NaOH Aq Research Articles

Evaluation of the dissolution behavior of zircon using high-resolution phase-shift interferometry microscope

The dissolution behavior of the (101) plane of zircon mineral in ultrapure water, 1 M HCl (aq), and 1 M NaOH (aq), under room temperature and nearly atmospheric pressure was evaluated by in situ measurement of the change in the surface height. A high-resolution phase-shift interferometry microscope (HR-PSI) was employed to evaluate the velocity of the change in the surface height of zircon in different solutions, and the application of this method in evaluating the dissolution behavior of nuclear materials was examined. In all cases, the measured surface height decreased linearly with small variations. Although the measured change in height of zircon in 1 M NaOH (aq) was the smallest under these conditions, the concentration of dissolved Zr in NaOH (aq) was two orders of magnitude higher than that in ultrapure water. This indicates that a high amount of dissolved Zr in 1 M NaOH (aq) was immediately precipitated on the zircon surface as a secondary phase, and the surface shape was almost retained. On the other hand, the precipitation on the reference of the surface height was confirmed while measuring the zircon in 1 M HCl (aq). This shows that the precipitation in 1 M HCl (aq) occurred far from the dissolution points, and the surface shape changed. As a result, the velocity of surface change and the precipitation behavior of zircon, which is one of the extremely durable minerals, was successfully evaluated using HR-PSI. This relatively quick method would be useful for evaluating the detailed surface change behaviors of nuclear materials, such as fuel debris, ceramic waste forms, and UO 2 , during the reaction with various solutions, since it minimises radiation exposure times and also the amount of radioactive waste generation during measurement.

Insights into the removal of Cd and Pb from aqueous solutions by NaOH–EtOH-modified biochar

The enhancement of surface functional groups on biochar is essential to improving its toxic metals adsorption capacity. In this study, we used two solutions: NaOH (aq) and NaOH dissolved in absolute ethanol (C 2 H 5 OH) to dope the surface of powdered oiltea camellia shell. Then, the shells were pyrolyzed at 500 °C for 120 min to obtain NaOH-modified biochar (SBC), NaOH–C 2 H 5 OH-modified biochar (EBC), and the undoped sample (BC). After modification, the special surface area, O-containing functional groups, especially C=C were improved. The specific surface area of EBC and SBC (91.76 and 56.83 m 2 g −1 , respectively) were superior to that of the BC (36.98 m 2 g −1 ). With NaOH–C 2 H 5 OH, more C=C groups were introduced via elimination reaction, enhancing its adsorption properties. EBC consistently showed higher adsorption efficiency than BC for Cd(II) and Pb(II). Moreover, the spectroscopic analysis revealed that Cd(II)- π , Pb(II)- π interactions were the predominant mechanisms for the toxic metals’ collection on the EBC, each contributing 75.45% and 58.60%, respectively. Besides, the O-functional groups onto EBC surface bonded easily to Pb(II) than Cd(II) in the mixture solution. Therefore, EBC produced in the NaOH–C 2 H 5 OH system, as efficient and cost-effective biochar, is promising for toxic metals adsorption. • NaOH–EtOH-modified improves special surface area and functional groups on biochar surface. • Cd(II) − π , Pb(II) − π interactions were the predominant mechanisms for toxic metals’ adsorption on the EBC. • The O − functional groups onto EBC surface bonded easily to Pb(II) than Cd(II) in the binary solution. • EBC exerts a relatively higher adsorption capacity for Cd(II) and Pb(II) than BC.

Alkaline aerobic oxidation of native softwood lignin in the presence of Na+-cyclic polyether complexes

Alkaline aerobic oxidation is a promising way to convert lignin to low molecular weight phenols, especially 4-hydroxybenzaldehydes. Our previous studies reported that oxidation of softwood lignin samples with a bulky cation, Bu4N+, facilitates selective production of vanillin (4-hydroxy-3-methoxybenzaldehyde). This study presents vanillin production from native softwood lignin in Japanese cedar (Cryptomeria japonica) in NaOH aq. in the presence of cyclic polyethers, with our expectation that Na+-polyether complexes exhibit effects similar to those of Bu4N+. Oxidation of wood flour (10 mg) in 4.0 M NaOH aq. (2.0 mL) at 120 °C under air gave vanillin with 6.2 wt% lignin-based yield, which was raised to 15.2 wt% by the addition of 15-crown-5 (1,4,7,10,13-pentaoxacyclopentadecane). On the other hand, such effect was not observed with the addition of tetraethylene glycol dimethyl ether, a non-cyclic analog of 15-crown-5. Mechanistic study with a lignin model compound revealed that stabilization of a vanillin precursor by the complex cation was a reason for the increased vanillin yield exhibited by the crown ether. This is similar to the influence of Bu4N+ reported previously, suggesting effective control of aerobic oxidation by large size cationic species.

Capacitive Behavior Study of Free Standing Titanium Carbide (Mxene) Film Under External Pressure

Titanium carbide (Ti3C2Tx, also called Mxene), uniquely combining metallic conductivity with hydrophilicity, has attracted burgeoning attention in batteries and supercapacitors application since reported in 2013. No matter with aqueous electrolytes or organic electrolytes, cation intercalation and pseudocapacitance contributes to the majority of the energy stored in Mxene-based electrochemical capacitors1-3, therefore, it is critical to understand its charge transport behavior within those negatively charged and electrically conductive Ti3C2X layers, especially the ionic diffusion process during charging/discharging.Pressure can cause peculiar and interesting structural changes in Ti3C2X Mxene as compared to other 2D materials such as graphene. Barsoum, et al. 6 have reported the phenomenon of interlayer expansion of Ti3C2X Mxene with external pressure up to 300MPa applied on in the presence of water, and they attribute the expansion to the shear-induced insertion of water molecules. To study its capacitive behavior under pressure will be of significant impact, because as a film of mechanical durability and flexibility, Ti3C2X free-standing films hold great potential in the field of wearable and portable electronics4,5, while in which, structure deformation caused by external pressure or temperature induced internal pressure is inevitable.In this work, the electrochemical performance under pressure of Ti3C2X Mxene free-standing film in various aqueous electrolytes (such as LiOH(aq), NaOH(aq), KOH(aq)) has been systematically investigated. Interestingly, different from other reported carbon-based electrode materials, Ti3C2X Mxene does not simply reach a capacitance saturation state as pressure increases. Further analysis on the structural changes and ionic diffusion under pressure suggests that complex mechanism occurs when charging/discharging under pressure. These findings should contribute to a more comprehensive understanding of the charge transport process within Mxene, and to future work of designing Mxene-based flexible electrodes for more advanced performance.Reference[1] M.R. Lukatskaya, O. Mashtalir, C.E. Ren, Y. Dall’Agnese, P. Rozier, P.L. Taberna, M. Naguib, P. Simon, M.W. Barsoum, Y. Gogotsi, Science, 2013, 341(6153), 1502-1505.[2] X. Wang, X. Chen, Y. Gao, Z. Wang, R. Yu, L. Chen, J. Am. Chem. Soc., 2015, 137, 7, 2715-2721.[3] H. Shao, Z. Lin, K. Xu, P.-L. Taberna, P. Simon, Energy Storage Materials, 2019, 18, 456-461.[4] J. Yan, C.E. Ren, K. Maleski, C.B. Hatter, B. Anasori, P. Urbankowski, A. Sarycheva, Y. Gogotsi, Adv. Funct. Mater., 2017, 27, 1701264.[5] C. Yang, Y. Tang, Y. Tian, Y. Luo, Y. He, X. Yin, W. Que, Adv. Funct. Mater., 2018, 1705487.[6] M. Ghidiu, S. Kota, V. Drozd, M.W. Barsoum, Sci. Adv., 2018, 4, 6850.

Influence of Silica Modulus and Curing Temperature on the Strength of Alkali-Activated Volcanic Ash and Limestone Powder Mortar

This present study evaluates the effect of silica modulus (Ms) and curing temperature on strengths and the microstructures of binary blended alkali-activated volcanic ash and limestone powder mortar. Mortar samples were prepared using mass ratio of combined Na2SiO3(aq)/10 M NaOH(aq) of 0.5 to 1.5 at an interval of 0.25, corresponding to Ms of 0.52, 0.72, 0.89, 1.05 and 1.18, respectively, and sole 10 M NaOH(aq). Samples were then subjected to ambient room temperature, and the oven-cured temperature was maintained from 45 to 90 °C at an interval of 15 °C for 24 h. The maximum achievable 28-day strength was 27 MPa at Ms value of 0.89 cured at 75 °C. Samples synthesised with the sole 10 M NaOH(aq) activator resulted in a binder with a low 28-day compressive strength (15 MPa) compared to combined usage of Na2SiO3(aq)/10 M NaOH(aq) activators. Results further revealed that curing at low temperatures (25 °C to 45 °C) does not favour strength development, whereas higher curing temperature positively enhanced strength development. More than 70% of the 28-day compressive strength could be achieved within 12 h of curing with the usage of combined Na2SiO3(aq)/10 M NaOH(aq). XRD, FTIR and SEM + EDX characterisations revealed that activation with combined Na2SiO3(aq)/10 M NaOH(aq) leads to the formation of anorthite (CaAl2Si2O8), gehlenite (CaO.Al2O3.SiO2) and albite (NaAlSi3O8) that improve the amorphosity, homogeneity and microstructural density of the binder compared to that of samples synthesised with sole 10 M NaOH(aq).

Scattering studies of the size and structure of cellulose dissolved in aqueous hydroxide base solvents

Combining NaOH with other hydroxide bases with superior dissolution properties can be a means of improving dissolution of cellulose. However, this raises questions about how the size and structure of cellulose vary when dissolved in different hydroxide bases. Here, cellulose in aqueous solutions of NaOH, Tetramethylammonium hydroxide (TMAH), Benzyltrimethylammonium hydroxide (Triton B) and previously studied equimolar solutions of NaOH/TMAH and NaOH/Triton B were investigated using small angle X-ray scattering, static and dynamic light scattering. The results show that cellulose in NaOH(aq) is largely aggregated and that the more hydrophobic TMAH and Triton are capable of molecularly dissolving cellulose into worm-like conformations, stiffer than in NaOH. The dissolution properties of mixtures are highly dependent on the compatibility of the individual bases; in line with previous observations of the properties of the solutions which now could be correlated to the structure of the cellulose on a nano- and microscale.

Mixed-Phase Ion-Exchangers from Waste Amber Container Glass.

This study investigated the one-pot hydrothermal synthesis of mixed-phase ion-exchangers from waste amber container glass and three different aluminium sources (Si/Al = 2) in 4.5 M NaOH(aq) at 100 °C. Reaction products were characterised by X-ray diffraction analysis, Fourier transform infrared spectroscopy, 27Al and 29Si magic angle spinning nuclear magnetic resonance spectroscopy and scanning electron microscopy at 24, 48 and 150 h. Nitrated forms of cancrinite and sodalite were the predominant products obtained with reagent grade aluminium nitrate (Al(NO3)3∙9H2O). Waste aluminium foil gave rise to sodalite, tobermorite and zeolite Na-P1 as major phases; and the principal products arising from amorphous aluminium hydroxide waste were sodalite, tobermorite and zeolite A. Minor proportions of the hydrogarnet, katoite, and calcite were also present in each sample. In each case, crystallisation was incomplete and products of 52, 65 and 49% crystallinity were obtained at 150 h for the samples prepared with aluminium nitrate (AN-150), aluminium foil (AF-150) and amorphous aluminium hydroxide waste (AH-150), respectively. Batch Pb2+-uptake (~100 mg g−1) was similar for all 150-h samples irrespective of the nature of the aluminium reagent and composition of the product. Batch Cd2+-uptakes of AF-150 (54 mg g−1) and AH-150 (48 mg g−1) were greater than that of AN-150 (36 mg g−1) indicating that the sodalite- and tobermorite-rich products exhibited a superior affinity for Cd2+ ions. The observed Pb2+- and Cd2+-uptake capacities of the mixed-product ion-exchangers compared favourably with those of other inorganic waste-derived sorbents reported in the literature.

Quick-fix agarose beads impregnated with hydrous ferric oxide for As(III) species removal from pharmaceutical wastewater

ABSTRACT Hydrous ferric oxide (HFO)-impregnated agarose beads were prepared as an adsorbent to reduce As(III) concentration in the pharmaceutical wastewater effluent generated from the manufacturing process of an arsenic-containing chemotherapeutic drug. The adsorbent was prepared by immersing wet agarose beads into FeCl3 (aq), followed by another immersion into NaOH (aq), resulting in HFO precipitation directly within the agarose beads. The As(III) adsorption rate of HFO-impregnated agarose beads was determined to be external diffusion-limited, and having a Langmuir maximum adsorption capacity of 76.1 mg As(III)/g. Passing 6 L of the pharmaceutical wastewater through a packed column filled with the adsorbent in an upflow mode of 50 mL/min repeatedly for five times resulted in the reduction of As(III) concentration from 250 to 10 μg of As(III)/L of H2O. Column desorption was performed by passing 0.6 L of 0.1 M NaOH (aq) through the column in an upflow mode of 50 mL/min repeatedly for five times to regenerate the As(III)-adsorbed HFO-impregnated agarose beads. Chemical characterizations revealed that the As(III) species were adsorbed on HFO by the “inner-sphere” bidentate complexation via ligand exchange or “outer-sphere” association via electrostatic interaction, while the “outer-sphere”-associated As(III) species were most likely desorbed.

Reversible Rapid Hydrogen Doping of WO3 in Non-Acid Solution.

Hydrogenation, an effective way to tune the properties of transition metal oxide (TMO) thin films, has been long awaited to be performed safely and without an external energy input. Recently, metal-acid-TMO has been reported to be an effective approach for hydrogenation, but the requirement of acid limits its application. In this work, the reversible and rapid hydrogen doping of WO3 in NaOH(aq) | Al(s) | WO3(s) is revealed by structural and electrical measurements. Accompanied by the structural phase transition identified by in situ X-ray diffraction, the electric resistance of the WO3 film is found to be able to change by 5 orders of magnitude. A significant electrical response of touching, 8-fold in amplitude and 3 s in a cycle, can be achieved in the low-resistance state. These reactions are reversible at room temperature. This study unambiguously proves that the hydrogenation-driven dynamic phase transition of WO3 in metal-solution-WO3 systems could occur not only in acid solutions but also in some non-acid environments. Unlike the monotonic increase of resistance revealed during HδWO3 to WO3 transition, an intriguing non-monotonic evolution was found for crystal lattice parameter c, indicating that the mechanism of WO3 hydrogenation involves a series of metastable states, more comprehensive and reasonable. This work sheds light on the potential applications of metal-solution-TMO hydrogenation in touching sensors, circuits survey, and information storage.

Pre-treatments of pre-consumer cotton-based textile waste for production of textile fibres in the cold NaOH(aq) and cellulose carbamate processes

Recycling of textiles is of importance due to the large amount of waste generated from the increasing consumption and use worldwide. Cotton-rich pre-consumer textiles are considered as potential raw material for production of man-made regenerated fibres, but demands purification from the blends with synthetic fibres as well as the dyes and finishing chemicals. In this study we explore the use of different pre-treatments of pre-consumer textiles to meet specific parameters for production of fibres in the cold NaOH(aq) or cellulose carbamate process. The pre-treatments consisted of different bleaching sequences and were performed on both uncoloured and coloured pre-consumer textiles. For the uncoloured textile, degree of polymerisation and amount of inorganic content was efficiently reduced making the material suitable for both the cold NaOH(aq) and the cellulose carbamate process. In case of the coloured textile, the pre-treatments were able to remove the dye and decrease the inorganic content as well as reduce the degree of polymerisation but only sufficiently enough for production of fibres in the cellulose carbamate process. The work was able to prove a fibre-to-fibre concept while further optimisation of the regeneration steps is expected to improve the mechanical properties of the produced fibres in future studies.

Synthesis and characterization of low-cost zeolite NaA from coal gangue by hydrothermal method

Through this investigation, we have demonstrated a low-cost preparation method of zeolite NaA from coal gangue. The well-developed zeolite NaA of 87.56% crystallinity was successfully prepared by hydrothermal alkali activation method, which required low alkali concentration (1.8 mol/L) compared to other researches (3–6 mol/L). The characterization results of product prepared at different conditions suggest that the purity and crystallinity of zeolite NaA are high at low alkali concentration and longer crystallization time. The Ca2+ exchange value of synthesized zeolite attained 265 mg CaCO3/g compared to commercial zeolite, which is typically 340 mg CaCO3/g. The basic structure parameters and thermal stability have also been studied. The results suggest that the obtained zeolite has a potential to be used as hard water softening agent. Moreover, the result of Rietveld quantitative phase analysis and Box-Behnken's response surface methodology showed that the weight fraction of zeolite NaA in product can reach 71.9%, and the crystallinity can attain 88.14% at the optimal condition of n(SiO2)/n(Al2O3) of 2.60, NaOH(aq) concentration of 1.86 mol/L at 95 °C for 10.08 h.

Dissolution studies of α-chitin fibers in freezing NaOH(aq)

Our gradual understanding of the capabilities of organic solvent systems has allowed us to realize a rich diversity of valuable polysaccharide applications; however, their industrial scale implementation remains a challenge for the sustainable societies of the next generations. While exploring a systems thinking approach, researchers studying aqueous alkali solutions have shown that the overlooked region of subzero temperatures offers a dynamic driving force for efficient solubilization of natural carbohydrate polymers. Herein, α-chitin fibers of decreasing crystallinities/molecular weights (MW) dissolve rapidly by stirring in cold 19 wt% NaOH(aq) and freezing at − 28 °C. Kinematic viscosity measurements confirm the polymers’ stretched exponential solution dynamics for solubilities > 97% (up to ~ 130 g/L). A preliminary mechanistic hypothesis involves higher diffusion rates of the solvent’s hydrated counter ions for decreasing temperatures. The method was used with subsequent casting to fabricate 5 wt% films from high crystallinity/MW fibers. This proof of concept allows for homogeneous chitin deacetylation as well as for additive-free technology drivers towards sustainable commercial exploitation of abundant natural polysaccharide streams.

Emergent Self-Assembly of a Multicomponent Capsule via Iodine Capture.

Described here is a three-component self-assembly system that displays emergent behavior that differs from that of its constituents. The system comprises an all-hydrocarbon octaaryl macrocycle cyclo[8](1,3-(4,6-dimethyl)benzene (D4d-CDMB-8), corannulene (Cora), and I2. No appreciable interaction is seen between any pair of these three-components, either in cyclohexane or under various crystallization conditions. On the other hand, when all three-components are mixed in cyclohexane and allowed to undergo crystallization, a supramolecular iodine-containing capsule, ((D4d-CDMB-8)3⊃(Cora)2)⊃I2, is obtained. This all-hydrocarbon capsule consists of three D4d-CDMB-8 and two Cora subunits and contains a centrally bound I2 molecule as inferred from single-crystal and powder X-ray diffraction studies as well as solid-state 13C NMR and Raman spectroscopy. These analyses were complemented by solution-phase 1H NMR and UV-vis spectroscopic studies. No evidence of I2 escape from the capsule is seen, even at high temperatures (e.g., up to 418 K). The bound I2 is likewise protected from reaction with alkali or standard reductants in aqueous solution (e.g., saturated NaOH(aq) or aqueous Na2S2O3). It was also found that a mixed powder containing D4d-CDMB-8 and Cora in a 3:2 molar ratio could capture saturated I2 vapor or iodine from aqueous sources (e.g., 1.0 mM I2 in NaCl (35 wt %) or I2 + NaI(aq) (1.0 mM each)). The present system displays structural and functional features that go beyond what would be expected on the basis of a simple sum-of-the-components analysis. As such, it illustrates a new approach to creating self-assembled ensembles with emergent features.

Effect of sodium hydroxide concentration on strength and microstructure of alkali-activated natural pozzolan and limestone powder mortar

The present study evaluates the effect of sodium hydroxide concentrations on strength, bond properties, reaction products and the microstructures of binary blended alkali-activated volcanic natural pozzolan and limestone powder (AANL) mortar. Six AANL mortar were prepared with alkaline activators of 4–14 M NaOH(aq) and Na2SiO3(aq) such that the activators ratio was 1:1. Curing was done at 75 °C for 24 h duration. The maximum 90-day compressive strength of 31.3 MPa was achieved with 10 M NaOH(aq) while 76% of the strength could be achieved within three days when 10 M NaOH was used. The 28-day tensile strength of 2.32 MPa was achieved with 14 M NaOH(aq). XRD characterizations revealed that activation with a strong concentration of sodium hydroxide (10 M NaOH(aq)) led to the formation of anorthite (CaAl2Si2O8) and gehlenite (Ca0.Al2O3SiO2). SEM + EDX indicated that strong alkali (10 M NaOH) enhanced microstructural density compared to that of mild alkali (4 M NaOH(aq)).

PHARMACOGNOSTIC INVESTIGATION, ISOLATION, CHARACTERIZATION AND CONFIRMATION OF THE STRUCTURE OF PHENACETINE EXTRACTED FROM THE DRIED POWDERED LEAVES OF TRADITIONAL MEDICINAL PLANT ALLOPHYLUS AFRICANUS USED FOR THE TREATMENT OF PAIN, FLU and HEAD ACHE

Pharmacognostic investigation involving organoleptic evaluation, fluorescent analysis, phytochemical screening and mineral analysis was carried out on the dried powdered leaves of Allophylus africanus used for treating pain, headaches, common cold, Fever and as antibiotics in Eastern Province of Sierra Leone. The powdered leaves were light brown in colour with woody odour, bitter taste and gave significant fluorescent derivatives with the reagents 1M NaOH (aq), 1M NaOH(alc.), Ammonia, 50% HCl, and 50% HNO3 when viewed under ordinary visible light and ultraviolet light. The plant organ investigated during phytochemical screening gave positive for carbohydrates and reducing sugar, Amino acids and Proteins, Alkaloids, tannins and phenolic compounds, saponins glycosides Flavonoids, sterols/terpenes and triterpenes all of which have been reported to be pharmacologically active compounds responsible for the medicinal use of Allophylus africanus plant.
 Elemental analysis of the plant organ was performed with a Niton XL3t GOLDD + Hand held X-ray Fluorescence (Thermo Fisher) and the results indicated that the plant organs investigated contained large amounts of K, Ca, Mg, Al and Fe whilst Ti, Zr, Mn, Zn, Sr, Sc, Rb, Cu, V and Mo were present in minute quantities. The presence of the above elements also support the use of the plant organ investigated as food and medicine.
 The compounds LK003 isolated from the ethanol extract of the dried powdered leaves of the plant and structure identified using fragmentation patterns from LCMS, Proton NMR spectroscopy and by McLafferty rearrangement as N-(3-methoxyphenyl) acetamide called phenacetamide which has been reported to be a clinically tested drug for pain and fever. Hence, we concluded in this research work that the presence of N-(3-methoxyphenyl) acetamide called phenacetamide, the secondary plant metabolites and minerals present in the dried powdered leaves traditional medicinal plant Allophylus africanus support the use of the plant as a traditional pharmaceutical.

Nanoscale silica coating of porous stainless steel and its impact on water wettability

The water wettability of porous stainless steel specimens was enhanced via a nanoscaled silica coating for application to passive two-phase heat transfer devices. A combination of porous stainless steel and water has attracted attention in the area of the heat transfer devices. However, the water wettability of stainless steel is poor, limiting the performance of the devices. In the present study, the silica coating of the specimens was conducted via a reaction of tetraethyl orthosilicate (TEOS) after pretreatment using NaOH aq. or HCl aq. Energy-dispersive X-ray spectrometry revealed that the amount of silica deposited on the surface was dependent on the pretreatment conditions and the composition of the silica-coating solutions. Measurement of porous properties indicated that the silica coating did not affect pore diameter and gas permeability since the coating was in nanoscale. Microscale contact angles were directly evaluated using an environmental SEM. The specimens showed excellent water wettability when they were covered with numerous tiny silica bumps. When the specimen was pretreated with 2 M NaOH aq. and coated in weak alkaline TEOS solution, the contact angle of the porous stainless steel decreased from 87° to 54° after silica coating. The excellent water wettability originated from the relatively smooth surface and a sufficient coverage ratio, which resulted from the moderate strength of chemical etching of the NaOH aq. and the mild silica-coating condition in the weak alkaline solution.

Hydrothermal synthesis of zeolites from green container glass

Landfilling and stockpiling unrecycled colored container glass represents a considerable failure in sustainability with respect to the conservation of energy and mineral resources. In this study, the single-step hydrothermal synthesis of low-silica zeolites from a mixture of waste green container glass and aluminum foil (Al:Si = 1) in 4 M NaOH(aq) at 125 °C was followed at 1, 3, 7 and 14 days. The principal phases, sodalite and cancrinite, appeared within 1 day accompanied by minor quantities of hydrogarnet and tobermorite arising from a stoichiometric excess of calcium ions in the parent glass. Products of 63, 67, 71 and 72% crystallinity were obtained at 1, 3, 7 and 14 days, respectively, with partial successive conversion of sodalite to cancrinite over time. Ion-exchange and catalytic applications of sodalite and cancrinite arise from the high anionic charge of the 1:1 ratio of alternating SiO44- and AlO45- units within their aluminosilicate frameworks. In this respect, the uptake capacity of the 14-day zeolitic product for Cu2+ and Cd2+ ions (1.58 meq g-1 and 1.66 meq g-1, respectively) was within the expected range for zeolites and compared favorably with those reported for other inorganic sorbents derived from industrial and municipal wastes. The 14-day product was also found to be an effective basic heterogeneous catalyst for the Knoevenagel condensation reaction.

Two-Phase Dibromocyclopropanation of Unsaturated Alcohols Using Flow Chemistry.

Dibromocyclopropanations are conventionally done by addition of dibromocarbene to alkenes under phase-transfer conditions in batch reactions using a strong base (50% NaOH (aq)), vigorous stirring and long reaction times. We have shown that cyclopropanation of unsaturated alcohols can be done under ambient conditions using continuous flow chemistry with 40% (w/w) NaOH (aq) as the base. The reactions were generally rapid; the yields were comparable to yields reported in the literature for the conventional batch reaction

Photonic Crystal Improves the Absorptiometric Sensitivity of Colorimetric Membrane By Cavity-Induced Light-Matter Interaction

Photonic Crystal Improves the Absorptiometric Sensitivity of Colorimetric Membrane By Cavity-Induced Light-Matter Interaction

Durability and mechanical properties of seashell partially-replaced cement

This research investigates the possibility of grinding and burning bivalve clam seashells to produce seashell ash powder. This ash is used to partially replace cement by 5, 10, 15 and 20% by weight. These mixes are tested and compared with a SC0 that has 0% seashell ash powder (SC0). The fresh and hardened properties of all mixes are studied through a variety of tests, including: slump, unit weight, compressive strength and splitting tensile strength. The durability of seashell concrete cubic specimens is studied by immersion in 5% NaOH(aq) and MgSO4(aq) solutions. The addition of thermally treated seashells increased the calcium hydroxide content. The results also show that the compressive strength of the 5% replacement is slightly higher than the SC0 at 28 and 90 days of age, while the tensile strength is higher than the standard for the 5% and 10% of replacement at 7 and 28 days. Furthermore, the slump test value generally increases with increasing the percentage of replacement. The highest durability against sulfate and alkaline attacks is obtained with 5% replacement of cement with seashells which reported the lowest decrease in weight and the highest compressive strength after immersion in 5% NaOH(aq) and MgSO4(aq) solutions. The 5% replacement mix is the optimum percentage of replacement. Therefore, this study recommends replacing cement with 5% seashell cement.