Sulfuric Acid Treatment Research Articles

An aerobic detoxification photofermentation by Rhodospirillum rubrum for converting soy sauce residue into feed with moderate pretreatment.

This paper reports an effective process for converting soy sauce residue into feeds by combining moderate acid hydrolysis and ammonization with Rhodospirillum rubrum fermentation. After pretreatment with dilute sulfuric or phosphoric acid (1%, w/w) at 100°C, materials were subjected to fermentation under several gases (N2, CO2, and air) and different light intensities in a 2-L fermentor. Following sulfuric acid treatment, the true protein increased from 188 to 362gkg-1 and the crude fiber decreased from 226 to 66gkg-1 after fermentation at 0.5Lmin-1L-1 of air flow and a light intensity of 750lx and following phosphoric acid treatment, the true protein increased by 90% and the crude fiber decreased by 67% after fermentation at 0.6Lmin-1L-1 of air flow and a light intensity of 600lx Other contents, including crude fat, crude ash, phosphorus, sulfur, sulfur-containing amino acids, sodium chloride, and calcium, were also improved for use as feed. Meantime, some toxic substances, including furfural, hydroxymethylfurfural (5-HMF), acetic acid, phenol, and cresol, which were produced by the pretreatments, could be removed by 12-32, 5-8, 49-53, 7-8, and 7-8%, respectively; and total sugars, glucose, and xylose could be utilized by 68-69, 71-72, and 63-67% respectively. The quality of soy sauce residue is improved for use as feed and some toxic substances can be decreased via the R. rubrum fermentation.

Study of the combination of sulfuric acid treatment and thermal regeneration of spent powdered activated carbons from decolourization process in glucosamine production

In this study, the combination of sulfuric acid treatment and thermal regeneration of spent powdered activated carbon (SPAC) saturated with color impurities and pigments was analyzed. The purposes of this work was to investigate effect of regeneration temperature on spent powdered activated carbons pretreated by H2SO4 solution (SPAC-H2SO4), and characterize porosity structure and property of regenerated samples by TG, BET, and FTIR methods in order to infer regeneration mechanism. The results showed that sintering rate of SPAC-H2SO4 was higher than that of SPAC at any temperature, indicating that H2SO4 pretreatment made SPAC more conducive to pyrolysis. Regeneration temperature had a noticeable effect on the regenerated yield. The optimal regeneration effect was obtained at 600°C for SPAC-H2SO4. The iodine value, MB value, and SBET of SPAC-H2SO4-600 were 1294.69mg/g, 13.97mL/0.1g, and 1839.09m2/g, respectively, which accounted for 99%, 93%, and 87% of fresh PAC, respectively. The adsorption rate of SPAC-H2SO4-600 and virgin PAC for methylene blue (MB) solution both followed well pseudo-second-order kinetics. These results indicated that combination of sulfuric acid treatment and thermal regeneration was a promising method for SPAC regeneration.

The role of interface in improving fracture toughness of shaped steel fiber-reinforced composites

Mechanical properties of composite materials and their final performance are strongly influenced by the structure and properties of the fiber–matrix interface. A balance between sufficient load transfer and fiber pullout properties helps improve the performance of the composite materials. In this research, we employed sulfuric acid treatment to enhance fiber pullout and debonding through decreasing the fiber–matrix interlock. Atomic force microscope and scanning electron microscopy were employed to investigate the surface morphology of both treated and untreated steel fibers. Our results indicate that surface treatment improves the fiber roughness and therefore hinders brittle failures of the epoxy fiber-reinforced composite materials.

Domestication of Xylopia parviflora (A. Rich.) Benth: testing different pre-treatment protocols and substrates for inducing seeds germination

Xylopia parviflora, one of the most highly valued indigenous fruit tree species in sub-Saharan Africa, is still exploited in the wild because it has not been domesticated yet. As a contribution to its domestication process, investigations were undertaken on germination requirements and desiccation tolerance of its seeds. Three substrates, three accessions, 13 pre-germination treatments and different levels of seed dehydration were tested for their effect on seed germination. Results showed that mean germination percentages were significantly higher both on river sand (37.95 ± 1.8%) and on mixture of forest top soil + river sand (40 ± 1.8%) than on forest top soil alone (31.03 ± 1.8%). Bangoua had the highest germination percentage (41.3 ± 1.8%), followed by Bayangam 2 (38.2 ± 1.8%) and Bayangam 1 (27.18 ± 1.8%). Untreated control seeds exhibited coat-imposed dormancy which was expressed by overall 5.5 ± 3.7% germination. The most effective treatment to overcome dormancy was hydrochloric acid treatment for 10 min, followed by sulfuric acid treatment for 5 min and mechanical scarification with respective germination percentages of 80.0 ± 3.7, 63.3 ± 3.7, and 56.6 ± 3.7%. The desiccation tolerance test showed that X. parviflora seeds are desiccation-tolerant and that their storage behaviour is orthodox.

Formation and characterization of BC and BC-paper pulp films for packaging application

It was found beneficial to manufacture bacterial cellulose (BC) obtained from waste food sources to create value-added packaging products by firstly performing purification and disintegration processing of the BC and then reinforcing it with paper pulp. The purification treatment involved using sodium hydroxide (2% w/v at 100°C for 1 h) on BC pulp to remove the bacterial protein and the resulting cultured medium film was characterized with respect to its physical properties. An acid treatment on the purified BC pulp was applied to disintegrate cellulose network before forming a film. The results showed that the sodium hydroxide treatment increased the film burst index and brightness. Heating the BC pulp to 70–100°C in 1.25–5.00% v/v sulfuric acid treatment for 30 min degraded the film’s mechanical properties. Also, a study of the addition and mixing of paper pulps or modified cationic starch to the BC was found to improve the film properties with respect to packaging properties. Inclusion of short fiber paper pulp by 30 wt.% created a good synergistic effect by improving the mechanical properties of film especially for tear strength. Moreover, cationic-modified cassava starch (2% w/w) improved the tensile and burst index as well as resistance to oxygen permeation of the BC film. The results indicate that the BC pulp could be used to improve mechanical properties and resistance to water vapor and oxygen permeation of the short fiber paper pulp film which is ideal for packaging materials.

Toxicity assessment of ash and dust from handmade gold jewelry manufacturing workshops in Bangladesh.

Traditionally, handmade gold jewelry played a very important role in the cultural heritage of Bangladesh. Goldsmiths still are partially using ancient manufacturing process with coal fire, candle flame blowing, and nitric and sulfuric acid treatments. Such process leads to the contamination of workplace with the dust of toxic metals, acidic vapors, and particles of different natures. To evaluate contamination by particulate matter (PM), the passive particle collectors were installed in different manufacturing units for a period of 85days at Tanti Bazar, Dhaka, Bangladesh. The laser diffraction analysis of the samples collected at the soldering units showed significant amounts of particulates, both PM10 and PM 2.5, and also nanoparticles in both nucleation and accumulation mode. SEM/EDS analysis revealed partially melted micro blebs that contain a very high concentration of Fe along with Cu. The toxic elements were detected with ICP analysis and include higher concentrations of cadmium (Cd), chromium (Cr), lead (Pb), and arsenic (As). It is notable that detection of arsenic contamination was unexpected since raw materials used for jewelry making should not have any arsenic.

A bottom-up, template-free route to mesoporous N-doped carbons for efficient oxygen electroreduction

Herein, we report a facile, bottom-up route to the preparation of N-doped carbons with a high surface area as well as plenty of hierarchical pores by thermal annealing the black bread-like sulfuric acid-dehydrated sucrose. This simple sulfuric acid treatment created a remarkable surface area of 645.7 m2/g in the dehydrated sucrose, and the subsequent thermal annealing with activated reagent ZnCl2 and nitrogen source NH4Cl helped further generated more porous textures in the carbon matrix, which contributes to a high surface area of 2450 m2/g, a large number of hierarchical pores ranging from 2 to 150 nm in a highly porous N-doped carbon to sufficiently expose active sites and boost mass transfer. The best sample N/PC-800, which was thermally annealed at 800 °C, is able to selectively catalyze the 4e− ORR process and shows higher working stability, stronger tolerance to methanol crossover effect, a very comparable onset potential and diffusion-limited current density in alkaline electrolyte, compared to the benchmark Pt/C catalyst. The results in this study signify the validity of present facile, robust template-free method in the synthesis of highly porous N-doped carbons for electrochemical energy conversion and storage.

Dormancy overcoming, temperatures and substrates on germination of Mimosa tenuiflora Willd seeds

Mimosa tenuiflora Willd., popularly known as jurema-preta, is an arboreal species of great importance for the brazilian Northeast due to its uses as a medicinal plant and in the restoration of degraded soils. No information is available in the Rules for Seed Analysis and the Instructions for Seed Analysis of Forest Species regarding ideal conditions for of this species. Thus, this study aimed at evaluating the influence of pre-germination treatments, in addition to verifying the germination performance at different temperatures and in different substrates. In both experiments, four replicates of 25 seeds were used for each treatment. In experiment I, seeds were submitted to the following methods for overcoming dormancy: witness - Intact seeds (T1) immersion in water at 100 °C for 1 (T2), 2 (T3), 3 (T4), 4 (T5), 5 (T6) and 6 min (T7), immersion in concentrated sulfuric acid for 1 (T8), 4 (T9), 7 (T10), 10 (T11) and 13 min (T12), scarification on sandpaper n° 80 (T13) and lopping in the region opposite the micropyle (T14). In experiment II, seed germination was evaluated in four types of substrates: between sand, paper on, paper roll and between vermiculite and at six different temperatures: 20, 25, 30, 35, 40 °C and alternating between 20 and 30 °C. Immersion in hot water for 1, 2, 3, 4, 5 and 6 min, sulfuric acid treatment for 10 and 13 min, sand paper and lopping were the most appropriate treatments to overcome seed dormancy. The seed germination of M. Tenuiflora should be carried out at 25 °C on paper roll substrate.

Isolation of cellulose nanocrystals from medium density fiberboards

Cellulose fibers have been successfully isolated from medium density fiberboards (MDFs) by sodium chlorite oxidation-potassium hydroxide (NaClO2-KOH) leaching process, at 37.6% yield, comparable to the 39.3% and 37.3% cellulose fibers from eucalyptus and eucalyptus with 12% cured urea-formaldehyde (UF) resin, respectively. At the same sulfuric acid hydrolysis conditions (65% H2SO4, 60°C and 30min), MDF cellulose nanocrystals (CNCs) were produced at 27.5% yield, similar to 27.4% of CNC yield from eucalyptus with UF resin, but less than 31.2% yield from eucalyptus. MDF CNCs were slightly thicker in lateral dimension (16.8±8.6nm), less crystalline (59% CrI), and surface esterificated (0.045mmol/g sulfate/CNC) than eucalyptus CNCs (11.6±3.9nm, 75% CrI, 0.060mmol/g) and CNCs from eucalyptus with UF resin (14.9±9.1nm, 65% CrI, 0.046mmol/g). All CNCs were free of UF resin and thermal stable. The residual resin in cellulose pulps hydrolyzed completely during the sulfuric acid treatment and contributed to the unique properties of CNCs. Therefore, CNCs derived from MDF are comparable to CNC from wood and promising for expanded applications.

Elimination of N,O-bis(trimethylsilyl)trifluoroacetamide interference by base treatment in derivatization gas chromatography mass spectrometry determination of parts per billion of alcohols in a food additive

A novel base treatment followed by liquid-liquid extraction was developed to remove the interference of excess derivatization reagent BSTFA [N,O-Bis(trimethylsilyl)trifluoroacetamide] and its byproducts for trace determination of 1-chloro-2-propanol and 2-chloro-1-propanol in a food additive. The corresponding trimethylsilyl derivatives were analyzed by gas chromatography mass spectrometry (GC/MS) detection in selective ion monitoring mode. Due to a large volume splitless injection needed for achieving the required sensitivity, excess BSTFA in the derivatization sample solution interfered with the trimethylsilyl derivatives of the analytes of interest, making their quantitation not attainable. Efforts were made to decompose BSTFA while keeping the trimethylsilyl derivatives intact. Water or aqueous sulfuric acid treatment converted BSTFA into mainly N-trimethylsilyltrifluoroacetamide, which partitions between aqueous and organic layers. In contrast, aqueous sodium hydroxide decomposed BSTFA into trifluoroacetic acid, which went entirely into the aqueous layer. No BSTFA or its byproduct N-trimethylsilyltrifluoroacetamide or trifluroacetamide was found in the organic layer where the derivatized alcohols existed, which in turn completely eliminated their interference, enabling accurate and precise determination of parts per billion of the short-chain alcohols in the food additive. Contrary to the conventional wisdom that a trimethylsilyl derivative is susceptible to hydrolysis, the derivatized short-chain alcohols were found stable even in the presence of 0.17N aqueous sodium hydroxide as the improved GC/MS method was validated successfully, with a satisfactory linearity response in the concentration range of 10–400ng/g (regression coefficient greater than 0.999), good method precision (<4%), good recovery (90–98%), and excellent limit of detection (3ng/g) and limit of quantitation (10ng/g).

Sulfuric acid treatment of ground tire rubber and its effect on the mechanical and thermal properties of polypropylene composites

ABSTRACTGround tire rubber (GTR) was modified by sulfuric acid in order to improve its compatibility with and reinforcement of a polypropylene (PP) matrix. Polymer composites PP/GTR were prepared by melt mixing at different concentrations, with a maximum of 50 wt % of GTR. Studies by Fourier transform infrared spectroscopy (FTIR), surface specific area by BET (Brunauer, Emmett, and Teller), and scanning electron microscopy were used to characterize the untreated GTR and treated GTR, while the mechanical and thermal properties of the PP/GTR composites were assessed to understand how the surface treatment of GTR affected the mechanical and thermal properties of the composite PP/GTR. FTIR revealed the presence of sulfonic groups on the surface of sulfuric acid–treated GTR, and BET analyses showed an increase of about 625% in the specific surface area as a result of the high porosity produced by the treatment. In all composites containing treated GTR, a higher Young's modulus was obtained than for composites containing untreated GTR. Particularly, an increase of about 275% in the Young's modulus was obtained in composites with treated GTR (40 wt %) against that containing untreated GTR. However, a more significant reduction of the elongation at break was observed in composites containing treated GTR than in those containing untreated GTR. Also, an increase of the crystallization temperature of PP as a function of GTR was observed by differential scanning calorimetry, but the crystallinity of the composites was reduced by the addition of both untreated and treated GTR. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44858.

Technoeconomic Study of Biobutanol AB Production. 1. Biomass Pretreatment and Hydrolysis

This paper presents a comprehensive study of different chemical pretreatments and enzymatic hydrolysis processes for the production of sugars from lignocellulosic biomass: switchgrass (Panicum virgatum L.) and corn stover. Experimental results were used to scale up the production process for biobutanol. With regards to pretreatments, acid, alkali, surfactants, and organic solvents were tested to break down biomass structure. Acid pretreatment turned out to be the most efficient in terms of total released sugar. Besides, the optimal operating conditions for the enzymatic hydrolysis were determined experimentally. Comparing the degradation of biomass types, switchgrass showed high degradation when sulfuric acid treatment is used. However, corn stover showed the highest sugar production at complete degradation. Therefore, it will be the preferred raw material and determines the operating conditions of choice for process scale up.

Mesolite: An Efficient Heterogeneous Catalyst for One-Pot Synthesis of 2-Amino-4H-chromenes

An efficient and environmentally benign method for one-pot three-component synthesis of 2-Amino-4H-chromenes has been developed by cyclocondensation of benzaldehyde, malononitrile and resorcinol using newly modified mesolite-type natural zeolite as green catalyst. The catalyst was structurally modified by sulfuric acid treatment and characterized by X-ray diffraction, FT-IR, NH3-TPD, SEM-EDS and BET. This method offers several advantages over the reported methods such as simple and inexpensive modification of catalyst, mild reaction conditions, excellent yield and reusability of catalyst.

Exploring the role of the catalytic support sorption capacity on the hydrodechlorination kinetics by the use of carbide-derived carbons

This work aims at evaluating the effect of the catalytic support sorption capacity on the hydrodechlorination (HDC) process. Carbide-derived carbons (CDCs) have been selected for such goal as their high purity and tunable pore structure makes them a suitable carbon model material. CDCs were synthesized from TiC by chlorination at different extraction temperatures (800–1300°C) in order to selectively modify their pore structure and crystallinity. Afterwards, the catalysts were produced using a three step process of sulfuric acid treatment, ion-adsorption of palladium precursor and gas phase reduction. Pd/TiC-CDC (1% wt.) catalysts were tested in the HDC of 4-chlorophenol (4-CP) in both aqueous and organic phases under ambient conditions (30°C, 1atm, [4-CP]0=2.9mmolL−1, [Pd-TiC-CDC]=1gL−1, 50NmL H2min−1). The experimental results were successfully fitted by an expanded kinetic model which accounts for consecutive reaction and sorption processes in parallel, allowing to deduce true HDC kinetic constants.The sorption capacity of the support was found to determine the HDC rates in aqueous phase. In this sense, those catalysts showing the highest surface areas and lowered ordered structures led to higher HDC rates, confirming that a high surface density of 4-CP onto the catalyst surface enhances significantly the HDC reaction. The optimum catalyst (Pd/TiC-CDC-1000) led to the complete conversion of 4-CP in 15min at a HDC rate of 4.1×10−2Ls−1gcat−1.

Efficient recycling of WC-Co hardmetal sludge by oxidation followed by alkali and sulfuric acid treatments

We present a process to recycle strategic metals, viz. tungsten and cobalt, from a WC-Co hardmetal sludge (WCHS) via oxidation followed by a two-step hydrometallurgical treatment with alkali and acid solutions. The oxidation of WCHS was investigated in the temperature range of 500 to 1000 °C and optimized at 600 °C to transform the maximum WC into an alkali-soluble WO3. The conditions for the selective dissolution of WO3 in stage-I were optimized as follows: 4.0 M NaOH, pulp density of 175 g/L, and temperature of 100 °C for 1 h, yielding maximum efficacy. Subsequently, in the second step, the optimal conditions for cobalt leaching from the alkali-treated residue were established as follows: 2.0 M H2SO4, 25 g/L pulp density, and 75 °C temperature for 30 min. Downstream processing of the obtained metal ions in solutions was also easier, as the only impurity of dicobaltite ions with the Na2WO4 solution was precipitated as Co(OH)3 under atmospheric O2; meanwhile, the CoSO4 solution obtained through the second step of processing can be treated via electrolysis to recover the metallic cobalt. The present process is simpler in operation, and the efficient use of eco-friendly lixiviants eliminates the previously reported disadvantage.

Impact of Sulfuric Acid Treatment of Halloysite on Physico-Chemic Property Modification.

Halloysite (HNT) is treated with sulfuric acid and the physico-chemical properties of its morphology, surface activity, physical and chemical properties have been investigated when HNT is exposed to sulfuric acid with treatment periods of 1 h (H1), 3 h (H3), 8 h (H8), and 21 h (H21). The significance of this and similar work lies in the importance of using HNT as a functional material in nanocomposites. The chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR). The spectrum demonstrates that the hydroxyl groups were active for grafting modification using sulfuric acid, promoting a promising potential use for halloysite in ceramic applications as filler for novel clay-polymer nanocomposites. From the X-ray diffraction (XRD) spectrum, it can be seen that the sulfuric acid breaks down the HNT crystal structure and alters it into amorphous silica. In addition, the FESEM images reveal that the sulfuric acid treatment dissolves the AlO6 octahedral layers and induces the disintegration of SiO4 tetrahedral layers, resulting in porous nanorods. The Bruncher-Emmett-Teller (BET) surface area and total pore volume of HNTs showed an increase. The reaction of the acid with both the outer and inner surfaces of the nanotubes causes the AlO6 octahedral layers to dissolve, which leads to the breakdown and collapse of the tetrahedral layers of SiO4. The multi-fold results presented in this paper serve as a guide for further HNT functional treatment for producing new and advanced nanocomposites.

Enhanced conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film by acid treatment for indium tin oxide-free organic solar cells

An acid treatment is used in the enhancement of the conductivity of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) thin film, which is often used as the anode in organic solar cells. There are three types of acid treatment for PEDOT:PSS thin film: hydrochloric, sulfuric, and phosphoric acid treatments. In this study, we examine and compare these three ways with each other for differences in conductivity. Hydrochloric acid results in the highest conductivity enhancement, from 0.3 to 1109 S/cm. We also discuss the optical transmittance, conductivity, surface roughness, surface morphology, and stability, as well as the factors that can influence device efficiency. The devices are fabricated using an acid-treated PEDOT:PSS thin film as the anode. The highest power conversion efficiency was 1.32%, which is a large improvement over that of the unmodified organic solar cell (0.21%). It is comparable to that obtained when using indium tin oxide (ITO) as an electrode, ca. 1.46%.

Eficiência de tratamentos químicos e térmico na quebra de dormência de três espécies de Brachiaria

This study was conducted in 2011 at the Universidade Estadual de Mato Grosso do Sul, Unidade Universitaria de Aquidauana, and aimed to evaluate the effect of chemical and thermal treatments to overcome dormancy in seeds of different Brachiaria species. The experimental design was completely randomized 3 x 4 factorial with five replications and composed by the combination of three Brachiaria species - B. decumbens, B. humidicola and B. ruziziensis - and four seed pre-treatments - control, thermal, H2SO4 and KNO3. The total germination in three periods (7, 14 and 21 days) was evaluated, according to seed pre-treatment, and the comparison between germination and tetrazolium test, performed in the control, was done. The values found by the tetrazolium test did not correspond at all with those obtained by germination test, revealing inefficiency of the seed pre-treatments used. B. decumbens showed higher total percentage of germination, but B. ruziziensis showed better seed viability. The sulfuric acid treatment was more efficient than the other, which did not differ for the total germination of seeds of tropical forages.

Production of fermentable sugars from corn fiber using soaking in aqueous ammonia (SAA) pretreatment and fermentation to succinic acid using Escherichia coli AFP184

Conversion of corn fiber (CF), a by-product from the corn-to-ethanol conversion process, into fermentable sugar and succinic acid was investigated using soaking in aqueous ammonia (SAA) pretreatment followed by biological conversions, including enzymatic hydrolysis and fermentation using genetically engineered E. coli (AFP184). The SAA pretreatment (using a 15% w/w NH4OH solution at a solid-to-liquid ratio of 1: 10 at 60 °C for 24 h) removed 20-38% of lignin and significantly improved the digestibility of the treated solid (85-99% of glucan digestibility). Following the enzymatic hydrolysis, the sugar-rich hydrolysate was subjected to dilute sulfuric acid treatment (1 wt% sulfuric acid and 120 °C for 1 h), which hydrolyzed the oligosaccharides in the hydrolysate into fermentable monomeric sugars. The mixed sugar hydrolysates containing hexose and pentose obtained from the two-step hydrolysis and SAA pretreatment were fermented to succinic acid using a genetically engineered microorganism, Escherichia coli AFP184, for evaluating the fermentability. Engineered E. coli AFP184 effectively converted soluble sugars in the hydrolysate to succinic acid (20.7 g/L), and the production rate and yield were further enhanced with additional nutrients; the highest concentration of succinic acid was 26.3 g/L for 48 h of fermentation.

Fluorine distribution during thermal treatment of sulfuric acid leaching products of complex beryllium raw materials at JSC UMP

X-ray diffraction, infrared spectroscopy, thermogravimetry and mass spectrometry were employed to study the behavior and distribution of fluorine in sulfuric acid treatment of the melt of beryl-bertrandite-phenakite-fluorite concentrates with alkali fluxes. It was established that fluorine in a solid phase is predominantly present in the form of sodium and calcium fluorosilicates and in a gaseous phase it is evolved in the form of silicon tetrafluoride and fluorosulfonic acid.