H2SO4 Treatment Research Articles

Recovery of Sugar and Nutrients from Algae and Colocasia esculenta (Taro) Leaves Using Chemical Hydrolysis

Algal biomass and Colocasia esculenta (Taro) leaves are available as waste biomass all over India. These biomasses can be used as renewable and sustainable resources for sugars and nutrients. Recovered nutrients and sugars can be used as cheap raw materials for biofuels and biomaterials production. The hydrolysis of dried algal biomass and Colocasia esculenta (Taro) leaves were investigated using 1%, 2%, and 5% solutions of ferric-chloride, nitric acid, and acetic acid for the reaction times of 30 and 60 min at 121 °C and 103.4 kPa (15 psi). 1% and 2% H2SO4 treatments were used as the reference. The solid: liquid ratio was kept at 1:10 for all the experiments. For algal biomass, a 5% acetic acid treatment for 60 min was found to be optimum with a total carbohydrate release of 44.2 mg/g biomass (solubilized monomers-0.82 mg/g of biomass) and N and P solubilization of 1.8 mg total nitrogen/g biomass and 7 mg total phosphorus/g biomass. Moreover, for Colocasia esculenta (Taro) leaves, the maximum carbohydrate yield of 95 mg/g biomass (solubilized monomers-43.6 mg/g of biomass) and nutrient solubilization of 5.02 mg total nitrogen/g biomass was obtained with 5% ferric chloride treatment for 60 min. The results obtained showed that various hydrolyzing agents used in this study acted differently on different types of biomasses. Acetic acid worked best in hydrolyzing the algal biomass, and for the hydrolysis of Taro leaves, ferric chloride and nitric acid were effective. Statistical analysis showed that the chemical concentration was one of the prime factors for releasing P from algal biomass. For carbohydrate release from Taro leaves, either time or concentration, or both, were the prime factors that affected the carbohydrate release.

Valorization of date palm leaves for adsorptive remediation of 2,4-dichlorophenoxyacetic acid herbicide polluted agricultural runoff

Alarming rates of water contamination by toxic herbicides have prompted the need and attention for easy, efficient, and affordable treatment options with a touch of circular economy aspects. This study valorized date palm leaf (DPL) wastes into a valuable adsorbent for remediating agricultural wastewater polluted with 2,4-Dichlorophenoxyacetic acid (2,4-DPA) herbicide. The DPL precursor was modified with H2SO4 treatment and both biomass samples were characterized by various analytical techniques. Acid treatment modified the morphology, thermal, and textural properties of the final product (TDPL) while maintaining the structure and surface chemistry intact. Simulated wastewaters containing 2,4-DPA were subsequently treated using TDPL as an adsorbent. Optimum adsorption conditions of pH 2, dosage 0.95 g/L, shaking speed 200 rpm, time 120 min, and temperature 30 °C showed a good herbicide removal efficiency in the range of 55.1–72.6% for different initial feed concentrations (50–250 mg/L). Experimental kinetic data were better represented by the pseudo-second-order model, while the Freundlich isotherm was reliable in describing the equilibrium behavior of the adsorption system. Further, the thermodynamic analysis revealed that the adsorption occurred spontaneously, favorably, and exothermically. Plausible sorption mechanism involved electrostatic interactions, weak van der Waals forces, hydrogen bonds, and π-π interactions between the participating phases. Conspicuously, TDPL application to real-world situations of treating actual herbicide-polluted agricultural runoff resulted in a 69.4% remediation efficiency. Thus, the study demonstrated the valorization of date palm leaves into a valuable and industry-ready adsorbent that can sequester toxic 2,4-DPA herbicide contaminant from aqueous streams.

Effects of Alkali and Acid on the Solubility and Molecular Weight of Collagen Hydrolysates Extracted from Bovine Hide

Preparation of collagen hydrolysates with high molecular weight to meet its industrial demand is a crucial step for resource utilization of solid waste of animal skins/hides. However, it is very difficult to achieve both higher molecular weight and solubility of collagen hydrolysates through the traditional methods. In this study, we attempted to prepare bovine hide collagen hydrolysates with high molecular weight and solubility through the application of NaOH or different types of acid. Influences of the concentration of alkali and acid, hydrolysis temperature and time on the molecular weight and solubility were studied, respectively. The results showed that NaOH has a strong hydrolysis effect on bovine collagen, making it a suitable candidate for the preparation of collagen hydrolysates with medium or low molecular weight. Under these optimized NaOH treatment conditions, i.e., NaOH concentration of 0.13 mol/L, hydrolysis temperature of 60 - 70°C and time of 5 h, we achieved 96% of solubility for hide pieces and the molecular weight of collagen hydrolysates were in the range of 25 - 30 kDa. By contrast, the molecular weight of the hydrolysates prepared through H2SO4 hydrolysis method was higher than that of NaOH hydrolysis method. Under the optimized H2SO4 treatment conditions, i.e. H2SO4 concentration of 0.5 mol/L, hydrolysis temperature of 50°C and time in the range of 5 - 7 h, the solubility of hide pieces reached up to 80 - 97%. Additionally, in the H2SO4 hydrolysates, the proportion of macromolecular components with molecular weight of about 100 kDa was 41 - 55% and that of medium molecular components with molecular weight of about 20 kDa was 45 - 59%. This study showed that high solubility and high molecular weight collagen products can be obtained by H2SO4hydrolysis under specific conditions. Thus, this study provided a useful scientific method and process parameters to guide the controlling of molecular weight and the industrial application of collagen from waste on a bigger scale.

Fabrication of cellulose nanocrystals (CNCs) in choline chloride-citric acid (ChCl-CA) solvent to lodge antimicrobial activity

Surface-modified cellulose nanocrystals (CNCs) have gained substantial interest in industry. The renewability and abundance of the raw material to prepare CNCs make them a promising green material. In this study, two types of CNCs were prepared by sulfuric acid (H2SO4) and stepwise H2SO4 and choline chloride-citric acid (ChCl-CA) deep eutectic solvent-like (DES) treatments. The DES treatment led to esterification and further degradation of the CNCs. The obtained nanoparticles were distributed in size range of 50 nm to 500 nm and 20 nm to 70 nm for the H2SO4 and stepwise treatments, respectively. The effects of the nanoparticles on the mechanical properties, thermal stability, and antibacterial activity of poly(vinyl alcohol) (PVOH) were determined using a universal mechanical testing machine, thermogravimetric analysis (TGA), and the agar diffusion method. The results indicated that nanoparticles had good compatibility in PVOH at a concentration below 10%. The CNCs had greater effect on the mechanical properties and the thermal stability of films than the esterified CNCs. However, the CA modified CNCs showed more favorable antibacterial activity than the CNCs from H2SO4 treatment. Taking the mechanical properties, the thermal stability, and the antibacterial activity into consideration, 5% was selected as a suitable concentration for composite film preparation.

Reducing greenhouse gas emissions from pig slurry by acidification with organic and inorganic acids.

Methane (CH4) emission from pig slurry is a large contributor to the climate footprint of livestock production. Acidification of excreta from livestock animals with sulfuric acid, reduce CH4 emission and is practiced at many Danish farms. Possible interaction effects with other acidic agents or management practices (e.g. frequent slurry removal and residual slurry acidification) have not been fully investigated. Here we assessed the effect of pig slurry acidification with a range of organic and inorganic acids with respect to their CH4 inhibitor potential in several batch experiments (BS). After careful selection of promising CH4 inhibitors, three continuous headspace experiments (CHS) were carried out to simulate management of manure in pig houses. In BS experiments, more than <99% CH4 reduction was observed with HNO3 treatment to pH 5.5. Treatments with HNO3, H2SO4, and H3PO4 reduced CH4 production more than acetic acid and other organic acids when acidified to the same initial pH of 5.5. Synergistic effects were not observed when mixing inorganic and organic acids as otherwise proposed in the literature, which was attributed to the high amount of acetic acid in the slurry to start with. In the CHS experiments, HNO3 treatment reduced CH4 more than H2SO4, but increased nitrous oxide (N2O) emission, particularly when the acidification target pH was above 6, suggesting considerable denitrification activity. Due to increased N2O emission from HNO3 treatments, HNO3 reduced total CO2-eq by 67%, whereas H2SO4 reduced CO2-eq by 91.5% compared to untreated slurry. In experiments with daily slurry addition, weekly slurry removal, and residual acidification, HNO3 and H2SO4 treatments reduced CO2-eq by 27% and 48%, respectively (not significant). More cycles of residual acidification are recommended in future research. The study provides solid evidence that HNO3 treatment is not suitable for reducing CO2-eq and H2SO4 should be the preferred acidic agent for slurry acidification.

Determination of Dichlorodiphenyltrichloroethane (DDT) and metabolites residues in Gangetic mystus (Mystus cavasius) and Spotted Snakehead (Channa punctatus) of Bangladesh

A study was carried out to determine dichlorodiphenyltrichloroethane (DDT) and its metabolites in Gangetic mystus, Mystus cavasius and spotted snakehead, Channa punctatus. DDTs was extracted by QuEChERS method, cleaned-up by H2SO4 treatment and analyzed by GC with Electron Capture Detector. The calibration curves were linear over the range of the tested concentrations as shown by the fact that the correlation coefficients (r2) for the linearity range were 0.995-0.999. The detection limit was found to be 5ppb for DDTs and the quantification limit was 6.5ppb. Recoveries were found (70-130%); this is acceptable for fish samples according to standard methodology. The DDT and its metabolites were not detected in the liver of M. cavasius and C. punctatus. In this study, M. cavasius was found to contain detectable amount of residual targeted pesticides DDTs at 64.21 ppb in digestive tract, 75.23 ppb in gill, 119.82 ppb in gonad and 45.84 ppb in muscle. The C. punctatus residual targeted DDTs were at 8.42 ppb in digestive tract, 4.04 ppb in gill, 56.44 ppb in gonad and 23.15 ppb in muscle. However, this study shows the higher DDT and its metabolites were in the gonad of M. cavasius and C. punctatus. Bangladesh J. Zool. 49 (3): 393-402, 2021

Construction of chlorine doped graphitic carbon nitride nanodisc for enhanced photocatalytic activity and mechanism insight

The development of high-performance doped graphite carbon nitride (g-C3N4) by one-step method has always been potential and yet demanding. Here, we designed a novel Cl doped nanodisc structure g-C3N4 (Cl(CN)) by one step HCl treatment, without calcination and adding any precursors during the preparation procedure. The photocatalytic activities of samples were assessed toward the hydrogen (H2) generation and degradation of rhodamine B (RhB) under simulated solar irradiation, of which the hydrogen production efficiency and degradation efficiency of Cl(CN) were 4 folds and 2.18 folds that of g-C3N4 (CN), respectively. The overwhelming photocatalytic performance of Cl(CN) was attributed to the synergy effect between the unique nanodisc morphology with high surface area and the regulation of the band structure by the Cl element. To exclude the effect of protonation, the CH3COOH, H2SO4, HNO3, KCl, NaCl and NH4Cl treatments were introduced to compare with HCl treatment. The position of doped Cl and its influence on the band gap as well as electronic structure over g-C3N4 were investigated by the density functional theory (DFT). In addition, the photocatalytic mechanism of as-prepared samples was further investigated and discussed in detail. This work provided a green and facile protocol for highly active and reusable g-C3N4 that can address the environmental issuers and energy challenges.

Preparation of self‐healing hydrophobic coating and its anticorrosion property

AbstractIn this study, a composite coating of polytetrafluoroethylene (PTFE) and fluorinated alkyl silane (FAS, C16H19F17O3Si) is prepared on AISI 304 L stainless steel. Scanning electron microscope and X‐ray photoelectron spectroscopy are used to analyze the microstructure and chemical group changes of PTFE–FAS coating (PF coating) before and after sulfuric acid (H2SO4) corrosion and after heat treatment. In addition, differential scanning calorimeter is performed to study the thermodynamic properties of PF coating. The corrosion resistance of PF coating under the above conditions is tested by the electrochemical experiment. The results show that acid and abrasion treatments can reduce the hydrophobic properties of the coatings, and the damage caused by acid is more serious. Heat treatment can repair the hydrophobic properties of the coating damaged by acid and abrasion. In addition, PF coating has an excellent corrosion resistance, but after H2SO4 treatment, the protection efficiency (PE) decreases from 89.09% to 2.51%, indicating that the corrosion resistance of PF is severely damaged. However, PE of PF coating increases to 76.83% after heat treatment. This repair ability improves the corrosion resistance of the coating. At the same time, the related mechanism is also clarified.

Performance improvement induced by membrane treatment in proton exchange membrane water electrolysis cells

Hydrogen has been widely accepted as the best alternative energy carrier to store intermittent renewable energies. Proton exchange membrane water electrolysis (PEMWE) represents a promising technology to produce highly pure hydrogen with high efficiency and low footprint. While great progress has been made on components, materials and even fabrication processes, new materials or complicated processes still require refinement in the process of continuously improving PEMWE performance and durability. In this study, we demonstrate a facile treatment on membranes, aiming at improving cell performance at low costs. By adopting the hydration in DI water or 0.5 M H2SO4, or by varying the treatment sequence with the catalyst layer deposition, the PEMWE performance was tuned with the overpotential improvement as high as 50 mV at 2.0 A cm−2. The PEMWE cells after different treatments were characterized both ex-situ and in-situ, and the mechanism was also proposed. The H2SO4 treatment swelled the micro micelle structure of the Nafion membranes, resulting in a higher proton conductivity and better cell performance compared with those from DI water treatment. In addition, the treatment sequence also had great impact, and the treatment after the catalyst layer deposition would result in better performance due to the reduced resistance and better kinetics. Not only the types of membrane, but also the thickness should be measured and reported when tested, which is more critical when compared across the published works from different groups. This work could also provide a guideline for future membrane treatment and PEMWE cell testing.

Tamarind extract pretreatment: Valorization of sugarcane bagasse for cellulase production by Aspergillus flavus

Effective pretreatment is crucial for cellulase production from sugarcane bagasse. Pretreatment with tamarind extract could reduce the hazardous effect associated with chemical pretreatment. The present work investigated tamarind (Tamarindus indica) extract in combination with H2SO4 and thermal pretreatment of sugarcane bagasse for cellulase production by Aspergillus flavus. The sugarcane bagasse was pretreated with tamarind extract pH 2 and pH 4, followed by 1% H2SO4 and thermal treatment at 121°C for 15 min. The pretreatment slurry was analysed for reducing sugar while solid bagasse was analysed for weight loss. Aspergillus flavus grew on sugarcane bagasse under solid state fermentation and the Carboxy Methyl Cellulase (CMCase) and Filter Paper Assay (FPA) activities were compared on the various pretreatments. The pretreatments changed the visible morphology of the sugarcane bagasse observed by the swelling, fibrous appearance and colour change. Pretreatment slurry yielded highest soluble reducing sugar at 60.01 mg/ml in tamarind extract (pH 4/1% H2SO4 ) and highest weight loss of solids at 73.70% in tamarind extract (pH 2/1% H2SO4 /thermal 121°C). Aspergillus flavus performed better on tamarind extract (pH 2/1% H2SO4 ) by producing optimal CMCase and FPA activities at 0.100 U/ml and 0.409 U/ml respectively after 3 days of fermentation. Cellulase was maximally active at temperature of 50 °C. The tamarind extract pretreatment successfully proved to be an alternative organo-chemical pretreatment of sugarcane bagasse as evidenced by the physical properties, soluble reducing sugars and cellulase activities.&#x0D; Keywords: Aspergillus flavus, Cellulase, Pretreatment, Sugarcane bagasse, Tamarind extract

Effects of acid treatment on the physicochemical and functional properties of wheat bran insoluble dietary fiber

AbstractBackground and ObjectivesWheat bran is a by‐product of the wheat milling industry but most are used as animal fodder or discarded. To extend the applications of wheat bran, the structural, physicochemical, and functional properties of sulfuric acid‐modified wheat bran insoluble fibers (WBIDF) produced using 1%, 2%, 4%, and 8% H2SO4 and 1.5% potassium hydroxide were investigated.FindingsDue to cell wall disintegration, 1.0% and 2.0% H2SO4 treatments increased the concentration of soluble dietary fiber. Scanning electron microscopy indicated that acid treatment disrupted WBIDF structure, removed starch granules from the surface, and significantly reduced starch content. Higher H2SO4 concentrations increased WBIDF crystallinity due to hydrolysis of hemicellulose and amorphous cellulose. Acid treatment below 2% not only enhanced the water holding, water swelling, oil binding, and cation exchange capacities of WBIDF, but also increased cholesterol, sodium cholate, and glucose adsorption capacities and α‐amylase inhibition activity.ConclusionsAcid‐modified WBIDF has potential as a functional food ingredient.Significance and noveltyAcid treatment can be used to disrupt the microstructure of wheat bran to improve its functional properties. These findings can be utilized to improve the technological functionality of wheat bran as a high fiber ingredient for food applications.

Facile fabrication of highly flexible, porous PEDOT:PSS/SWCNTs films for thermoelectric applications

High-performance organic composite thermoelectric (TE) materials are considered as a promising alternative for harvesting heat energy. Herein, composite films of poly (3,4-ethyienedioxythiophene):poly(styrene sulfonate)/single-walled carbon nanotubes (PEDOT:PSS/SWCNTs) were fabricated by utilizing a convenient solution mixing method. Thereafter, the as-prepared hybrid films were treated using sulfuric acid (H2SO4) to further optimize the TE performance. Film morphological studies revealed that the sulfuric acid treated PEDOT:PSS/SWCNTs composite samples all possessed porous structures. Due to the successful fabrication of highly conductive networks, the porous nano-architecture also exhibited much more excellent TE properties when compared with the dense structure of the pristine samples. For the post-treated sample, a high power factor of 156.43 μW⋅m−1⋅K–2 can be achieved by adjusting the content of CNTs, which is approximately 3 orders of magnitude higher than that of the corresponding untreated samples (0.23 μW⋅m−1⋅K–2). Besides, the obtained films also showed excellent mechanical flexibility, owing to the porous nanostructure and the strong π–π interactions between the two components. This work indicates that the H2SO4 treatment could be a promising strategy for fabricating highly-flexible and porous PEDOT:PSS/SWCNTs films with high TE performances.

Pitting Corrosion Resistance and Electrochemical Properties of Equimolar CoCrFeMnNi and Non-Equimolar Alcocrfeni High-entropy Alloys

Equimolar CoCrFeMnNi high entropy alloy (HEA) exhibits excellent mechanical properties, but the corrosion resistance is relatively poor because of high Mn content. Thus, this study focused on Al addition and non-equimolar AlCoCrFeNi HEAs were fabricated. To investigate the effect of alloy composition on corrosion resistance, non-equimolar HEAs, Al8Co19Cr23Fe32Ni18 and Al25Co14Cr10Fe19Ni32, were fabricated by arc-melting. Their pitting corrosion resistance was studied by polarization in 0.1 M NaCl. Moreover, Al-containing HEAs have great potential to develop high corrosion resistant alloys by anodizing. Thus, the properties and the pitting corrosion resistance of passive oxide film formed by polarization from -0.55 to 0.5 VSCE in H2SO4 were also investigated.On the basis of the XRD results and surface images, Al8Co19Cr23Fe32Ni18 alloy was single phase alloy. On the other hand, equimolar AlCoCrFeNi and Al25Co14Cr10Fe19Ni32 alloys have multi-phase structures of Al and Ni rich phase and Cr and Fe rich phase. The pitting potential of Al8Co19Cr23Fe32Ni18 alloy was higher than that of equimolar CoCrFeMnNi alloy. After H2SO4 treatment, both alloys have apparent increase in their pitting potential. In the case of multi-phase alloy, Al25Co14Cr10Fe19Ni32 alloy has a lower pitting potential than that of equimolar AlCoCrFeNi alloy. After H2SO4 treatment, the Al and Ni rich phase was dissolved, and a Cr rich oxide layer was formed. This was likely to contribute the improvement of pitting corrosion of both AlCoCrFeNi and Al25Co14Cr10Fe19Ni32 alloys.

Improved effect of manure acidification technology for gas emission mitigation by substituting sulfuric acid with acetic acid

Animal manure is a significant source of ammonia, methane, hydrogen sulfide, and odor emissions. Manure acidification to pH 5.5 using sulfuric acid (H2SO4) is an approved method for reducing ammonia and methane emissions from barns and retaining bioavailable nitrogen in the slurry for subsequent field fertilization. However, the use of H2SO4 may increase the emission of malodorous sulfur compounds and reduces subsequent biogas production. In this study, we investigated if substituting a part of the H2SO4 treatment with acetic acid (CH3COOH) improves manure emissions. In two experiments, cattle manure was incubated for 11 days each and acidified daily with either i) H2SO4 (4M) or CH3COOH (4M), or ii) mixes of both acids (4M H2SO4 + 8M CH3COOH, in volume ratios of 75:25, 50:50, and 25:75) until pH 5.5. The emission of ammonia, methane, hydrogen sulfide, and volatile organic compounds (VOCs) was monitored continuously. At the end of both experiments, cumulative ammonia emission was reduced by 75% by H2SO4 and by 83% by CH3COOH, indicating that CH3COOH was more efficient. Acetic acid almost completely eliminated CH4 emission, while H2SO4 reduced CH4 emission by 89%. Furthermore, CH3COOH acidification resulted in lower odorant emissions compared to H2SO4. Based on the second experiment, we recommend using a high percentage of CH3COOH during the first days of acidification, followed by a mix containing at least 50% CH3COOH, to achieve a high mitigation efficiency with a lower emission of sulfur compounds compared to H2SO4 alone.

Fossil-like pollen grains for construction of UV-responsive photochromic and fluorogenic dual-functional film

Natural pollen, one of the most fascinating biological materials in existence, exhibits chemical modifications and tunable optical property in the process of fossilization. Herein, we firstly fabricated nature-based fossil-like pollen grains (F-PGs) with UV-responsive optical properties through a facile concentrated H2SO4 treatment. The F-PGs featured incomplete carbonization property while remaining the UV-active alkyl aliphatic groups, which could initiate the carbonylation of F-PGs surface under UV irradiation, thus endowing the distinct UV dose-dependent photochromic and fluorogenic dual-function of F-PGs. With the sustainable, easy-preparation and cost-effective advantages, the F-PGs were used to construct dual-functional films. The F-PG films presented high photochromic contrast (ΔE* = 32) to serve as smartphone-readable quick response code-patterned UV sensors, which indicated the highest reported cumulative dose of UV irradiation (108 J cm−2, equivalent to 10 days of exposure to sunlight). In addition, the UV-irradiated F-PG films with the fluorogenic property also showed wide applications in one-step and flexible photo-reduction of various metal ions to nanoparticles. Collectively, the novel fossil-like pollen grains and functional films pave the way for utilization of natural pollen for UV-responsive applications and provide a new insight for transporting the renewable biomass into photochromic and fluorogenic materials in the future.

Characteristics of Graphite Felt Electrodes Treated by Atmospheric Pressure Plasma Jets for an All-Vanadium Redox Flow Battery.

In an all-vanadium redox flow battery (VRFB), redox reaction occurs on the fiber surface of the graphite felts. Therefore, the VRFB performance highly depends on the characteristics of the graphite felts. Although atmospheric pressure plasma jets (APPJs) have been applied for surface modification of graphite felt electrode in VRFBs for the enhancement of electrochemical reactivity, the influence of APPJ plasma reactivity and working temperature (by changing the flow rate) on the VRFB performance is still unknown. In this work, the performance of the graphite felts with different APPJ plasma reactivity and working temperatures, changed by varying the flow rates (the conditions are denoted as APPJ temperatures hereafter), was analyzed and compared with those treated with sulfuric acid. X-ray photoelectron spectroscopy (XPS) indicated that the APPJ treatment led to an increase in O-/N-containing functional groups on the GF surface to ~21.0% as compared to ~15.0% for untreated GF and 18.0% for H2SO4-treated GF. Scanning electron microscopy (SEM) indicated that the surface morphology of graphite felt electrodes was still smooth, and no visible changes were detected after oxidation in the sulfuric acid or after APPJ treatment. The polarization measurements indicated that the APPJ treatment increased the limiting current densities from 0.56 A·cm−2 for the GFs treated by H2SO4 to 0.64, 0.68, and 0.64 A·cm−2, respectively, for the GFs APPJ-treated at 450, 550, and 650 °C, as well as reduced the activation overpotential when compared with the H2SO4-treated electrode. The electrochemical charge/discharge measurements showed that the APPJ treatment temperature of 550 °C gave the highest energy efficiency of 83.5% as compared to 72.0% with the H2SO4 treatment.

Extraction and Purification of Phosphorus from the Ashes of Incinerated Biological Sewage Sludge

Phosphorus depletion represents a significant problem. Ash of incinerated biological sewage sludge (BSS) contains P, but the presence of heavy metals (e.g., Fe and Al) is the main issue. Based on chemical characterization by SEM-EDS, ED-XRF and ICP-OES techniques, the characteristics and P content of bottom ash (BA) and fly ash (FA) of incinerated BSS were very similar. On BA, P extraction carried out in counter- current with an S:L ratio of 1:10 and H2SO4 0.5 M led to better extraction yields than those of a similar test with H2SO4 1 M and an S:L ratio of 1:5 (93% vs. 86%). Comparing yields with H2SO4 0.5 M (S:L ratio of 1:10), the counter-current method gave better results than those of the crossflow method (93% vs. 83.9%), also improving the performance obtained with HCl in crossflow (93% vs. 89.3%). The results suggest that the purification of the acid extract from heavy metals with pH variation was impractical due to metal precipitation as phosphates. Extraction with H2SO4 and subsequent treatment with isoamyl alcohol represented the best option to extract and purify P, leading to 81% extraction yields of P with low amounts of metals.

Production of activated biochar from Luffa cylindrica and its application for adsorption of 4-Nitrophenol

Activated biochar was prepared from dried Luffa cylindrica fruits as a convenient source of carbon-rich biomass. In this regard, a commonly practiced single-step H3PO4 pretreatment and combined H3PO4 and H2SO4 treatments before and after the pyrolysis were utilized for the production of loofah-derived biochar (LB) and sulfuric acid-treated LB (SLB). These biochars were compared in terms of physicochemical characteristics and the potential for removal of 4-Nitrophenol (4NP). It was indicated that the adsorption of 4NP was more efficient on SLB compared to LB with a Langmuir maximum monolayer adsorption of 436.6 mg/g vs 265.4 mg/g at 30 °C. Thermodynamic studies demonstrated that the adsorption process was endothermic and associated with entropy increase for both biochars. BET analysis showed that the surface area of LB and SLB were 28 and 46 times as high as that of non-activated carbonized loofah, respectively. Based on the analysis of the surface functional groups by FTIR spectroscopy and N2 adsorption-desorption experiments, pore filling and hydrogen bonding were suggested as major factors contributing to the high performance of the prepared adsorbents. Other notable mechanisms for 4NP removal were π-interactions and degradation. The possibility of reusing the adsorbents and recycling the waste sulfuric acid was also investigated, demonstrating the commercial attractiveness and environmental friendliness of the produced biochars.

Preparation of a novel poly (ether ether ketone) self-reinforced paper appropriate for harsh conditions

It remains a challenge to prepare special engineering paper with excellent mechanical properties, high temperature resistance and chemical resistance. The emergence of high-performance fiber provides support for the technical progress of special engineering paper. Herein, a novel method to obtain a novel self-reinforced poly (ether ether ketone) (PEEK) composite paper (SR-DI-PEEK/paper) by vacuum filtration, impregnation and hot pressing. Specially, PEEK fibers were used as the skeleton fiber and a small amount of aramid pulp was added as the decanted fiber. By optimizing the process of SR-DI-PEEK/paper preparation, the best mechanical properties of SR-DI-PEEK/paper was presented. Compared with the composite paper prepared with Phenolic solution (PF-PEEK/paper) and Polyimide solution (PI-PEEK/paper), the mechanical properties of SR-DI-PEEK/paper was significantly improved. In particular, when the concentration of impregnation was 3 wt%, the tensile index of SR-DI-PEEK/paper reached 51.10 N m g−1 (tensile strength 47.16 kN m−1), which is 16.48 times than that of the un-impregnated PEEK/paper (2.86 kN m−1). SR-DI-PEEK/paper also exhibited excellent chemical resistance among acid, alkali, and polar solvents, while the tensile index maintained 96.3% after 40 wt% H2SO4 treatment. Besides, SR-DI-PEEK/paper showed superior thermal performance, while the temperatures corresponding to the weight loss of 5% were 574 °C.

Synergetic effect of functionalized graphitic carbon nitride catalyst and ultrasound in aqueous medium: An efficient and sustainable synthesis of 1,3,5-trisubstituted hexahydro-1,3,5-triazines

Graphitic carbon nitride (g-C3N4) was synthesized by melamine and functionalized by H2SO4 treatment using ultrasound assisted method. As prepared functional carbon nitride (Sg–C3N4) was characterized by diverse analytical technique and used as a reusable catalyst for the preparation of 1,3,5-trisubstituted hexahydro-1,3,5-triazine derivatives using aryl amines and formaldehyde as a reactant in aqueous media under ultrasound irradiation. Different comparable experiments shows that the SO3H functionality of the catalyst show a decisive function in this metal-free approach. In contrast to the conventional process, Sg–C3N4 exhibit 21-fold higher catalytic activity under ultrasound irradiation. Protocol shows significant synergistic effect of ultrasound irradiation with water and catalyst over the reaction. With this synergetic methodology we have found that the reactions are cleaner, highly selective, easy work-up procedure and having appreciable economic advantage. It's give us a chance to make the whole procedure green starting from the beginning.