Alkali Process Research Articles

The Effect of Sago Starch Filler Dispersion preparation on the Biodegradation Properties of Natural Rubber Latex Films

Sago starch dispersion was prepared by mechanical (ball milling) and chemical (reaction with alkali) processes in order to reduce the size of dispersed sago starch particles. The sago starch dispersion was compounded with natural rubber latex (NRL) as a filler and a NRL thin film was prepared by coagulant dipping technique. The ball milled sago starch (MSS) and alkali dispersed sago starch (CSS) filled NRL films were then subjected to soil burial test. The effect of the degradation process on weight loss percentages, surface morphologies, tensile strength behavior and Fourier Transform Infrared (FTIR) analysis of the starch filled NRL films were investigated. The utilization of sago starch dispersion prepared by alkali treatment showed the improvement in mechanical properties of NRL films compared to sago starch dispersion prepared by the ball milling method. From the results obtained, CSS/NRL films are more feasible to degrade compared to MSS/NRL films.

Recovery of Gallium from Corundum Flue Dust by Two-Stage Alkali Leaching, Carbonation, Acid Leaching and Solvent Extraction Process

Flue dust generated during the process of manufacturing corundum is a carrier of critical metal gallium. In this study, a process of alkali leaching-carbonation-acid leaching-solvent extraction was developed to recover and enrich gallium from corundum flue dust. Over 93% of the gallium in corundum flue dust could be recovered through a two-stage alkali leaching process, which consists of 120 min of concentrated alkali leaching in NaOH solution and a subsequent 30-min dilute alkali leaching (after dilution), with an alkali-to-ore mass ratio of 1.2:1. Liquid to solid ratios in two alkali leaching stages were 1.5:1 and 8:1, respectively. The carbonation process was employed to remove high-level Si in alkali leachate. After carbonation and HCl leaching, over 96% of gallium in the NaOH leachate could be dissolved into acid solution. After extracting gallium from the HCl leachate using N235 as extracting agent, 1% NaOH solution was used to strip gallium from the organic phase. The extraction and stripping efficiency of gallium was over 99% and 97%, respectively.

Biochemical and physicochemical analysis of fish protein isolate recovered from red snapper (Lutjanus sp.) by-product using isoelectric solubilization/precipitation method

The effect of acid- and alkali-process on biochemical and physicochemical characteristics of fish protein isolate from red snapper (Lutjanus sp) by-product was evaluated. Protein recovered by alkali process (16.79%) was higher compared to acid process (13.75%). Reduction of lipid content and total volatile basic nitrogen (TVB-N) exhibited in both treatments indicated both process improved fish protein isolate recovered from red snapper by-product. In addition, the increasing of water holding capacity and oil binding capacity were observed. However, high peroxide value of fish protein isolate was showed in both treatment. This finding indicated that acid and alkali process can be used as a useful method to recover proteins from red snapper by-product. Alkali process gave a protein isolate with better overall quality compared to acid process.

Intelligently designed fly-ash based hybrid composites with very high hardness and Young’s modulus

Currently, India generates annually about 112 million tones of fly ash (FA), as an industrial waste from thermal power plants. As part of the global journey to convert waste to wealth here we report the intelligent design based synthesis of FA based hybrid composites with spectacular improvement in Young’s modulus and nanohardness. The novel design approach utilized alkali activation as well as simultaneous reinforcements of the porous FA matrix with a layered white china clay (WCC) and chopped E glass fiber. The developed materials were subsequently characterized by nanoindentation technique, pH measurement, alkali dissolution, FESEM, etc. techniques to evolve the structure-property correlation. The optimized design and optimal alkali activation lead to achievements of about 233% and 545% enhancements in Young’s modulus and hardness, respectively. These results are rationalized in terms of chemical analysis, Si:Al ratio, presence of silicate network modifiers e.g., Na2O and CaO, microstructure, density, extent of polymerization due to alkali activation, processing condition and elastic recovery as well as the ratio of energy spent in elastic and plastic deformations during the nanoindentation processes. Finally, a schematic model is proposed to explain the experimental observations.

Ball Milling for Biomass Fractionation and Pretreatment with Aqueous Hydroxide Solutions

A promising approach in the selective separation and modification of cellulose from raw biomass under a mild alkali process was proposed. In our study, ball milling was applied to wheat straw prior to alkali treatment. With ball milling, ultrafine powder formed an amorphous microstructure and displayed a level of solubilization in aqueous NaOH higher than that of general ground samples. Alkali-treated ultrafine powder resulted in up to 93.76% removal of hemicellulose and 86.14% removal of lignin, whereas cellulose remains largely undissolved. A high glucose yield (98.48%) was obtained via a 72 h enzymatic hydrolysis. X-ray diffraction and solid state 13C cross-polarization magic angle spinning nuclear magnetic resonance analysis revealed evidence of the transformation of crystalline cellulose I to cellulose II in alkali-treated ultrafine wheat straw. Prolonging the alkaline treatment time can significantly decrease the level of cellulose hydrogen bonding and increase the hydrolysis yield. The combination of ultrafine ball milling and low-severity alkali treatment played a significant role in the cellulose supramolecular change, which can then be used for downstream biorefinery processes or as a feedstock for the biomaterial industry.

Alkali pretreatments and crosslinking of lyocell fabrics

Lyocell fabrics were pretreated with NaOH, KOH and LiOH and subsequently crosslinked with three urea–formaldehyde based crosslinkers DMDHEU, DMeDHEU and DMU. The mechanical properties varied with the alkali concentration in fabrics crosslinked after pretreatment with 2–8 mol/l NaOH and 4 mol/l LiOH. In fabrics crosslinked after pretreatment with 2–8 mol/l KOH and 1–3 mol/l LiOH, in contrast, the mechanical properties were relatively insensitive to the alkali concentration. The difference in effects is attributed to the alkali influence on the accessibility of crosslinker in fiber structures. The NaOH and 4 mol/l LiOH pretreatments increase the accessibility of crosslinker but the KOH and 1–3 mol/l LiOH pretreatments do not appear to change accessibilities to the same extent. The results underscore the importance of alkali choice and process control in the pretreatments of lyocell. Both NaOH and KOH may be used to good effect. However, lyocell is more sensitive to changes of alkali concentration in NaOH treatments as compared to KOH pretreatments. Thus, the use of NaOH in pretreatments of lyocell will require a greater degree of monitoring and control of alkali concentrations as compared to when KOH is used.

Role of vitamin A in the healing process of alkali caused corneal injury of adult male albino rat: Histological and immunohistochemical study

Background and Aim: Alkali burn of the cornea is considered as the most dangerous injury to the eye. It causes cornealinfection, ulceration, perforation, neovascularization (NV) and opacification. Vitamin A is necessary for the normal growth and differentiation of epithelium; it is expected to promote the mechanical repair of corneal epithelial defectsThe present study is planned to investigate the effect of vitamin A eyegel on wound healing of the corneal alkali burn in rats. Materials and Methods: A total of thirty male albino rats were used. Rats were divided randomly into four groups: Group I,the control group; included three rats, received distilled water. Each of group II, III, IV included 9 rats: their central corneas of the right eyes were injured by contacting them with filter paper saturated with 0.01 m NaOH for 45 seconds. Group II, the non-treated group, injured and received distilled water. Group III, the antibiotic treated group, received antibiotic eye drops (lincomycin hydrochloride eye drops) 3 times per day for 3 days. Group IV, vitamin A treated group, received the same course of antibiotic and vitamin A eye gel (Hypotear gel 1000 IU/g) three times per day. for 3 days. The eyeball was taken out, rapidly fixed and processed for light microscopic, immunohistochemical and morphometric studies. Specimens were taken after 24,48 and 72 hr. post-injury for tissue preparation and study of structural changes and immuno-histochemical analysis using Ki67 (detection of cellular proliferation) and transforming growth factor – beta (TGF-β) which is one of the most critical growth factors in establishing the pathologic lesion after corneal alkali burn. Results: Hematoxylin and eosin stained sections showed rapid healing of corneal ulcer in vitamin A treated group, with absence of neo-vasculariztion and inflammatory cellular infiltration. Immunohistochemical results showed that the use of vitamin A enhance cell proliferation (detected with Ki67) and decrease the expression of TGF-β which is one of the most critical growth factors in establishing the pathological lesion after corneal alkali burn.Conclusions: Vitamin A eye gel helped rapid healing of corneal alkali burn. This effect may be due to its anti-inflammatoryeffect and stimulation of cell proliferation.

Ethanol production from hazelnut shells through enzymatic saccharification and fermentation by low-temperature alkali pretreatment

Low-temperature sodium hydroxide (NaOH) pretreatment, enzymatic saccharification and ethanol fermentation were evaluated for hazelnut shell cellulose to fermentable sugars and ethanol. Maximum glucose recovery (48.33g/100g cellulose) was achieved with 6% NaOH for 72h and at 1/10 solid/liquid ratio. At these conditions, 41.18% of lignin was removed. The theoretical ethanol yield (ethanol produced/potential glucose in biomass) was 40.71%, overall process efficiency was 37.73g/kg biomass, ethanol productivity and fermentation efficiency were 0.115g/(Lh) and 96.7%, respectively. Total energy consumed for the low-temperature–long-residence-time alkali process was 34.8MJ/kg untreated hazelnut shells. Pretreatment time has a significant effect on thermal energy consumption for the low-temperature alkali process.

Quantitative phase analysis of the calcium silicate slag as the residue of extracting alumina from high-alumina fly ash

Calcium silicate slag is the residue of process of pre-desilication alkali lime sintering applied in the high-alumina fly ash to extract the alumina. The quantitative phase analysis (QPA) of the calcium silicate slag has been performed by the Rietveld method based on the powder X-ray diffraction (XRD) with the aid of noncommercial software GSAS-EXPGUI. A known weight of crystalline internal standard (10% CaF2) was added to the calcium silicate slag to calculate the fraction of amorphous phase and other crystalline phases on an absolute basis. Besides, the calcium silicate slag was characterized by X-ray fluorescence (XRF) and thermo gravimetric (TG) differential scanning calorimetry (DSC) to test the QPA results and investigate its other characters. Finally, the results show that the amorphous fraction is 17.5% (hereinafter, the percentages refer to the mass fraction), and the major crystalline phases detected in the calcium silicate slag consist of 23.5% Beta-Ca2SiO4, 10.0% bredigite, 10.3% Ca3Al2O6 (C3A) and 21.6% CaCO3.

Morphological effect governed by sandblasting and anodic surface reforming on the super-hydrophobicity of AISI 304 stainless steel

Super-hydrophobicity, enabling self-cleaning and antifouling capability, has attracted intensive researches by using different surface techniques. To achieve super-hydrophobicity on metal surfaces, morphological control of the surface shares equal importance with surface energy control. This study aims to develop a micro/nano coexisted surface morphology presenting super-hydrophobicity on an AISI 304 stainless steel, which was previously prepared by sandblasting and anodic reforming followed by a plasma treatment. By proper choice of the sand material, micrometer-scale morphology was shaped by sandblasting. Meanwhile, the nanometer-scale sub-feature can be reformed through the use of anodic electrochemical treatment, where the alkali electrolyte concentration, discharge voltage, and processing time were carefully controlled. By doing so, super-hydrophobicity perform well on AISI 304 stainless steel after Steel Wool test.

Chemical Treatment and Characterization of Fiber of Babassu Coconut Epicarp (Orbignya phalerata) for Application in Polymeric Composite

This set of mechanical properties of plant fibers allows its use as a reinforcement element in polymeric matrices and composites can be used in various sectors, and thus expanding the scope of use and the aggregate value of plant fibers. In this work, the choice by the use of alkali process to make the treatment of epicarp babassu fibers was decided in view of that it provides an effective, simple and low cost implementation process and also for being the most widely used method for modifying the surface of the fiber forming polymer composites. By SEM, it was observed the removal of wax layers, the impurities on the fiber surface and tyloses. With alkali treatment, it was also possible to notice the narrowing and closing of craters due to the packaging of denser material.

Development of building material utilizing a low pozzolanic activity mineral

In this work, the effects of different activators, particle size and curing conditions on the mechanical properties and hydration progress of alkali activated Pisha mortars were studied. Four different activators (NaOH, Na2CO3, Na2SO4 and water glass) based on two different fineness Pisha were used, two kinds of curing temperature, 25 and 80°C were considerate. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG) and scanning electron microscopy (SEM) were conducted to analyze the reaction products, indentify the phase composition and observe the micro-morphology, respectively. It was found that the modulus of water glass and fineness of Pisha have significant influence on the compressive strength and hydration process of alkali activated Pisha mortars. The optimum activators were water glass, the sample (Ms=1.5, curing at 80°C) exhibited the highest compressive strength (14.4MPa) at 28days. The results of the investigation also show that the amorphous aluminosilicate gels were the main hydration products.

Development and characterization of a high-solids deacetylation process

Dilute-acid pretreatment has proven to be a robust means of converting herbaceous feedstock to fermentable sugars. However, it also releases acetic acid, a known fermentation inhibitor, from acetyl groups present in the biomass. A mild, dilute alkaline extraction stage was implemented prior to acid pretreatment to separate acetic acid from the hydrolysate sugar stream. This step, termed deacetylation, improved the glucose and xylose yields from enzymatic hydrolysis and ethanol yields from fermentation of the sugars relative to the control experiments using dilute-acid pretreatment of native corn stover without deacetylation. While promising, deacetylation as it was historically practiced is conducted at low solids loadings, and at fixed conditions. Thus, many questions have been left unanswered, including the relationship between sodium hydroxide and solids loading, and acetate and xylan solubilization, as well as the impact of temperature and residence time on the process efficacy. A central composite experiment was designed to evaluate the impact of solids loading, sodium hydroxide loading, reaction time and temperature during deacetylation on the acetate and xylan solubilization of corn stover. Using the ANOVA test, it became apparent that neither of the responses was significantly impacted by the solids loading, while the reaction time was a minor factor—the responses were largely driven by reaction temperature and the sodium hydroxide loading. Based on the results, we successfully demonstrated the ability to transition the low-solids (10 % w/w) deacetylation process to a higher-solids process (30 % w/w) with minimal impact on the ability to extract acetate from biomass. Conditions were selected to minimize xylose loss during deacetylation, while also removing 70 % of acetyl groups. The impact of selected conditions on the enzymatic hydrolysis and fermentation was further investigated. Evaluation of the whole-process impact demonstrated that despite the upfront reduction in carbohydrate loss during deacetylation, the overall process sugar yields were depressed by the high-solids, low alkali process relative to the historical control. Consequently, ethanol titers were reduced, though strong fermentation performance was still observed, indicating that 70 % acetate removal is sufficient to depress acetic acid concentrations to a level that does not substantially inhibit ethanol fermentation by rZymomo nas.

Material Integration for Flexible Electronics for Energy Application Using Nanoparticulated Dense and Stress-Free Ceramic Thick Film

Material Integration for Flexible Electronics for Energy Application Using Nanoparticulated Dense and Stress-Free Ceramic Thick Film

Cross-flow leaching of alkali and alkaline-earth metals from sawdust and wheat straw – Modelling of the process

Cross-flow washing of wheat straw and beech sawdust with water was carried out in order to leach the alkali and alkaline earth metals from them. Incremental concentration change (C = Δm/ΔV) of alkali and alkaline-earth metals in the leachate was plotted against the wash water volume. Maximum increase in Δm/ΔV was achieved after passing 0.04 to 0.06 dm3 of water through the washed biomass. After passing 0.2 dm3 of water through the biomass, leaching of alkali metals was practically completed. Concentration of potassium ion was predominant in the leachate. From the whole amount of alkali and alkaline-earth metal ions, found in the aqueous phase after washing, K+ ions make about 80% in case of wheat straw and 64% in case of beech sawdust. Concentration of other considered metal ions was much less comparing to the potassium ones.Change in the pH and electrical conductivity (EC) were measured after passing of each portion of wash water through the biomass. Change of the EC against the wash water volume follows fairly the change of leachate composition. Based on the experimental results, the process of alkali and alkaline-earth metals leaching was modelled assuming the cross-flow scheme of leaching process. Proposed model follows fairly the experimental data. Discrepancy between the experimental and calculated values for alkaline-earth metals in case of beech sawdust is attributed to a different leaching mechanism.

Ameliorated enzymatic saccharification of corn stover with a novel modified alkali pretreatment

Enzymatic saccharification/hydrolysis is one of the key steps for the bioconversion of lignocelluloses into sustainable biofuels. In this work, corn stover was pretreated with a novel modified alkali process (NaOH + anthraquinone (AQ) + sodium lignosulfonate (SLS)), and then enzymatically hydrolyzed with an enzyme cocktail (cellulase (Celluclast 1.5L), β-glucosidase (Novozyme 188) and xylanase (from thermomyceslanuginosus)) in the pH range of 4.0-6.5. It was found that the suitable pH for the enzymatic saccharification process to achieve a high glucan yield was between 4.2 and 5.7, while the appropriate pH to obtain a high xylan yield was in the range of 4.0-4.7. The best pH for the enzymatic saccharification process was found to be 4.4 in terms of the final total sugar yield, as xylanase worked most efficiently in the pH range of 4.0-4.7, under the conditions in the study. The addition of xylanase in the enzymatic saccharification process could hydrolyze xylan in the substrates and reduce the nonspecific binding of cellulase, thus improving the total sugar yields.

Review on Alkali-Activated Fly Ash Based Geopolymer Concrete

Due to environmental pollution form cement industries, some efforts for alternative construction material are increasing. Recently, geopolymer concrete has drawn attention of researchers and engineers because of its lower carbon print and better mechanical property over Portland cement concrete. According to previous studies, geopolymer concrete results almost up to 90% reduction in carbon dioxide (CO2) emission to atmosphere. Mechanical properties of geopolymer concrete such as compressive strength, durability, sulfate resistance, early strength and low shrinkage are better than Portland cement concrete. In addition, the appropriate usage of one ton of fly ash earns one carbon-credit redemption value of about 20 Euros, and hence earned monetary benefits through carbon-credit trade.Therefore, this paper presents a review on the fly ash-based geopolymer concrete. The paper mainly covers composition, mixing and curing process, benefits, limitations and applications of alkali activated fly ash based geopolymer concrete.

Zero-valent iron enhanced methanogenic activity in anaerobic digestion of waste activated sludge after heat and alkali pretreatment

Heat or alkali pretreatment is the effective method to improve hydrolysis of waste sludge and then enhance anaerobic sludge digestion. However the pretreatment may inactivate the methanogens in the sludge. In the present work, zero-valent iron (ZVI) was used to enhance the methanogenic activity in anaerobic sludge digester under two methanogens-suppressing conditions, i.e. heat-pretreatment and alkali condition respectively. With the addition of ZVI, the lag time of methane production was shortened, and the methane yield increased by 91.5% compared to the control group. The consumption of VFA was accelerated by ZVI, especially for acetate, indicating that the acetoclastic methanogenesis was enhanced. In the alkali-condition experiment, the hydrogen produced decreased from 27.6 to 18.8mL when increasing the ZVI dosage from 0 to 10g/L. Correspondingly, the methane yield increased from 1.9 to 32.2mL, which meant that the H2-utilizing methanogenes was enriched. These results suggested that the addition of ZVI into anaerobic digestion of sludge after pretreated by the heat or alkali process could efficiently recover the methanogenic activity and increase the methane production and sludge reduction.

A Study on Damage to PLA Knitted Fabrics During Scouring and Bleaching

Abstract Ingeo® PLA (polylactic acid) knitted fabric was scoured through an exhaust technique. The scouring was carried out with sodium carbonate in the presence of a detergent at various concentrations and temperatures. The scoured fabric was bleached with various oxidative bleaching agents. Bleaching was carried out with hydrogen peroxide, sodium chlorite and sodium hypochlorite. Hydrogen peroxide was applied by exhaust and cold pad batch (CPB) techniques. It was observed that during scouring PLA fabric was degraded at high alkali concentrations and processing temperatures. The scouring temperature above 60ºC proved to be deleterious due to the scouring solution penetrating into the polymer structure and damaged the fiber. Sodium chlorite and sodium hypochlorite caused little damage to the mechanical properties of PLA. Hydrogen peroxide when applied by the CPB technique did not reduce strength appreciably but when applied by the exhaust technique decreased the strength significantly. SEM analysis revealed that hydrogen peroxide caused holes and slit formation in the fiber structure.

Experimental Study on the Effective Separation of Chromium-Iron Ions in Multi-Component Solution System by Ihleite Method

As one of the raw material resources in China, chromium salt production has been paid to close attention. Alkali process of chromium salt produces serious environmental pollution, while acid production of chromium salt has separation problems of chromium-iron ions. The separation process of chromium-iron ions in acidic solution by the combination technology of hydrothermal method and ihleite method is studied in this paper. which finds that: with the increase of reaction temperature or with the extension of reaction time, precipitation rate of iron increases, while loss rate of chromium decreases.