Acid Alkali Research Articles

CHARACTERIZATION OF CHEMICALS FROM PROSOPIS JULIFLORA (PJ) – A POTENTIAL ENHANCER FOR LIGHTWEIGHT POLYMER APPLICATIONS

The latest research is about ProsopisJuliflora’s mining and characterization officers. The fibres were cut, chemically treated using sodium and hydrochloric acid (alkali) solutions. Chemically modified and non-modified fibres have been analysed for their thermal, chemical, crystalline, electrical, morphological and tensile characteristics. The findings showed that a cellulose content was increased by 59.8 % with a reduction of amorphous content and humidity by chemical treatment with alkali. However, due to its acid-plus attacks whose values were lower than untreated, the treatment for hydrochloric acid reduced cellulosis material. There were four hundred and seventeen nm of crystalline fibre of alkaline therapy, less than one 68.01 nm. Thus the ProsopisJuliflora can be suggested for lightweight polymer applications as a possible reinforcement.

Scalable Preparation of Cellulose Nanofibers from Office Waste Paper by an Environment-Friendly Method.

Waste paper is often underutilized as a low-value recyclable resource and can be a potential source of cellulose nanofibers (CNFs) due to its rich cellulose content. Three different processes, low acid treatment, alkali treatment and bleaching treatment, were used to pretreat the waste paper in order to investigate the effect of different pretreatments on the prepared CNFs, and CNFs obtained from bleached pulp boards were used as control. All sample fibers were successfully prepared into CNFs by 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) oxidation. It was quite obvious that the bleached CNFs samples showed dense fibrous structures on a scanning electron microscopy (SEM), while needle-like fibers with width less than 20 nm were observed on a transmission electron microscopy (TEM). Meanwhile, the bleaching treatment resulted in a 13.5% increase in crystallinity and a higher TEMPO yield (e.g., BCNF, 60.88%), but a decrease in thermal stability. All pretreated CNFs samples showed narrow particle size distribution, good dispersion stability (zeta potential less than −29.58 mV), good light transmission (higher than 86.5%) and low haze parameters (lower than 3.92%). This provides a good process option and pathway for scalable production of CNFs from waste papers.

Separation and Simultaneous Quantitation of Tolterodine Tartrate and Tamsulosin Hydrochloride in Capsule Formulation by using Stability-Indicating RP-HPLC-DAD Method

In the present work, a precise, accurate and selective stability-indicating RP-HPLC method has been developed and validated according to International Conference on Harmonization guidelines Q2-(R1) for the simultaneous quantitative determination of Tolterodine tartrate and Tamsulosin hydrochloride in bulk and its capsule formulation. The chromatographic separation was achieved on Hypersil octadecyl silane C18 (250 x 4.6mm, 5 μm) column at room temperature and mobile phase comprised of methanol: 0.05 M phosphate buffer, pH 7.0 in the ratio of 90:10 V/V. The flow rate of mobile phase was set at 1.0mL/min and compounds were monitored at 255nm using photodiode array detector. Tamsulosin hydrochloride and Tolterodine tartrate retention time were found to be 4.15±0.2 min and 8.42±0.2 min, respectively. The drug substances and products were subjected to acid hydrolysis, alkali hydrolysis, oxidative hydrolysis, photolytic and thermal degradation. The percent degradation of drugs was calculated in all stressed conditions. The analytical method validation parameters such as linearity, accuracy, precision, detection limits, quantitation limits and robustness indicate that drug substances and products were efficiently separated in present of their degradants and successfully applied for the routine analysis of Tolterodine tartrate and Tamsulosin hydrochloride in bulk and its capsule formulation in the quality control laboratory.

Positive Effect of Antagonistic Additives on the Homogeneous Catalytic Etherification Reaction of Glycerol

Various compounds prepared using glycerol, diglycerol (DG), and triglycerol (TG) have been gaining increasing attention due to their wide range of applications. To increase the yield and selectivity of DG and TG syntheses, previous studies investigated a variety of catalysts with different basicity and variable reaction temperatures. In this study, we introduced additives that act as inhibitors to increase the selectivity of the etherification reaction for DG and TG production and depress the formation of higher oligomers by moderating the activity of the catalyst. By adding weakly acidic alkali metal-based inorganic salts (NaHSO4 and KHSO4), the selectivity of DG and TG formation could be enhanced, although the conversion of glycerol decreased due to the reduced activity of catalyst. We found that the decrease in the activity of the catalyst caused by the additives could be recovered and that side reactions were reduced if the reaction was carried out at an increased temperature of 280 °C and if the reaction time was shortened to 2 h to suppress the formation of oligomers. The dependence of the reaction on the amount of the additive, the reaction time, and the reaction temperature was investigated to elucidate the role of the additive.

Obtaining Humic Preparations From The Waste Of A Hydraulic Dump Of Coal Deposits As A Promising Waste-Free Technology

Humic substances are the main organic component of soil and water, as well as solid fossil fuels. These important components are formed during the de-composition of plant and animal residues under the influence of abiotic envi-ronmental factors and as a result of the activity of microorganisms. In the future, humic substances are of great interest for medicine, veterinary medicine and plant protection as bioregulators, biostimulants and adaptogens, which deter-mine the normal functioning of various body systems. As a result of enrichment of coal from the Angren deposit, a large amount of waste accumulates, which negatively affects the ecological situation in the region and occupies large areas, in connection with which the question of their processing arises, in particular, to obtain humic preparations and bacterial fertilizers of prolonged action. The iso-lation of humic acids from the dumps was carried out with weak solutions of po-tassium and sodium hydroxides, and then precipitated from the obtained alka-line extracts by acidification with mineral acids to pH 2.0. In the residual cakes, the synthesis of humic acids was carried out by inoculation of an association of microorganisms BK 5 grown on rice flour. In the course of the research it has been found, that optimal separation of humic acid alkali consumption solvents NaOH or KOH is 8g per 100g of the crude product in a ratio of T:F = 1:5 at a temperature of 80° C for 30 minutes.

Acid-based modified NiCo2O4 as high-performance supercapacitor electrode materials

The performance of supercapacitor electrode materials was greatly affected by the specific surface area. The urchin-like NiCo2O4 was transformed into porous NiCo2O4 (AA-NiCo2O[Formula: see text] using the acid–alkali treatment method. The specific surface area of AA-NiCo2O4 was 165.0660 m2/g, which was about three times larger than that of NiCo2O4. The specific capacitance of the AA-NiCo2O4 was enhanced significantly (1700 F/g at 1 A/g), and AA-NiCo2O4 possesses good rate capacitance (1277 F/g at 10 A/g). This is mainly attributed to the larger specific surface area, fast and convenient electron–ion transport and redox reaction. Therefore, AA-NiCo2O4 is a promising high-performance supercapacitor electrode material.

Recovery of rare earths from glass polishing waste for the production of aluminium-rare earth alloys

The circular economy demands waste utilization for the production of high-value products, and this requires the development of novel processing routes. In this study, rare earth (La and Ce) oxides were completely (>99%) recovered from polishing waste by a combined novel reductive acid leaching and alkali treatment process. About 70% of rare earths were dissolved during the first leaching step. The undissolved rare earth compounds are converted to oxides/hydroxides by alkali treatment and dissolved in the acid solution – the 2nd leaching step – for the complete recovery of rare earths. The recovered rare earth oxides were used for producing in-situ high-value Al-La-Ce alloys with fused salt electrolysis. Mechanical properties of our Al-La-Ce alloys are similar to the known high temperature Al-Ce alloys. This development of new alloys by our novel process helps in utilization of both overproduced primary La and Ce oxides as well as La and Ce recovered from polishing waste.

Research Status and Development Trend of High-Value Utilization of Marine Fish Offal

China's marine fish fishing and aquaculture industry has developed rapidly in recent years. Only a small part of the large amount of by-products produced during the processing of marine fish is used as feed, and most of them are discarded to cause environmental pollution. The internal organs of marine fish are rich in bioactive peptides, enzymes and lipids that can be effectively utilized, and it is necessary to develop and utilize them. This article reviews the bioactive peptides such as antioxidant peptides, anti-fatigue peptides, and anti-hypertensive peptides, visceral enzymes such as protease, superoxide dismutase, cholinesterase, and acid (alkali) in marine fish internal organs in recent years. Research progress on the extraction process and application of phosphatase, phospholipids, fatty acids and unsaponified lipids in lipids, and the future development and utilization of marine fish offal with high value suggestions are made to provide a reference for the high-value utilization of marine fish offal and to promote zero-waste high-value and high-quality processing of the marine fish industry.

Research on Purification Technology of Ultra-Large Flake Graphite Based on Alkali-Acid Method

Graphite is a strategically scarce resource, and the preparation of high-purity graphite is the prerequisite and basis for the application of graphite. In order to determine the optimal purification technology parameters of an ultra-large flake graphite mine pneumatic separation ore with a fixed carbon content of 77.69%, a particle size of mainly 10 to 40 mesh, and main impurities of calcium carbonate, iron oxide and silica , two additional experiments of acid method and alkali method were added on the basis of alkali-acid method, to investigate the purification effect of different technological processes and acid leaching times on graphite raw materials, as well as to analyze the retention extent of different methods and alkali fusion temperature on graphite ultra-large flake structure. The results show that all three methods can increase the fixed carbon content of graphite to above 99%. However, compared with the acid method and the alkali method, the alkali-acid method can obtain high-purity graphite while also better protecting the graphite's ultra-large flake structure. The optimal fusion temperature is 400 °C, the optimal acid leaching time is 30% sulfuric acid thrice and 5% hydrofluoric acid once. After purification, the fixed carbon content of the product exceeds 99.97%.

Basic Mechanical and Neutron Shielding Performance of Mortar Mixed with Boron Compounds with Various Alkalinity

This study conducted fundamental tests on mortars using the boron compounds recycled industrial wastes to replace uneconomic boron products. The boron compounds were three types according to the pH and the physical and neutron shielding performance of mortar mixed with boron compounds was examined. The adopted boron compounds classified as acid, slightly alkaline, and strongly alkaline with respect to the pH are acidic boric acid, alkali borax, and high alkali borax, respectively. The physical properties were evaluated by measuring the compressive strength and setting time as well as the thermal neutron shielding performance. The measured compressive strength revealed that the strengths of the specimens mixed with boron compounds were generally lower than that of the basic specimen made of control specimen. In addition, the initial and final setting times were longer than those of the control specimen. The thermal neutron shielding performances of the specimens mixed with boron compounds were higher than that of the control specimen. Consequently, the differences of the type and chemical composition of boron compounds influenced the physical properties and thermal neutron shielding performance of mortar, including its compressive strength, setting time, and neutron shielding performance. Therefore, it is important to determine the optimal amount of boron compounds in the fabrication of mortar.

Properties of Bitumen Composition Modified by Petroleum Resins

It was advised to use aliphatic, cycloaliphatic, aromatic petroleum resins and their derivatives obtained by oxidation of resins with a mixture of hydrogen peroxide and acetic acid as bitumen polymer-modifiers. Petroleum resins were obtained by ionic polymerization of unsaturated compounds of liquid pyrolysis products under the influence of titanium tetrachloride-diethylaluminium chloride catalyst. It was established that the maximum values of adhesion of modified bitumen coatings to metal substrates, corresponding to the minimum values of the wetting angle of the metal surface coated with solutions of bitumen compositions with different content of the polymer modifier were achieved using oxidized resins. All modified bitumen coatings have low water absorptivity and high acid resistance, alkali resistance and salt resistance, which allow using them as protective coatings

Pure Hydrolyzable Cellulose from Rice Straw, Wheat Straw and Sugarcane Bagasse by a Simple Scalable Two-Step Treatment

Utilization of amply available lignocellulosic biomass for a cost-effective conversion to renewable chemicals has proven more difficult than anticipated. Sustainable and viable fractionation of any biomass to its individual monomeric components for their further conversion to products at commercial scale therefore remains elusive. A rapid and scalable multi-step pretreatment strategy for fractionation of rice straw using a combination of dilute aqueous acid and aqueous alkali treatment steps under subcritical conditions was investigated. The process steps and parameters were optimized for yield and purity of the resulting biomass components. Effects of acid and alkali concentrations on the fractionation efficiency were studied in the range of 0.2% to 12% w/v at temperatures ranging from 110°C to 200°C for time spanning from 15 to 30 min. The simple optimum sequence of operations and conditions was found to be a diluteacid hydrolysis step at 130°C for 15 min with 2% HNO3 followed by the second treatment step at 130°C for 15 min with 2% NaOH. This combination gave 90% pure cellulose in more than 80% overall yield. Formation of furfurals in the hydrolysate was prevented significantly, and the cellulose obtained showed good amenability for enzymatic hydrolysis to sugars. The same process was applied to wheat straw and sugarcane bagasse, and the obtained results were found to be similar to those obtained for rice straw. The process was successfully scaled up to 50 L batch process with negligible deviations from smaller scale run results.

Superhydrophobic wood surface fabricated by Cu2O nano-particles and stearic acid: its acid/alkali and wear resistance

Abstract Reducing the hydrophilic nature of wood could enhance dimensional stability and improve life cycle performance. Masson pine and pecan wood were modified to create superhydrophobic, self-cleaning functions by spray-coating with Cu2O nano-particles (Cu2O NPs)/phenol formaldehyde (PF) resin mixed solution followed by immersion in a stearic acid ethanol solution. Two types of Cu2O NPs, derived from different concentrations of copper chloride (CuCl2) were evaluated for their ability to improve hydrophobicity of wood surface. A special petal-shaped structure on the edge of Cu2O NPs was found on modified pecan wood, and water contact angles (WCA) of both kind of modified wood reached around 155° and sliding angles (SA) less than 10°. Meanwhile, low liquid permeability and excellent repellency to aqueous solutions with pH = 1 to 13 were achieved. The critical WCA around 150° was also maintained on modified wood surfaces after being immersed in strong acid (pH = 2) and strong alkali (pH = 12) solutions for 12 h. Furthermore, remarkable mechanical durability was obtained after harsh abrading test, which could be attributed to the high bond strength from cured PF resin adhesive. Such highly waterproof, acid/alkali resistant and hard-wearing superhydrophobic surface must have potential to be widely applied in wood products industry.

Refining of Banana Fiber for Load Bearing Application through Emulsion Treatment and Its Comparison with Other Traditional Methods

ABSTRACT Following their mechanical extraction, the fibers coming from the banana pseudo-stem are coarse and the inter fiber cohesive substances need to be removed before their transformation into textile yarns/technical textiles. To reach this objective, dry-coarse banana fibers previously extracted using compressive rollers are treated using an oil-water-based emulsion. Various properties such as mechanical properties, thermal properties, surface morphology, chemical structure, crystallinity, color value, and moisture content of the banana fibers extracted through emulsion treatment have been evaluated and are compared with those of untreated banana fibers, and the fibers extracted through acetic acid treatment and alkali treatment, respectively. It is observed that the banana fibers extracted through oil/water emulsion treatment show higher crystallinity, tensile properties, thermal stability, moisture content, and brightness than that of untreated fibers and the fibers extracted through other treatments. Following oil-water emulsion treatment, the banana fibers possess suitable properties for recyclable thermoplastic composite manufacturing with technical-grade polymers, such as PP or PLA.

CMC and CNF-based intelligent pH-responsive color indicator films integrated with shikonin to monitor fish freshness

Intelligent pH-responsive color indicator films based on carboxymethyl cellulose (CMC) and cellulose nanofibers (CNF) were prepared using shikonin extracted from Lithospermum erythrorhizon roots. The addition of shikonin did not affect the thermal stability and water vapor barrier properties of the film; however, the surface hydrophobicity increased significantly. The shikonin-added films showed high antioxidant activity, especially in aqueous solutions. The color indicator films showed a noticeable color response function for various pH values, showed reddish-pink at pH below 7, and turned reddish-purple, purple, and light blue as the pH increased from 7 to 12. When the indicator film was used to monitor the fish freshness, it showed a reddish-pink for fresh fish (pH = 5.7) and turned blue-violet after 36 h, indicating that it was spoiled (pH = 6.9). The shikonin-added color indicator films with a distinct discoloration function between a weak acid and weak alkali are likely to be applied to monitor seafood quality.

Influence of dilute acid, alkali and hydrothermalpretreatments on methane improvement from datepalm waste “Takarboucht” cultivar

This research assesses the impacts of hydrothermal (120 °C for 30 min), dilute acid (2%(w/w) H2SO4 at 120 °C for 30 min) and alkali (6% (w/w) NaOH at 35 °C for 24 h)pretreatments on the methane yield from date palm waste “Takarboucht” cultivar. The pretreated and untreated date palm waste (DPW) were digested at mesophilic temperature (36 °C) for 20 days. The highest soluble chemical oxygen demand (sCOD) was obtained by DPW hydrolysate from alkali pretreatment. The highest methane yield of 161.86 ml/g VS was obtained from untreated DPW. Among all pretreatments, higher methane yield was obtained from hydrothermally pretreated DPW (153.35 ml/g VS), followed by acid pretreated DPW (141.65 ml/g VS) and alkali pretreated DPW (50.78 ml/g VS). Alkali pretreatment improved the solubilization of DPW, however, it may not necessarily provide an enhancement in the methane yield. The optimization of the conditions of each pretreatment is proposed.

Effect of different pretreatment methods on pore structure of activated carbon

The effects of pretreatment on the pore structure of activated carbon were studied by the methods of water washing, acid washing, alkali washing and a combination of acid washing and alkali washing. It can be known from experiments that water washing has a cleaning effect on activated carbon, while acid washing helps to open the micropores of activated carbon and improve its porosity. Sodium hydroxide solution has an etching effect on activated carbon, which can increase the porosity and average particle size of activated carbon. All the pretreatment methods in this article can improve the adsorption capacity of activated carbon for nitrogen, and the pretreatment by dilute hydrochloric acid is tested to be the most effective.

Effect of Oil Content in Tea-seed Pancake on the Determination of Tea Saponin

According to the national standard for the determination of tea saponin content in tea-seed pancake (GB/T 35131-2017), tea saponin was obtained by extracting oil with ethanol and removing solvent. The actual samples of tea-seed pancake did not completely remove the oil, and some of the residual oil content was as high as 9%. Due to the long period of national standard determination, people often use ethanol to extract tea saponin directly, instead of subsequent acid hydrolysis or alkali hydrolysis steps, so as to realize the rapid evaluation of tea-seed pancake quality. In this case, the residual oil has a greater impact on the results. If it was still tested according to the national standard method, the result will be much higher than the actual result. In this work, petroleum ether extraction process was selected before ethanol extraction to remove the residual oil. Experimental results showed that, the accuracy of the determination was effectively improved.

Polydopamine-coated bimetallic ZIF derivatives as an air cathode for acidic Zn-air batteries with super-high potential.

NC@Co-HPNC is synthesized, which exhibits a superior ORR/OER performance in acid/base solution. Hence, acid-base dual-electrolyte-based Zn-air batteries using NC@Co-HPNC reveal a long cycling life and a super-high voltage (2.1 V).

Enhanced adsorption performance for aromatic sulfur compounds over a hierarchical structured AgX zeolite

Schematic illustration of the design for the synthesis of hierarchical-AgX. (a) Sequential acid–alkali treatments of NaX; (b) silver supported on original NaX; (c) silver supported on hierarchical NaX after sequential acid–alkali treatments.