Acid Concentration Ratio Research Articles

Optimization of Synthesis Conditions of Indigotindisulfonate Lithium Based on Orthogonal Experimental Design Method

With the developing research on anode materials for lithium ion batteries, organic anode materials have gained increasing attention nowadays. Compared with inorganic anode materials, organic anode materials have numerous material options and extensive sources. Moreover, they consume low energy and can enter carbon cycles, which are environment friendly. indigotindisulfonate lithium is characterized with a unique redox reaction and can be used as an anode material. Indigotindisulfonate Lithium can be produced by using indigo as a raw material sulfonated with fuming sulfuric acid, and further reacted with Li2CO3. Regarding this issue, impacts of various factors under different conditions were investigated, and an orthogonal experimental design method was proposed based on optimization conditions. This method was established through T-6 new century ultraviolet spectrophotometer to determine the influence of different conditions, and develop a best combination based on different microwave powers (w), temperatures (°C), and time lengths (min). In this experiment, the maximum absorption peak was determined by scanning wave length, under which the absorbency was identified and the standard curve was established. In order to determine the optimized synthesis condition of indigotindisulfonate lithium, orthogonal experiment design method was applied combining three levels coupled with four factors. From this study, it is concluded that 550w, 3min, 30°C with an indigo-fuming sulfuric acid concentration ratio of 0.02:1 is the best condition to synthesize indigotindisulfonate lithium.

Biodegradable PLGA nanoparticles restore lysosomal acidity and protect neural PC-12 cells against mitochondrial toxicity.

Exposure of mitochondrial parkinsonian neurotoxin 1-methyl-4-phenylpyridinium ion (MPP+) to PC-12 cells results in significant cell death, decreases lysosomal acidity, and inhibits autophagic flux. Biodegradable poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) of ≈100 nm diameter localize to the lysosome, degrade, and subsequently release their acidic components to acidify the local lysosomal environment. The performance of PLGA NPs with different lysosomal pH modulating capabilities is investigated in PC-12 cells under MPP+ induced mitochondrial toxicity. PLGA NPs perform in a compositional dependent manner, where NPs with a higher glycolic acid to lactic acid ratio content degrade faster, and yield greater degrees of lysosomal pH modulation as well as autophagic flux modulation in PC-12 cells under MPP+ insult. These results show that slight compositional changes of the polymeric NP give rise to differing degrees of lysosomal acidification in PC-12 cells and afford improved cellular degradative activity.

Photoelectrocatalytic oxidation of phenol by UV-assisted electrogenerated Ce(IV) in aqueous solution

Abstract A UV (UV-C, 254 nm)-assisted Ce(IV) mediated electrochemical oxidation (MEO) system is developed to treat phenol-containing water. For comparison, an individual Ce(IV)-MEO system without UV and a UV photocatalytic oxidation system without applying an electrical current are also evaluated. The operation conditions of electrical current, nitric acid concentration, stirring speed, and electrode area ratio of anode to cathode for Ce(IV) electrogeneration are optimized in terms of percent yield of Ce(IV) and energy consumption. According to the kinetic model of the Ce(IV)/Ce(III) redox reaction, the forward rate constant of Ce(III) oxidation is twice as high as that of the reverse reaction. For the wastewater treatment, Ce(IV)-MEO and photocatalytic oxidation systems both show good capability for degrading phenol in an acidic environment rather than the direct electrochemical oxidation (DEO) system. Importantly, the UV-assisted MEO system exhibits excellent removal efficiency (RE) of phenol (up to 98%) in only 40 min because of the synergistic effect of the electrocatalytic and photocatalytic systems, which individually exhibit REs of

Three-dimensional CFD modeling of a direct formic acid fuel cell

A three-dimensional (3D) with one straight channel computational fluid dynamics (CFD) model is developed by using the ESI-CFD software to investigate the effect of varying operating parameters on the performance of direct formic acid fuel cell (DFAFC) and formic acid crossover from the anode to the cathode side through the membrane. Formic acid concentration (4 M–10 M), temperature (313 K–353 K), anode stoichiometry (1.5–3.0), and cathode stoichiometry (2.0–3.0) are the selected operating parameters in this study. Validation results of the DFAFC are in reasonable agreement with the typical trends reported in the literature on DFAFC performance. Simulation results indicate that formic acid concentration, temperature, anode, and cathode stoichiometry influenced the DFAFC performance and the formic acid crossover. The increments of formic acid concentration or stoichiometric ratio will improve the cell performance; however, the current densities obtained are declining to the increasing temperature. The increase in temperature of the formic acid concentration is found to lead to the decrease in performance. For the formic acid crossover phenomenon, the formic acid crossover flux increases with the increments of formic acid concentration, DFAFC operating temperature, and anode and cathode stoichiometric ratios.

Recovering valuable metals from LiNixCoyMn1-x-yO2 cathode materials of spent lithium ion batteries via a combination of reduction roasting and stepwise leaching

This work focuses on the recovery of valuable metal from the cathode materials of spent lithium ion batteries to ensure resource recycling and environmental protection. An environmentally friendly process involving reduction roasting and stepwise leaching is proposed to recover Li and Ni, Co, and Mn from spent LiNixCoyMn1-x-yO2 materials. Suitable leaching conditions are obtained from thermodynamic analysis (Eh-pH diagram). The effects of several factors, such as acid concentration, temperature, leaching time and liquid‒solid ratio, on the leaching efficiency of valuable metals are investigated. Under optimum conditions, the leaching efficiency of Li, Ni, Co, and Mn are as high as 93.68%, 99.56%, 99.87%, and 99.9%, respectively. The kinetic aspect of the acid leaching process is analyzed by shrinking the core model, which suggests a residue layer diffusion process. The reaction activation energies of Ni, Co, and Mn are 29.35 kJ mol−1, 24.00 kJ mol−1, and 23.29 kJ mol−1, respectively. This metallurgic method contributes to environmentally friendly and economical recovery of valuable metals from spent lithium-ion batteries.

Effect of solvents and reaction parameters on the morphology of Ta2O5 and photocatalytic activity

We report a facile and efficient hydrothermal method for the controlled preparation of tantalum oxide (Ta2O5) flower-like hierarchical structures. The formation of flower-like hierarchical structure is systematically studied by tuning the reaction parameters such as precursor amount, reaction time, reaction temperature, hydrofluoric acid (HF) volume, hydrochloric acid (HCl) concentration and propanol-HCl volume ratio. The results reveal that simply altering the reaction conditions can easily modulate the morphology of the resultant Ta2O5 product. The growth mechanism for the formation of flower-like hierarchical structures has been proposed, where HF and propanol play a key role. A comparative study for photocatalytic hydrogen production was conducted by calcinating the product at 450 °C and 700 °C. The product calcinated at 450 °C revealed a higher photocatalytic activity than that calcined at 700 °C. The successful and convenient preparation of flower-like hierarchical structures can be easily scaled up and extended for the designing and fabrication of 3D hierarchical structures and visible-light driven heterostructures nanomaterial for energy production, environmental remediation and optical devices.

Effect of applying lactic acid bacteria and cellulase on the fermentation quality, nutritive value, tannins profile and in vitro digestibility of Neolamarckia cadamba leaves silage.

This study was designed to evaluate the effect of applying lactic acid bacteria (LAB, Lactobacillus plantarum LP) (0 and 1×106 cfu/g fresh matter (FM)) and cellulase (0, 30, 60 and 120U/gFM) on the ensiling characteristics of N.cadamba leaves. The experimental design was a completely randomized 2×4 factorial arrangement. Fermentation parameters, microbial populations, chemical compositions and in vitro digestibility of the silages were measured after 60-day fermentation. LAB inoculation decreased the pH (p<0.05), ammonium nitrogen (NH3 -N) proportion (p=0.08), the concentrations of crude protein (CP, p<0.05) and condensed tannins (CT, p=0.07), and the microbial counts (p<0.01) of LAB and yeasts along with increased (p<0.01) concentrations of neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and hemicellulose. Cellulase addition increased (p<0.01) the microbial populations and protein fractions and decreased (p<0.01) the concentrations of acetic acid, cell wall components, total phenols (TP), soluble tannins (ST) and CT with increasing enzyme inclusions. The interaction of LAB and cellulase showed an effect (p<0.01) on the NH3 -N proportion, microbial counts, fibre fractions and CP. No effect (p>0.05) was found on the dry matter recovery and digestibility of the silages with LAB or cellulase application. Besides, high lactic acid concentration and true protein ratio, low pH and NH3 -N proportion, and a few spoilage organism counts were found in all silages, indicating a successful preservation. These results infer that, with some improvement, the ensiling characteristics and chemical compositions of N.cadamba leaves silage show specific responses to the addition of LAB inoculant or cellulase.

Ultrasonic study of silver nanoparticles for various applications

ABSTRACTAcoustic properties of aqueous solution of AgNO3 at various concentrations, in presence of Tannic Acid at a fixed concentration (1 × 10−4 M/L) are studied by ultrasonic method. Tannic acid, a compound derived from plant extracts, is used as the reducing and stabilizing agent to synthesize Ag-NPs and also enables variation of the mean size of Ag-NPs by taking a suitable concentration ratio of AgNO3 and Tannic acid in distilled water. Ag-NPs are synthesized at room temperature and further stabilized with the aid of sonication. The temperature dependence of acoustic properties is studied and discussed in this paper. Acoustic properties were measured using multi-frequency nano fluid interferometer. It is found that there is a systematic increase in ultrasonic velocity upto 60 oC for almost all the concentrations studied and thereafter its value decreases, while this velocity decreases with increasing concentration of AgNO3 in solution at higher concentrations only. This study is important to find optimum concentration required for a particular application. The present result will be useful as data for various applications.

Body mass index and contralateral ratio predict outcome following unilateral adrenalectomy in primary aldosteronism.

The effect of unilateral adrenalectomy on blood pressure (BP) outcome in primary aldosteronism (PA) is diverse. Therefore, we sought to investigate the preoperative factors contributing to postoperative BP outcome. Data for 96 PA patients who underwent unilateral adrenalectomy at our institution from January 2000 to February 2015 were retrospectively collected. Based on postoperative BP after a 12-month follow-up period, the patients were categorized into two groups: cured (C) (<140/90 mm Hg with no antihypertensive drug) and not cured (NC) (if not normotensive). Patient demographics, blood and urine data, data of loading tests and adrenal vein sampling were evaluated. In all, 46 patients were categorized as C and 50 patients as NC. There were significantly more males in the NC group. Age, body mass index (BMI), number of antihypertensive drugs prescribed, serum uric acid concentration and contralateral ratio (CR) after adrenocorticotropic hormone stimulation were significantly higher in the NC group. In the multivariate model, BMI and CR significantly correlated with resolution outcome. The optimal cutoff values were 23.3 kg m-2 for BMI and 0.5 for CR, and when both parameters were used as predictors, the most optimal cutoff values for BMI and CR were 25.2 kg m-2 and 0.1, respectively. BMI and CR significantly correlated with BP outcome after adrenalectomy. To our knowledge, this is the first report to show that in addition to BMI, CR is a factor in postoperative BP outcome and to determine the optimal cutoff values of BMI and CR and calculate their sensitivities and specificities.

Secondary formation of oxalic acid and related organic species from biogenic sources in a larch forest at the northern slope of Mt. Fuji

To better understand the formation of water-soluble organic aerosols in the forest atmosphere, we measured low molecular weight (LMW) dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, unsaturated fatty acids (UFAs), and water-soluble organic carbon (WSOC) in aerosols from a Larix kaempferi forest located at the northern slope of Mt. Fuji, Japan, in summer 2012. Concentrations of dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and WSOC showed maxima in daytime. Relative abundance of oxalic acid in LMW dicarboxylic acids was on average 52% and its average concentration was 214 ng m−3. We found that diurnal and temporal variations of oxalic acid are different from those of isoprene and α-pinene, whereas biogenic secondary organic aerosols (BSOAs) derived from isoprene and α-pinene showed similar variations with oxalic acid. The mass concentration ratios of oxalic acid/BSOAs were relatively constant, although a large variation in the concentrations of toluene that is an anthropogenic volatile organic compound was observed. These results suggest that formation of oxalic acid is associated with the oxidation of isoprene and α-pinene with O3 and other oxidants in the forest atmosphere. In addition, concentrations of UFAs were observed, for the first time, to decrease dramatically during daytime in the forest. Mass concentration ratios of azelaic acid to UFAs showed a positive correlation with O3, suggesting that UFAs are oxidized to yield azelaic acid, which may be further decomposed to oxalic acid in the forest atmosphere. We found that contributions of oxalic acid to WSOC are significantly high ranging from 3.7 to 9.7% (average 6.0%). This study demonstrates that forest ecosystem is an important source of oxalic acid and other dicarboxylic acids in the atmosphere.

Kinetic Study of the Leaching of Low-Grade Manganese Ores by Using Pretreated Sawdust as Reductant

The reductive leaching of manganese from a low-grade manganese oxide ore was investigated by using pretreated sawdust as the reductant in a sulfuric acid medium. The effects of stirring speed, liquid/solid ratio, sawdust/ore mass ratio, sulfuric acid concentration, reaction temperature, and time on the manganese extraction were examined. It was found that the leaching efficiency is strongly dependent on temperature and acid concentration. The leaching efficiency of manganese reached 94.1% under the optimal conditions: stirring speed of 300 rpm, liquid/solid ratio of 8:1, mass ratio of sawdust to ore 0.25, sulfuric acid concentration of 1 mol/L and a temperature of 363 K for 180 min. The kinetic analysis was carried out based on the shrinking core model, which indicated that the reductive leaching process was controlled by the chemical reaction. The reaction orders with respect to the sulfuric acid concentration and mass ratio of sawdust are 1.66 and 0.57, respectively. The apparent activation energy for the leaching process has been calculated using the Arrhenius expression and was found to be 51.7 kJ/mol.

Analysis of organic and conventional milk from Queensland, Australia using markers suggested for European milk samples

In order to prevent fraud, there need to be analytical methods which enable the authentication of organic milk. This is important in order to protect both consumers and organic producers. In addition to mandatory farm inspections of organic producers, several markers have been established for organic milk from Europe. These markers feature stable carbon isotope ratios (δ13C values), the concentration and diastereomer ratio of phytanic acid as well as the amount of phytol. In this initial study, these markers were determined in organic (n = 4) and conventional milk (n = 6) from Queensland (northeastern Australia). Despite the low number of milk samples available, results from the markers indicated pronounced statistical differences between samples from Europe and Queensland.

Anaerobic treatment of wastewater using a two-stage packed-bed reactor containing polyvinyl alcohol gel beads as biofilm carrier

Anaerobic treatment of wastewater is a viable alternative to aerobic treatment with the advantage of low net energy requirement and less sludge production. Successful establishment of a two-stage anaerobic treatment process resulted in better performance and improved tolerance to perturbations in operating conditions such as high organic loading rate and higher methane production. In this study we have reported process development, microbial enrichment and validation of performance of a two-stage anaerobic packed-bed reactor comprising of an acidogenic reactor followed by a methanogenic reactor, each containing porous polyvinyl alcohol (PVA)-gel beads as biofilm carrier, harboring different consortia of microorganisms for treating wastewater at mesophilic temperature. The stage-separated reactor system demonstrated chemical oxygen demand (COD) removal efficiency up to 89% with overall methane productivity of 0.08L methane/(L reactor.d). During steady-state operation, the acidogenic reactor produced an effluent with concentration ratio of propionic acid to acetic acid as low as 0.2, which indicated the stability of the reactor system against environmental shock-related failure. During an event of deliberately imposed low-temperature shock period of 60days, the COD removal efficiency decreased from 89% at steady-state to as low as 33% with concomitant decline in methanogenic productivity. The predominance in microbial community changed from steady-state characteristics of Gram positive to Gram negative during the temperature shock. After the shock was withdrawn, the reactor system regained its original performance within 28days; the Gram positive bacteria also switched back to the predominance.

Kinetic Studies on Pisum sativum Waste (Pea pod) Hydrolysis to Furfural

To obtain a higher furfural yield from Pisum sativum (pea pod) waste, the effects of the process variables phosphoric acid concentration (wt.%), reaction temperature, and liquid solid ratio (LSR) were investigated. A new reaction scheme was proposed consisting of series and parallel reactions for the formation of furfural. Kinetic models were developed to describe changes in the concentration of furfural with time. A modified Arrhenius equation was used to find out correlations between kinetic coefficients and reaction parameters. A maximum furfural concentration of 5.27 g/L (40.6% yield based on total conversion of pentosans) was obtained using 6% (wt.%) H3PO4 and liquid-to-solid ratio of 1:10 at 160 °C. Reaction parameters such as acid concentration, reaction temperature, and liquid solid ratio had a strong effect on the yield of furfural.

Wet process of phosphoric acid purification by solvent extraction using tri-n-butyl phosphate and cyclohexanol mixtures

Solvent extraction is an efficient, economical and widely-used technology for the purification of wet process phosphoric acid (WPA). This present work focused on the development of a solvent extraction system, TC, representing tri-n-butyl phosphate (TBP) and cyclohexanol mixtures. The equilibrium phase diagram of the system H3PO4?H2O?TC at 298.2 K and atmospheric pressure was obtained. The effects of extraction time, phosphoric acid concentration, extractant concentration, temperature and phase volume ratio on extraction efficiency were studied. The extracted complexes were estimated to be 1.8H3PO4 2TC. The extraction process of H3PO4 was exothermic and the enthalpy change, ?H, was obtained. The solvent mixtures had a high efficiency for phosphoric acid purification via multi-stage counter-current extraction from the industrial WPA in a reciprocating plate extraction column with an H3PO4 extraction yield of 85.08 % at 313.2 K. The stability, extraction efficiency and recycling capability of TC for H3PO4 extraction were also estimated.

Esterification of acetic acid to methyl acetate using activated TiO2 under UV light irradiation at ambient temperature

Abstract The advancement in the synthesis process of esters has always attracted immense interest of researchers due to its vast applications. To contribute in the technology development UV light has been used as major driving force in the esterification of acetic acid to synthesize methyl acetate using acid activated TiO 2 nanoparticles as catalyst at ambient temperature conditions. Acid activated TiO 2 catalyst can efficiently catalyse the reaction to produce methyl acetate at ambient conditions for repeated experiments. TiO 2 gains ultraviolet radiation from light source promoting electrons from the valence band to the conduction band thus creating electron–hole (e − + h + ) pairs further activating the acid sites lying on the catalyst surface created during activation. These active acid sites further combines with acetic acid and facilitate its conversion to methyl acetate, the desired product. The efficiency of acid activated TiO 2 catalyst lean on activating acid concentration, catalyst loading & molar ratio of reactants. Maximum of 94.2% acid conversion was obtained at the catalyst loading of 66.6 g/L, at 303.15 K and RPM of 1100. Efficiency of the catalyst was found to be proficient even after ten repeated reaction cycles. This research finding will broaden the understanding of utilization of active sites for the reaction on TiO 2 surface as a catalyst and show a low energy route for esterification reaction. Knowledge acquired from this study may inspire further studies in new efficient photo catalysts and wide range of organic synthesis.

Electrochemical determination of eugenol using a three-dimensional molecularly imprinted poly (p-aminothiophenol-co-p-aminobenzoic acids) film modified electrode

A novel electrochemical sensor for eugenol determination was presented, which was composed of molecularly imprinted poly (p-aminobenzenethiol-co-p-aminobenzoic acid) and ionic liquid (IL, i.e. 1-aminopropyl-3-methylimidazolium bromide) functionalized graphene-carbon nanotubes composite (GN-CNTs-IL). The porous molecularly imprinted copolymer film was prepared on the GN-CNTs-IL by cyclic voltammetry. The template molecule was eugenol, the supporting electrolyte was 25mM tetrabutylammonium perchlorate ethanol solution, and the concentration ratio of p-aminothiophenol and p-aminobenzoic acid was 1:3. The 3D porous GN-CNTs-IL composite was synthesized through a simple one-step hydrothermal method. After optimizing the preparation and measurement conditions, the obtained sensor showed a linear response to eugenol in the concentration range of 5.0×10−7 to 2.0×10−5M, and the limit of detection was 1.0×10−7M (S/N=3). The sensor had good selectivity, 100-fold glucose, lactose and sucrose did not affect the detection of 5.0×10−6M eugenol, while 10-fold analogues (i. e. vanillin, methyl eugenol, paeonol and methyl isoeugenol) had no interference. In addition, it also displayed good reproducibility and practicability, and was successfully applied to detect eugenol in real samples.

Short communication: Association of milk fatty acids with early lactation hyperketonemia and elevated concentration of nonesterified fatty acids

The objective of our study was to extend the limited research available on the association between concentrations of milk fatty acids and elevated nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHB) concentrations in early lactation dairy cattle. Measurement of milk fatty acids for detection of cows in excessive negative energy balance has the potential to be incorporated in routine in-line monitoring systems. Blood samples were taken from 84 cows in second or greater lactation 3 times per week between 3 to 14 d in milk. Cows were characterized as hyperketonemic (HYK) if blood BHB concentration was ≥1.2mmol/L at least once and characterized as having elevated concentrations of NEFA (NEFAH) if serum NEFA concentration was ≥1mmol/L at least once. Composition of colostrum and milk fatty acids at wk 2 postpartum was used to investigate the potential diagnostic value of individual fatty acids and fatty acid ratios for the correct classification of cows with NEFA and BHB concentrations above these thresholds, respectively. Receiver operating characteristic (ROC) curves were used to identify thresholds of fatty acid concentration and fatty acid ratios when ROC area under the curve was ≥0.70. Correct classification rate (CCR, %) was calculated as {[(number of true positives + number of true negatives)/total number tested] × 100}. None of the colostrum fatty acids yielded a sufficiently high area under the curve in ROC analysis for the association with HYK and NEFAH. The following fatty acids and fatty acid ratios were identified for an association with NEFAH (threshold, CCR): C15:0 (≤0.65g/100g, 68.3%); cis-9 C16:1 (≥1.85g/100g, 70.7%); cis-9 C18:1 (≥26g/100g, 69.5%), cis-9 C18:1 to C15:0 ratio (≥45, 69.5%); cis-9 C16:1 to C15:0 (≥2.50, 73.2%). Several fatty acids were associated with HYK (threshold, CCR): C6:0 (≤1.68g/100g, 80.5%), C8:0 (≤0.80g/100g, 80.5%), C10:0 (≤1.6g/100g, 79.3%); C12:0 (≤1.42g/100g, 82.9%); C14:0 (≤6.10g/100g, 84.1%); C15:0 (≤0.50g/100g, 82.9%), cis-9 C18:1 (≥30g/100g, 81.7%). The use of fatty acid ratios did not improve CCR over using individual fatty acids for the classification of HYK. Colostrum fatty acid composition was not useful in predicting NEFAH or HYK between 3 to 14 d in milk. Accuracy of milk fatty acids and fatty acid ratios to correctly classify cows with elevated concentrations of NEFA and BHB between 3 to 14 d in milk was moderate and overall higher for HYK. Determining changes in the fatty acid composition of milk fat from milk samples at wk 2 postpartum for the detection of cows with elevated concentrations of BHB and NEFA can currently not be recommended to replace direct measurement. Future applications should target repeated milk sampling between 3 to 14 d in milk to identify the best sampling for determination of milk fatty acid composition within the first 2 wk postpartum.

Production of Levulinic Acid from Pennisetum alopecuroides in the Presence of an Acid Catalyst

The perennial grass Pennisetum alopecuroides was degraded using a conventional heating method with sulfuric acid. The effects of temperature (150 to 200 °C), reaction time (30 to 210 min), acid concentration (2% to 10%), and solid-liquid ratio (1:10 to 1:4) were optimized for P. alopecuroides hydrolysis. The production of levulinic acid was strongly affected by variations in these parameters. The optimum conditions with respect to reaction temperature, time, acid concentration, and solid-liquid ratio were 190 °C, 60 min, 8%, and 1:6, respectively. The maximum levulinic acid yield using the optimum conditions was 50.49%. The residues obtained from various temperatures were also intensively characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric (TG) analyses. These results extend the current understanding of the bioconversion and utilization of renewable lignocellulosic biomass.

Selective hydrolysis of cellulose for the preparation of microcrystalline cellulose by phosphotungstic acid

Microcrystalline cellulose (MCC), prepared from natural cellulose through acid hydrolysis, has been widely used in the food, chemical and pharmaceutical industries because of its high degree of crystallinity, small particle size and other characteristics. Being different from conventional mineral acids, phosphotungstic acid (H3PW12O40, HPW) was explored for hydrolyzing cellulose selectively for the preparation of MCC in this study. Various reaction parameters, such as the acid concentration, reaction time, temperature and solid-liquid ratio, were optimized. Rod-like MCC was obtained with a high yield of 93.62 % and also exhibited higher crystallinity and narrower particle diameter distribution (76.37 %, 13.77–26.17 μm) compared with the raw material (56.47 %, 32.41–49.74 μm) at 90 °C for 2 h with 58 % (w/w) HPW catalyst and a solid-liquid radio of 1:40. Furthermore, HPW can easily be extracted and recycled with diethyl ether for four runs without affecting the quality of the MCC products. The technology of protecting the crystalline region while selectively hydrolyzing the amorphous region of cellulose as much as possible by using HPW is of great significance. Due to the strong Bronsted acid sites and highest activity in solid heteropoly acid, the use of effective homogeneous HPW may offer an eco-friendly and sustainable way to selectively convert fiber resources into chemicals in the future.