulfur oxides undoubtedly contribute to global warming and climate change. Therefore, they should be minimized. The current study accurately describes a novel and direct synthetic pathway for the incorporation of sulfonic acid groups (-SO3H) into mesoporous silica surface. The structure of the prepared materials was confirmed using FTIR, SEM, BET, SA-XRD, TEM, and TGA techniques. The batch adsorption technique was used to carefully evaluate the adsorption efficiency of the prepared adsorbent towards dibenzothiophene (DBT). At optimal adsorption conditions, a maximum adsorption capacity of 75-mg DBT/g adsorbent was achieved. The desulfurization process fitted well to Langmuir and pseudo-second-order models. In addition, the desulfurization process was found to be a spontaneous and exothermic process. As a final point, the practical applicability of the prepared adsorbent, as well as its reusability, was properly investigated, and the results were promising.

Magnetically modified hydroxyapatite nanoparticles for the removal of uranium (VI): Preparation, characterization and adsorption optimization.

Recently, magnetically modified nanomaterials have gained a great interest in the field of wastewater remediation. In this regard, the present work introduces a facile microwave-assisted pathway for the preparation of magnetically modified hydroxyapatite nanoparticles (MNHA) and evaluates its adsorption capability towards the removal of uranium (VI) ions from wastewaters. The prepared magnetic nanocomposite went through a full characterization procedure using different techniques, such as transmission electron microscope (TEM), X-ray diffraction (XRD), FT-IR, Brunauer-Emmett-Teller (BET) surface area measurements and magnetization curve. Involvement of the prepared MNHA in the remediation of wastewater containing U(VI) ions was investigated and the factors that influence the adsorption capacity were considered and optimized. The adsorption's optimum pH was found to be 5.0 and equilibrium was attended after 120 min. A maximum adsorption capacity of 310 mg/g was achieved after 120 min at 25 °C. The experimental data were well explained by Langmuir adsorption isotherm model. Kinetically, the adsorption process follows the pseudo-second order model. Thermodynamically, it is endothermic, irreversible and spontaneous adsorption process. Removal of U(VI) ions was found to take place via complex formation between the phosphate groups on the adsorbent and uranyl ions. The recovery of U(VI) ions from MNHA beads and the reusability of the spent beads were also explored. It was concluded that the prepared MNHA nanocomposite is simple, fast, ecofriendly adsorbent for the removal of U(VI) ions from water with excellent adsorption capacity.

Novel polyacrylamide-based solid scale inhibitor.

Novel solid-state phosphorus-containing polymer was synthesized, characterized and investigated as anti-scaling agent for the removal of alkaline earth metals ions from water. An optimization protocol for the sorption process of the metal ions on the polymer surface was proposed and executed. The protocol involved parameters such as pH, contact time, polymer dose, and the initial concentration of the metal ion. The optimum pH was found to be around seven for all of the tested metal ions. The maximum sorption capacities of the prepared polymer were 667, 794, 769 and 709 (mg/g) for Mg, Ca, Sr and Ba ions, respectively. Evaluation of the sorption process from the isotherm, kinetic and thermodynamic points of view was also studied. The experimental evidence revealed that the sorption obeys Langmuir isotherm model and follows a pseudo-second order mechanism. Moreover, the sorption process is exothermic. Possibility of polymer reuse was also investigated.

A separation strategy combining three HPLC modes and polysaccharide-based chiral stationary phases.

Nine polysaccharide-based chiral stationary phases (CSPs) were used to define a separation strategy that combines normal-phase (NP), reversed-phase (RP) and polar organic solvent chromatography (POSC) modes. After limiting ourselves to two CSPs per mode, in total, five CSPs, Chiralpak AD (NP), Chiralcel OD (RP and POSC), Lux Cellulose-1 (NP), Lux Cellulose-2 (POSC) and Lux Cellulose-3 (RP), showed the broadest enantioselectivity and most complementarity. Six sequences of the three modes were considered to decide which sequence is the most successful for screening a set of 56 pharmaceutical compounds. Starting the strategy with the NP mode, followed by RP and finally POSC was found preferable from both the number of cumulative separations and of baseline separations. Two approaches were considered for strategy fine tuning using an additional set of eight racemic mixtures. In both approaches, seven of the eight compounds were baseline resolved, on one of the examined columns at either screening or optimization conditions of a mode. One approach was finally preferred because of its lower workload.

Enantioselectivity of polysaccharide-based chiral selectors in polar organic solvents chromatography: implementation of chlorinated selectors in a separation strategy.

The enantioselectivity of polysaccharide-based chiral stationary phases in polar organic solvents chromatography (POSC) is investigated using both chlorinated and non-chlorinated selectors. A test set of 58 drug compounds was analyzed at the screening conditions of a previously developed separation strategy. Eight stationary phases were screened with eight mobile phases, resulting in 64 chromatographic systems. After selection of the two most successful mobile phases, a preferred testing sequence for the polysaccharide selectors was determined, based on their success rate and complementarity. These stationary phases, screened in the sequence Lux Cellulose-2>Chiralcel OD-RH>Lux Cellulose 4>Sepapak-5, each with two mobile phases, showed 48/58 separations (83% of the test set). An attempt was also made to update the existing separation strategy. The existing screening conditions were found to be easily applicable on stationary phases with chlorinated selectors, but the optimization steps appeared to be less successful.

Chiral separations in reversed-phase liquid chromatography: evaluation of several polysaccharide-based chiral stationary phases for a separation strategy update.

By application of the reversed-phase generic screening conditions of a separation strategy defined in Matthijs et al. (2004) [18], the chiral discrimination abilities of six recently commercialized polysaccharide-based columns, Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-3, Lux Cellulose-4, Lux Amylose-2 and Sepapak-5, and of three classic ones, Chiralpak AD-RH, Chiralcel OD-RH and Chiralcel OJ-RH, were evaluated using a set of 58 compounds. Two mobile phases, an acidic and a basic, were sequentially applied on the columns. Using both mobile phases, a column set of Chiralcel OD-RH (or Lux Cellulose-1), Lux Cellulose-3 and Lux Amylose-2 gave the maximal number of cumulative separations, i.e. 51/58 (or 50), of which 35 (or 32) had baseline resolutions. Therefore, this set of systems was selected to update the screening step of the existing separation strategy. The selected columns were subsequently used to evaluate the applicability of the initial optimization steps, part of the existing RPLC strategy, using 66 different optimization cases. The existing optimization steps increased both the number of separations and of baseline separations by eight and by 18, respectively, relative to the screening results. Introduction of some modifications to the existing steps added eight more separations and three more baseline separations. In addition, a new optimization step for late eluting compounds was proposed and implemented. Based on these results, an updated chiral separation strategy in RPLC was defined.

Chiral separations in normal-phase liquid chromatography: Enantioselectivity of recently commercialized polysaccharide-based selectors. Part II. Optimization of enantioselectivity.

Earlier, a set of pharmaceuticals with different chemical structures has been used to evaluate the enantioselectivity of four recently commercialized polysaccharide-based chiral stationary phases, Lux Cellulose-1/Sepapak 1, Lux Cellulose-2/Sepapak 2, Lux Amylose-2/Sepapak 3 and Lux Cellulose-4/Sepapak 4 and of three Daicel columns, Chiralpak AD-H, Chiralcel OD-H and Chiralcel OJ-H, using the screening conditions of an existing generic separation strategy in normal-phase liquid chromatography (NPLC). In this study, the applicability of the optimization steps of the existing separation strategy was examined using 44 drugs (70 optimization cases) representing the three possible resolution situations that occur after screening. Optimizations are demonstrated by modifying parameters such as polar modifier percentages, temperatures, flow rates and additives concentration. Changing the percentage of polar modifier was found to have the largest influence on the resolution. The resolution, peak shape and the analysis time were nicely improved for 49/70 cases (70%) after the application of the original optimization steps. The introduction of some modifications to the original optimization increased this number from 49 to 62 cases, i.e. from 70% to 88.6%. Finally, an updated generic separation strategy in NPLC was proposed.

Chiral separations in normal phase liquid chromatography: enantioselectivity of recently commercialized polysaccharide-based selectors. Part I: enantioselectivity under generic screening conditions.

Four recently commercialized polysaccharide-based chiral stationary phases, Sepapak(®) 1, Sepapak(®) 2, Sepapak(®) 3, and Sepapak(®) 4, now called Lux(®) Cellulose-1, Lux(®) Cellulose-2, Lux(®) Amylose-2 and Lux(®) Cellulose-4, respectively, were examined for their enantioselectivity on a set of 61 racemic compounds by applying the screening conditions of a previously developed chiral screening strategy in normal phase liquid chromatography (NPLC) [N. Matthijs et al., J. Chromatogr. A 1041 (2004) 119-133]. The enantioselectivity on these phases was compared to that on the initial set of polysaccharide-based phases, Chiralpak(®) AD-H, Chiralcel(®) OD-H, and Chiralcel(®) OJ-H, used in the earlier defined strategy. The results showed that 53 compounds out of 61 (86.9%) were resolved on the initial set of chiral stationary phases (CSPs) using two mobile phases per compound, either heptane-ethanol-diethylamine (DEA) or heptane-isopropanol-DEA for testing basic compounds and heptane-ethanol-trifluoroacetic acid (TFA) or heptane-isopropanol-TFA for acidic, bifunctional and neutral compounds. The recently commercialized set of columns gave 54 separations in total (88.5%). Our results indicated that ethanol (EtOH) as polar modifier provides a higher success rate and better resolutions than isopropanol (IPA) on both sets of stationary phases. However, the usefulness of the mobile phase with IPA as polar modifier cannot be neglected for complementarity reasons. It was found that the screening is improved by the introduction of the recently commercialized polysaccharides based CSPs since they provided enantioseparation for compounds that were not resolved by the traditional CSPs. The combination between the initial and the recently commercialized CSPs showed enantioresolution for 55 compounds out of 61 (90%), among which 47 were baseline resolved.

External nasal valve collapse repair: the limited alar-facial stab approach.

OBJECTIVES: Permanent treatment for external nasal valve collapse (ENCV) is primarily surgical. In some situations, instead of a major operation, the placement of structural alar rim graft may be all that is needed. Alar rim graft placement is usually achieved through a marginal incision as a part of a rhinoplasty. We compared the aesthetic and functional outcomes of a simple technique in which the graft is placed via an external incision in the alar-facial groove with the outcomes of the more commonly used method. METHODS: All patients who underwent ENCV repair in 2007 and 2008 were reviewed. Fifteen cases in which grafts were placed using the alar-facial stab technique were identified. Twenty cases with marginal incision graft placement in that time period were then randomly selected. All of the patients underwent concurrent additional procedures such as rhinoplasty/septorhinoplasty. The aesthetic and functional assessments of both techniques were explored by means of blinded observers rating the aesthetic outcome and patients rating their functional outcome through the use of questionnaires. STUDY DESIGN: A retrospective cohort study. RESULTS: A comparison between the patients' subjective results showed no difference between the outcomes of these two techniques (P > .05). The blinded surgeon evaluators could not differentiate between the different approaches utilized in the vast majority of cases studied. CONCLUSIONS: The alar-facial stab incision with alar rim grafting for treatment of ENCV is a very simple and effective technique that does not require significant rhinoplasty experience and may be performed in the office under local anesthesia.