Influence Of Chemical Pretreatment Research Articles

Postindustrial Jute Waste as a Support for Nano-Carbon Nitride Photocatalyst: Influence of Chemical Pretreatment.

Non-woven jute (NWJ) produced from carpet industry waste was oxidized by H2O2 or alkali-treated by NaOH and compared with water-washed samples. Changes in the structure of the NWJ, tracked by X-ray diffraction (XRD), showed that both chemical treatments disrupt hydrogen bond networks between cellulose Iβ chains of the NWJ fibers. Thereafter, nano-carbon nitride (nCN) was impregnated, using a layer-by-layer technique, onto water-washed jute samples (nCN-Jw), NaOH-treated samples (nCN-Ja) and-H2O2 treated samples (nCN-Jo). Analysis of the Fourier transform infrared spectroscopy (FTIR) spectra of the impregnated samples revealed that nCN anchors to the water-washed NWJ surface through hemicellulose and secondary hydroxyl groups of the cellulose. In the case of chemically treated samples, nCN is preferentially bonded to the hydroxymethyl groups of cellulose. The stability and reusability of prepared nCN-jute (nCN-J) samples were assessed by tracking the photocatalytic degradation of Acid Orange 7 (AO7) dye under simulated solar light irradiation. Results from up to ten consecutive photocatalytic cycles demonstrated varying degrees of effectiveness across different samples. nCN-Jo and nCN-Ja samples exhibited declining effectiveness over cycles, attributed to bond instability between nCN and jute. In contrast, the nCN-Jw sample consistently maintained high degradation rates over ten cycles, with a dye removal percentage constantly above 90%.

Influence of chemical pretreatment on the pozzolanicity of recycled glass microparticles used as a substitute for Portland cement

This research investigated the influence of using chemically treated glass microparticles as a partial replacement for cement in Portland cement pastes and mortars. The microparticles were obtained by grinding glass waste into three different particle size fractions (< 75 µm, < 45 µm, and < 25 µm), treated with calcium hydroxide (CH), and characterized using SEM/EDS and a laser particle size analyzer. Samples prepared with the incorporation of glass were characterized using XRD, TGA/DTG, and SEM/EDS. The pretreatment with calcium hydroxide induced the formation of C-S-H with different morphologies on the surface of the particles, in addition to causing changes in particle size distribution due to the formation of agglomerates. The pastes prepared with treated particles had lower amounts of CH and higher levels of hydrated silicates. However, when indirectly measuring the pozzolanicity of treated particles through the compressive strength of mortars, no significant differences were observed in the strengths of mortars made with treated and untreated particles.

PENGARUH PRETREATMENT BAHAN KIMA DAN BIOLOGI TERHADAP AKUMULASI VOLUME BIOGAS DARI LIMBAH MAKANAN

PENGARUH PRETREATMENT BAHAN KIMA DAN BIOLOGI TERHADAP AKUMULASI VOLUME BIOGAS DARI LIMBAH MAKANAN

Influence of Chemical Pretreatment on the Mechanical, Chemical, and Interfacial Properties of 3D-Printed, Rice-Husk-Fiber-Reinforced Composites

This article explores using biomass, namely rice husks, as a reinforcement material in thermoplastic copolyester (TPC) composites. Rice husks were subjected to three chemical pretreatments: single-stage sulfuric acid hydrolysis, first-stage sulfuric acid hydrolysis followed by a second-stage methanesulfonic acid (MSA) treatment, and first-stage sulfuric acid hydrolysis followed by a second-stage sodium hydroxide alkali treatment. We studied the effects of these treatments on the rheological, thermal, interfacial, and mechanical properties of composites. The fibers were mixed with polymers at high shear rates and temperatures, and 3D-printed filaments were produced using a desktop 3D printer. The printed parts were analyzed using tensile tests, torque and viscosity measurements, and thermogravimetric analysis to obtain their mechanical, rheological, and thermal properties. SEM imaging was performed to understand the fiber–polymer interface and how it affects the other properties. The results showed that first-stage sulfuric acid hydrolysis followed by a second-stage pretreatment of the fibers with MSA showed better fiber–polymer adhesion and a 20.4% increase in stress at 5% strain, a 30% increase in stress at 50% strain, and a 22.6% increase in the elastic modulus as compared to untreated rice husk composites. These findings indicate that readily available and inexpensive rice husks have significant potential for use in natural fiber-reinforced composites when pretreated using dilute sulfuric acid followed by methane sulfonic acid hydrolysis.

Influence of Chemical Pretreatment on the Adsorption of N2 and O2 in Ca-Clinoptilolite

N2 and O2 adsorption isotherms in chemically modified clinoptilolite-Ca zeolites were experimentally estimated by inverse adsorption chromatography. Natural zeolites (CLINA) were chemically treated with HCl at different concentrations (H1-H4). The adsorption of N2 and O2 on these zeolites was studied in the temperature zone of 398–498 K using gas chromatography. This technique used a thermal-conductivity detector and He as carrier gas, at a rate of 30 mL min−1. The Langmuir and Henry equations were used to describe the experimental results of these gases’ adsorption. To evaluate the selectivity of the components of atmospheric air, the chemical activation of the zeolite clinoptilolite-Ca has been carried out. The results are attractive because of the ability to separate the gases these nanomaterials present under dynamic conditions. The structural modifications of the crystalline phases of the studied zeolites were carried out through X-ray diffraction, where the average crystal size was evaluated with the Scherrer equation, finding values of 25.86 nm for CLINA and 15.12 nm for H3 zeolites. The variation of their chemical composition was carried out by energy-dispersive EDS, while the adsorption of N2 carried out their texture properties at 77 K. The selectivity coefficients (α) were evaluated for these gases in pure form and in a mixture (atmospheric air), finding the highest values in zeolites H4 and H3. The interaction energies between these gases with the porous structures of the studied zeolites were evaluated from the evolution of the isosteric enthalpies of adsorption through the Clausius–Clapeyron equation.

Influence of Chemical Pre-Treatments and Ultrasonication on the Dimensions and Appearance of Cellulose Fibers.

Due to the wider use of nanocellulose in various areas of economic life, better and more optimal methods of obtaining nanocellulose are constantly being sought. Therefore, an attempt was made to evaluate the hybrid cellulose treatment, based on the use of a chemical method combined with an ultrasound of medium frequency. The study employs two different starting materials (Södra Black R cellulose or microcrystalline cellulose), two types of chemical pre-treatments (acid hydrolysis or oxidation), and two sonication durations. It was found that the reduction fiber cross-sectional dimensions was the result of prolonged exposure of cellulose to the ultrasound. From Södra Black R and the microcrystalline cellulose nanometer scale, structures were obtained in the form of isolated fibers. The TEMPO reagent accelerated the degradation process of two cellulose varieties due to its oxidizing character. The resulting products had nanofibrous structures. Cellulose degradation as a result of the combined action of sonication and TEMPO activity progressed gradually. Places of fiber degradation were characterized by their longitudinal breakage and initiated the next stages of the defibering process.

Evaluation of humic acids produced from Pakistani subbituminous coal by chemical and fungal treatments

The development of bio-processing low rank coal into fuels and non-fuel products has received growing interest in recent years, e.g., production of alternative chemical stock (i.e., humic acids) by the fungal transformation. Previous studies have demonstrated that fungal strains isolated from coal environments can play an important role in the coal-transformation processes with in vivo optimization and chemical pretreatments. In this study, the influence of chemical pretreatments (nitric acid and hydrogen peroxide) with a fungal isolate from coal on the depolymerization of Pakistani subbituminous coal was conducted. The chemical pretreatment exhibited enhanced production of humic acid from 13.5% to 54.2% for nitric acid and 45.7% for hydrogen peroxide. Nitric acid was more effective pretreatment in individual and combination with fungal-mediated depolymerization than hydrogen peroxide. The production of fungal-transformed liquid-derived humic acids were 36.4% and 31.1% for nitric acid and hydrogen peroxide pretreated coal. The results showed that the fungal-transformed humic acid has a high molecular weight, elevated aromatic condensation with mono and poly-substituted functional groups than the chemically treated and raw coal-derived humic acids. The fungal treatment also increased the nitrogen content in the resultant extract, which can be beneficial to the functionality of humic acids. By combining chemical and fungal treatment, it is possible to improve the quantity and quality of humic acids extracted from low rank coal. This is a promising approach in the development of more sustainable-cleaner products from Pakistan’s coal resources for the production of bio-active humic acid.

Influence of chemical pretreatments on plant fiber cell wall and their implications on the appearance of fiber dislocations

AbstractThe cell wall of plant fibers may contain irregular regions called dislocations. This study evaluated the effect of chemical pretreatment as a mechanochemical dislocation initiator in unbleached and bleachedEucalyptussp. fibers. Accordingly, bleached and unbleached pulps of eucalyptus were subjected to chemical pretreatments with sodium hydroxide at concentrations of 5% for 2 h, 10% for 1 h and 10% for 2 h or with hydrogen peroxide. The extent of dislocations was evaluated by polarized light microscopy. Based on the observation, an index of dislocations (ID) expressing their ratio of cell wall as per two-dimensional (2D) imaging and their angle relative to the longitudinal direction of the fiber were estimated. Chemical pretreatments increased the ID for bleached and unbleached fibers as well as increased the changes in the curl of bleached and unbleached fibers for chemical pretreatments. Chemical pretreatment extracted the hemicellulose of the fiber cell wall causing some fiber to curl, which in turn generated new dislocations and modifications in the dislocation angles which may be useful for improving the deconstruction process of the cellulose fibers.

Thermal decomposition of Nephelium lappaceum L. peel

Influence of chemical pretreatment in thermal behavior of Nephelium lappaceum L. peels was studied through thermogravimetric analysis, SEM, X-ray diffraction, FTIR and EDXRF. Results of derivate thermogravimetry were deconvoluted with Fraser–Suzuki function, demonstrating that the distribution of pseudo-components is affected by chemical pretreatment, where sulfuric acid pretreated sample (Ras) has not indicated the cellulose pseudo-component peak and the phosphoric acid pretreated sample (Rap) also did not demonstrate the lignin peak, indicating itself to be an effective tool in the prediction of pseudo-components of lignocellulosic samples. This result corroborates with FTIR spectra and XRD. The sample Rna (sodium hydroxide treated) has indicated modifications in cellulose crystalline structure, conversion of cellulose I/II, revealed by XRD. An EDXRF analysis demonstrated that the chemical pretreatment also influenced the distribution of minerals, constituted essentially of Na, Mg, Fe, K, Al and Cl. This change is evidenced when carrying out statistical analysis of the samples, and principal component analysis applied in EDXRF data revealed statistical differences between samples, separating in distinct quadrants.

Influence of Chemical Pretreatment on the Dissolved Organics in Poplar Alkaline Peroxide Mechanical Pulping Effluent

Influence of Chemical Pretreatment on the Dissolved Organics in Poplar Alkaline Peroxide Mechanical Pulping Effluent

Influence of Chemical Pretreatment on the Internal Structure and Reactivity of Pyrolysis Chars Produced from Sugar Cane Bagasse

The characterization of char obtained from the vacuum pyrolysis (8 kPaabs, 460 °C, 18 °C/min) of sugar cane bagasse followed by steam gasification (60 wt % of steam, 700–900 °C) was studied. The influence of different chemical pretreatments prior to pyrolysis (acetone, ethanol, HNO3 and HF) on the ash content, the pore structure, and chemical composition of resulting chars and activated carbons were investigated. Changes in the pore structure were observed during the pyrolysis process and the steam gasification, namely, the development of a channel network and the increase of meso- and macroporosity distributions, respectively. These porous changes affect the pyrolytic yields. Clear influences of the surface area and ash content on the pyrolytic water yields and the inorganic devolatilization effect on the meso- and macropore distributions of chars were shown. Furthermore, the structural reorganization of chars obtained during the vacuum pyrolysis of HF and solvent-leached bagasse was beneficial to their ...

The Influence of Chemical Pre-treatment and Magnesium Surface Enrichment on Bonding of Succinic Acid Molecules to Aluminium Alloy

In the present study a combined Fourier Transform Infrared Reflection–Absorption Spectroscopy (FT-IR–RAS) and Auger electron spectroscopy (AES) analysis was performed to investigate the bonding of organic coatings to oxides formed on Al–Mg based alloys. The interfacial bonding of a model molecule, succinic acid, mimicking the functional groups used in practical coatings was studied in detail on various differently pre-treated aluminium alloy (AA5182, 4.8 wt% magnesium) surfaces. Besides these differently pre-treated alloy surfaces, also pure magnesium and aluminium were studied for reference. The surface and near-surface composition of the alloys was studied by Auger electron spectroscopy, ion-milling away the surface oxides to obtain a depth profile. The results show that after heat treatment, the oxides are as much enriched in magnesium as aluminium although the bulk concentration of magnesium is only 4.8 wt%. FT-IR–RAS shows that bonding of the succinic acid molecules takes place in a range of configurations, varying between bridging bidentates and unidentates. The relative portion of unidentates increases with the magnesium surface concentration. This is attributed to the difference in bond lengths of Mg–O and Al–O, forcing the carboxylic acid groups to stretch or to attach to only one oxide group (unidentate) instead of two (bidentate). Also the mixed OH/CO3 surface after Mg enrichment at the surface has less room for bonding with two groups, thus affecting the bonding configuration in a similar way.

Influence of Chemical Additives upon Both Filtration and Electroosmotic Dehydration of a Kaolin Suspension

The filtration of a kaolin suspension and the electroosmosic dehydration of a formed cake are studied. The influence of chemical pretreatments upon these two stages is studied for various added compounds: salts, acids, coagulants, flocculants, and surfactants. The main parameters of the process, such as the cake specific resistance, the energy consumption, and the cake dryness, are compared. The added compounds influence the process parameters differently. The choice of an appropriate method of pretreatment depends on which of these process parameters is of interest to improve. However, with an appropriate pretreatment, electroosmotic dehydration allows cake dryness to be markedly increased at low energy consumption.

Influence of chemical pretreatment on the surface properties of silicon nitride powder

Adsorption energy distributions for nitrogen at the surface of silicon nitride samples with different pretreatment have been obtained and related to the heats of adsorption determined by Brunauer–Emmett–Teller analysis of adsorption isotherms. This has confirmed the conjecture that, in normal conditions, the surface of silicon nitride is covered by a layer of silica, as suggested by earlier studies. An attempt to correlate adsorption data with ab initio potentials of the adsorbate–adsorbent interaction has been made. The charge-regulated behaviour of the surface of silicon nitride in aqueous electrolytic solutions has been investigated in relation to charge titration and electrokinetic experiments. An important role of surface hydrolysis in the interpretation of experimental data has been pointed out. Based on the surface ionization parameters extracted from charge titration data, interparticle forces governing the stability of colloidal dispersions have been calculated in the framework of Derjaguin’s approximation.

Influence of Chemical Pretreatments on Surface Morphology and Bondability of Aluminium

Abstract Wettability combined with a strong oxide layer are needed for adhesive bonding and these properties can only be examined by making joints with an adhesive and testing them. The best test for this purpose is the climbing drum peel test. Surfaces must be pickled and anodized. The acids used for pickling influence the anodized structure and chromic-sulphuric acid mixture followed by anodizing in chromic acid gives optimum results. Metal pickled in sulphuric acid shows lower peel strength on bonding. Electron-micrographs show a clear relation between surface morphology and bondability and a fine etchpit structure within coarser etchpits gives the most desirable structure. Low strengths are associated with either weak oxide or a weakened aluminium surface.