Hydroxide Solution Research Articles

Enhanced pozzolanic reactivity in hydrogen-form zeolites as supplementary cementitious materials

Pozzolans rich in silica and alumina react with lime to form cementing compounds and are incorporated into portland cement as supplementary cementitious materials (SCMs). However, pozzolanic reactions progress slower than portland cement hydration, limiting their use in modern construction due to insufficient early-age strength. Hence, alternative SCMs that enable faster pozzolanic reactions are necessary including synthetic zeolites, which have high surface areas and compositional purity that indicate the possibility of rapid pozzolanic reactivity. Synthetic zeolites with varying cation composition (Na-zeolite, H-zeolite), SiO2/Al2O3 ratio, and framework type were evaluated for pozzolanic reactivity via Ca(OH)2 consumption using ion exchange and in-situ X-ray diffraction experiments. Na-zeolites exhibited limited exchange reactions with KOH and Ca(OH)2 due to the occupancy of acid sites by Na+ and hydroxyl groups. Meanwhile, H-zeolites readily adsorbed K+ and Ca2+ from a hydroxide solution by exchanging cations with H+ at Brønsted acid sites or cation adsorption at vacant acid sites. By adsorbing cations, the H-zeolite reduced the pH and increased Ca2+ solubility to promote pozzolanic reactions in a system where Ca(OH)2 dissolution/diffusion was a rate limiting factor. High H-zeolite reactivity resulted in 0.8 g of Ca(OH)2 consumed per 1 g of zeolites after 16 h of reaction versus 0.4 g of Ca(OH)2 consumed per 1 g of Na-zeolite. The H-zeolite modulated the pore fluid alkalinity and created a low-density amorphous silicate phase via mechanisms analogous to two-step C-S-H nucleation experiments. Controlling these reaction mechanisms is key to developing next generation pozzolanic cementitious systems with comparable hydration rates to portland cement.

Influence of biphasic phenoxyethanol-alkaline pretreatment on the correlation between inter-structure and enzymatic hydrolysis in bamboo residues

The effective promotion of delignification (67.6 %) and xylan removal (44.8 %) from bamboo residues using a 2-phenoxyethanol/sodium hydroxide solution (P/A) system is demonstrated, while simultaneously enriching oligosaccharides contents of the pre-hydrolysate to 10.2 g/L. Increasing the P/A ratio from 0:1 to 4:1 improves the enzymatic digestibility of the substrates from 55.7 % to 70.1 % at 100 °C and from 73.8 % to 83.7 % at 120 °C. Furthermore, partial correlation analysis demonstrates that the physiochemical properties, including delignification, xylan removal, and crystallinity, show a significant positive correlation with enzymatic hydrolysis efficiency. Higher temperatures and P/A ratios during alkaline biphasic pretreatment promote the shrinkage of plant cells and delignification, with temperature being a particularly significant driver. These findings provide valuable insights into the alkaline and biphasic pretreatment of biomass and facilitate the optimization of the bio-refining system.

Systematic Study on Swelling/Delamination of Layered Metal Oxides with Quaternary Ammonium Ions: Production of Well-Shaped/Oversized Unilamellar Nanosheets.

Enormous swelling of layered host compounds in an aqueous solution of various amines has been investigated as an important step in the synthesis of molecularly thin 2D nanosheets. However, a complete understanding of the reaction process has not been attained, which is the barrier for producing high-quality unilamellar nanosheets. Here, the swelling and delamination behaviors of platelet single crystals of protonated layered metal oxides are systematically examined with a series of tetraalkylammonium (TAA) hydroxide solutions. Upon contact with the solutions, the crystals immediately underwent massive expansion by several tens to hundreds of times. The swollen crystals can be delaminated into elementary layers by the application of external shear force. The exfoliation behavior is dependent on TAA ions, especially in terms of yield and lateral size/shape of the delaminated nanosheets. The swollen crystals with TAA ions with longer alkyl chains are delaminated almost completely, but irregular and fractured small sheets are yielded. Such long alkyl chains become entangled on the oxide layer and resulting hydrophobic interactions may be responsible for the lateral fragmentation. It is found that replacement of aqueous solutions with organic solvents to suppress the hydrophobic interactions is effective to produce oversized nanosheets in rectangular shape with sharp edges.

Alkali hydroxide (LiOH, NaOH, KOH) in water: Structural and vibrational properties, including neutron scattering results.

Structural and vibrational properties of aqueous solutions of alkali hydroxides (LiOH, NaOH, and KOH) are computed using quantum molecular dynamics simulations for solute concentrations ranging between 1 and 10M. Element-resolved partial radial distribution functions, neutron and x-ray structure factors, and angular distribution functions are computed for the three hydroxide solutions as a function of concentration. The vibrational spectra and frequency-dependent conductivity are computed from the Fourier transforms of velocity autocorrelation and current autocorrelation functions. Our results for the structure are validated with the available neutron data for 17M concentration of NaOH in water [Semrouni et al., Phys. Chem. Chem. Phys. 21, 6828 (2019)]. We found that the larger ionic radius [rLi+<rNa+<rK+] and higher concentration disturb the hydrogen-bond network of water, resulting in more disordered cationic hydration shell. Our abinitio simulation data for solute concentrations ranging between 1 and 10M can be used to guide future elastic and inelastic neutron-scattering experiments.

3D-printed hydrogels based on amphiphilic chitosan derivative loaded with levofloxacin for wound healing applications

Skin wounds not only cause physical pain to patients but also pose an economic burden to society. Consequently, effective approaches to promote skin repair remain a challenge. Specifically, chitosan-based hydrogels are ideal candidates to promote wound healing at different stages and while diminishing the factors that impede this process (such as excessive inflammatory and chronic wound infection). Furthermore, the unique biological properties of a chitosan-based hydrogel enable it to serve as both a wound dressing and a drug delivery system (DDS). In the present work, chitosan (CS) graft copolymer with [2-(methacryloyloxy)ethyl] trimethyl ammonium chloride (CS-MTAC), a cationic monomer with promising antibacterial properties, was synthesized. The successful synthesis of the copolymer was confirmed, while it was studied for its swelling ability and water absorption capacity, as well as for its biocompatibility and antibacterial properties. Expecting to improve its printability, the copolymer was blended with elastin (EL), collagen (COL), and increasing concentrations of gelatin (GEL). The hydrogel with 6% w/v CS, 4% w/w EL, 4% w/w COL and 1% w/v GEL was selected for its potential to be 3D-printed and was neutralized with ammonia vapors or ethanol/sodium hydroxide solution and loaded with levofloxacin. The feasibility of CS-MTAC/EL/COL/GEL bioink, loaded with Levo, as a suitable candidate for wound healing and drug delivery applications, has been demonstrated.

Alkaline activated cements obtained from ferrous and non-ferrous slags. Electric arc furnace slag, ladle furnace slag, copper slag and silico-manganese slag

Ferrous slag: electric arc furnace slag (EAFS) and ladle furnace slag (LFS); and non-ferrous slag: copper slag (CS) and silicon-manganese slag (SiMnS) have been used as precursors for alkali activated cements (AACs). The objective of the study was to evaluate the effect of the silica modulus (Ms = SiO2/K2O) (0.5–1.8) of the potassium silicate/potassium hydroxide solution on the microstructure and technological properties of AACs using individual slags. The results obtained indicate that under the activation conditions used, CS and EAFS are more reactive slags, giving rise to AACs with optimum flexural and compressive strengths of 7.5 and 51.5 MPa and 5.7 and 30.5 MPa for a Ms = 1.4, respectively. While the SiMnS and LFS are less reactive resulting in AACs with flexural and compressive strengths of 3.2 and 11.6 MPa at Ms = 1.4 for SiMnS and 1.1 MPa and 4.6 MPa at Ms = 0.9 for LFS. In all AACs, the development of the alkaline activation reaction is confirmed due to the presence of gel, of different nature and quantity depending on the precursor used. The lower mechanical properties of the AACs using SiMnS and LFS as precursor may also be due to the presence of microcracks. Therefore, this study confirms that ferrous and non-ferrous slags can be used as precursors of AACs, with the type of precursor and the modulus of the activating solution influencing mechanical properties. AACs using CS and EAFS can be used in structural applications, while those using SiMnS and LFS can be used in non-structural applications in civil engineering.

Using a Tunable Triblock Cationic Polymer to Unravel Performance and Durability Effects in Anion Exchange Membrane Based Electrolysis

The use of anion exchange membranes (AEMs) as the polymer electrolyte membrane and related cationic polymers as ionomers in the electrodes of water splitting electrolyzers could lead to significant advantages including the elimination of precious metal electrocatalysts. Because oxygenated radicals in base have a very much lower half life than in acid these materials can be based on hydrocarbon backbones. This leads to an enormous possible variation in polymer chemistry and, while exciting from the point of view of the creation of new polymer chemistries, has led to a lack of detail in determining exactly how all of these many polymers really behave in terms of performance and durability. All of the new materials that are currently being commercialized are designed to be free standing films that are chemically stable to attack by the strongly nucleophilic hydroxide anion. Often these polymers have excessive swelling and poor mechanical properties and lack easy variation enabling their modification to the properties required for an ionomer. Studies where the effect of film processing on performance or durability are also lacking. There is a chronic lack of knowledge in how cationic polymers interact with catalyst particles, charge carrier and the AEM in electrodes. Further complicating these studies is whether the device is operated in water, carbonate or hydroxide solution. The first of which give unexpectedly low performance but may be more amenable to long durability and latter of which gives high performance and low durability.We have developed a triblock co-polymer, with polychlorostyrene blocks that can be quaternized to give a hydrophilic phase and a central hydrophobic polyethylene (pE) block that gives the material good mechanical properties. This seemingly simple system can show tremendous variations. We can control the polymer block lengths and overall molecular weight of the polymer. The material can be suspension cast or melt processed to obtain uniform films. The films are post-quaternized and we can control the degree of functionalization and the nature of the cation. What is interesting about these materials is that for all anions that we have studied their conductivity behavior indicates that they are fully dissociated. We hypothesize that the pE content of the films localizes the water, this has the effect of both promoting anion conduction and also not wetting much of the polymer and so improving the durability and mechanical properties. In a series of films where we systematically increase the pE content, the materials swell less but do not necessarily loose performance. They do however show durability improvements, where a material that is 50% pE will thin in an electrolysis test giving rise to a degradation rate of -23 mV/h, a material with 80% pE will show a degradation rate of +400mV/h, at 500 μA/cm2. Further understanding of these materials is likely to result in further durability improvements. Performance and durability can also be varied by the method by which the film is processed.By using an unsaturated version of the cationic triblock co-polymer in electrode formulations and post hydrogenating we can insolubilize the polymer (by creating an insoluble pE containing polymer insitu) as the ionomer in the electrode. This allows us to study, ionomer loading and to begin to control the positioning of the ionomer. We have baselined these materials using Ni supports, and studied Membrane electrode assemblies on our optimized membranes. These ionomers are surprisingly durable as they contain aromatic groups, leading to further speculation that the localization of the water in the material again gives performance and durability advantages. In this talk we will also show how ionomer chemistry can be used to improve the performance and durability of electrolysis electrodes with either silver, cobalt oxide, or manganese oxide.

Simultaneous Phosphate Removal and Power Generation by the Aluminum–Air Fuel Cell for Energy Self-Sufficient Electrocoagulation

A self-powered electrocoagulation system with a single-chamber aluminum–air fuel cell was employed for phosphate removal in this study. Electricity production and aluminum hydroxides in solution were also investigated. When the NaCl concentration increased from 2 mmol/L to 10 mmol/L, the phosphate removal increased from 86.9% to 97.8% in 60 min. An electrolyte composed of 10 mmol/L of NaCl was shown to obtain a maximum power density generation of 265.7 mW/m2. When the initial solution pH ranged from 5.0 to 9.0, 98.5% phosphate removal and a maximum power density of 338.1 mW/m2 were obtained at pH 6.0. Phosphate was mainly removed by aluminum hydroxide adsorption. These results demonstrate that the aluminum–air fuel cell can be applied as electricity-producing electrocoagulation equipment. Aluminum–air fuel cells provide an alternative method to meet the goal of carbon neutrality in wastewater treatment compared with traditional energy-consuming electrocoagulation systems.

Clay rich river sediments calcined into precursors for alkali activated materials

Alkali activated materials (AAMs), a potential alternative to cement-based products or ceramics, can incorporate large amounts of currently landfilled aluminosilicate rich materials such as calcined clay-rich river sediments collected at hydropower plant dams. Untreated fresh sediment and untreated aged sediment intended to serve as AAM precursors were calcined to increase their amorphous content, then activated by Na or K-based silicate or hydroxide solutions and cured at 60 °C for three days.Up to 30 mass % (ma%) of fly ash (FA) or ladle slag (LS) increased the mechanical performance. The phase composition and microstructure are analyzed using X-ray diffraction, fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and mercury intrusion porosimetry to gain further insight into how the additives influence the final properties of the resulting AAMs. The main crystalline components of the prepared AAMs are quartz, illite/muscovite and feldspar. The amorphous content reaches up to 52.5 ma% in the Na-activated AAMs and up to 48.8 ma% in K-activated AAMs. The acquired results confirm the suitability of the investigated sediments as sole precursors for AAMs. The mechanical properties of the AAMs can be improved by adding FA and/or LS.

(Invited) Controlling Charge Transfer and Ion Transport in Electrodes for the Oxygen Evolution Reaction

Anion Exchange Membrane (AEM) based energy conversion devices offer the possibility of utilizing non-precious metals as the catalyst and the advantage of more facile electrochemical conversions. While many AEMs are showing practical performance and durability’s, their potential will only be realized if the catalyst particles are modulated by the cationic ionomer for maximum performance. The catalyst layer in the electrode provides the triple-phase boundary between the anion-conducting polymer, supported catalyst particles, and reactants where the electrochemical reactions take place. In proton-exchange membrane fuel cells (PEMFC), the electrode catalyst layer was developed empirically over many decades. State of the art AEM devices could be developed with new scientific insight and methodology facilitating the opportunity to be much more quickly developed as well as to exhibit maximum performance and durability. Also for PEMFC to improve Pt catalyst utilization, high surface area carbon-supported Pt catalysts were developed, followed by the development of catalyst inks and the implementation of electrode spraying techniques commonly in use today. However, carbon supported catalysts do not have the necessary durability for the oxygen evolution reaction (OER) necessitating the use of Iridium oxide in acid systems.We hypothesize that the crucial component of an electrode is the ionomer that modulates the transport of ions and neutrals to the catalyst surface and by its interaction with the surface of the catalyst can also modulates charge transfer in solid state electrodes. So, by understanding the ionomer chemistry we can design ionomer catalyst interfaces for maximum performance. For the OER we use porous Ni electrodes that we imbibe with catalyst ionomer inks. In these inks we can not only vary the catalyst to ionomer ratio, but the ionomer chemistry and IEC. To date we have studied nano-structured silver1 or cobalt oxide catalysts. The ionomers are either random or block co-polymers consisting of polyisoprene or polycyclooctene hydrophobic components as the hydrophobic component that can be hydrogenated to polymethylbutylene or polyethylene. The other component is a quaternizable polychlorostyrene that can we functionalize with trimethyl amine or methylpyrolidine. These combinations give a large experimental space in which to probe the effect of ionomer chemistry on electrode performance. We test the electrodes in a separated anode experiment where linear sweep voltammetry is used to get kinetic information and cyclic voltammetry is used to determine the double layer capacity that we use as a measure of electrochemical surface area. Using silver the ionomer chemistry clearly effcts charge transfer and transport of ions and neutrals in the electrode.1 Optimized electrodes are them used to construct 5 cm2 electrolysis cells where the electrolyzer performance and durability is evaluated. In these cells we use a Pt on carbon anode with a cationic ionomer of fixed composition and high performance triblock AEM2 that we developed that is currently being commercialized under license to SparkIonix as Tuffbrane™. Our studies to date use pumped carbonate as the water source, but we are also extending this work to distilled water or hydroxide solutions. Removing the supporting anions from the water feed by ionomer/catalyst interface engineering would dramatically improve these AEM based water electrolysis systems. “Evaluating the Effect of Ionomer Chemical Composition in Silver-Ionomer Catalyst Inks toward the Oxygen Evolution Reaction by Half-Cell Measurements and Water Electrolysis.” N.C. Buggy, I. Wu, Y. Du, R. Ghosh, M.-C. Kuo, M.S. Ezell, J.M. Crawford, S. Seifert, M.A. Carreon, E.B. Coughlin, A.M. Herring,* Electrochimica Acta., 2022, 412, 140124.“A Polyethylene-based Triblock Copolymer Anion Exchange Membrane with High Conductivity and Practical Mechanical Properties.” N.C. Buggy, Y. Du, M.-C. Kuo, K.A. Ahrens,S. Wilkinson, S. Seifert, E.B. Coughlin,* and A.M. Herring*, ACS Applied Polymer Materials, 2020, 2, 1294 – 1303.

Ascorbic acid as a corrosion inhibitor of steel in chloride-containing solutions of calcium hydroxide

Ascorbic acid as a corrosion inhibitor of steel in chloride-containing solutions of calcium hydroxide

Single Particle Electrochemical Oxidation of Polyvinylpyrrolidone-Capped Silver Nanospheres, Nanocubes, and Nanoplates in Potassium Nitrate and Potassium Hydroxide Solutions

Single particle electrochemical oxidation of polyvinylpyrrolidone-capped silver nanoparticles at a microdisk electrode is investigated as a function of particle shape (spheres, cubes, and plates) in potassium nitrate and potassium hydroxide solutions. In potassium nitrate, extreme anodic potentials (≥1500 mV vs Ag/AgCl (3 M KCl)) are necessary to achieve oxidation, while lower anodic potentials are required in potassium hydroxide (≥900 mV vs Ag/AgCl (saturated KCl)). Upon oxidation, silver oxide is formed, readily catalyzing water oxidation, producing a spike-step current response. The spike duration for each particle is used to probe effects of particle shape on the oxidation mechanism, and is substantially shorter in nitrate solution at the large overpotentials than in hydroxide solution. The integration of current spikes indicates oxidation to a mixed-valence complex. In both electrolytes, the rate of silver oxidation strongly depends on silver content of the nanoparticles, rather than the shape-dependent variable–surface area. The step height, which reflects rate of water oxidation, also tracks the silver content more so than shape. The reactivity of less-protected citrate-capped particles toward silver oxidation is also compared with that of the polymer-capped particles under these anodic conditions in the nitrate and hydroxide solutions.

Highly Hydrophilic Ti−Beta Zeolite with Ti−Rich Exterior as Efficient Catalyst for Cyclohexene Epoxidation

Nanocrystalline Ti−Beta zeolite with high hydrophilicity and a Ti−rich exterior was successfully prepared via a dissolution–recrystallization method. With the post−treatment of tetraethylammonium hydroxide (TEAOH) solution at elevated temperature, the Si and Ti species within the Ti−Beta matrix were partially dissolved and recrystallized on the outer surface of crystals, resulting in the Ti−rich exterior and higher hydrophilicity, which improved the accessibility of the active Ti sites and the enrichment of H2O2. Simultaneously, some of the closed Ti(OSi)4 species were transformed to more active open Ti(OSi)3OH or Ti(OSi)2(H2O)2(OH)2 species. The modified Ti−Beta zeolite exhibited greatly enhanced catalytic performance in the epoxidation of cyclohexene in comparison to the parent Ti−Beta.

A novel and simple dynamic coating capillary electrophoresis method for the chiral separation and quantification of mitiglinide enantiomers using hydroxyethyl cellulose as a dynamic coating agent.

A capillary electrophoretic method for the chiral separation and quantification of mitiglinide (MTG) enantiomers is described (less than 9.5 min) with resolution value Rs = 5.25 and with excellent peak shapes after performing the dynamically coating for the bare fused capillary. The study aims to develop and validate a novel and simple method for the separation and quantification of MTG enantiomers using CE after dynamic coating the capillary wall using the hydroxyethyl cellulose (HEC) coating agent. Dynamic coating procedure of the capillary inner surface is conducted via rapid flushes using 0.1 M sodium hydroxide, water, and aqueous solution containing HEC, and hydroxypropyl-γ-cyclodextrin (HP-γ-CD). Besides buffer was used for the dynamic coating process in addition to its use as the separation medium. When the dynamic coating was used, peak symmetry was improved. A bare fused-silica capillary was used throughout the separation after being coated using HEC dissolved in the background electrolyte (BGE) of 50 mM Na₂HPO₄ - 1 M H₃PO₄ solution; pH 8.5; containing 25 25 mg mL-1 of each HP-γ-CD and HEC. The dynamic coating procedure achieved an improvement in migration time as well as peak area precision. The adsorbed coating agent showed slight interactions with MTG, providing efficient separation with outstanding durability and reproducibility at slightly alkaline conditions (pH 8.5). Acceptable validation criteria for selectivity, linearity, precision, and accuracy were also studied. The newly developed method was effectively applied to the assay of enantiomers of MTG in pharmaceutical formulations. Additionally, it was proven to have the advantages of being simple, rapid, and accurate.

Alkaline Extraction of Organomineral Potassium Humate from Coal Mining Waste

Organomineral potassium humate was extracted from coal mining waste from the Lenger deposit (Turkestan region, Kazakhstan) by alkaline extraction using an aqueous solution of potassium hydroxide. The time and temperature of the process were investigated for the degree of extraction and yield of the product. A comprehensive study of the physicochemical properties of the raw material and the resulting production potassium humate was carried out by chemical analysis, scanning electron microscope, energy dispersion, IR-Fourier spectrometric and X-ray diffractographic analyses. The maximum degree of extraction and yield of the product wasachieved at 80 °C and 90 min. Moreover, the experimental data were subjected to kinetic processing, as a result of which it was established that the process of extraction of potassium humate occurs in the external diffusion region.

Alkali-activation of cellulose nanofibrils to facilitate surface chemical modification under aqueous conditions

In this study, we developed a surface-activation technique for cellulose nanofibrils (CNFs) using mild-alkali and aqueous conditions. CNFs were initially processed using the aqueous counter collision (ACC) method to produce Janus-type amphiphilic CNFs with both hydrophilic and hydrophobic faces on the surface of a single nanofibril (ACC-CNF). Selective functionalization of the hydroxy groups on the hydrophilic faces creates an opportunity to develop novel nano-building blocks that introduce heterogeneous and tailored surface characteristics into the design of nanomaterials. In this study, alkaline conditions were used to activate the hydroxy groups on the surface of ACC-CNFs as a pre-treatment for the partial crystalline transformation from cellulose I to cellulose II. We found that alkali treatment with sodium hydroxide (NaOH) solutions (concentration range 1–7 wt%) did not fully transform the structure of ACC-CNFs into cellulose II, nor change the morphology of nanofibrils, as seen from their wide-angle X-ray diffraction patterns and atomic force microscopy images. We also found that the hydroxy groups at the surface region of the ACC-CNFs were sufficiently reactive under the moderate alkali and aqueous conditions to undergo subsequent carboxymethylation. Therefore, alkali treatment of ACC-CNFs with a 1–7 wt% NaOH solution rendered the surface of the ACC-CNFs as sufficiently reactive for chemical modification without morphological changes. This simple method for surface activation of CNFs can be useful in the development of future sustainable and novel materials for a variety of applications.

Organic Matter, Agricultural Use, and Dispersion of Ferralsols for Grain Size Analysis

ABSTRACT Ferralsols are a class of highly weathered, oxidic and often acidic and low fertility soils ubiquitous of the tropical environments. Ferralsols can present anomalous behavior when dispersion is performed for grain size analysis using settling methods. This study evaluates the effect of total dispersion and dispersed solution stability of two Ferralsols from Brazil, under cultivated areas and native savannah vegetation with or without organic matter removal using hydrogen peroxide (H2O2), on percent clay, silt, and sand estimation. Samples of a Rhodic Ferralsol and an Orthic Ferralsol were dispersed using a reciprocating shaker for 16 h at 120 rpm in sodium hydroxide (NaOH) solutions. Results show that chemical modifications associated with agriculture alter the dispersion behavior of the two Ferralsols. Removal of organic matter in cultivated areas caused coagulation of fine particles. For native vegetation sites, removal of organic matter increased soil dispersion increasing clay content and decreasing sand content. NaOH was not an effective dispersant agent in all conditions and thus there is a need for investigating better chemical compounds or combinations of thereof for the dispersion of Ferralsols. Standardization of grain size analysis of Ferralsols is needed for comparisons between different studies and laboratories to be possible.

Synthesis of polyaminophosphonated-functionalized hydrochar for efficient sorption of Pb(II).

Surface modification can effectively improve the ability of hydrochar to capture pollutants from wastewater. In this work, polyaminophosphonated-functionalized hydrochar (PAP-HC) was successfully synthesized by a chemical grafting approach and applied efficiently to adsorb aqueous Pb(II). Properties of PAP-HC were characterized by ICP, FTIR, XPS, SEM-EDS, elemental analysis, zeta potential, and BET. The Pb(II) adsorbing behavior of PAP-HC was tested by batch adsorbing assays, including the pH impact, uptake kinetics, sorption isotherms, sorption thermodynamics, and PAP-HC recycling. Sorption isotherms were better illustrated by a Langmuir equation, while the kinetic profile was modeled by a pseudo-second-order equation. Adsorption of Pb(II) onto PAP-HC mainly relied on chelating Pb(II) with aminophosphonate groups of PAP-HC by XPS and FTIR analyses. The actual adsorbed amount of PAP-HC maximized to 179.92mg·g-1 at 298K, which showed high adsorption ability. Nitric acid and hydroxide solutions were suitable for desorption of adsorbed Pb(II) and activated PAP-HC, respectively. PAP-HC can be reused for at least five cycles without obvious change in adsorption performance. The results suggest PAP-HC is a prospective adsorbent to capture Pb(II) from wastewater.

One-step foam assisted synthesis of robust superhydrophobic lignin-based magnetic foams for highly efficient oil-water separation and rapid solar-driven heavy oil removal

Taking effective measures to remove oil and organic pollutants from water has become a top priority. In this study, we developed a novel superhydrophobic and magnetic lignin-based polyurethane foam for highly efficient adsorption of organic pollutants and removal of viscous crude oil from water. The superhydrophobic bio-based magnetic foam was prepared by the addition of Fe3O4 nanoparticles during the foaming process followed by the immersion in an octadecyltrimethoxysilane (OTMS) solution. After modification by OTMS, the water contact angle (WCA) of the foam adsorbent was increased by 37.1°, exhibiting a high WCA of 156°. Fe3O4 nanoparticles endowed the foam with excellent photo-thermal performance, allowing the efficient adsorption of both crude oil and a wide range of organic solvents. The foam adsorbent had a high adsorption capacity up to 18.8 times of its own weight. The bio-based adsorbent could still retain a high adsorption capacity after over ten cycles. The magnetic property facilitated control and recycling of the foam adsorbent by using a magnetic field. Moreover, the bio-based foam adsorbent was fully degraded in a methanol/sodium hydroxide solution (0.5 mol/L) at 60 °C after 8 h. The outstanding mechanical stability, reusability, and environmental friendliness make these bio-based foam adsorbent highly promising for cleaning up pollutions in water.

A Study on Sexual Dimorphism of Adult Wet Scaphoid Specimens.

BackgroundSexual dimorphism in human bones has mostly been confined to the study of the bony pelvis. However, considerable changes also exist in the other parts of the skeletal system. This study focuses on the differences in the morphometry of male and female adult scaphoids.Aims and objectivesWe aim to study the morphometry of male and female adult human scaphoids and determine the differences between the same.Materials and methodsA total of 100 scaphoids were freshly dissected from both hands of 25 male and 25 female cadavers in Saveetha Medical College, Chennai, India. The soft tissues were loosened using 5% potassium hydroxide (KOH) solution. Further, the soft tissues were removed by meticulous dissection. For the measurements, vernier calipers and threads for circumference measurement were used.ResultsThe morphometric parameters included length, proximal width, width of the middle part (waist), distal width and circumference of the waist, and circumference of the tubercle in scaphoids. Statistical differences were found in most of the parameters.ConclusionA statistically significant difference exists between the morphometric measurements of male and female adult scaphoids, which may prove helpful in the fracture fixation of the scaphoid, as scaphoid fracture has a risk of avascular necrosis.