Removal Rate Of Acid Research Articles

The impact of benzoic acid and lactic acid on the treatment efficiency and microbial community in the sulfur autotrophic denitrification process.

Nitrate poses a potential threat to aquatic ecosystems. This study focuses on the sulfur autotrophic denitrification mechanism in the process of water culture wastewater treatment, which has been successfully applied to the degradation of nitrogen in water culture farm effluents. However, the coexistence of organic acids in the treatment process is a common environmental challenge, significantly affecting the activity of denitrifying bacteria. This paper aims to explore the effects of adding benzoic acid and lactic acid on denitrification performance, organic acid removal rate, and microbial population abundance in sulfur autotrophic denitrification systems under optimal operating conditions, sulfur deficiency, and high hydraulic load. In experiments with 50 mg·L-1 of benzoic acid or lactic acid alone, the results show that benzoic acid and lactic acid have a stimulating effect on denitrification activity, with the stimulating effect significantly greater than the inhibitory effect. Under optimal operating conditions, the average denitrification rate of the system remained above 99%; under S/N = 1.5 conditions, the average denitrification rate increased from 88.34% to 91.93% and 85.91%; under HRT = 6h conditions, the average denitrification rate increased from 75.25% to 97.79% and 96.58%. In addition, the addition of organic acids led to a decrease in microbial population abundance. At the phylum level, Proteobacteria has always been the dominant bacterial genus, and its relative abundance significantly increased after the addition of benzoic acid, from 40.2% to 61.5% and 62.4%. At the genus level, Thiobacillus, Sulfurimonas, Chryseobacterium, and Thermomonas maintained high population abundances under different conditions. PRACTITIONER POINTS: Employing autotrophic denitrification process for treating high-nitrate wastewater. Utilizing organic acids as external carbon sources. Denitrifying bacteria demonstrate high utilization efficiency towards organic acids. Organic acids promote denitrification more than they inhibit it. The promotion is manifested in the enhancement of activity and microbial abundance.

Novel Technologies for Butyric Acid Fermentation: Use of Cellulosic Biomass, Rapid Bioreactor, and Efficient Product Recovery

Butyric acid, a four-carbon fatty acid, is an important industrial chemical and feedstock. To produce this chemical, a control fermentation was run with a 126.5 g.L−1 glucose concentration in the feed medium. In this medium, the strain produced 44.8 g.L−1 total acid with a productivity of 0.23 g.L−1h−1 and a yield of 0.41 g.g−1. The strain (Clostridium tyrobutyricum ATCC 25755) was also able to utilize glucose and xylose simultaneously with similar fermentation performance. The culture was also used to produce butyric acid from wheat straw hydrolysate (WSH) employing a hot water pretreatment. In a batch system, the strain resulted in a productivity and yield of 0.27 g.L−1h−1 and 0.44 g.g−1, respectively, which was an improvement over the use of glucose or xylose alone or mixtures of both. To improve reactor productivity, a membrane cell recycle bioreactor was used which resulted in a productivity of 1.89 g.L−1h−1. This productivity was 822% of that achieved in the glucose or xylose batch fermentation. Furthermore, a butyric acid recovery method was developed using XAD-4 adsorbent resin. In this system, up to 206.1 g.L−1 of butyric acid was used in the feed and, as a result of the quick adsorption, the residual butyric acid concentration was 29.5 g.L−1. In this experiment, the rate of acid removal of 1059.4 g.L−1h−1 was achieved.

Application of carbon nitride nanosheets for adsorption of various humic substances from aqueous solutions

Humic substances (HSs) cause serious problems such as membrane fouling and disinfection by-products. Particularly, HSs as the main UV-quenching substances in landfill leachate pose great challenges. In this study, we evaluated the application of carbon nitride nanosheets (CN-Ns) for adsorption of various HSs, as well as leachate nanofiltration concentrates (LNCs). The characterization revealed that as increasing thermal oxidation temperature, the properties of CN-Ns were affected, such as morphology, porosity, and crystallinity. The surface area of CN-N at 575 °C (CN-N-575) was 145.3 m2·g−1, resulting in an enhanced adsorption performance. The adsorption capacity of CN-N-575 for lignite humic acid (LHA) and soil fulvic acid (SFA) was considerably greater than that of bulk CN; the maximum adsorption amounts of LHA and SFA were 143.11 and 63.27 mg C·g−1, respectively. Upon adsorption, the removal rate of LHA and Elliott soil humic acid was about 90 %. Among HSs and LNCs, the humic-like components showed superior affinity; in some cases, the removal rate reached 100 %. The adsorption preference of aromatic compounds in HSs and LNCs was ascribed to π-electron interactions. The adsorption of LHA was more pH-dependent than that of SFA, attributed to the interactions (electrostatic, hydrogen bonding, and complexation) along with a specific conformation effect. The findings proved the great potential of CN-Ns in HSs adsorption, especially in the treatment of landfill leachate.

Adsorption of perfluoroalkyl acids on granular activated carbon supported chitosan: Role of nanobubbles

The safety threat posed by Perfluoroalkyl acids (PFAAs) in drinking water is a growing concern. In this study, we loaded chitosan (CS) on granular activated carbon (GAC) to adsorb PFAAs, and we explored the role of nanobubbles in the adsorption process through experiments and density functional theory (DFT) calculations. Compared with GAC, we found that the use of the composite adsorbent (CS/GAC) enhanced the removal rate of perfluorooctanoic acid by 136% with the assistance of nanobubbles. PFAAs with different chain lengths have different adsorption mechanisms owing to surface activity differences. PFAAs with longer C–F chains can be directly enriched with amino groups on the CS or air–water interface on composite adsorbents. Additionally, PFAAs can be enriched with nanobubbles in solution to form nanobubble–PFAA colloids, which are adsorbed by protonated amino groups on CS through electrostatic interactions. We found that PFAAs with shorter C–F chains are less affected by nanobubbles, and DFT calculations indicated that the adsorption of short-chain PFAAs is mainly affected by electrostatic interactions. We also proved that the electrostatic interactions between CS and PFAAs are mainly derived from the abundant protonated amino groups.

Photocatalytic destruction of stearic acid by TiO2 films: Evidence of highly efficient transport of photogenerated electrons and holes

The oxidation of stearic acid (SA) by ambient air, photocatalysed by a TiO2 film, a common test for self-cleaning glass, often exhibits a rate of stearic acid removal, rSA, which is proportional to the fraction of UV light absorbed, which suggests that the transport of both photogenerated electrons and holes from the bulk to the surface is very efficient. This electron, hole transport (EHT) model is tested to the extreme using highly absorbing, absorbance ≫ 2, mesoporous (sol-gel) and microporous (P25) TiO2 films, ca. 0.5–1 μm thick, coated with a layer of SA. Scanning electron micrographs of these films show them to comprise closely connected clusters, which themselves comprise a network of primary photocatalytic particles. Each film produced identical [SA] vs irradiation time decay profiles when irradiated from the front or the back, even though in the latter case the UV irradiance reaching the photocatalyst particles in contact with the SA layer is at least 1000 times lower than the incident irradiance. These results suggest the transport of the photogenerated holes, and most likely electrons too, in these films is very efficient. When the SA layer is replaced with an Ag photocatalyst indicator ink, Ag paii, on a P25 TiO2 film, and irradiated from the back, the ink changes colour quickly due to the reduction of Ag+ in the ink, indicating that the transport of photogenerated electrons through the film is also efficient. The same effect is demonstrated using highly absorbing, and scattering, films of rutile TiO2, ZnO and WO3, thereby suggesting the EHT model is a general feature of networked nanoparticle films. The limitations of the EHT model, and how it differs from the commonly cited antenna model, are discussed along with the relevance of these findings with regard to self-cleaning glass.

Removal of acetic acid from aqueous post‐fermentation streams and fermented beverages using membrane contactors

AbstractBACKGROUNDThe removal of volatile organic acids from aqueous post‐fermentation wastewater streams and spoiled fermented liquid food was investigated using hollow‐fiber membrane contactors. Acetic acid, being the most common volatile acid in post‐fermentation products, was used to prepare acidic feed solutions. 1200–4000 ppm of aqueous acetic acid solutions with and without ethanol were prepared to assess the acid removal. Aqueous acetic acid solutions were used as model wastewater, while ethanol was included in the feed solutions to simulate the fermented beverages. Furthermore, the experiments were carried out using real spoiled wine to remove the excess acid. The feed solution was circulated through the shell side of the membrane contactor, while a reactive stripping solution of NaOH was circulated on the lumen side. Thus the acetic acid was transferred to the stripping solution by chemical absorption.RESULTSThe effect of several process parameters including feed and stripping solution concentrations, temperature and solution flow rates on acid removal rate was investigated. Temperature had the most important effect on mass transfer. Experiments showed that acetic acid can be removed from aqueous solutions and recovered in the stripping phase efficiently. Up to 86% of the acetic acid could be removed from the feed solution.CONCLUSIONThis process is found to be effective for volatile organic acid removal from both industrial aqueous post‐fermentation waste streams and spoiled fermented liquid food. The theoretical model developed for the acetic acid transfer allows a flexible and predictable design of the system for further scale‐up studies. © 2022 Society of Chemical Industry (SCI).

A non-specific surface area dominated catalytic ozonation with CuO modified β-MnO2 in efficient oxalic acid degradation

In this paper, a series of copper oxide supported manganese dioxide (CuXMnT) composites were prepared by the hydrothermal and deposition precipitation methods. The effects of different hydrothermal temperatures (100 °C–180 °C) and copper doping amounts (1–10 mM) on the structural and physicochemical properties of CuXMnT composites were systematically investigated. The BET, SEM, and XRD characterizations revealed that the CuXMnT composites exhibited a typical rod-like structure. Besides, with the increscent hydrothermal temperature, the BET specific surface area decreased and the crystal form of the composites changed from α-MnO2 to β-MnO2. The Cu1Mn180 with low specific surface area (3.277 m2 g−1) exhibited the splendid catalytic ozonation activity and the oxalic acid (OA) removal rate reached 87.5% in O3/Cu1Mn180 process compared with single ozonation (3.2%). Additionally, it was noteworthy that the excellent catalytic performance of Cu1Mn180 (91.8% of OA removal rate) at pH 3.0 was resulted from the electrostatic adsorption. While, the complexation played a vital role for OA degradation at pH 6.0 and 9.0 with the OA removal efficiencies of 87.5 and 70.3% within 30 min, respectively. Furthermore, Cu1Mn180 could obtain more than 90.9% of OA removal rate during multiple consecutive cycles, representing the satisfactory stability and reusability. Moreover, the multivalent Mn, the structural oxygen species, and Cu species played the key roles for OA degradation in O3/Cu1Mn180 process at pH 6.0 via the TEM, ESR, XPS and O2-TPD characterizations. Overall, the results presented a promising alternative material for efficient catalytic ozonation application in water.

Study on the Synergistic Extraction of Lithium from Spent Lithium Cobalt Oxide Batteries by Molten Salt Electrolysis and Two-Step Precipitation Method

With the continuous development of society, the number of spent lithium-ion batteries has also increased, and the recovery of valuable metals such as Ni, Co, and Li has become the main research direction of many scholars. In this paper, the extraction process of lithium that enters the molten salt after LiCoO2 electrolysis is studied. Oxalic acid and phosphate are added to molten salt containing lithium ions to realize the two-part precipitation method to extract lithium. The influence of pH value, temperature, reaction time, and oxalic acid (or phosphate) addition on the process of oxalic acid calcium removal and phosphate lithium precipitation is analyzed. The results show that the calcium removal rate of oxalic acid has reached 99.72% (Initial conditions: PH = 7.0, T = 70 °C, t = 1.5 h, n(H2C2O4):n(Ca2+) = 1.2:1). The precipitation of Li3PO4 obtained in the phosphate extraction experiment of lithium is as high as 88.44% (Initial conditions: PH = 8.0, T = 70 °C, t = 1.5 h, n(actual dosage of Na3PO4):n(theoretical dosage of Na3PO4) = 1.2:1). The obtained lithium phosphate crystals show regular spherical particles, which can be seen by SEM.

Experimental study on lowering oleic acid value and peroxide value of camellia sinensis by scraping film molecular distillation

Camellia oil is a kind of natural product with high added value. In the process of production, processing, and transportation, acidic substances and peroxides that reduce the quality of oil are produced. In this paper, it was refined by scraping membrane molecular distillation device. The factors affecting the molecular distillation results were analyzed and studied through a single factor experiment and orthogonal experiment. On the surface of the experiment, the optimal process parameters were as follows: the temperature was 190℃, the pressure was 1 Pa, the scraping speed was 300r/min, and the feed amount was 900g/h. Under this condition, the acid value in camellia oil decreased from 2.67mgKOH/g to 0.19mgKOH/g, and the free fatty acid removal rate was 92.88%. The peroxide value decreased from 16.78mmol/kg to 1.03mmol/kg, and the peroxide removal rate was 93.86%. The experimental results showed that the surface of the scraping membrane molecular distillation equipment could meet the national standard of acid value and peroxide value under the appropriate technological parameters, and there was no solvent residue, which was a safe physical purification process.

The adsorption removal of tannic acid by regenerated activated carbon from the spent catalyst of vinyl acetate synthesis

Activated carbon can remove humic acid organic pollutants to reduce trihalomethanes carcinogens generated in the chlorination disinfection process. In this study, regenerated activated carbon (RAC) was recycled from the spent catalyst of vinyl acetate synthesis via a thermal regeneration method. The influences of regeneration temperature and time on the regeneration rate and iodine adsorption value of the RAC samples were determined, the nitrogen adsorption isotherms and pore structure characteristics of RAC samples were characterised, and the effects of RAC additive amount, pH, adsorption temperature, and time on tannic acid removal rate were investigated. Results indicated that regeneration time and temperature presented pronounced influences on the regeneration rate and iodine adsorption performance of RAC samples. For the RAC sample optimally prepared at 900 °C for 2 h, the iodine adsorption value, BET surface area, and the regeneration rate were 817 mg/g, 1346 m2/g, and 65.9%, respectively. Under the optimal conditions including RAC additive amount of 3.5 g, temperature of 25 °C, adsorption time of 200 min and pH of 4.0, and tannic acid concentration of 50 mg/L, the tannic acid removal rate reached 89.96%. The adsorption kinetic characteristics for tannic acid onto RAC matched to Pseudo-second-order model, meanwhile the analysis of Boyd dynamic equation and Intraparticle diffusion model denoted the absorption process was mainly controlled by film diffusion. This work provides a technology aiming at the joint treatment of hazardous waste resources, which involve the regeneration activated carbon from spent catalysts and the absorption removal of tannic acid organic pollutants.

Performance and community structure dynamics of microbial electrolysis cells operated on multiple complex feedstocks

BackgroundMicrobial electrolysis is a promising technology for converting aqueous wastes into hydrogen. However, substrate adaptability is an important feature, seldom documented in microbial electrolysis cells (MECs). In addition, the correlation between substrate composition and community structure has not been well established. This study used an MEC capable of producing over 10 L/L-day of hydrogen from a switchgrass-derived bio-oil aqueous phase and investigated four additional substrates, tested in sequence on a mature biofilm. The additional substrates included a red oak-derived bio-oil aqueous phase, a corn stover fermentation product, a mixture of phenol and acetate, and acetate alone.ResultsThe MECs fed with the corn stover fermentation product resulted in the highest performance among the complex feedstocks, producing an average current density of 7.3 ± 0.51 A/m2, although the acetate fed MECs outperformed complex substrates, producing 12.3 ± 0.01 A/m2. 16S rRNA gene sequencing showed that community structure and community diversity were not predictive of performance, and replicate community structures diverged despite identical inoculum and enrichment procedure. The trends in each replicate, however, were indicative of the influence of the substrates. Geobacter was the most dominant genus across most of the samples tested, but its abundance did not correlate strongly to current density. High-performance liquid chromatography (HPLC) showed that acetic acid accumulated during open circuit conditions when MECs were fed with complex feedstocks and was quickly degraded once closed circuit conditions were applied. The largest net acetic acid removal rate occurred when MECs were fed with red oak bio-oil aqueous phase, consuming 2.93 ± 0.00 g/L-day. Principal component analysis found that MEC performance metrics such as current density, hydrogen productivity, and chemical oxygen demand removal were closely correlated. Net acetic acid removal was also found to correlate with performance. However, no bacterial genus appeared to correlated to these performance metrics strongly, and the analysis suggested that less than 70% of the variance was accounted for by the two components.ConclusionsThis study demonstrates the robustness of microbial communities to adapt to a range of feedstocks and conditions without relying on specific species, delivering high hydrogen productivities despite differences in community structure. The results indicate that functional adaptation may play a larger role in performance than community composition. Further investigation of the roles each microbe plays in these communities will help MECs to become integral in the 21st-century bioeconomy to produce zero-emission fuels.

Treatment of Wastewater Containing Naphthalene Sulfonic Acid by Persulfate Oxidation

Naphthalene sulfonic acid is widely used in the industry. In this study, H acid (1-amino-8-naphthol-3,6-disulfonic acid) was selected as the characteristic pollutant, and the alkali-activated, thermally-activated, and alkali-heat-complex activated persulfate (PS) degradation of H acid was analyzed. The effects of other factors on complex activation were discussed. The experimental results showed that with the addition of calcium oxide from 0 to 1250 mg ·L-1, the H acid removal rate increased from 42.5% to 82.8% after 100 min of reaction. The removal rate of H acid in thermal activation is positively correlated with temperature. The removal rate of H acid at 65℃ is 77.5%, and the apparent activation energy is 37.85 kJ ·mol-1. Although composite activation speeds up the reaction rate, rapid degradation of PS at high temperatures caused the degradation of H acid to be worse than single thermal activation. The change in PS concentration did not significantly improve the removal rate of H acid, and the inorganic anion CO32- was not conducive to the removal of H acid. Compound activation is not ideal for the mineralization of H acid, and the removal rate of TOC is only 16%. GC-MS identified the degradation product of H acid as terephthalic acid, indicating that phthalic anhydride may be formed after the naphthalene ring is opened.

The Investigation of Oxidation Flocculation Characteristics of Ferrate Solution

The fresh ferrate solution was prepared by in situ electrolysis method and directly added into the simulated surface micro-polluted water to proceed purification and pretreatment process. To explore the influence on the dosage of ferrate and pH of raw water, the simulated water sample was treated by single factor change coagulation experiment. Combining with turbidity, ammonia nitrogen, humic acid removal rate as the judgment index, and the fractal dimension of floc was calculated by using the platform of floc morphology analysis, the optimal dosage of the ferrate solution and reaction pH range were confirmed. This work revealed profoundly the correlation of turbidity, ammonia nitrogen, humic acid removal rate and flocculation fractal dimension.

Synthetic NiO catalyst-assisted peroxymonosulfate for degradation of benzoic acid from aqueous solution.

A heterogeneous NiO catalyst was prepared by a precipitation process using nickel nitrate with oxalic acid and tested for heterogeneous oxidation of benzoic acid (BA) in the presence of peroxymonosulfate (PMS). It was found that the synthetic NiO is highly effective in heterogeneous activation of PMS to produce sulfate radicals ( ) and hydroxyl radicals (· OH), and also presents stable performance in the heterogeneous activation of PMS for BA degradation. Physicochemical properties of the NiO catalyst were characterized by several techniques, such as thermogravimetric analysis, Brunauer-Emmett-Teller, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. It was found that NiO and NiOOH were formed on the synthetic NiO catalyst and were stably distributed on the catalyst surface. Nearly 95% decomposition could be achieved in 30min at the conditions of 500ml 20μM BA solution, 0.25g catalyst, and [PMS]:[BA]=30:1. The heterogeneous reactions, the effects of PMS concentration, and catalyst dosage on the BA degradation were investigated. The heterogeneous BA degradation reactions followed first-order kinetics. Additionally, quenching experiments proved that the dominant radical in the solution was · OH. The experiments results also showed that this approach is effective for the degradation of many other pollutants (such as tetracycline hydrochloride, 2, 4-dichlorophenol, Acid orange 7, rhodamine B, and methyl red). PRACTITIONER POINTS: A novel NiO material was fabricated for degradation of benzoic acid. The synthetic NiO catalyst comprised active NiO and NiOOH. The main radical for benzoic acid removal rate was · OH. A plausible mechanism for catalyzed degradation of the benzoic acid was proposed.

Evaluation of Deodorization Capabilities, Morphologies, and Thermal Stabilities of Baking Soda, Charcoal, Coffee, and Green Tea for Kimchi Packaging Application

We evaluated the applicability of baking soda, charco‘al, coffee, and green tea as a natural deodorant in Kimchi packaging. Moreover, to evaluate the potential usage of these deodorants in packaging materials and confirm their applicability in high-temperature melt-extrusion processing, the thermal stabilities of the deodorants were investigated, and heat-treated deodorants were evaluated in terms of the deodorizing function compared with non-treated deodorants. Aroma patterns were decreased after deodorizing treatment with all-natural deodorants. Dimethyl disulfide, methyl trisulfide, and diallyl disulfide, the most significant odorous Volatile organic compounds (VOCs) of Kimchi, decreased after treatment with the deodorants. In particular, baking soda and charcoal showed the highest efficiency in removing odorous compounds and VOCs from Kimchi, even after high-temperature processing. The acetic acid removal rates for both baking soda and charcoal were 99.9±0.0%. The heating process increases the deodorizing effects of baking soda. Sensory evaluation results showed that there is a significant increase (p < 0.05) in the overall preference for Kimchi samples packaged with charcoal and baking soda. This study provides useful information for the deodorization effects of natural deodorants for Kimchi smell and their applicability for packaging materials.

Study on deacidification process of waste internal combustion engine oil under the action of ultrasound

Internal combustion engine oil must be replaced periodically because it deteriorates during use, owing to the formation of oxidized species, particularly organic acids. The oil can be regenerated by removing the acids through alkali washing and neutralization. However the neutralization forms soaps that can cause significant emulsification that decrease the rate of acid removal. We have found that the washing process can be enhanced by using ultrasound, which produces strong shock waves and cavitation that increase the rates of diffusion and mass transfer, leading to an increased rate of deacidification. Our experiments show that a binary base composed of 58 wt% alum and 1.8 wt% diethylamine works well at a deacidification temperature of 50 °C, ultrasonic power of 800W, deacidification reaction time of 18 min. The extent of deacidification can be as high as 88% at 1.5 h.

Alkalinization of acid whey by means of electrodialysis with bipolar membranes and analysis of induced membrane fouling

An issue of acid whey processing, well known in the dairy industry, is its high amount of lactic acid, a key feature that hampers acid whey industrial utilization. As a result, dried products of acid whey treatment possess a number of undesirable properties such as elevated acidity, hygroscopicity and caking. In the present study, electrodialysis with bipolar membranes (EDBM) was used to alkalinize acid whey at laboratory scale. Two alternative configurations of electrodialysis cells were designed, where the whey stream was directly connected to the bipolar membrane generating hydroxide ions. pH of acid whey was raised up to 6.5. The above said pH adjustment corresponded to 25% lactic acid removal rate and 24–34% demineralization rate. The operation of EDBM, although efficient, induced fouling on the anion-exchange side of bipolar membranes after acid whey alkalinization. A complex analysis of membranes after whey processing was conducted. The analysis of whey precipitate and membrane fouling revealed 13 and 7% protein content in respective dried samples. Membrane fouling displayed minor protein content; thus, mineral fraction was likely to be dominant in the fouling matter.

Integration of a liquid membrane in Taylor flow regime with a fermentation by Lactobacillus casei ATCC 393 for in-situ lactic acid removal

A new type of liquid membranes called liquid membrane in Taylor flow was integrated to a lactic acid fermentation, using Lactobacillus casei ATCC 393, for lactic acid removal during fermentation. The performance in terms of lactic acid production of the hybrid batch system is compared to a conventional batch fermentation. Lactic acid removal rate increases proportionally with the LA concentration within the fermenter. The lactic acid, the biomass production and the LA productivity in the hybrid system increased by 41.8, 12 and 26.6%, respectively, as compared to the conventional batch fermentation. However, toxicity effects reduce LA to glucose yield in 15.9% as compared to conventional fermentation. Liquid membranes in Taylor flow results promising for enhancing batch and continuous fermentation processes by a hybrid system.

Optimization of deacidification for concentrated grape juice.

Excessive organic acids in grape juice will not only result in poor taste but will also cause turbidity and sedimentation. Tartaric acid exerts the most significant acidity among all organic acids in grape juice. In this study, we used tartaric acid as the main target and anion‐exchange resin to remove tartaric acid from concentrated grape juice. Factors influencing the removal process were optimized by liquid chromatography with ultraviolet detection and statistical analysis for optimal deacidification of concentrated grape juice. Use of the anion‐exchange resin 335 treat the concentrated grape juice at a ratio of 1:6 (2:11.98) at 15.57°C for 4.35 hr. The tartaric acid removal rate reached 69.01%; the anion‐exchange resin 335 demonstrated the best removal effect.

In-situ pyrolysis of Enteromorpha as carbocatalyst for catalytic removal of organic contaminants: Considering the intrinsic N/Fe in Enteromorpha and non-radical reaction

An environmentally friendly, facile, and economical Fe/N co-doped carbonaceous material (Fe-N@C) was prepared by the in-situ pyrolysis of Fe/N rich Enteromorpha biomass for peroxymonosulfate activation and organic contaminants degradation. Results indicated that Enteromorpha-based catalysts prepared at high pyrolysis temperature displayed some highly graphitic nanosheets with rich nitrogen doped. The graphitic N derived from the intrinsic N in Enteromorpha showed the high correlation with the paracetamol (PCM) removal rate; this was confirmed by the Density Functional Theory (DFT) calculation, showing the high adsorption energy (ΔEads, −2.62 eV) of PMS molecular adsorbed onto the graphitic N area. A weak correlation between the PCM removal rate and adsorption capacity was also observed, revealing that the PCM catalytic reaction could be greatly accelerated after the pre-adsorption. It was interesting that the intrinsic Fe in Enteromorpha did not affect the PCM degradation, but PCM removal rate of acid treated Fe-N/C was improved as more active sites were formed after the Fe extraction by acid treatment. Both the radical pathways of O2− and non-radical 1O2 generated in the Fe-N@C/PMS system were the primary mechanisms for the PCM degradation, which was consistent with the Fukui function values of f° and f- based on the DFT calculation. In addition, high stability of the carbon-based catalysts was observed after three runs and calcinating regeneration, which showed the promising applications for environmental remediation.