Phosphoric Acid Treatment Research Articles

Effects of temperature and catalytic methods on the physicochemical properties of microwave-assisted hydrothermal products of crop residues

We studied the effects of temperature (180–260 °C) and catalytic methods (ultrafine grinding and phosphoric acid treatment) on the microwave-assisted hydrothermal carbonization of crop residues by taking rice straw, corn stover and rape stalk as the research materials. The physicochemical and structural properties of hydrochars and liquid products generated under different conditions were characterized. The results showed that with increasing temperature, the hydrochar yield of crop residues decreased from 62.97–83.09% to 42.73–57.38%; the liquid yield rose from 15.03–33.38% to 37.94–47.58%; and the gas yield increased from 1.88–4.92% to 4.68–10.90%. The liquid products were all acidic (pH = 2.53–4.40), and the NH4+–N and PO43–P concentrations respectively showed an upward trend and a downward trend with increasing temperature. Higher temperature led to enhanced carbonization degree, causing decreases in H/C and O/C atomic ratios but increases in higher heating value (HHV). Hydrochars prepared at 240 °C had the most intensified oxygenated functional groups, the largest specific surface area (5.5652–15.5058 m2/g), total pore volume (0.0403–0.1116 cm3/g) and mesopore volume (0.0395–0.1101 cm3/g), and the most carbon microspheres. However, temperature had a rather limited effect on the micropore volume of hydrochars derived from the three types of crop residues. Both ultrafine grinding and phosphoric acid catalysis could enhance hydrochar properties, with the latter being the more low-cost and efficient method. Hydrochars from ultrafine grinding crop residues had the highest peak strength of oxygenated functional groups, while those from phosphoric acid catalysis had higher fixed carbon (23.58–35.91%), C (45.03–65.50%) and HHV (17.45–27.18 MJ/kg), and lower ash content (4.21–15.67%), as well as the largest specific surface area (6.9140–15.5058 m2/g), total pore volume (0.0638–0.1116 cm3/g), micropore volume (0.0007–0.0015 cm3/g) and mesopore volume (0.0631–0.1101 cm3/g). Besides, crop residue type was also found to be an inherent factor determining hydrochar property.

Cadmium and iron removal from phosphoric acid using commercial resins for purification purpose.

Three commercial resins bearing sulfonic, amino phosphonic, or phosphonic/sulfonic reactive groups have been tested for the removal of iron and cadmium from phosphoric acid solutions. The sorption properties are compared for different experimental conditions such as sorbent dosage (0.5-2.5gL-1), phosphoric acid concentration (from bi-component solutions, 0.25-2M), and metal concentrations (i.e., in the range 0.27-2.7mmolCdL-1 and 0.54mmolFeL-1) with a special attention paid to the impact of the type of reactive groups held on the resins. The sulfonic-based resin (MTC1600H) is more selective for Cd (against Fe), especially at high phosphoric acid concentration and low sorbent dosage, while MTS9500 (aminophosphonic resin) is more selective for Fe removal (regardless of acid concentration and sorbent dosage). Equilibrium is reached within 2-4h. The resins can be ranked in terms of cumulative sorption capacities according the series: MTC1600H > MTS9570 > MTS 9500. Sulfuric acid (0.5-1M) can be efficiently used for the desorption of both iron and cadmiumfor MTC1600H, while for MTS9570 (phosphonic/sulfonic resin) sulfuric acid correctly desorbs Cd (above 96% at 1M concentration), contrary to Fe (less than 30%). The aminophosphonic resin shows much poorer efficiency in terms of desorption. The sulfonic resin (i.e., MTC1600H) shows much higher sorption capacity, better selectivity, comparable uptake kinetics (about 2h equilibrium time), and better metal desorption ability (higher than 98% with 1M acid concentration, regardless of the type of acid). This conclusion is confirmed by the comparison of removal properties in the treatment of different types of industrial phosphoric acid solutions (crude, and pre-treated H3PO4 solutions). The three resins are inefficient for the treatment of crude phosphoric acid, and activated charcoal pre-treatment (MTC1600H reduced cadmium content by 77%). However, MTC1600H allows removing over 93% of Fe and Cd for H3PO4 pre-treated by TBP solvent extraction, while the others show much lower efficiencies (< 53%).

Iron Adsorption from Textile Industrial Effluent on Activated Carbon Prepared from Tamarind Seeds (Tamarindus indica L.)

Water pollution contributes the major environmental pollution in many countries which shows great impact on human life and biodiversity. The important source of water pollution is industrial effluent. General contaminants in effluent water are heavy metals, phenols, dyes, harmful organics, ligands and suspended solids .Treatment of effluent water plays vital role in many industries, the treatment of adsorption proved to be most important well known and economical process. The ability of certain solids of preferentially concentrate specific substance on their surface is the basic principle for adsorption. Water with high content of iron can be very objectionable. In our research work the activated carbon prepared from tamarind seeds was employed to take up selected heavy metal that is iron ions. Tamarind seeds which are an agricultural waste and also waste product in many industries was activated by phosphoric acid treatment, is investigated for the removal of iron ions from textile industrial effluent sample.

Immobilization of cadmium (Cd2+) in contaminated soil using biochar derived from Calophyllum inophyllum (bitaog) seed husks

Many heavy metals such as cadmium found in contaminated soil naturally leach out and seep in groundwater through time. Natural leaching is further accelerated in acidic conditions specifically with acid rain. This study investigated the effectiveness of biochar derived from Calophyllum inophyllum (Bitaog) seed husks as an immobilizing agent through a simulated acid rain leaching test (equivalent to 100 years of acid rain) using artificially contaminated soil. Furthermore, magnetization and phosphoric acid treatment were utilized to produce modified biochar where Thermo-gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) analyses revealed that the modifications led to the enhancement of physiochemical properties such as fixed carbon content, surface morphology, and surface chemistry respectively. Walkley-Black Loss on Ignition test showed that all the biochar amendment increased the organic matter content of soil making it attractive for in-soil applications. Adsorption kinetic and isotherm models were used to describe the adsorption mechanism of cadmium onto the soil amended with modified and unmodified biochar where experimental results showed that the adsorption best fitted the pseudo-second order kinetic and Langmuir isotherm models. The leaching test results showed that the soil amended with magnetic and phosphoric acid modified biochar were not suitable as immobilizing agents especially in highly acidic conditions. Whereas the unmodified biochar significantly reduced leached cadmium concentration by 40.02% than in unamended soil as shown by the AAS results. Bitaog derived biochar was affirmed to be potentially effective for the long-term immobilization of cadmium in contaminated soil while may simultaneously increase soil fertility.

Optimization of copper adsorption from synthetic wastewater by oil palm-based adsorbent using Central Composite Design

Oil palm empty fruit bunch (EFB) was chemically activated by phosphoric acid and heat treatment to produce porous activated carbon (AC) for adsorption of copper ions from synthetic wastewater using static batch test. Copper adsorption process was optimized using Response Surface Method (RSM) by varying four operating parameters i.e. pH (A), initial concentration (B), adsorbent dosage (C) and contact time (D) through a quadratic model developed based on Central Composite Design (CCD) approach. Within the tested parameter range, copper adsorption was found to be at optimum condition at pH 5, initial concentration of 200 mg/L, adsorbent dosage of 0.55 g per 200 mL copper solution and contact time of 2.5 hours, yielding 52.5% of copper removal. A good agreement was achieved by comparing the predicted model with experimental data (R2=0.9618). All four operating parameters tested are significant in affecting the adsorption process, with pH being the most significant with an F-value of 171.70. The interaction between pH and initial concentration (AB) has the most significant interacting effects (F-value of 18.30), while quadratic effects of pH (A2) and adsorbent dosage (C2) are most significant with F-values of 62.80 and 42.58 respectively.

Microstructure evolution for oxide film of anodic aluminum foil used in high voltage electrolytic capacitor

The oxide film of anodic aluminum foil is the main working medium of aluminum electrolytic capacitor, and its quality directly affects the electrical performance of capacitor. The fabrication of anodic aluminum foil is conducted by a multiple-step anodizing process, including hydration, formation, heat treatment and phosphoric acid treatment. The microstructure evolution for oxide film of anodic aluminum foil during preparation process is studied quantitatively in this paper. The results show that, the pores area on the foil surface keeps decreasing after hydration and subsequent formation. However, after phosphoric acid treatment, the pores area stops decreasing and increases to a local maximum value. The length distribution of ‘corn-flake’ structures keeps increasing, from the range of 60–120 nm to 100–140 nm. After phosphoric acid treatment, the petal edges become serrated, and many small corrosion holes with the length of 20–30 nm are left inside. The thickness of the outer amorphous layer in the anodized oxide film keeps decreasing from the initial 390 nm to the final 90 nm. In contrast, the thickness of the inner dense layer keeps increasing from the initial 130 nm to the final 550 nm. The decreasing trend of grain size continues until the end of preparation process, and reaches the final value of 10 nm. The analysis of microstructure of oxide film is helpful for obtaining optimal process parameters and improving performance of aluminum foil.

Probing Electrochemical Behaviour of Lignocellulosic, Orange Peel Derived Hard Carbon as Anode for Sodium Ion Battery

Hard carbon (HC) has emerged as potential anode material for sodium-ion batteries (SIB). However, it is plagued with several issues like low capacity, poor cyclability, significant electrolyte degradation on interface. Realization of HC as anode requires fundamental understanding of the effect of its porous structure/composition on electrochemical performance. Herein, we report the use of lignocellulosic orange peel precursor for HC synthesis with tuneable surface area (SA), controlled porosity using phosphoric acid treatment. Physicochemical properties of HC were further tailored using N-doping. The electrochemical response of various HCs was tested with careful attention to the effect of HC SA and nitrogen content on the performances as anode. We show that optimized bio-waste based HC exhibits Na+ specific capacity of 125 mAhg−1 at 70 mAg−1 with significantly suppressed CO2 evolution during cycling, indicating mitigated electrolyte degradation and superior performance. We believe that this study sheds light on design rules for bio-waste low-cost precursors for synthesizing HC with tailored physical and electrochemical properties. Using such design guidelines, is crucial for developing HC based anode materials for SIB’s.

Removal of vanadium from aquatic environment using phosphoric acid modified rice straw

Vanadium (V) is a toxic metal, which dominantly exists as V5+ in an aquatic environment. Rice straw, which is an abundant agricultural by-product throughout China was used to treat V5+ containing wastewater as an adsorbent after phosphoric acid treatment. The effects of initial V5+ concentration, solution temperature, pH and reaction time on V removal by phosphoric acid modified rice straw (AcM) were systematically assessed. A pH range of 2.0–3.0 was favorable for V removal and the adsorption capacity of V by AcM increased with elevated solution temperature. The maximum adsorption capacity for water containing 500 mg V5+ L−1 was 24.70 mg V g−1 dry matter under the optimum operation (3.33 g L−1 AcM, pH = 2.0, 50 °C, and 200 rpm for 4 h). Adsorption experiment data fitted well to pseudo-second-order kinetic and Langmuir adsorption isotherm models. In the presence of coexisting ions, Na+, Cu2+, NO3− and Cl− had no significant (P > 0.05) effect on V removal. These results indicated that AcM derived from agricultural waste was effective to remove V5+ from aqueous solution.

Effect of Silver Diamine Fluoride on the Bonding Properties to Caries-affected Dentin.

To evaluate 1. the microtensile bond strength (µTBS) and in situ degree of conversion (DC) of adhesives applied using two bonding strategies after silver diamine fluoride (diamine) application on carious dentinal lesions, and 2. dentin etching patterns using SEM and energy dispersive x-ray spectroscopy. Human molars were randomly divided into 12 experimental groups according to: 1. application of a silver diamine fluoride solution (carious dentinal lesion without silver diamine fluoride treatment [control], with 12% silver diamine fluoride [diamine 12%] or 38% silver diamine fluoride [diamine 38%]); 2. adhesives (Clearfil Universal Bond Quick [CUQ] and Scotchbond Universal [SBU]); 3. adhesive strategy (etch-and-rinse [ER] and self-etch [SE]). After restoration, the specimens were sectioned and submitted to µTBS testing. Sticks from each tooth were used for DC evaluation. To examine the changes induced by diamine before and after phosphoric acid treatment, SEM/EDX analysis was performed. Data from the µTBS and DC tests were analyzed using three-way ANOVA and Tukey's test (α = 0.05). Both concentrations of diamine resulted in a statistically significantly higher mean µTBS compared to the control (p < 0.0001). Diamine 38% showed a statistically significantly higher mean µTBS for both adhesives in SE mode compared to diamine 12% (p < 0.0001). The application of diamine to carious dentinal lesions did not significantly influence the mean DC values for either adhesive (p = 0.72). SBU showed a higher mean DC compared to CUQ (p = 0.03). After diamine treatment, there was an increase in the Ca peak intensity and the presence of residual silver ions mainly when diamine 38% was applied along with the SE approach. Independent of the adhesive application approach, the use of diamine may be a promising alternative to increase µTBS without jeopardizing the DC of the two adhesives in carious dentinal lesions.

A supercapacitor with ultrahigh volumetric capacitance produced by self-assembly of reduced graphene oxide through phosphoric acid treatment

Self-assembled reduced graphene oxide was prepared by a phosphoric acid heat-treatment method and exhibited an ultra-high volumetric capacitance.

Effect of Diode Laser Office Bleaching on Mineral Content and Surface Topography of Enamel Surface: An SEM Study.

AimTo assess the effects of different bleaching procedures on the mineral component and surface topography of the enamel using scanning electron microscope (SEM) and energy-dispersive X-ray spectrometry (EDX).Materials and methodsForty samples of approximately 3 × 3 mm size from the coronal portion of 20 extracted human anterior teeth were obtained. The samples were divided into two control groups and three experimental groups. In group I or positive control (n = 5), no bleaching or phosphoric acid treatment to the enamel surface was done. Group II samples or negative controls (n = 5) were treated with 37% phosphoric acid. In group III (n = 10), the tooth was treated with 35% hydrogen peroxide (HP) without any activation. Group IV (n = 10) was treated with 37.5% HP with LED light activation and group V (n = 10) was treated with 45% HP with diode laser activation. The calcium (Ca) and phosphorus (P) levels of each sample were measured using an EDX system prior to bleaching treatments. All the samples were again subjected to the EDX analysis after the bleaching treatment and two samples (after EDX analysis) from each group were subjected to the SEM analysis.ResultNo significant difference was seen in phosphorus levels before and after the bleaching. However, significant increase in calcium levels was observed after bleaching activated with LASER and LED light. The SEM observations revealed maximum surface alterations on the enamel after chemically activated bleaching.ConclusionThe LASER-activated bleaching agent seems to be more surface-friendly and less time-consuming as compared to other bleaching systems.How to cite this articleSuresh S, Navit S, Khan SA, et al. Effect of Diode Laser Office Bleaching on Mineral Content and Surface Topography of Enamel Surface: An SEM Study. Int J Clin Pediatr Dent 2020;13(5):481–485.

Influence of Acid-Treatment on Waste Lignin for Synthesis of Carbon Nanoparticle

Waste lignin (WL) obtained from paper mills, was studied for its potential application in preparing carbon nanoparticles (CNPs) with high porosity. This was done by impregnation of 0, 5, 10 and 20% concentrations of phosphoric acid under various carbonization temperatures (600, 700, 800 and 900°C). The physicochemical properties of CNPs were characterized through nitrogen sorption, X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Fourier transforms infrared spectroscopy (FTIR). Nitrogen sorption revealed that the condition using 10% concentration of phosphoric acid treatment at a carbonization temperature of 700°C formed carbon nanoparticles with a highly porous structure (Surface area 27.65 m2/g and pore volume 0.07 cm3/g). Additionally, in order to high surface area, porosity and concentrated carbon nanoparticle.

Production and Characterization of Rice Husk Biosorbent from Far North Cameroon

The objective of this study is the production and the characterization of rice husk biosorbent. In fact, the biosorbent has been obtained by phosphoric acid treatment; its physicochemicals characteristics such as point of zero charge, specific surface, iodine number and chemicals functions have been determined. The analysis indicaded that, the point of zero charge is 8.7; for the pH value less than 8.7, the biosorbent surface is posotively charged and for pH value higher than 8.7, the biosorbent surface is negatively charged. The biosorbent iodine number is 1560.87&amp;plusmn;1 mg/g, it means that, the biosorbent is constituted in majority of microspores. Furthermore, the specific surface of biosorbent is 104.45&amp;plusmn;1m2/g, it is five times as big than untreated rice husk obtained by Dada and al., (2012). Acid treatment improve the porosity of biosorbent. Infrarouge spectrum present ether and aromatic functions.

Synthesis of P- and N-doped carbon catalysts for the oxygen reduction reaction via controlled phosphoric acid treatment of folic acid.

Herein, we synthesized P- and N-doped carbon materials (PN-doped carbon materials) through controlled phosphoric acid treatment (CPAT) of folic acid (FA) and probed their ability to catalyze the oxygen reduction reaction (ORR) at the cathode of a fuel cell. Precursors obtained by heating FA in the presence of phosphoric acid at temperatures of 400–1000 °C were further annealed at 1000 °C to afford PN-doped carbon materials. The extent of precursor P doping was maximized at 700 °C, and the use of higher temperatures resulted in activation and increased porosity rather than in increased P content. The P/C atomic ratios of PN-doped carbon materials correlated well with those of the precursors, which indicated that CPAT is well suited for the preparation of PN-doped carbon materials. The carbon material prepared using a CPAT temperature of 700 °C exhibited the highest ORR activity and was shown to contain –C–PO2 and –C–PO3 moieties as the major P species and pyridinic N as the major N species. Moreover, no N–P bonds were detected. It was concluded that the presence of –C–PO2 and –C–PO3 units decreases the work function and thus raises the Fermi level above the standard O2/H2O reduction potential, which resulted in enhanced ORR activity. Finally, CPAT was concluded to be applicable to the synthesis of PN-doped carbon materials from N-containing organic compounds other than FA.

Optimisation of sepiolite clay with phosphoric acid treatment as support material for CoB catalyst and application to produce hydrogen from the NaBH4 hydrolysis

Herein, the CoB catalyst supported on the sepiolite clay treated with phosphoric acid was utilized to produce hydrogen from the NaBH4 hydrolysis. In order to analyse the performance of the phosphoric acid treated sepiolite clay supported-CoB catalyst, the NaBH4 concentration effect, phosphoric acid concentration effect, phosphoric acid impregnation time effect, CoB catalyst percentage effect, and temperature effect were studied. In addition, XRD, XPS, SEM, TEM, BET, and FTIR analysis were performed for characterization of Co–B catalyst supported on the acid-treated sepiolite. The completion time of this hydrolysis reaction with Co–B (20%) catalyst supported on the sepiolite treated by 5 M phosphoric acid was approximately 80 min, whereas the completion time of this hydrolysis reaction with acid-free sepiolite-supported Co–B (20%) catalyst was approximately 260 min. There is a five-fold increase in the maximum production rate. The maximum hydrogen production rates of this hydrolysis reaction at 30 and 60 °C were found as 1486 and 5025 ml min−1g−1catalyst, respectively. Activation energy was found as 21.4 kJ/mol. This result indicates that the acid treatment on sepiolite is quite successful. The re-usability of NaBH4 hydrolysis reaction by CoB catalyst supported on sepiolite treated phosphoric acid for successive five cycles of NaBH4 at 30 °C was investigated.

Preparation of amphiphilic mesoporous carbon-based solid acid from kraft lignin activated by phosphoric acid and its catalytic performance for hydration of α-pinene

An amphiphilic mesoporous carbon-based solid acid (LCx-SO3H) with high specific surface area was prepared from kraft lignin that was carbonized using a phosphoric acid treatment. It was found that the specific surface area, pore structure, and amphiphilic nature of the catalyst was effectively controlled through adjusting the phosphoric acid dosage during lignin carbonization. Under optimum preparation conditions, the specific surface area, pore volume, and average pore size of the catalyst were 282.2 m2/g, 0.26 cm3/g, and 6.73 nm, respectively. The performance of this solid acid catalyst for the hydration of α-pinene was characterized via gas chromatography analysis. The conversion of α-pinene and the yield of α-terpineol during hydration reaction were as high as 95.3% and 55.3%, respectively; these results were greater than the results from other hydration methods with sulfuric acid and commercially available solid acid catalysts (e.g., Amberlyst-15). After five recycles of the carbon-based solid acid without regeneration, conversion of α-pinene decreased from 95.3% to 92.6%, and the yield of α-terpineol decreased from 55.3% to 47.6%. These observations indicated that the solid acid catalyst derived from kraft lignin carbonization has high potential as a hydration agent for α-pinene.

Two-step conversion of cellulose to levoglucosenone using updraft fixed bed pyrolyzer and catalytic reformer

In this work, production of levoglucosenone, a promising biorenewable platform chemical, from cellulose was investigated using a two-step continuous process that consists of an updraft fixed bed reactor for fast pyrolysis of cellulose and a catalytic reformer for the volatiles conversion. The updraft fixed bed pyrolyzer produced levoglucosan, which was a precursor of levoglucosenone, with the yield of 38.4% on a carbon basis (%-C) at the optimized temperature of 500 °C. The yield of levoglucosenone significantly depended on the type of catalyst used for the reforming of volatiles. Acidic activated carbons prepared with sulfuric or phosphoric acid treatment showed good catalytic activity toward levoglucosenone formation, when mixed with cellulose in the catalytic pyrolysis, but were unavailable in the two-step process due to the quick deactivation by coke deposition. Supported ionic liquid (IL: 1-butyl-2,3-dimethylimidazolium triflate) phase catalysts enabled selective production of levoglucosenone independent of the support material examined (silica, γ-alumina, and activated carbon). The continuous operation was possible with the maximum levoglucosenone yield of 16.6%-C, but the IL catalysts also suffered from problems such as coke deposition and IL decomposition. The problems were quantitatively assessed in the experiments at different conditions.

Characterization of mechanical pulverization/phosphoric acid pretreatment of corn stover for enzymatic hydrolysis

Lignocellulosic biomass from corn stover holds promise as a raw material for the production of alternative energy to replace fossil fuels. In this study, structural properties of corn stover after pretreatment using mechanical pulverization with or without subsequent phosphoric acid treatment were investigated. The results showed that a pulverization step loosened the compact structure of corn stover lignocellulose and effectively reduced particle size, while both pulverization and phosphoric acid pretreatment steps altered the crystallinity index. During pretreatment, hemicellulose content was reduced and accessibility of β-1,4 glycosidic bonds to hydrolysis by cellulase increased, while almost all lignin was retained. The results showed that the combined two-step pretreatment method improved sugar yield from lignocellulose during subsequent enzymatic hydrolysis from 20.01 mg/g to 41.41 mg/g in glucose yield. These results should guide the development of methods for improved lignocellulose conversion to sugars for enhanced bioethanol production.

Effects of Dilute Phosphoric Acid Treatment on Structure and Burning Characteristics of Lignocellulosic Biomass

Pretreatment of biomass with phosphoric acid (H3PO4) has been a popular method since it facilitates the generation of biofuels and mitigates the problems arising from the use of corrosive sulfuric acid that is otherwise commonly employed for pretreatment. However, variations took place in the structure of biomass through this treatment have not so far been investigated in detail. This paper focuses on the effects of aqueous H3PO4 treatment on the lignocellulosic residue of corn (CR) considering the fuel properties, ash fusion temperatures, combustion characteristics and kinetics, mineral phases, surface functionalities, and the morphology of the treated biomass. It was determined that interaction of biomass with 5% H3PO4 solution led to important variations from cellulose crystallinity to thermal reactivity of this lignocellulosic material. Although elements such as Na, K, Ca, Mg, and Fe could be effectively removed by treatment, formation of phosphorus containing new phases caused to increase in ash yield. Also, the change in mineral matter composition led to an increase in ash fusion temperatures along with reduction in the burning rates. Thus, the combustibility and combustion performance indices dropped.

Development and characterization of calcium phosphate scaffold by phosphoric acid treatment

Development and characterization of calcium phosphate scaffold by phosphoric acid treatment