Dilute Alkali Solution Research Articles

Enhanced Steelmaking Slag Mineral Carbonation in Dilute Alkali Solution

Steelmaking slag mineral carbonation is a possible technology for the reduction of carbon dioxide (CO2) emissions to the atmosphere, which has been studied both in aqueous and dilute alkali medium. A set of variables, the stirring speed, reaction time, alkali to slag ratio and reaction temperature, were systematically investigated. The results indicated that reaction time, alkali to slag ratio and reaction temperature were the major factors for CO2mineral sequestration. Under the optimal conditions with the alkali to slag ratio of 4 % at 80 °C, 16.64 g CO2can be sequestrated in per 100g steel slag and both calcite and aragonite were generated. This work would be of significance to understand the reaction mechanism deeply and provide valuable information for further study in this field.

A Method of Fabricating Electroplated Structures using Side-wall Electrical Contact

A method for fabricating electroplated structures using side wall electrical contact has been developed. This method consists of three key processes: first, a lift-off process using an aluminum sacrifice layer; second, an electroplating process using side wall electrical contact between the aluminum sacrifice layer and the metal layer; and third, a conductive layer removal process, which prevents abnormal etching due to a local cell effect of the metal layers. In the lift-off process, a roof shaped pattern is fabricated by side-etching an aluminum layer. It is easy to remove the metal layer and the resist. In the electroplating process, the resistance of the electrical contact in the side-wall between the aluminum sacrifice layer and the metal layer is nearly equal to that of a conventional seed layer and can be applied as a feed line. In the conductive layer removal process, the aluminum sacrifice layer is an amphoteric, and can be removed with a dilute alkali solution. With this method, abnormal etching of the electroplated structure and the metal layer does not occur.

Removal of Fluoride from Aqueous Solution by Using Porous Resins Containing Hydrated Oxide of Cerium(IV) and Zirconium(IV)

The adsorption behaviors of two types of commercial porous resins containing hydrated zirconium and cerium oxide, whose commercial names are READF-(PG) and READF-(HG), respectively, have been investigated relative to fluoride from aqueous solution. The adsorbents were characterized by XRD, EDX and surface area analyzer. Fluoride adsorption was found to be strongly pH dependent and optimum adsorption on both types of resins was observed at pH 2–4. The measurement of adsorption kinetics of fluoride demonstrated a fast adsorption process. The isotherm experiments showed Langmuir type monolayer adsorption. The complete removal of fluoride from trace concentration can be achieved using 4 g/L of the resins tested under the mentioned experimental condition. The maximum uptake capacity of the READF-(HG) and READF-(PG) were evaluated as 2.35 and 2.10 mmol F/g dry resin. The complete desorption of adsorbed fluoride was successfully achieved using a dilute alkali (NaOH) solution. Column adsorption followed by elution demonstrated the possible application of this system in a continuous system.

Structure and solution properties of cyanoethyl celluloses synthesized in LiOH/urea aqueous solution

Cyanoethyl celluloses (CECs) with different degree of substitution (DS) were synthesized by homogeneous reaction of cellulose (cotton linter pulp and absorbent cotton) with acrylonitrile (AN) in LiOH/urea aqueous solutions. The reaction showed quick reactivity and high transfer efficiency of etherification agent. The DS values of CECs were controlled by varying the molar ratio of AN to anhydroglucose unit (AGU) and the cellulose concentration. The DS values of the CEC-1–CEC-10 increased from 0.27 to 1.78 with increasing molar ratio of AN to AGU from 0.5:1 to 9:1. While the CEC-11–CEC-21 with DS values of 0.26–1.81 could be obtained by adjusting the molar ratio from 1:1 to 27:1. The relative reactivity of hydroxyl groups is in the order of C-6 > C-2 > C-3. The DS values of the water-soluble derivatives are in the range of 0.47–1.01. As the DS values increase to 1.37, CEC samples can not be dissolved in water or dilute alkali solution, but have good solubility in organic solvents, such as DMSO, DMF and pyridine. The dilute solution properties and molecular parameters of the CEC samples were studied by static light scattering and dynamic light scattering. The results indicated that the water-soluble samples could form a small number of aggregates spontaneously in 0.9 wt% NaCl aqueous solution, while the water-insoluble samples showed extended stiff chains in 0.5% LiCl–DMAc.

The effects of malting conditions on the diastatic power of three malted Nigerian sorghum cultivars

The effects of malting conditions on the diastatic power of three malted sorghum cultivars (SK 5912, ICSV 400 and KSV 8) were investigated. The three Nigerian sorghum cultivars were steeped in 0.01M NaOH, 0.01M Ca(OH)2 and distilled water, respectively, under air-rest and continuous steeping regimes. SK 5912 steeped in Ca(OH)2 gave higher hot water and cold water extract values than when steeped in NaOH and distilled water. KSV 8 when steeped in distilled water gave peak values for cold water extract during air-rest and continuous steeping regimes. For hot water extract, KSV 8 had peak values when steeped in NaOH whereas SK 5912 gave the least values when steeped in distilled water. Cold water soluble-carbohydrate gave peak values for ICSV 400 when steeped in Ca(OH)2 and the least values were recorded in NaOH steeped grains. The diastatic power of the three sorghum cultivars improved with increase in germination time except for ICSV 400-steeped in Ca(OH)2 and KSV 8 steeped in distilled water which showed decrease in activity on the 4th day in continuous steeping regime. The results show that steeping in dilute alkali solutions gave higher values than distilled water while air-rested steeping regime gave better values than continuous steeping regime. The results from this study suggest that increase in germination time enhanced the diastatic power of the malted grain. Keywords: Sorghum varieties, Malting, Diastatic power, Cold water extract, Hot water extract

Digestibility Improvement of Sorted Waste with Alkaline Hydrothermal Pretreatment

The digestibility of sorted municipal solid waste (MSW) is often limited by the high content of structured green waste. The objectives of this study are to investigate the effect of alkaline hydrothermal pretreatment on the anaerobic digestion of sorted waste and to analyze the biogas production of different parts of the waste. The waste was hydrothermally pretreated in a dilute alkali solution. The hydrolysis product was then incubated in a 500 mL saline bottle to determine the biochemical methane potential (BMP) under mesophilic anaerobic conditions. The optimum hydrothermal condition was 170°C at 4 g NaOH/100 g solid for one hour. The concentration of chemical oxygen demand (COD) was 13 936 mg/L and the methane yield was 164 mL/g volatile solid (VS) for 6 days incubation at the optimum conditions. The biogas production was increased more than 50% over the control, with the methane conversion ratio on a carbon basis enhanced to 30.6%. The organic part of the sorted waste was mainly kitchen garbage and leaves. Model kitchen garbage completely liquified at 130°C for one hour had a methane yield of 276 mL/g VS. The alkali addition slightly enhanced the hydrolyzation rate and methane yield. The biogas potential of leaves was improved by pretreatment at above 150°C under alkaline conditions.

Preparation and characterization of cross‐linked polymeric nanoparticles for enhanced oil recovery applications

AbstractChemically cross‐linked nanoparticles from dilute aqueous alkali solutions of hydroxyethylcellulose (HEC) in the presence of a cross‐linker agent (divinyl sulfone, DVS) were prepared from a reaction mixture, which was exposed to different stirring speeds during the cross‐linking process. At various stages during the cross‐linking procedure, the reaction was terminated and the species were characterized by means of turbidimetry, asymmetric flow field‐flow fractionation (AFFFF), dynamic light scattering (DLS), and rheo‐small‐angle light scattering (rheo‐SALS) methods. During the cross‐linking of a dilute polymer solution, the competition between intrapolymer and interpolymer is a prominent feature. The DLS results show that at early times in the cross‐linking process, intrachain cross‐linking with contraction of the complexes is promoted by high stirring speeds; at later times the growth of aggregates is inhibited by high stirring speeds. The results from the rheo‐SALS measurements disclosed that at early times during the cross‐linker reaction, the complexes are fragile against shear forces if the reaction mixture had been subjected to low stirring speeds. At a later state of cross‐linking, more cross‐links lead to better stability of the species, even for solutions that have been exposed to low stirring speeds during the cross‐linking process. This study shows that the sizes of the particles can be tuned by exposing the solutions to different stirring speeds during the cross‐linker reaction and to terminate the reaction at desired reaction times. The strategy discussed in this work for the preparation of particles of various sizes is of special interest in connection with enhanced oil recovery applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Cyclic Voltammetric Behavior of Copper Powder Immobilized on Paraffin Impregnated Graphite Electrode in Dilute Alkali Solution

Cyclic Voltammetric Behavior of Copper Powder Immobilized on Paraffin Impregnated Graphite Electrode in Dilute Alkali Solution

Intramolecular and Intermolecular Association during Chemical Cross-Linking of Dilute Solutions of Different Polysaccharides under the Influence of Shear Flow

Effects of shear flow on intramolecular and intermolecular associations of dilute aqueous alkali solutions of dextran, hydroxyethylcellulose (HEC), and a hydrophobically modified analogue (HM-HEC) in the presence of a chemical cross-linker agent were characterized with the aid of viscometry and rheo-small-angle light scattering (rheo-SALS) methods. The picture that emerges at short times in the course of cross-linking of the polymer solutions under the influence of a constant shear rate is that HEC coils contract because of intramolecular cross-linking, whereas the HM-HEC species show an incipient association and the dextran molecules are unaffected. At longer times, interchain cross-linking of the polymers promoted the growth of large flocs, which were disrupted by shear forces when they were sufficiently large. These findings are novel, and both the building up of aggregates and disaggregation are well substantiated by the SALS results.

Physical, thermal, dielectric and chemical properties of a hyperbranched polyether and its linear analog

The hyperbranched and the linear polyethers were prepared by one-pot nucleophilic displacement polymerization technique using cyanuric chloride and aromatic diol as reported earlier. The physical, thermal, dielectric and chemical properties of the hyperbranched polyether and its linear analog have been studied. The amorphous character of both the polyethers was observed in XRD study. The solubility studies showed that the hyperbranched polyether has relatively higher solubility in different solvents compared to its linear analog. The thermal properties of both polymers have been studied by thermogravimetric (TG) and differential scanning calorimetric (DSC) analyses. The chemical resistance tests indicated that both polyethers are very good chemical resistances except in dilute aqueous alkali solution. The dielectric properties such as dielectric constant and loss factor for both polyethers have also been studied with respect to changes of frequency (50–500 kHz) and temperature (303–343 K).

Effect of Shear on Intramolecular and Intermolecular Association during Cross-Linking of Hydroxyethylcellulose in Dilute Aqueous Solutions

Intramolecular and intermolecular associations of dilute aqueous alkali solutions of hydroxyethylcellulose (HEC) in the presence of a chemical cross-linker agent (divinyl sulfone, DVS) are studied with the aid of dynamic light scattering (DLS) and rheological methods. At quiescent state, DLS detected only interchain aggregation of HEC during the cross-linker reaction, and the magnitude and start of this effect depend on the cross-linker concentration. The growth of clusters has been investigated at various stages in the course of the cross-linking process by quenching the reaction mixture to a lower pH. After quenching, no further association of the species occurred. When the dilute reaction mixtures are subjected to shear, intrapolymer cross-linking with contraction of the molecules is observed, and at moderate shear rates this effect is followed by interpolymer cross-linking and the formation of aggregates at longer times. The rate of the growth of the multichain aggregates decreases with increasing shear rate, and at sufficiently high shear rates no cross-linking effect is observed. Depending on the shear rate, the aggregates continue to grow until they reach a certain size where an incipient breakup of interaggregate chains can be observed. The delicate interplay between intramolecular and intermolecular association effects is governed by factors such as the magnitude of the shear rate, polymer concentration, and cross-linker density.

Molecular dynamics simulation of PAMAM dendrimer in aqueous solution

The properties of ethylenediamine (EDA) cored and amine surface poly(amidoamine) (PAMAM) dendrimers of generation 1 through 7 in the explicit solvent were studied by the atomistic force field based molecular dynamics. Since amines are assumed to be protonated the simulation condition is designed to represent the dilute alkali solution. All the generations are spherical in shape, while the higher generations show edges or slightly polyhedral shape. The density profile indicates that the dendrimers are constant density spheres and the densities are independent of generation in this aqueous solution. The scaling properties of the radius of gyration with the numbers of atoms and solvent accessible surface with radius of gyration indicate the PAMAM dendrimers are densely compact structures which result from the highly flexibility confirmed by the terminal group distribution. Dynamic behaviors such as autocorrelation function of the squared radius of gyration and mean square displacement were also studied too.

Simultaneous saccharification and cofermentation of peracetic acid-pretreated biomass.

Previous work in our laboratories has demonstrated the effectiveness of peracetic acid for improving enzymatic digestibility of lignocellulosic materials. The use of dilute alkali solutions as a pre-pretreatment prior to peracetic acid lignin oxidation increased carbohydrate hydrolysis yields in a synergistic as opposed to additive manner. Deacetylation of xylan is easily achieved using dilute alkali solutions under mild conditions. In this article, we evaluate the effectiveness of peracetic acid combined with an alkaline pre-pretreatment through simultaneous saccharification and cofermentation (SSCF) of pretreated hybrid poplar wood and sugar cane bagasse. Respective ethanol yields of 92.8 and 91.9% of theoretical are achieved using 6% NaOH/15% peracetic acid-pretreated substrates and recombinant Zymomonas mobilis CP4/pZB5. Reduction of acetyl groups of the lignocellulosic materials is demonstrated following alkaline pre-pretreatments. Such processing may be helpful in reducing peracetic acid requirements. The influence of deacetylation is more significant in combined pretreatments using lower peracetic acid loadings.

Fundamental study of noncross-linking anion exchange membranes

Noncross-linking anion exchange membranes were prepared by casting a solution of animated chloromethylstyrene-styrene copolymers. The ion exchange capacity, water content, membrane potential, and transport number of the membranes were studied. Chloromethylstyrene-styrene copolymers containing 87.2, 50.0, 25.0, and 19.5 mol% of chloromethylstyrene were synthesized, and the results showed that the 25.0 mol% grade can be fabricated in membrane form after treatment with trimethylamine or with triethylamine. The two membranes thus prepared were soluble in a variety of organic solvents, and exhibited good chemical and dimensional stability for dilute alkali solution, dilute acid solution, and salt solution. Their transport numbers determined from the membrane potential measurement in 0.01 N/0.1 N KCl solution were 0.91 and 0.94, respectively.

Preparation and characterization of new synthetic noncross‐linked anion exchange membranes

AbstractNew synthetic noncross‐linked anion exchange membranes have been prepared by casting a solution of quaternized chloromethylstyrene‐methyl methacrylate copolymers containing 64.0, 42.9, 19.7, 12.9 and 11.0 mol‐% chloromethylstyrene. The ion exchange capacity, water content and physicochemical properties (membrane potential and transport number) of these membranes were studied. The results showed that the copolymers can be fabricated in membrane form after treatment with tertiary amine, of which the membranes produced from the 12.9 and 11.0 mol‐% copolymer exhibited excellent dimensional stability and mechanical strength towards dilute alkali solution, dilute acid solution and salt solution, and were soluble in a variety of organic solvents, such as acetone, methyl ethyl ketone and methanol. Their anion transport numbers determined from the membrane potential measurements in 0.01 N and 0.3 N KCI solution were 0.96 and 0.97, respectively.

Models for the interactions between pectin molecules and other cell-wall constituents in vegetable tissues

In experiments to study the relationships between textural change and chemical changes in pectins of vegetables after different cooking treatments, pectins in the alcohol-insoluble solids (AIS) of the vegetables were fractionated into four groups according to their solubility in different extractants, and their yields were correlated with the firmness of the tissues. Based on the correlations observed for various vegetables, a simple model consisting of five types of basic pectin interactions in the tissues was proposed first. It includes S-type pectin extractable with cold water, A-type pectin extractable with cold chelating-agent solutions, B-type pectin extractable with hot water, C-type pectin extractable with hot chelating-agent solutions, and P-type pectin extractable with hot dilute acid or alkali solutions, among which C-type pectin was obtained by calculation rather than direct determination. It was found later that, in some cases, the amount of C-type pectin thus obtained came out as a negative value, which is apparently unreasonable. We therefore proposed, by speculation, an elaborate model consisting of twelve sub-types of complicated pectin interactions, which are based on the simple model, in order to explain the unreasonable situation resulting from the calculated value of C-type pectin content. Using snap-bean pods as sample, we now present several experiments to support the real existence of some of the complicated pectin interactions previously proposed. The supporting data came from the analysis and comparison of the amounts of bound calcium in the pectin fractions extracted and from the measurement and comparison of the size of pectin molecules extracted before and after further treatment by either heating or calcium removal.

Some Characteristic Features of Dilute Aqueous Alkali Solutions of Specific Alkali Concentration (2.5 mol l−1) Which Possess Maximum Solubility Power against Cellulose

Some Characteristic Features of Dilute Aqueous Alkali Solutions of Specific Alkali Concentration (2.5 mol l −1 ) Which Possess Maximum Solubility Power against Cellulose

Antitumor activity and structural characterization of a (1----3)-beta-D-glucan extracted with cold alkali from sclerotia of Sclerotinia sclerotiorum IFO 9395.

An antitumor (1→3)-β-D-glucan (TS-CAG III) was purified from the cold aqueous sodium hydroxide extract of the residue of hot water extract of sclerotia of Sclerotinia sclerotiorum IFO 9395 by sequential use of ion exchange chromatography on diethylaminoethyl Sephadex A-25, ethanol precipitation, and gel filtration on Sepharose CL-2B. TS-CAG III showed [α]D-18°(0.4 N NaOH). From the results of methylation analysis and carbon-13 nuclear magnetic resonance spectroscopy, TS-CAG III was concluded to be a (1→3)-β-D-glucan bronched at position 6 of two in every five main chain glucosyl units. TS-CAG III formed a complex with Congo Red in dilute alkali solution, and showed potent antitumor activity against the solid form of sarcoma 180 in ICR mice.

New aspects in cationization of lignocellulose materials. VIII. Modification of immitted spruce wood with quarternary ammonium groups

AbstractImmitted spruce wood meal (ISWM) was modified with 3‐chlor‐2‐hydroxypropyltrimethyl‐ammoniuchloride (CHMAC) or 1,3‐bis(3‐chlor‐2‐hydroxypropyl)imidazoliumhydrogensulphate (BCHIHS) in alkaline medium. The obtained material was gradually extracted with water and 5% NaOH. The yields of water‐soluble hemicelluloses modified with quarternary ammonium groups were lower in comparison to healthy spruce material obtained under the same conditions but even more material could be obtained from ISWM‐holocellulose. The quantity of alkali‐soluble polysaccharides from ISWM was the same as obtained from undamaged spruce. The residues after alkali extractions are suitable ion exchangers with low solubility in dilute alkali solutions. The yields of extracts from material modified with BCHIHS were lower than yields of extracts from material modified with CHMAC because ISWM was crosslinked when alkylated with bifunctional chemicals.

Structure and antitumor activity of a beta-1,3-glucan isolated from the culture filtrate of Sclerotinia sclerotiorum IFO 9395.

An antitumor glucan (SSG) was isolated from the culture filtrate of Sclerotinia sclerotiorum IFO 9395 by sequential use of ethanol precipitation, ion exchange chromatography on diethyl-aminoethyl-Sephadex A-25, and precipitation with ammonium sulfate. From the results of methylation analysis and carbon-13 nuclear magnetic resonance spectroscopy, SSG was concluded to be a β-1, 3-D-glucan branched at position 6 of every two 3-substituted β-glucosyl units. SSG formed a complex with congo red in dilute alkali solution, and showed potent antitumor activity against the solid form of sarcoma 180 in ICR mice.