Effect Of Chemical Pretreatment Research Articles

Effect of Hot Dip Galvanizing on the Mechanical Properties of High Strength Steels

Present study focuses on investigating the hot dip galvanizing effect on the mechanical properties of high strength steel. The effect of chemical pre-treatment (hydrogen diffusion) and the effect of hot dip galvanizing temperature on mechanical properties was studied with high strength steel S650MC. Additional tests were made with widely used structural steel S355J2. A batch type hot dip galvanizing process was used and zinc bath temperature was 450 °C and 550 °C. Results of the study show the behaviour of high strength steel during hot dip galvanizing process.

The effects of chemical pretreatment on tribocharging of density fraction coal

Abstract Dry triboelectric separation of coal depends on tribocharge difference of the coal and gangue mineral. The coal samples of different density fraction prepared by sink-and-float method were pretreated by chemicals and their effects on the tribocharge performance with stainless steel were studied by measuring the charge-to-mass and relative dielectric constant. The results show the tribocharging performance of middle density fraction coal is the worst compared with other density fractions. The charge of lower density fraction was increased by chemical conditioning with light diesel oil, ammonia, and kerosene, while the charge of higher density fraction was decreased with ethanol and lignin.

Dynamics and Thermodynamics Studies on the Lead and Cadmium Removal from Aqueous Solutions by Padina sp. Algae: Studies in Single and Binary Metal Systems

Raw and modified biomasses prepared from Padina sp. algae have been used as sorbent for the removal of lead and cadmium from single and binary aqueous solutions. The effects of chemical pretreatment, exposure time, initial solution pH, initial metal concentration, and temperature on the metal uptake by the algae were investigated. It was observed that initial solution pH considerably influenced Pb and Cd uptake. The maximum removal occurred at initial pH of 5.0 for lead and 6.0 for cadmium. Also, alkali modified biomass has been shown to have a high uptake capacity for both lead and cadmium. The kinetic and equilibrium experimental data fitting tested with various models. The pseudo-first-order kinetic model and Langmuir isotherm provided the best correlation of the kinetic and equilibrium experimental data, respectively. The maximum uptake estimated from the Langmuir isotherm was 264 mg g−1 for lead and 164 mg g−1 for cadmium ions. Experimental biosorption data in binary system were well described by the extended Langmuir model. Various thermodynamic parameters, such as ΔG°, ΔH°, and ΔS° were calculated.

Chemical Treatments for Reducing the Yellow Discoloration of Channel Catfish (Ictalurus punctatus) Fillets

The effect of chemical pretreatments on the color and carotenoid content of yellow discolored channel catfish fillets was studied. The color and carotenoid content of the fillets were analyzed by the L*a*b* color system and high-performance liquid chromatography, respectively. Untreated fillets turned more yellow and darker after 12-d storage. Sodium bicarbonate had a beneficial effect on reducing the degree of yellowness, but the fillets still turned darker after storage. Sodium bisulfite gave the best results with fillets becoming less yellow and brighter after storage. Ascorbic acid, butylated hydroxyanisole, citric acid, and sodium metabisulfite were not successful at reducing the discoloration. The sum of carotenoid contents of untreated fillets decreased significantly (P < 0.05) during storage as compared to the fresh fillets. However, the sum of the carotenoid contents of fillets treated by various chemicals was not significantly (P > 0.05) different from the fresh or untreated fillets. The appearance of catfish fillets may be improved during storage by pretreating with sodium bisulfite.

Evaluation of whole Jerusalem artichoke (Helianthus tuberosus L.) for consolidated bioprocessing ethanol production

For consolidated bioprocessing (CBP), components of Jerusalem artichoke (Helianthus tuberosus L.) tubers and stalks as a potential bioenergy crop were analyzed as carbon and nutrient sources, respectively. The effectiveness of chemical pretreatment with dilute acid or alkali was evaluated to develop a CBP method. Cellulose content, delignification, and enzymatic hydrolysis efficiency of the pretreated stalks were increased more effectively by NaOH treatment than dilute H2SO4 treatment. However, weight loss was greater during alkali pretreatment. Additionally, large volumes of water were required to wash the alkali-treated biomass. Therefore, CBP using the dilute acid-pretreated stalk and the ground tuber of Kluyveromyces marxianus were investigated. Fermentation of both pretreated stalks and tubers by K. marxianus with no nutrient supplementation proceeded acceptably. At 10% (w/v) stalk and 8% (w/v) tuber loading, K. marxianus produced 45.3 g/L ethanol after 30 h. The ethanol yield was 0.252 g ethanol per g dry biomass, or 0.32 g ethanol per g fermentable sugars, with a fermentable sugar conversion rate of 60%. These results suggest a cost-effective CBP strategy for bioethanol production from the whole Jerusalem artichoke plant.

Effect of chemical and physical pretreatments on the convective drying of cape gooseberry fruits (Physalis peruviana)

Drying of cape gooseberry fruits is a slow process because of the low permeability to moisture of the fruit’s waxy skin. In this work, the effect of chemical pretreatments (sunflower oil/K2CO3 or olive oil/K2CO3 at 28°C, and NaOH/olive oil at 96°C) and physical pretreatments (blanching) to break down the waxy surface and accelerate moisture diffusion during drying, was assessed. Drying was carried out at 60°C and 2m/s air velocity for 10h. The lowest moisture content (0.27kg water/kgdb), the highest vitamin C content (0.36mg/g), and the greatest rehydration capacity (1.89) were obtained in fruits pretreated with olive oil (9.48%) and K2CO3 (4.74%). However, the greatest changes in color (ΔE*=15.05) and chroma (ΔC*=9.03) were also associated to fruits pretreated with olive oil and K2CO3. The effective diffusivity of water during drying was 7.37×10−11m2/s in pretreated samples compared with 6.61×10−11m2/s for untreated samples.

On the mechanical interaction between cellulose microfibrils and matrix substances in wood cell walls: effects of chemical pretreatment and subsequent repeated dry-and-wet treatment

We investigated the influences of chemical pretreatments and subsequent repeated dry-and-wet (RDW) treatments on the mechanical linkage between cellulose microfibrils (CMFs) and matrix substances (MT) in wood cell wall. Sugi (Cryptomeria japonica D. Don) quarter-sawn specimens were subjected to various types of chemical pretreatments, including ethanol and benzene extraction, delignification, alkali extraction, and hygrothermal treatment, to give substantial damages to principal constituents of wood cell wall, followed by 5 times of RDW treatment. After giving chemical pretreatment, the d-spacing of (200) lattice plane of cellulose Iβ (d 200), the crystallinity of wood cell wall, and the crystal size of the cellulose were measured at the fiber saturated point, using X-ray diffraction techniques. Thereafter, these were measured again at the absolutely dried condition in the process of subsequent RDW treatments. The d 200 in specimens, which were given to light pretreatments, largely expanded by drying at the early stages of RDW treatments, then it decreased and became constant after 5 times of RDW treatments. On the other hand, d 200 in specimens, which were given to intensive pretreatments, remained constant at a relatively small level throughout the whole process of RDW treatments. After 5 times of RDW treatments, d 200 became similar values between the above two groups. This suggests that RDW treatments have similar effects as intensive pretreatments, which induce substantial damages to the microscopic region in the wood cell wall such as interfacial separation between CMF, MT, and so forth. These defects would weaken mechanical interaction between CMF and MT in the wood cell wall during drying.

Effects of chemical pretreatments on the hydrogen isotope composition of 2:1 clay minerals

Clays are a commonly occurring authigenic mineral within soils, and the hydrogen isotope ratios of their structural hydroxyl groups can serve as a useful environmental proxy. Chemical and physical treatments are necessary to eliminate contaminating materials from clays, but they have the potential to alter their isotopic composition. Several pure, commonly occurring 2:1 clay mineralogies were treated with typical chemical procedures for the removal of carbonates, organic matter, and amorphous hydroxides. Samples were heated under vacuum to remove the adsorbed and interlayer water that occurs universally in natural clays. The samples were then analyzed for hydrogen content and isotope ratios through thermal conversion elemental analyzer/isotope ratio mass spectrometry (TC-EA/IRMS). No effects on hydrogen composition were found for most of the analyzed mineralogies. Smectite samples showed significant alteration following treatments for carbonate and organic matter. In addition, the smectites showed variable levels of hydrogen exchange with isotopically labeled H2 O. Smectites show significant and highly variable alteration following common chemical treatments, and analysis for paleoclimate reconstruction is problematic. A minor amount of H isotope exchange is likely at temperatures sufficient to remove adsorbed water, and efforts must be made to minimize and quantify this exchange during analyses of clay samples.

Effect of Chemical Pretreatments on the Quality of Minimally Processed Pineapple Stored in Polystyrene Packages

Minimally processed pineapple (Ananas comosus L.) cv. Mauritius stored at cold temperature for seven days were evaluated for physicochemical, sensory and microbiological qualities. Pineapple pieces were treated with 1% sodium chloride, 1% calcium chloride, a combination of 1% sodium chloride and calcium chloride, 1% ascorbic acid, 1% citric acid, 0.1% chitosan and distilled water (control) and packed in polystyrene packages before storage. Pretreatments did not significantly affect the physicochemical properties studied. Many sensory attributes in minimally processed pineapple decreased after seven days of storage. However, sodium chloride (1%) and a combination of 1% sodium chloride and calcium chloride pretreatments resulted in maintaining a better flavour in pineapple after a seven day storage period than the rest of the treatments. Microbial counts for all treatments and the control were within safe-to-consume limits while Salmonella was not detected in any sample. Ceylon Journal of Science (Bio. Sci.) 41 (2): 151-155, 2012 DOI: http://dx.doi.org/10.4038/cjsbs.v41i2.5385

Monitoring surface ion mobility on aluminum oxide: Effect of chemical pretreatments

Despite of its crucial role in many electrochemical processes, a clear surface chemistry-correlated understanding of interfacial ion mobility is missing. This study presents an improved application of a previously introduced method making use of the scanning Kelvin probe (SKP) technique on aluminum oxide surfaces. The local work function changes, induced by the displacement of the mobile surface ions in an electric field applied across the surface, are monitored as a function of surface chemistry modified by different surface pretreatments and ambient atmosphere. Complementary quartz crystal microbalance (QCM) and surface current measurements reveal how the modified surface chemistry affects the thickness of the adsorbed water layer and the surface conductivity, respectively. Besides the usefulness of the SKP technique for mobility studies, we demonstrate a selective control of the superficial ion mobility by engineering the surface fixed charges.

Evaluation of pre-treatment processes for increasing biodegradability of agro-food wastes

Anaerobic digestion (AD) technology can be employed for treating sewage sludge, livestock waste or food waste. Generally, the hydrolysis stage is the rate-limiting step of the AD processes for solid waste degradation. Therefore, physical, chemical and biological pre-treatment methods or their combination are required, in order to reduce the rate of such a limiting step. In this study, four methods (mechanical shredding, acid hydrolysis, alkaline hydrolysis and sonication) were tested to improve methane production and anaerobic biodegradability of different agro-food wastes and their mixtures. The kinetics of anaerobic degradation and methane production of pre-treated individual wastes and selected mixtures were investigated with batch tests. Sonication at lower frequencies (37 kHz) proved to give the best results with methane productivity enhancements of over 100% in the case of pig manure and in the range of 10–47% for the other wastes assayed. Furthermore, the ultimate methane production was proportional, in all the cases, to the specific energy input applied (Es). Sonication can, thus, enhance waste digestion and the rate and quantity of biogas generated. The behaviour of the other pre-treatments under the conditions assayed is not significant. Only a slight enhancement of biogas production (around 10%) was detected for whey and waste activated sludge (WAS) after mechanical shredding. The lack of effectiveness of chemical pre-treatments (acid and alkaline hydrolysis) can be justified by the inhibition of the methanogenic process due to the presence of high concentrations of sodium (up to 8 g l−1 in some tests). Only in the case of WAS did the acid hydrolysis considerably increase the biodegradability of the sample (79%), because in this case no inhibition by sodium took place. Some hints of a synergistic effect have been observed when co-digestion of the mixtures was performed.

Effect of Chemical Pretreatment on Cotton Stalk SCMP Bleaching Properties

Effect of chlorine, potassium permanganate and peracetic acid pretreatment on H2O2 bleaching properties of cotton stalk SCMP was studied in the paper. The results showed that brightness gradually increased with dosage of chlorine, however, the increase is small, and bursting index and breaking length firstly increased and then decreased as dosage of chlorine is great than 1.5%. Brightness of H2O2 bleached pulp decreased for potassium permanganate pretreatment, even change the bleaching sequence. Brightness of PaPP bleaching is the highest with peracetic acid pretreatment. Among the studied reagents, chlorine and peracetic acid can increase brightness of H2O2 bleaching, however, pretreatment with potassium permanganate can not improve bleaching properties. The brightness with CH3COOOH pretreatment is higher than that of chlorine pretreatment.

Effects of chemical pretreatments on δ18O measurements, chemical composition, and morphology of chironomid head capsules

Stable oxygen isotope measurements on fossil chironomid head capsules from lake sediments show that these chitinous remains can be used to reconstruct past lake water d 18 O and, indirectly, past climate change. We examined the impact of chemical pretreatment procedures on the chemical and stable oxygen isotope composition, and morphology of chironomid cuticles. Use of alkali, acids, and sodium chlorite alters the chemical composition and the morphological structure of chironomid cuticles by selective removal of chitin or proteins. Gas chro- matograms of pyrolyzates show that NaClO2 causes deproteination, whereas the combined use of HCl and HF results in partial chitin removal. Head capsules pretreated with KOH contained both chitin- and protein-derived moieties, although the concentration of protein was reduced, especially after KOH treatment at high concentration (28%) and tempera- ture (100C). Scanning electron microscopy con- firmed that a proteinaceous matrix is still present in modern and fossil head capsules after KOH treat- ment. This matrix, however, is largely absent in head capsules pretreated with NaClO2. A change in the proportion of chitin and proteins in our samples was associated with differences in chironomid d 18 O values. Our results suggest that deproteination results in a relative increase of chironomid d 18 O, whereas removal of chitin leads to decreased d 18 O values. We

Effects of pretreatment on the aluminium etch pit formation

The effect of chemical pretreatments on the electrochemical etching behavior of aluminium was investigated with the topographic studies of surface and the analysis of initial potential transients. Two-step pretreatments with H 3PO 4 and H 2SiF 6 result in a high density of pre-etch pits on aluminium surface by the incorporation of phosphate ion inside the oxide film and the removal of surface layer by aggressive fluorosilicic acid solution. It generates a high density of etch pits during electrochemical etching and results in the capacitance increase of etched Al electrode by expanding the surface area, up to 61.3 μF/cm 2 with the pretreatment solution of 0.5 M H 3PO 4 at 65 °C and 10 mM H 2SiF 6 at 45 °C.

Pretreatment of empty palm fruit bunch for production of chemicals via catalytic pyrolysis

The effect of chemical pretreatments using NaOH, H 2O 2, and Ca(OH) 2 on Empty Palm Fruit Bunches (EPFB) to degrade EPFB lignin before pyrolyis was investigated. Spectrophotometer analysis proved consecutive addition of NaOH and H 2O 2 decomposed almost 100% of EPFB lignin compared to 44% for the Ca(OH) 2, H 2O 2 system while NaOH and Ca(OH) 2 used exclusively could not alter lignin much. Next, the pretreated EPFB was catalytically pyrolyzed. Experimental results indicated the phenolic yields over Al-MCM-41 and HZSM-5 catalysts were 90 wt% and 80 wt%, respectively compared to 67 wt% yield for the untreated sample under the same set of conditions. Meanwhile, the experiments with HY zeolite yielded 70 wt% phenols.

Effect of chemical pretreatment of some lignocellulosic wastes on the recovery of cellulase from Aspergillus niger AH3 mutant

Lignocellulosic biomass holds remarkable potential for conversion into commodity products presenting dual advantage of sustainable resource supply and environmental quality. Though their utilization does not compete with food and feed demand, its bioconversion and utilizability is facilitated by pretreatment. The effect of the substrate pre-treatment using acid and alkali at two different concentrations (0.5 and 2 M) for two different residence timings (1 and 3 h) on cellulase production from corncob, corn straw and bagasse was studied using Aspergillus niger AH3. The strain was inoculated into 10 g/L of the processed pre-treated lignocellulosic substrates previously added to batches of the Mandels basal medium. The pH of the medium was adjusted to optimum (4.8) and the flasks with the contents autoclaved, thereafter fermentation begun. Samples of each flask were taken aseptically at regular interval (24 h) throughout the growth phase until the enzyme activity peaked off (between 110 and 170 h), centrifuged and the clear supernatant was used for the enzyme assay. Enzyme expression in all the pretreated biomass increased steadily from day one and peaked off at day four or five for the alkali pretreated residues whereas it was at day six for acid pretreated residues. Generally for the alkali treated residues irrespective of residence time, maximum cellulase yield was at day 5 while for the acid treated residues, maximum cellulase yield was at day 6. Enzyme yield from residues treated for longer period (3 h) using alkali when compared to those using acid under the same condition of fermentation was highly significant. The alkali treated residues showed higher cellulase yield than the acid treated residues. Highest cellulase activity (0.06777 IU/ml/min) was displayed by the organism grown on bagasse substrate pretreated with 2M NaOH for one hour. The proximate analysis of the cellulosic residues differed from one substrate to another, with the bagasse being the best. Pulverized substrates syndicated with alkali pretreatment using 2 M NaOH for one hour was optimal for cellulase production from the cellulosic residues. Key words: Lignocellulosic biomass, utilization, pretreatment, cellulase, substrates, Aspergillus niger AH3, fermentation, supernatant, substrate

Effects of Pretreatment on the Etch Pit Formation during the Electrochemical Etching of Aluminum

The effect of chemical pretreatments on the electrochemical etching behavior of aluminum was investigated with the topographic studies of surface and the analysis of initial potential transients. Two-step pretreatments with H3PO4 and H2SiF6 result in a high density of pre-etch pits on aluminum surface by the incorporation of phosphate ion inside the oxide film and the removal of surface layer by aggressive fluorosilicic acid solution. It generates a high density of etch pits during electrochemical etching and results in the capacitance increase of etched Al electrode by expanding the surface area, up to 61.3 μF/cm2 with the pretreatment solution of 0.5M H3PO4 at 65°C and 10 mM H2SiF6 at 45°C.

Hydrogenation and Electrochemical Characteristics of Amorphous-nanostructured Mg-based Alloys

In the development of new hydrogen absorbing materials for a next generation of metal hydride electrodes for rechargeable batteries, metastable Mg-Ni-based compounds find currently special attention. Amor phous-nanocrystalline <TEX>$Mg_{63}Ni_{30}Y_7$</TEX> and <TEX>$Mg_{50}Ni_{30}Y_{20}$</TEX> alloys were produced by mechanical alloying and melt-spinning and characterized by means of XRD, TEM and DSC. On basis of mechanically alloyed Mg-Ni-Y powders, complex hydride electrodes were fabricated and their electrochemical behaviour in 6M KOH (pH=14,8) was investigated. The electrodes made from <TEX>$Mg_{63}Ni_{30}Y_7$</TEX> powders, which were prepared under use of a SPEX shaker mill, with a major fraction of nanocrystalline phase reveal a higher electrochemical activity far hydrogen reduction and a higher maximum discharge capacity (247 mAh/g) than the electrodes from alloy powder with predominantly amorphous microstructure (216 mAh/g) obtained when using a Retsch planetary ball mill at low temperatures. Those discharge capacities are higher that those fur nanocrystalline <TEX>$Mg_2Ni$</TEX> electrodes. However, the cyclic stability of those alloy powder electrodes was low. Therefore, fundamental stability studies were performed on <TEX>$Mg_{63}Ni_{30}Y_7$</TEX> and <TEX>$Mg_{50}Ni_{30}Y_{20}$</TEX> ribbon samples in the as-quenched state and after cathodic hydrogen charging by means of anodic and cathodic polarisation measurements. Gradual oxidation and dissolution of nickel governs the anodic behaviour before a passive state is attained. A stabilizing effect of higher fractions of yttrium in the alloy on the passivation was detected. During the cathodic hydrogen charging process the alloys exhibit a change in the surface state chemistry, i.e. an enrichment of nickel-species, causing preferential oxidation and dissolution during subsequent anodization. The effect of chemical pre-treatments in 1% HF and in <TEX>$10\;mg/l\;YCl_3/1%\;H_2O_2$</TEX> solution on the surface degradation processes was investigated. A HF treatment can improve their anodic passivation behavior by inhibiting a preferential nickel oxidation-dissolution at low polarisation, whereas a <TEX>$YCl_3/H_2O_2$</TEX> treatment has the opposite effect. Both pre-treatment methods lead to an enhancement of cathodically induced surface degradation processes.

Effect of Perozonation on Biodegradability and Toxicity of a Penicillin Formulation Effluent

The pretreatment of synthetic penicillin formulation effluent containing Procain Penicillin G (PPG) with the O3/H2O2 process (applied ozone dose = 1440 mg h−1 treatment time = 60 minutes; pH 7; H2O2 = 10 mM) was investigated. The effect of chemical pretreatment was assessed on the basis of acute toxicity and biodegradability with activated sludge using water flea Daphnia magna toxicity and activated sludge inhibition tests. Biological treatability studies were performed with a mixture of untreated or pretreated PPG effluent (25% on volume basis) and synthetic domestic wastewater simulating readily biodegradable organic substrate to simulate the characteristics of domestic wastewater (75% on volume basis). Pretreatment of PPG effluent the O3/H2O2 process resulted in more than 70% chemical oxygen demand (COD) removal and a 50% decrease in the acute toxicity towards Daphnia magna. On the other hand, biodegradation of untreated PPG effluent needed prolonged acclimation periods to obtain a significant biological COD removal (= 80%). Pretreatment employing the O3/H2O2 process not only decreased the ultimate biodegradability of PPG effluent but also increased its inhibitory effects on activated sludge treatment speculatively due to the formation of less biodegradable oxidation by-products.

Nitrogen Removal from Landfill Leachate Using a Compact Constructed Wetland and the Effect of Chemical Pretreatment

Onsite treatment of leachate was implemented at the Tveta Landfill, adjacent to the city of Södertälje, Sweden. The system consists of leachate collection in a pond, precipitation of metals with chemicals, a constructed wetland, and forest irrigation. This article describes the constructed wetland and its effectiveness at removing ammonia in the system. Pulsed-discharge hydrology and wetland ecology formed the basis for the development of a compact constructed wetland (CCW). The system presented here has most design similarities with vertical sub-surface flow wetlands, though this system is run in batch mode. Chemically purified leachate and untreated leachate were applied to separate sections of the CCW using a filling and emptying schedule. A leachate treatment cycle of about 14 days duration was used, involving a 7 day submerged phase followed by a 7 day drained period. The removal efficiency varied between 40 and 75% on a mass basis. A maximum mass removal rate of up to 5.1 g m− 2 d− 1 was achieved in wetlands receiving leachate after chemical pretreatment. In wetlands receiving non-treated leachate a net release of up to 18 g m− 2 N occurred in the form of nitrate. This indicated a considerable nitrification but limited denitrification in those systems. It was unclear whether the chemical treatment enhanced the nitrogen removal efficiency because of lower toxicity and/or content of fewer competing cations, or other mechanisms. Mechanisms responsible for the NH4-N removal in the CCW system have to be further investigated.