Influence Of Acid Type Research Articles

Acid‐doped polyaniline and its vertically aligned SWCNT composites: Influence of acid type and concentration on structural and electrochemical properties

Acid‐doped polyaniline and its vertically aligned <scp>SWCNT</scp> composites: Influence of acid type and concentration on structural and electrochemical properties

Optimization of indium recovery from waste crystalline silicon heterojunction solar cells by acid leaching

Recovery of rare metal indium from waste crystalline silicon heterojunction (HJT) solar cells is important with the large-scale development of photovoltaic industry, is becoming economically and environmentally justified. Thus, the objective of this work is to study hydrometallurgical recovery of indium and valuable materials from HJT solar cells. In addition, to study some parameters used in this process. In this study, three key processes including pretreatment, acid leaching and optimization design on singer-factor to minimize waste of resources were proposed and implemented. Firstly, the samples were characterized by Inductively coupled plasma optical emission spectrometer (ICP-OES) showed indium concentrations of 2950 mg/kg. Then, reacting with NaOH 10% at 90 °C for 8 min can separate the silver electrodes on the surface of the cells, which realize the primary recovery of the silver electrode. After this, the influence of acid type, acid concentration, retention time and temperature on indium leaching was analyzed. Subsequently, the BBD method under response surface methodology was used to optimize the leaching rate. Optimum operating conditions include a leaching step for 148 min at 93.2 °C in the presence of H 2 SO 4 6 mol/L with extraction rate of 95.2% and validate the feasibility with determination coefficient (99.55%) of the RSM model. • A novel experimental method is proposed for recovering indium from waste crystalline silicon heterojunction (HJT) solar cells. • A process to recovery of valuable materials in the HJT cells is designed. • Optimization of indium recovery by using Response Surface Model (RSM).

Structure and properties of chitosan films: Effect of the type of solvent acid

The properties of chitosan films can be modified by changing the solvent type, attributing to the different interaction patterns between chitosan and acids. However, little is known about how these interactions affect the structure and properties of chitosan films. In this work, the influence of acid type on the structure and properties of chitosan films was studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). FTIR spectra showed that the ionic interactions and hydrogen bonding could occur between chitosan and acid ions. Structural analysis revealed that chitosan was partially crystalline in hydrochloric and acetic acid films, whereas it was amorphous in lactic and citric acid films. DSC result indicated that the glass transition temperature of chitosan was much lower in citric acid film with low water content than in all the other films, suggesting that the citrate ions interacted more strongly with chitosan. A melting transition appeared in hydrochloric and acetic acid films. In addition, the tensile strength of these films decreased with an increase in the volume of acid. These observations indicate that the choice of a proper solvent for chitosan may be desirable for certain special applications.

Photocatalytic reforming of pinewood (Pinus ponderosa) acid hydrolysate for hydrogen generation

Dilute acid hydrolysis of milled Pinus ponderosa (pinewood) was performed in a high-temperature high-pressure 300 ml SS316 Parr reactor to produce sacrificial electron donors for downstream photocatalytic H2 generation. Samples of the hydrolysate withdrawn at regular time intervals were analysed for total organic carbon (TOC), sugars and organic compounds. The influence of acid type (HCl, H2SO4, and HNO3) and its concentration, temperature, residence time and biomass loading on pinewood hydrolysis and release of the glucose and xylose sugars (GX) was investigated. Maximum GX sugar yield was obtained with 1 v/v% HCl hydrolysis of 6.66 wt% pinewood slurry at 180 °C for 120 min. The hydrolysate was treated with activated charcoal (AC) and photoreformed for H2 generation using 1% Pt/TiO2 catalyst. Under optimized reaction conditions, 8 consecutive photocatalytic cycles of the hydrolysate produced cumulative yield of 19.9 ml H2/g pinewood, which is 26 mol% of GX observed in the hydrolysate.

The influence of acid type on self-assembly, rheological and textural properties of caseinomacropeptide

The influence of acid type (acetic, citric, lactic and hydrochloric acids) on caseinomacropeptide (CMP) self-assembly, rheological and textural properties was analysed. The acidulant selection had a large impact on self-assembly rate, gelation and the hardness of CMP gels. The highest self-assembly and gelation rates were for citric acid, followed by hydrochloric and lactic acids. CMP solutions did not gel when the pH was adjusted with acetic acid during the test period. Product development using CMP must be carefully designed from the point of view of gel properties. A product preparation with CMP gelled with lactic or acetic acids would not be recommended because these acids affect the rheological and textural properties of the gels.

Influence of acid type and concentration on the synthesis of nanostructured titanium dioxide photocatalysts from titanium-bearing electric arc furnace molten slag

TiO2 photocatalysts with different crystal phases and morphologies were synthesized from Ti-bearing EAF slag.

Characterization of citrus pectin samples extracted under different conditions: influence of acid type and pH of extraction.

Pectin is a complex macromolecule, the fine structure of which is influenced by many factors. It is used as a gelling, thickening and emulsifying agent in a wide range of applications, from food to pharmaceutical products. Current industrial pectin extraction processes are based on fruit peel, a waste product from the juicing industry, in which thousands of tons of citrus are processed worldwide every year. This study examines how pectin components vary in relation to the plant source (orange, lemon, lime, grapefruit) and considers the influence of extraction conditions on the chemical and macromolecular characteristics of pectin samples. Citrus peel (orange, lemon, lime and grapefruit) from a commercial supplier was used as raw material. Pectin samples were obtained on a bulk plant scale (kilograms; harsh nitric acid, mild nitric acid and harsh oxalic acid extraction) and on a laboratory scale (grams; mild oxalic acid extraction). Pectin composition (acidic and neutral sugars) and physicochemical properties (molar mass and intrinsic viscosity) were determined. Oxalic acid extraction allowed the recovery of pectin samples of high molecular weight. Mild oxalic acid-extracted pectins were rich in long homogalacturonan stretches and contained rhamnogalacturonan I stretches with conserved side chains. Nitric acid-extracted pectins exhibited lower molecular weights and contained rhamnogalacturonan I stretches encompassing few and/or short side chains. Grapefruit pectin was found to have short side chains compared with orange, lime and lemon. Orange and grapefruit pectin samples were both particularly rich in rhamnogalacturonan I backbones. Structural, and hence macromolecular, variations within the different citrus pectin samples were mainly related to their rhamnogalacturonan I contents and integrity, and, to a lesser extent, to the length of their homogalacturonan domains.

Influence of Acid Type on the Pore Structure of Gel-Derived Silica

Influence of Acid Type on the Pore Structure of Gel-Derived Silica

Fractal nature of acid-etched wormholes and the influence of acid type on wormholes

Abstract Two-scale (Darcy scale and pore scale) continuum wormholing models are built to study the fractal nature of the acid-etched wormholes in acidizing carbonate reservoirs and the influence of acid type on the conditions for wormholes to form. This model considers convection-diffusion mass transfer and reaction on the acid-rock interface, and the fractal dimension of dissolution patterns is calculated using box-counting method. The results show that wormholes are formed when convection and diffusion are equivalent in strength; when convection dominates, uniform dissolution is formed; when diffusion dominates, surface dissolution is generated. For the zones where the porosity is greater than 0.7, the fractal dimensions of the surface dissolution, wormholes and uniform dissolution are 1.46, 1.50 and 1.44, respectively, among which, the fractal dimension of the wormholes is approximate to the experimental results obtained by Daccord and Lenormand (1.60.1). The reaction between weak acid and rocks is controlled by reaction kinetics, the acid-etched wormholes are wide, and more acid is consumed. The reaction between strong acid and rocks is controlled by mass transfer, the acid-etched wormholes are narrow, and less acid is consumed. According to an example calculation, it is found that acidizing treatments should be performed in an isolated short section each time when the horizontal well is long.

Recovery of metal cations from lime softening sludge using Donnan dialysis

Advances in the application of ion exchange membrane processes for material separation provide new approaches for improving the sustainability of industrial operations. In this work, we report on the application of Donnan dialysis to recover metal cations from lime softening sludge, a byproduct of drinking water production. A cation exchange membrane, which preferentially allows the transport of cations, was used in the Donnan cell. Slurries containing lime softening sludge, gypsum, or calcite were placed on the feed side of the cell and an acidic solution was placed on the sweep side. A concentration gradient between the two sides of the cell extracts metal cations from the feed in exchange for hydrogen ions in the sweep side solution. The influence of acid type, starting pH, and time were evaluated. Although the limited solubility of calcite inhibited its study, significant calcium ion recovery was measured from the feed solutions with gypsum. The results were consistent with theoretical expectations and demonstrated that the pH of the sweep side solution controlled the extent and rate of cation recovery. For the treatment of the lime softening sludge, over 99% of the hydrogen ions were exchanged in the recovery of up to 20% of the calcium and 50% of the magnesium from the lime softening sludge. Over time, depletion of the sweep-side hydrogen ions resulted in the preferential recovery of magnesium from the softening sludge. Our results suggest the process exhibits promise in treating the sludge by recovering metal cations for reuse.

Influence of the acid type on the physical and drug liberation properties of chitosan–gelatin sponges

The influence of acid type used to dissolve chitosan on the resulting sponge physical properties, and their consequent effect on the drug liberation were investigated. Chitosan was dissolved in different acid solutions and chitosan–gelatin sponges were produced by frothing up the polymer solution and then freeze-drying the foam. Prednisolone was used as a model drug. Using tartaric or citric acid resulted in instable, soft, elastic and disintegrating sponges with fast drug release. Elastic but harder sponges from stable foams were obtained when hydrochloric or lactic acid were used. The use of acetic or formic acid enabled the production of stable foams, soft and elastic sponges and a slow drug release. The rate of drug release was decreased by crosslinking the polymers with glutaraldehyde, but only if acetic, formic or acetic acid were used. Therefore, it is possible to manipulate the mechanical properties and the drug liberation rate by using different acids to dissolve chitosan.

Effects of Acids on Gravels and Proppants

Summary The effects of acids on the integrity of gravels and proppants should be considered in acid treatments. This paper reports on the influence of acid type, acid concentration, and contact duration on the acid solubility of five sands and bauxitic materials. The effects of the acids on the mechanical strength and the size distribution of the solids are determined. We found that intermediate-density and low-density bauxites (IDB and LDB) are very soluble in HF acid and that sintered bauxite is weakened by HF acid.

Effect of acid type on kinetics and mechanism of dental enamel demineralization.

The influence of acid type (pKa effects) of weak organic acid buffers on dissolution kinetics of dental enamel was critically examined for rigorous testing of the behavioral validity of the physical model of Patel et al. (1987). Quantitative evaluation of this model indicated that monitoring initial dissolution rates was a viable approach to critical testing of the model. Initial dissolution rates were determined in 0.1 mol/L acetate (pKa = 4.77), benzoate (pKa = 4.20), and salicylate (pKa = 2.98) buffers (pH = 4.50, mu = 0.50), with ground bovine enamel blocks of known surface area mounted in a rotating disk apparatus. The Levich theory was used to study dependence of dissolution rates on stirring rates in these buffers. The experimental data were analyzed by the physical model which includes pKa effects, complexation of the buffer anion with the other ions, surface kinetics, simultaneous diffusion and equilibrium of all species in enamel pores, diffusion layer thickness, and bulk solution composition. The KIAP (formula: see text) governing the dissolution reaction and the surface resistance factor were deduced from the model. Dissolution kinetics was also followed in these buffers in the presence of calcium or phosphate common ions. In effect, by conducting both the stirring rate studies and common ion experiments, we derived the driving force function independently by these two techniques. The results obtained in this study were consistent with the model, indicating that pKa effects on the dissolution of dental enamel can be accounted for quantitatively by the model, and it was found that weak acids do not influence either the apparent solubility or the surface reaction process of bovine dental enamel.