Effects Of H3PO4 Research Articles

The effect of phosphoric acid on the properties of activated carbons made from Myrtus communis leaves: Textural characteristics, surface chemistry, and capacity to adsorb methyl orange

In this work, chemical activation was employed to produce activated carbons and assess the impact of phosphoric acid (H3PO4) on their physicochemical properties. Using Myrtus communis Leaves (MC-Leaves) as the precursor and varying H3PO4 impregnation ratios (30 %, 60 %, 100 %, and 150 wt.%). The activation was conducted at 450 °C (10 °C/min) for 1 h in a room atmosphere. The effects of H3PO4 were evaluated through various techniques, including BET surface area analysis, FESEM-EDS imaging, XPS, FT-IR-ATR, Raman spectroscopy, CHNS-(O) elemental analysis, and Methyl orange (MO) adsorption studies. The specific surface area (SSA) and total pore volume increased from 642m2/g to 1237m2/g, total pore volume increased from 0.29cm3/g to 0.97cm3/g, and the mean pore diameter increased from 1.9 nm to 3.2 nm by increasing the impregnation ratio from 30 wt.% to 150 wt.%. The pH(pzc) of MC-ACs exhibited an acidic character, owing to the presence of oxygen-containing functional groups such as hydroxyl, carboxyl, metaphosphate (-PO3-), phosphates, and pyrophosphate groups, as indicated by XPS and FT-IR analysis. At a room temperature of 22 °C and an ideal pH of 2.06, the maximum adsorption capacity (qmax) rose from 46.02±4.63 mg g-1 to 326.54±37.67 mg g-1 as the impregnation ratio increased from 30 wt.% to 150 wt.%. Freundlich isotherm well explained the adsorption equilibrium at 22 °C for all MC-ACs. The effect of temperature illustrates that the adsorption of MO onto MC-AC30 % was endothermic, while the adsorption of MO onto MC-AC150 % was an exothermic. The kinetic study was conducted at 22 °C, when the equilibrium time was at 4hours, and it was a pseudo-second order (PSO) model.

Effects of H3PO4 on synthesis and luminescence of metal halide perovskites

Metal halide perovskites are attractive light-emitting materials due to their excellent optoelectronic properties. However, the traditional preparation methods are mostly complicated. Recently, we introduced a near room temperature synthesis strategy, named H3PO4-assisted precipitation method, which has advantages of thermal- and pressure-free, eco-friendly, as well as short reaction time. Here, we taken Cs2InBr5·H2O as an example to study the impacts of H3PO4 on synthesis and luminescence of metal halide perovskites. Upon adding H3PO4, Cs2InBr5·H2O gives a bright red emission peaked at 630 nm. Various analytic techniques, including X-ray diffraction, FTIR spectra, X-ray photoelectron spectroscopy, Scanning electron microscope, Absorption spectra, and Photoluminescence spectra were employed to investigate the structure and luminescent properties of the prepared Cs2InBr5·H2O perovskites. The results indicate that H3PO4 significantly affects the crystallinity, morphology and STEs emission of Cs2InBr5·H2O. Additionally, various ions doping (such as Sb3+: Cs2InBr5·H2O) and other metal halide microcrystals (such as CsPbBr3 and CsPb2Br5) can also be obtained with the assistance of H3PO4, indicating H3PO4 is a significant additive for synthesizing and enhancing the luminescence of metal halide perovskites.

Effect of H3PO4 and NaOH additives on the Co-carbonization of cellulose and N-containing compounds to produce N-doped chars

N-doped carbons have significant applications in electronics, materials, and as tools for environmental services. However, few studies focus on N-containing compounds’ carbonization strategies to increase char N retention. For this purpose, H3PO4 and NaOH were used as additives during the co-carbonization of cellulose and four N-containing compounds (lysine, melamine, chitosan, and dicyandiamide (DCD)). Thermogravimetric and Py-GC/MS studies showed significant interactions between the N-containing compounds and cellulose with acid and basic additives. In all cases, an increase in char yield was observed. Acid-base treated samples were carbonized in a spoon reactor at 500 °C, and the resulting chars were thoroughly characterized. The maximum char yields were obtained in the presence of H3PO4 due to the impact of this additive on cellulose dehydration. N’s content in the char product varied from 2 to 12 wt. % depending on the N source. N conversion efficiency increases in the presence of H3PO4. In the case of chitosan, we obtained N conversion efficiencies as high as 77 % in acidic conditions. The deconvoluted XPS N 1s spectra showed that each acid-treated char contained a dominant pyrrolic N form, likely due to the acid’s effect on forming furanic compounds. NaOH-treated chars were richer in pyridinic structures. The first step in N-integration to biochar is the Maillard reaction. Carbonyls and amines react to form glycosylamine and the Amadori product. These intermediates form a Schiff’s base of hydroxymethyl furfural in acidic conditions. In basic conditions, reductones are produced. These are important mediators of melanoidins. The melanoidins are subjected to aromatization and polycondensation reactions to form N-containing polyaromatic ring systems at high temperatures.

Effect of bifunctional acid on the porosity improvement of biomass-derived activated carbon for methylene blue adsorption

Activated carbon (AC) with high specific surface area was prepared by using bifunctional H3PO4 agent, which led to dehydrating and activation effects through hydrothermal pretreatment and subsequent pyrolysis process. N2 adsorption and desorption isotherms of AC showed a high BET surface area of 2434m2g-1 and a total volume of pores (VT) of 2.0447m3g-1 for AC. The morphology and the chemical components of hydrochar and AC were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy, which indicated that H3PO4 was benefitting for the formation of porous structure of AC. Subsequently, the effect of H3PO4 in hydrothermal pretreatment and activation process was investigated by comparative experiments. The removal and adsorption of methylene blue (MB) dye with different concentrations onto the AC were studied. The monolayer equilibrium adsorption capacity was 644mgg-1, showing that AC has good adsorption qualities for methylene blue (MB). The adsorption balance data of MB on AC was best fitted to the Redlich-Peterson model. The adsorption kinetic data fit better to the pseudo-first-order model at low MB concentration, and the pseudo-second-order and Elovich models fit better when the MB concentration was rising.

Effect of H3PO4 and KOH as the Activating Agents on the Synthesis of Low-Cost Activated Carbon from Duckweeds Plants

Effect of H3PO4 and KOH as the Activating Agents on the Synthesis of Low-Cost Activated Carbon from Duckweeds Plants

An investigation on the effect of H 3 PO 4 and HCl-doped polyaniline nanoparticles on corrosion protection of carbon steel by means of scanning kelvin probe

In this work, the effect of H3PO4 and HCl dopants on the corrosion protection properties of polyaniline nanoparticles (PANs) dispersed in epoxy novolac, coated on carbon steel was compared using the Scanning Kelvin Probe (SKP). The nanometeric size and uniform dispersion of PANs in the coating were confirmed by scanning and transmission electron microscopy. Conductivity test, Potentiodynamic measurements and SKP technique were used to study theeffect of dopant type on the corrosion behavior of carbon steel in presence of PANs. The results show that PANs-containing nanocomposites can stabilize the potential of steel substrate in a passive state. Furthermore, variation coefficient (VC) of the surface Volta potential differences was introduced as an index for detection of the corrosion uniformity under the coating in presence of PANs. According to SKP results, the protection ability of coatings was improved in presence of PANs. In addition, the steel corrosion under the coating containing HCl-doped PANs tended to be more localized than that under the coating containing H3PO4-doped PANs. This is attributed to aggressive and inhibitive roles of chloride and phosphate anions respectively.

Preparation of block CaO from carbide slag and its compressive strength improved by H3PO4

The effects of H3PO4 on the compressive strength of block CaO, phase composition and morphology of calcined carbide slag were investigated. The results indicated that block CaO could be prepared from carbide slag through molding and calcination. H3PO4 had a promotive effect on the compressive strength of block CaO, which reached the maximum value at 3.2MPa with a H3PO4 content of 4%. Meanwhile, the compressive strength of block CaO increased with an increase of molding pressure. Moreover, the P-containing phase in carbide slag shifted from hydro-phosphate to phosphate after calcination. The close connection on the surface of particles was enhanced by the formation of phosphate.

Effects of H3PO4 and Ca(H2PO4)2 on mechanical properties and water resistance of thermally decomposed magnesium oxychloride cement

The effects of H3PO4 and Ca(H2PO4)2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement (TDMOC) pastes were studied. The mineral composition, hydration products and hydration heat release were analyzed by XRD, FT-IR, SEM and TAM air isothermal calorimeter, etc. After being modified by H3PO4 and Ca(H2PO4)2, the properties of the TDMOC are improved obviously. The compressive strength increases from 14.8 MPa to 48.1 MPa and 37.1 MPa, respectively. The strength retention coefficient (Kn) increases from 0.38 to 0.99 and 0.94, respectively. The 24 h hydration heat release decreases by 10% and 4% and the time of hydration peak appearing is delayed from 1 h to about 10 h. The XRD, FT-IR and SEM results show that the main composition is 5Mg(OH)2·MgCl2·8H2O in the modified TDMOC pastes. The possible mechanism for the strength enhancement was discussed. The purposes are to extend the potential applications of the salt lake magnesium resources and to improve the mechanical properties of TDMOC.

Effect of phosphoric acid on the properties of magnesium oxychloride cement as a biomaterial

Magnesium oxychloride cement (MOC) has been used in civil engineering for more than 100years, but its application has been limited by its poor water resistance. This property, however, could be exploited in the formulation of a resorbable orthopaedic biomaterial. In this study, H3PO4 was added to control the degradation process of MOC to provide a predictable and clinically appropriate resorption time. The effects of H3PO4 on the phases, microstructures, mechanical properties, hydration and degradation of MOC have been evaluated. The results revealed that the crystalline phases in MOC before and after adding H3PO4 were the same, but that the needle-like phase 5 (5Mg(OH)2·MgCl2·8H2O) crystals were formed more extensively in MOC with H3PO4 than that in MOC without H3PO4. Furthermore, the addition of H3PO4 was shown to retard the hydration process. H3PO4 did significantly improve the water resistance of MOC though its addition resulting in a reduction in compressive strength.

Effect of H3PO4 anodising variations on Al–epoxy adhesion strength

High adhesion strength of polymeric coatings on Al alloys requires special Al surface pretreatment. The formation of a thin layer of anodic Al oxide (AAO) leads to a strong polymer/Al bond. In this work, a thermosetting epoxy coating was applied on anodised Al surfaces. The effects of the electrolyte temperature, anodising voltage and time on the adhesion strength of coated samples were examined using a pull-off method. Surface morphology and topography of AAO layer were studied using field emission scanning electron microscopy and atomic force microscopy, respectively. Hydrophilic behaviour of the nanostructure anodised layer was investigated by a contact angle test. The results showed that the morphology of AAO layer has a remarkable impact on the adhesion strength. Morphological changes in the AAO layer from customary pore- to whisker-like structure led to a noticeable improvement in the strength of epoxy coatings; the latter structure was highly hydrophilic.

Analyzing the Influence of H3PO4 as Catalyst Poison in High Temperature PEM Fuel Cells Using in-operando X-ray Absorption Spectroscopy

The effect of H3PO4 as a poison in high temperature polymer electrolyte fuel cells using polybenzimidazole (PBI) membranes was studied as a function of phosphoric acid loading, potential, and temperature. In this work, for the first time, extensive in-operando X-ray absorption spectroscopy investigations were carried out on Pt/C fuel cell cathode catalysts at different temperatures and H3PO4 concentrations at varying fuel cell voltages. Under in-operando conditions, significant H3PO4 anion coverage of the Pt nanoparticles is observed. The Δμ-XANES analysis shows that the O(H)/H adsorption onset potential increases/decreases with temperature and that this is a result of phosphate anions being driven off the surface at high temperatures (170 °C). With initial coadsorption of H and O(H), the phosphate anions move into registry with the Pt, whereas random adsorption is observed when only phosphate anions are present on the Pt surface. By varying the temperature and the fuel cell potential, the adsorption geometry of the phosphoric acid anion changes with coverage, but in all cases, the anions block Pt sites and reduce the oxygen reduction reaction (ORR) rate.

Counter-current extraction process for recovery of U(IV) from phosphoric acid using octylphenyl acid phosphate (OPAP) extractant

The extraction of U(IV) from phosphoric acid by octylphenyl acid phosphate (OPAP) in kerosene was investigated. Parameters affecting the extraction of U(IV) from phosphoric acid were investigated. The effects of H3PO4, H2SO4, H2O2, Na2CO3 and (NH4)2CO3 concentrations, phase ratio and temperature on the stripping of uranium from the organic phase were studied. Based on the bench-scale results, a continuous counter-current extraction flow sheet was developed and tested using a 16-stage horizontal type mixer settler. The continuous extraction scrubbing stripping showed that the extraction efficiency of the developed process is 99%, whereas the stripping efficiency is 97%.

Effect of conditioning with fluoride and phosphoric acid on enamel surfaces as evaluated by scanning electron microscopy and fluoride incorporation.

The etching effect of 50% H-3PO-4 applied together with 2% NaF or SnF-2 was compared with the effect of H-3PO-4 on pre- and postfluoridated enamel by scanning electron microscopy. Substantial etching of enamel resulted with use of 50% H-3PO-4 with 2% NaF. High fluoride incorporation in the surface provided additional protection of the conditioned enamel.