Sulphuric Acid Treatment Research Articles

INVESTIGATION OF THERMAL AND STRUCTURAL PROPERTIES OF NITRIC, HYDROCHLORIC AND SULPHURIC ACID-TREATED ZEOLITE

In this study, in order to consider the effect of the hydrochloric acid (HCl), nitric acid (HNO3) and sulphuric acid (H2SO4) treatments on thermal and structural properties, zeolite was modified with 1 M acid solutions at 70 oC during 4 h using batch method. The structural and thermal properties of zeolites were studied by X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetric analysis (TG), differential thermogravimetric analysis (DTG) and differential thermal analysis (DTA). Quantitative XRD analysis show that the natural zeolite mainly consists of mordenite and clinoptilolite with varying amounts of quartz, feldspar and clay mineral. TG-DTG and DTA curves of all zeolite samples were obtained in the temperature range between 30 and 1000 oC. Based on the TG results, the total mass losses for all acid-treated samples (8.51-8.44 %) are less than that of the natural (Z) sample (10.14 %). SiO2/ Al2O3 ratio of the natural zeolite sample (Z) increased from 5.6 to 9.8, 9.7 and 8.8 in the Z-N, Z-H and Z-S samples, respectively, indicating the removal of the significant amount of aluminum from the zeolite structure.

Extraction and characterization of phenolic compounds and dietary fibres from banana peel

Phenolic extract from banana peel was extracted with 95% ethanol and characterized by LC-TOF-MS/MS. Epicatechin, rutin, 3,4-dihydroxybenzaldehyde, 3,4-dihydroxybenzoic acid, myricetin, ferulic acid, chlorogenic acid, and gallic acid were detected in the extract. Cholate test was performed for the initial examination of the hypolipidemic effect of the dietary fibres. The dietary fibres prepared by sequential treatment with sulphuric acid then sodium hydroxide (SST) and sodium hydroxide treatment (SHT) had high water-holding capacities (7.48 and 6.91 g g−1) and swelling capacities (4.8 and 4.3 ml g−1). The dietary fibres prepared by sequential treatment with trypsin then sulphuric acid (TST) and sulphuric acid treatment (SAT) had high oil-holding capacities (5.52 and 5.10 g g−1) and enhanced capacities for sodium cholate adsorption. Results indicated the potentials of banana peel as functional ingredient in food applications.

Dormancy Breaking and the Influence of Gibberellic Acid on the Early Growth of Tamarindus indica Seedlings in Mubi, Nigeria

The purpose of this research was to determine the appropriate methods of breaking seed dormancy, level of water uptake, and the influence of gibberellic acid on the early growth of Tamarindus indica seedlings. The scarification methods used included: concentrated sulphuric acid (H2SO4), manual scarification, flaming, hot and cold water treatments. The experiments were conducted in the laboratory on Petri dishes and in potting media. GA3 was used to optimize the production of seedlings by spraying the solution on the foliage. The treatment for 10 minutes with concentrated H2SO4 gave the maximum germination percentage and water uptake (80.41%). GA3 enhances the growth of the seedlings by increasing the height, the number of leaves and stem girth at eight weeks after sowing. In conclusion, all the scarification treatments applied to the seeds of T. indica proved effective. The ten minutes treatment with concentrated H2SO4 was the best treatment for breaking seed dormancy of T. indica. And gibberellic acid enhanced early and fast seedling growth as it increase height, number of leaves and stem girth of T. indica.

Synthesis and Characterization of Carbon Nanosheets from Stinging Nettle (Urtica Dioica)

Extensive research in nanotechnology has allowed us to improve and revolutionize technology and industry. This had led to an interest in the synthesis of other forms of carbon nanomaterial, such as graphene, fibre, carbon nanotubes and particles. Nowadays, a variety of carbon materials is available offering the flexibility to modify carbon properties. Therefore, the manufacture of carbon materials in different shapes is a likely way to take advantage of the morphology and relate it to the properties of the carbon nanomaterial. Stinging nettle is a new material to study for the production of carbon nanostructured materials. In this research, carbon nanosheets were successfully prepared from stinging nettle (nettle stem and leaf) using potassium hydroxide (KOH), sulphuric acid (H2SO4) and thermal treatment. This method is simple for producing carbon nanosheets from natural materials. Treating the nettle stem with KOH (solid) produces carbon nanosheets with a thickness of ∼159.2– 252.3 nm, while KOH (solute) treatment led to thinner nanosheets (∼70.43–111.2 nm). SEM micrographs of the nettle leaf with KOH (solute) activation show a smooth surface and clearly reveal the formation of carbon nanosheets. However, in the samples activated by KOH (solute) a greater number of micropores were found on the wall. The microstructure and morphology of the samples were investigated by scanning electron microscopy (SEM), the chemical composition was analysed by energy-dispersive X-ray spectrometry (EDS).

Anaerobic membrane reactor: Biomethane from chicken manure and high-quality effluent

Chicken manure was treated in a pilot scale reactor anaerobic membrane bioreactor constituted by a completely mixed reactor combined with an ultrafiltration tube-shaped membrane in a side-stream configuration. The process operated under mesophilic condition and the inhibition of high concentration of ammonia was avoided using an ammonia stripping system. The experimental plan included a preliminary evaluation, where organic loading rates between 1.0 and 7.6 kgVS/m3/day were tested. The organic load higher than 4 kgVS/m3/d caused the accumulation of volatile fatty acids and process instability. Application of the ammonia stripping was also evaluated. The best performances were achieved using a retention time of 21 days, an organic load between 1.4 and 2.0 kgVS/m3/d, and the recirculation of stripped permeate. Reduction of the ammonia permeate content by 90% through stripping and utilization of a mixture of chicken manure/water/permeate in a ratio of 0.22/0.72/0.72 w/w led to a specific biogas production of 0.59 m3biogas/kgVS and methane content of 66–69%. The ammonia thus removed can be recovered by sulphuric acid treatment as ammonium sulphate, which can be used as a fertilizer. The proposed configuration allowed satisfactory biogas production with appropriate methane percentages, recovery of ammonium sulphate, and a high-quality effluent.

Effect of Seed Priming Methods on Germination of Sweet Dattock (Detarium microcarpum) and Indian Jujube (Ziziphus mauritiana) in Sudan Savanna Ecological Zone of Nigeria

This study was conducted to evaluate the effect of different methods of seed pre-treatment on germination of two indigenous tree species, Sweet dattock and Indian jujube (Detarium microcarpum and Ziziphus mauritiana). The experiment is carried out at the Tree Seedlings Nursery of Faculty of Agriculture, Kebbi State University of Science and Technology, Aleiro. Treatments consisted of Boiled water (100ºC) for 10 minutes, 20 minutes and 30 minutes; three levels of diluted sulphuric acid (H2S04) soaking time for 10minutes, 20 minutes and 30 minutes; Seed scarification and control. The treatments were arranged in Completely Randomized Design (CRD) with three replications per treatment. Results revealed that the seed of Sweet dattock (Detarium microcarpum) soaked in hot water at 1000 C for 30 minutes exhibited the best germination percentage (100.00±0.00) within four (96 hours) days. This is followed by hot water treatment for 10 minutes and sulphuric acid treatment for 20 minutes which gave the same germination percentage of 93.33±11.54 within 4 (96 hours) days. The seeds under control treatment gave the least germination percentage of 86.67±11.54 and took a longer period to germinate (eleven days.) Indian jujube (Ziziphus maurtiana) seeds on the other hand, gave the highest germination percentage (93.33±5.77) with scarification, followed by soaking in hot water for 30minutes (46.57±11.54), while the lowest germination percentage was recorded for seeds in the untreated control (3.33±5.77). Based on the result, pre-treatment of Sweet dattock (Detarium microcarpum) seed with hot water at 1000 C for 30 minutes and scarification of Indian jujube (Ziziphus maurtiana) seed is recommended for effective germination.

High amounts of chlorinated paraffins in oil-based vitamin E dietary supplements on the German market

Chlorinated paraffins (CPs) are a group of man-made pollutants of growing environmental concern. Short-chain chlorinated paraffins (SCCPs) were recently classified as persistent organic pollutants (POPs), while medium-chain chlorinated paraffins (MCCPs) are still unregulated. Foodstuff is a major pathway for the human CP intake, and the regular diet has been analyzed in several studies recently. However, dietary supplements (DS) had not been analyzed on CPs. Our goal was to investigate the occurrence of CPs in DS and to evaluate the possible threat for the consumers. DS (n = 25) made from plant or fish oils were selected on the German market with main emphasis on vitamin E products. The lipid components were removed by sulphuric acid treatment and silica gel column chromatography. CP quantification was performed via gas chromatography coupled to electron capture negative ion mass spectrometry. Six vitamin E preparations containing palm oil showed alarmingly high CP concentrations of >35 μg/g fat. Six other DS contained much lower CP amounts (<4 μg/g fat). If consumed as recommended, the mean daily intake of CPs (5.5 μg SCCPs + 38 μg MCCPs) via palm oil based DS surpassed that of the regular diet by a factor of 4 for SCCPs and 13 for MCCPs, exceeding the PCB intake via food by up to two orders of magnitude. Samples reached up to 26% of the TDI of MCCPs for an average European adult. Consequently, the P95 intake of those samples would amount to ~43 mg CPs per year. The CP contamination probably originated from raw material, as CPs were also found in palm oils and vitamin E concentrates made from palm oil. Our findings suggest that DS can contain high amounts of contaminants that compromise the purpose of the product and should be considered for regular CP monitoring.

Lab-scale preparation and QC of phytase assay substrate from rice bran

Phytases are involved in the phosphate acquisition and remobilization in plants, microbes and animals. They have become important technical enzymes in the feed industry and are used to make phosphate, present in animal feed as phytate, available for monogastric animal nutrition. Phytases may also be beneficial to human nutrition because phytate is known to interfere with the uptake of important micronutrients. Accordingly, phytases attract considerable research attention and phytate substrate lacking contaminants that interfere with commonly used phosphate-release assays is essential for this field of science. A procedure to prepare suitable sodium phytate from rice bran is presented. Extracted phytate is precipitated with barium hydroxide and re-dissolved in methanol after washing steps and sulphuric acid treatment. Remaining impurities are precipitated before the dissolved phytate is recovered as the sodium salt by addition of sodium hydroxide. In order to make the substrate widely available for research communities, the procedure relies solely on basic laboratory equipment and materials. Methods for quality control and monitoring of the purified sodium phytate or commercial alternatives are also presented.

Improvement of the textural properties of templated carbon xerogels using cotton fibres as a hard template dehydrated by sulphuric acid

Carbon xerogels have generally low textural properties compared with carbon aerogels and carbon cryogels since the gas-liquid interface produces a capillary force in small pores. In this work, the templated carbon xerogels (TCXs), using resorcinol-formaldehyde (RF) and cotton fibres (CFs) as a hard template, were synthesized by CF removal from CF/RF composite hydrogels by sulphuric acid treatment. The TCX precursors were exchanged by t-butanol, dried by evaporation drying, and carbonized at high temperature. Scanning electron microscope images and Hg intrusion data confirm that TCXs possess macropores whose walls are the carbon xerogel scaffold. Their nitrogen adsorption and desorption isotherms also support that TCXs have micropores and mesopores. The quantities of micropores, mesopores and macropores are improved with the increase of CF utilization. X-ray diffraction allows us to know that TCXs have a graphitic structure. The intensity of D to G from the Raman spectra is also investigated.

On the sulphonated PEEK for implant dentistry: Biological and physicochemical assessment

Abstract Sulfonated PEEK (sPEEK) has been developed for drug delivery although there is still scarce evidence on its physicochemical and biological properties. The main aim of this study was to assess the cytotoxicity behavior of sPEEK processed for two different sulphonation times. PEEK was functionalized by sulphuric acid treatment for 1 or 1.5 h and then dissolved in dimethylsulfoxide (DMSO). The specimens were characterized by chemical, microstructural, thermophysical, hydrophobic, and roughness analysis. Cytotoxicity assays with fibroblasts followed ISO 10993-5. Thermophysical analyses by TGA and NMR revealed no statistical difference (p > 0,05) in the degree of sulphonation for both processing time points although chemical modifications were detected in the main polymer chain. PEEK surfaces were more hydrophilic than sPEEK surfaces and therefore biological assays revealed a higher cell proliferation on PEEK surfaces when compared to that recorded on sPEEK surfaces. Fibroblasts revealed a higher metabolic activity on PEEK than that on sPEEK specimens for 1 and 3 days of incubation. However, there was a significant increase in cell metabolic activity on sPEEK/DMSO of about 20% compared to that recorded on PEEK for 7 days of incubation. SPEEK specimens showed a limited cytocompatibility probably due to the release of sulfonic compounds to the surrounding medium. The sulphonation method should be adjusted considering different processing time and surface treatment to achieve a high biocompatibility performance of sPEEK for biomedical applications.

Comparison of the impacts of acid and nitrogen additions on carbon fluxes in European conifer and broadleaf forests

Increased reactive nitrogen (N) loadings to terrestrial ecosystems are believed to have positive effects on ecosystem carbon (C) sequestration. Global “hot spots” of N deposition are often associated with currently or formerly high deposition of sulphur (S); C fluxes in these regions might therefore not be responding solely to N loading, and could be undergoing transient change as S inputs change. In a four-year, two-forest stand (mature Norway spruce and European beech) replicated field experiment involving acidity manipulation (sulphuric acid addition), N addition (NH4NO3) and combined treatments, we tested the extent to which altered soil solution acidity or/and soil N availability affected the concentration of soil dissolved organic carbon (DOC), soil respiration (Rs), microbial community characteristics (respiration, biomass, fungi and bacteria abundances) and enzyme activity. We demonstrated a large and consistent suppression of soil water DOC concentration driven by chemical changes associated with increased hydrogen ion concentrations under acid treatments, independent of forest type. Soil respiration was suppressed by sulphuric acid addition in the spruce forest, accompanied by reduced microbial biomass, increased fungal:bacterial ratios and increased C to N enzyme ratios. We did not observe equivalent effects of sulphuric acid treatments on Rs in the beech forest, where microbial activity appeared to be more tightly linked to N acquisition. The only changes in C cycling following N addition were increased C to N enzyme ratios, with no impact on C fluxes (either Rs or DOC). We conclude that C accumulation previously attributed solely to N deposition could be partly attributable to their simultaneous acidification.

Recovery of dimethylglyoxime (DMG) from Ni-DMG complexes

Dimethylglyoxime (DMG) is an analytical reagent used to precipitate Ni from its aqueous solution. The process is very efficient for Ni recovery in terms of selectivity and completeness but hardly adopted industrially. The reason is attributed to the loss of the reagent when calcined. The paper outlines extraction of DMG from Ni-DMG complex by sulphuric acid treatment in two methods i.e. leaching and dissolution-recrystallization. In leaching the Ni-DMG is just treated with sulphuric acid and DMG is recovered. In the second case the Ni-DMG complex is completely dissolved in sulphuric acid and recrystallized through refrigeration.

Effect of Different Pretreatment Conditions on Saccharum spontaneum for Cellulase Production by B. subtilis K-18 Through Box–Bhenken Design

In the present investigation, dilute sulphuric acid pretreatment conditions were optimized for Saccharum spontaneum through Box–Bhenken design of response surface methodology for cellulase production. Cellulase production was carried out in 250 ml capacity Erlenmeyer flask using pretreated S. spontaneum as substrate by Bacillus subtilis K-18 incubated at 50 °C for 24 h of fermentation period. Results revealed that sulphuric acid followed by steam favored cellulase production as compared to sulphuric acid treatment. Maximum FPase production (1.389 IU/ml/min) was achieved under pretreatment condition of 1% H2SO4 concentration, 10% substrate concentration with residence time of 4 h at room temperature followed by steam at 121 °C for 15 min and 15 psi. The proposed model was found significant as revealed by F value, P value and coefficient of determination. The cellulase produced could effectively hydrolyze pretreated substrate releasing total sugars of 12.71 mg/ml after 20 h of incubation at 50 °C. These results suggested that the enzyme could effectively be used in industrial process especially in biofuel production from lignocellulosic biomass.

Valorisation of fruit and vegetable waste from open markets for the production of 2,3-butanediol

The bacterial strain Enterobacter ludwigii FMCC 204 was selected as the most efficient 2,3-butanediol (BDO) producer among five strains when cultivated on glucose, fructose, mannose, arabinose, xylose, galactose and sucrose in shake flask cultures. Plums, apples and pears were used for the production of fermentation medium via sequential maceration, suspension in water and centrifugation to collect the supernatant. Sugar production from mixed vegetables was evaluated via sulphuric acid treatment leading to 65.8% (w/w) of hemicellulose hydrolysis yield at initial solid concentrations of 50g/L (on a dry basis) treated with 3% (v/v) H2SO4. Fed-batch cultures of E. ludwidgii on fruit derived feedstock resulted in BDO concentration, yield and productivity of 50g/L, 0.4g/g and 0.41g/L/h. BDO production from vegetable waste hydrolysates via fed-batch cultures led to BDO concentration of 17.6g/L. This study demonstrated that fruit and vegetable wastes from open markets can be used as fermentation feedstocks for BDO production.

Evaluation of tropical seaweeds as feedstock for bioethanol production

Limited resources of freshwater and decreasing fossil fuel resources are two main reasons to consider the ocean as a huge resource for producing food, feed, fertilizer and feedstock for fuel. In this study, twenty-nine tropical seaweeds (11 green, 10 red and 8 brown seaweeds) collected in Malaysia were assessed as potential feedstock for bioethanol production. Total carbohydrate content ranged from 12.16 to 71.22% dry weight (DW) with total reducing sugar content ranging from 5.17 to 34.12% DW. During hydrolysis using dilute sulphuric acid, the dominant fermentation inhibitors were 5-hydroxymethylfurfural and phenolic compounds. Overliming was found to reduce the content of fermentation inhibitors by up to 79%. The red seaweeds, Kappaphycus alvarezii (Doty) Doty ex P.C.Silva and Gracilaria manilaensis Yamamoto and Trono, were selected for optimization of saccharification and fermentation of the hydrolysate, because they had the highest carbohydrate contents and are commercially cultivated. The most suitable dilute acid conditions obtained in present study was sulphuric acid (2.5%, w v−1) treatment at 121 °C for 40 min that produced 0.29 and 0.34 g g−1 DW reducing sugar for K. alvarezii and G. manilaensis, respectively. Fermentation of the hydrolysates with Saccharomyces cerevisiae produced bioethanol yields of 20.90 g L−1 (71.0% of theoretical yield) for K. alvarezii and 18.16 g L−1 (67.9% theoretical yield) for G. manilaensis.

Characterization of selectively etched halloysite nanotubes by acid treatment

Halloysite nanotubes (HNTs) are a type of naturally occurring inorganic nanotubes that are characterized by a different composition between their external and internal walls. The internal walls are mainly composed of alumina whilst external walls are composed of silica. This particular structure offers a dual surface chemistry that allows different selective surface treatments which can be focused on increasing the lumen, increasing porosity, etc. In this work, HNTs were chemically treated with different acids (sulphuric, acetic and acrylic acid), for 72h at a constant temperature of 50°C. As per the obtained results, the treatment with sulphuric acid is highly aggressive and the particular shape of HNTs is almost lost, with a remarkable increase in porosity. The BET surface area increases from 52.9 (untreated HNTs) up to 132.4m2g−1 with sulphuric acid treatment, thus showing an interesting potential in the field of catalysis. On the other hand, the treatment with acetic acid led to milder effects with a noticeable increase in the lumen diameter that changed from 13.8nm (untreated HNTs) up to 18.4nm which the subsequent increase in the loading capacity by 77.8%. The aluminium content was measured by X-ray fluorescence (XRF) and laser induced breakdown spectroscopy (LIBS). The final results using two systems, suggest a good correlation between the acid strength and the aluminium reduction. Consequently, is possible to conclude that new applications for HNTs can be derived from selective etching with acids. Sulphuric acid widens the potential of HNTs in the field of catalysis while weak acids such as acetic and acrylic acids give a controlled and homogeneous lumen increase with the corresponding increase in the loading capacity.

Modification, Characterization, and Catalytic Application of Mesolite for One Pot Synthesis of 3-Methyl-4-arylmethylene-isoxazol-5(4H)-ones

Natural mesolite type zeolite was collected, modified by sulphuric acid treatment and characterized by using Powder-X ray diffraction, Scanning electron microscopy and Energy dispersive spectroscopy, Fourier transform infrared spectroscopy. Temperature programmed ammonia desorption, Brunauer-Emmer-Teller surface area analysis. Modified dealuminated mesolite shows an efficient catalytic activity for one pot synthesis of 3-methyl-4-arylmethylene-isoxazol-5(4H)-ones derivatives, via one pot three component condensation of benzaldehyde, ethylacetoacetate and hydroxylamine hydrochloride. Present method offers several advantages over the reported methods like a simple and inexpensive modification of catalyst, mild reaction condition, easy separation of catalyst, simple work-up procedure, nonchromatographic isolation and purification desired product and excellent yield. Furthermore, catalyst could be reused without significant loose in activity.

Enhanced dark fermentative biohydrogen production from marine macroalgae Padina tetrastromatica by different pretreatment processes

Marine macroalgae are promising substrates for biofuel production. Pretreating macroalgae with chemicals could remove microbial inhibitors and enhance the accessibility of the microorganisms involved in the process to the substrates leading to increased product yield. In the present study, Padina tetrastromatica a seaweed species was subjected to different chemical pretreatment in order to remove phenolic content and to enhance biohydrogen production. Different mineral acids (i.e., HCl, H2SO4, and HNO3) and bases (NaOH and KOH) were applied for effective pretreatment of the seaweed. Dilute sulphuric acid treatment of seaweed resulted in the highest cumulative biohydrogen production of 78 ± 2.9 mL/0.05 g VS and reduced phenolic content to 1.6 ±0.072 mg gallic acid equivalent (GAE)/g. Optimization of three variables for pretreatment (i.e., substrate concentration, acid concentration, and reaction time) was examined by Response Surface Methodology. After the optimization of the pretreatment conditions, phenolic content was decreased to 0.06 mg GAE/g. and enhanced biohydrogen production was observed. Structural changes due to pretreatment was studied by FTIR and XRD analyses. The results clearly indicated that the dilute sulphuric acid pretreatment was effective in removing phenolic content and enhancing biohydrogen production.

Enhanced Adsorption Capacity of Biomass through Ultrasonication for the Removal of Toxic Cadmium Ions from Aquatic System: Temperature Influence on Isotherms and Kinetics

AbstractIn this research, a novel activated biomass was prepared from Caryota urens based on sulphuric acid treatment (surface-modified Caryota urens seeds, SMCUS) followed by ultrasonication (ultr...

Upgrading of a Nigerian Ixiolite ore to Columbite by Sulphuric acid treatment

A quantitative leaching of a Nigerian Ixiolite ore in sulphuric acid medium was carried out and the effect of some parameters such as acid concentration, temperature and particle size was evaluated as a function of time. The experimental results obtained showed that the Ixiolite dissolution increases with increasing acid concentration, temperature, leaching time and, decreases with particle size. With 3 mol/L H2SO4 solution, 71.14% of the ore reacted within 120 minutes at 80°C.The kinetics of dissolution of the mineral was also examined and the observed effects of the operating variables on the leaching rate were consistent with the diffusion controlled kinetic model. The calculated activation energy for the leaching process was 24.40 kJ/mol with the reaction order of 0.5, supported the proposed model. Detailed characterization of the ore before and after leaching were carried out. At optimal leaching conditions, thermodynamic feasibility of the conversion of raw Ixiolite to Columbite of industrial value, as confirmed by X-ray diffraction (XRD) technique is possible.