Reagent Dosage Research Articles

Gas hydrate nucleation and growth in the presence of water-soluble polymer, nonionic surfactants, and their mixtures

We investigated the effect of mixtures of commercial nonionic surfactants Sintanol ALM-7 (A7), Sintanol ALM-10 (A10), Surfynol 465 (S6), Surfynol 485 (S8), and well-known kinetic hydrate inhibitor Luvicap 55W (sample P) on nucleation and growth of sII gas hydrate. The ramp method (cooling at a constant rate of 1 °C × h−1) was employed to determine hydrate onset temperature and subcooling of individual and mixed samples. The dosage of reagents varied within 0.25–1.0 mass% range. A7 and A10 were tested at concentrations of 1.6∙10−4–2.5∙10−3 mass% (about or lower than CMC) as well. All surfactants were found to be weak antinucleators of gas hydrates. The inhibition performance of the surfactants was significantly lower in comparison with Luvicap 55W. We observed that ethoxylated fatty alcohols (A7 and A10) at low concentrations demonstrated a hydrate-inhibiting action at nucleation and growth stages.The Luvicap 55W – surfactant mixtures were tested as KHIs with a total dosage of 0.5 mass%, and in the ratio of 1:1, 1:2, and 1:5. Several mixed samples (1:1 P + A10), (1:2 P + A10), (1:2 P + S6) have demonstrated the same or higher efficacy in inhibition of hydrate nucleation than pure KHI. The results obtained indicate the presence of a synergistic effect of kinetic inhibition of gas hydrate with mixtures of the polymer and ethoxylated nonionic surfactants. Among the mixtures, the best results were obtained for the sample (1:2 P + S6). Surfynol 465 is characterized by high solubility in water, low foaming (compared to other surfactants), and lower cost than vinyl lactam-based KHI. Thus, the Surfynol 465 is a promising synergist for the vinyl lactam polymeric KHI and allows reducing the dosage of the expensive polymer.

Optimization and evaluation of the method for the determination of the manganese content in manganese ores and concentrates as described in ISO 4298:1984.

It has been 36years since ISO 4298:1984 was published, yet the role of sodium pyrophosphate in the oxidation of manganese(II) by potassium permanganate in this standard has not been fully recognized. The sample and reagent dosages exceed the actual detection needs, which creates challenges in the test operation and waste liquid treatment. In this study, a more scientific expression for the principle and reaction and the dosage of pyrophosphate in ISO 4298:1984 are discussed. The pyrophosphate ligand is involved in the oxidation of manganese(II) by potassium permanganate, and plays a role in preventing Mn(II) precipitation or Mn(III) dismutation during the whole reaction. The most appropriate amount of saturated sodium pyrophosphate is 150mL for the test of manganese ores and concentrates with manganese content from 15% to 60%. The method developed by reducing sample size and reagent consumption was evaluated with ten certified reference materials, showing high accuracy and meeting the analytical performance requirements. These results can provide technical support for the revision of ISO 4298:1984. Graphical abstract.

Mussel-inspired structure evolution customizing membrane interface hydrophilization

Advanced energy-water systems demand fabrication of high-performance water purification membranes. Polymeric membranes are typically hydrophobic, not amenable to conventional surface functionalization methods. Mussel adhesive proteins have inspired numerous adhesive polymer coatings via the structure-function simulation. Nonetheless, research about maximizing membrane interface hydrophilization and relevant concept guidance are still far from enough. Here, we put forward a “split-and-adjust” concept and proof it using a simplified catechol/silane biomimetic composite coating system for boosting interface hydrophilization. As a result, the hierarchically nanostructured silicified hydrophilic membranes were fabricated. The hydrophilicity could be tailored via tuning reagent dose recipes. The as-fabricated hydrophilic membrane presented benign fouling resistance in oil-in-water emulsion filtration tests. In addition, the rinsing examination indicates the coating is well stabilized. The as-developed “split-and-adjust” concept for the composite coating system provides promising guidance to broaden and optimize the customized biomimetic interface functionalization toolbox.

Wastewater treatment by coagulatıon wıth countercurrent sludge return

Industrial wastewater contains pollutants that do not oxidize under the biological wastewater treatment conditions of populated areas. The treatment of wastewater containing persistent organic substances can be effective in its extraction. Using only water treatment separation methods does not provide sufficient efficiency. Significantly better results are obtained by combining the persistent organic pollutant coagulation method with subsequent separation processes. The disadvantage of coagulation is the need to use large doses of reagents and a large number of wastewater treatment processes. The objective of the research was to determine the possibility of reducing the doses of mineral coagulants and related reagents while maintaining sufficient efficiency in the treatment of contaminant water by countercurrent transfer of the solid phase of the sludge to the previous separation stages. . For the experimental investigation, a facility was used, which included a three-section block of sedimentation chambers, equipment for the manufacture and dosage of reagents, devices for pumping sludge and water sampling. The research was carried out in aqueous solutions of contaminants: persistent synthetic dyes used in the textile industry. The concentration of the dye solutions was assumed to be constant, equal to 150 mg / l. Three series of experiments were carried out with different conditions to dose the coagulant and return the hydroxyl mud. The results of the experiments were analyzed using the Langmuir adsorption equation and the graphical constructions of the equilibrium and the lines of work of the contaminant extraction process. Compared to the traditional single-stage coagulation scheme, which includes a single addition of reagents without reusing the sludge, the use of solid-phase countercurrent transfer coagulation schemes was found, based on the research results. of sludge conductors gives a significant reduction in the number of reagents consumed and, consequently, a decrease in the amount of sludge removed.

Investigation of the polyphosphate-accumulating organism population in the full-scale simultaneous chemical phosphorus removal system.

The simultaneous chemical phosphorus removal (SCPR) process has been widely applied in wastewater treatment plants (WWTPs) due to the high phosphorus removal efficiency through the synergy of biological and chemical phosphorus removal (BPR and CPR). However, phosphorus removal reagents could affect the bacterial community structure in the SCPR system and further affect the BPR process. The BPR phenotypes and community structures in the SCPR system, especially the population of polyphosphate-accumulating organisms (PAOs), are not completely clear. In order to clarify these problems, the phosphorus removal performance and the PAO population in a full-scale SCPR system were investigated. Results showed that diverse PAOs still existed in the SCPR system though the BPR phenotypes were not observed. However, the relative abundances of Accumulibacter and Tetrasphaera, the two most important genera of PAOs, were only 0.59% and 0.20%, respectively, while the relative abundances of Competibacter and Defluviicoccus, two genera of glycogen-accumulating organisms (GAOs), were as high as 5.77% and 1.28%, respectively. Batch tests showed that PAOs in the SCPR system still had a certain polyphosphate accumulating metabolic activity, which could gradually recover after stopping the addition of chemical reagents. This study provided a microbiological basis for the SCPR system to recover the enhanced biological phosphorus removal (EBPR) performance under suitable conditions, which could reduce the dosage of chemical reagents and the operational cost.

Enhanced methane production from anaerobic digestion of rice straw pretreated by Fe3+/CaO2 catalyzed Fenton-like process

The performance of ferric iron/calcium peroxide (Fe3+/CaO2) catalyzed Fenton-like process at different reagent dosages for enhancing the digestibility of rice straw (RS) was investigated. Despite the fact that the pretreatment did open up the RS surface, no substantial destruction in the RS supramolecular structure was achieved, as evidenced by the slight decrease of lignin, hemicellulose and cellulose contents under all tested conditions. Soluble carbohydrates showed a negative correlation with the increase in Fe3+/CaO2 dosage presumably due to the oxidative destruction effect of the chemicals on the labile soluble organics. The highest methane yield of 143.3 mL/g-VSfed was obtained with the RS pretreated by 4.0 mM Fe3+ and 2.0 mM CaO2, which was 3.6 times higher than that with the raw RS (31.1 mL/g-VSfed). From the experimental results, Fe3+/CaO2 catalyzed Fenton-like chemistry could serve as a feasible strategy for enhancing the biodegradability of lignocellulosic biomass materials.

Bioorthogonal Tetrazine Carbamate Cleavage by Highly Reactive trans-Cyclooctene.

The high rate of the 'click-to-release' reaction between an allylic substituted trans-cyclooctene linker and a tetrazine activator has enabled exceptional control over chemical and biological processes. Here we report the development of a new bioorthogonal cleavage reaction based on trans-cyclooctene and tetrazine, which allows the use of highly reactive trans-cyclooctenes, leading to 3 orders of magnitude higher click rates compared to the parent reaction, and 4 to 6 orders higher than other cleavage reactions. In this new pyridazine elimination mechanism, wherein the roles are reversed, a trans-cyclooctene activator reacts with a tetrazine linker that is substituted with a methylene-linked carbamate, leading to a 1,4-elimination of the carbamate and liberation of a secondary amine. Through a series of mechanistic studies, we identified the 2,5-dihydropyridazine tautomer as the releasing species and found factors that govern its formation and subsequent fragmentation. The bioorthogonal utility was demonstrated by the selective cleavage of a tetrazine-linked antibody-drug conjugate by trans-cyclooctenes, affording efficient drug liberation in plasma and cell culture. Finally, the parent and the new reaction were compared at low concentration, showing that the use of a highly reactive trans-cyclooctene as the activator leads to a complete cycloaddition reaction with the antibody-drug conjugate in seconds vs hours for the parent system. Although the subsequent release from the IEDDA adduct is slower, we believe that this new reaction may allow markedly reduced click-to-release reagent doses in vitro and in vivo and could expand the application scope to conditions wherein the trans-cyclooctene has limited stability.

Flotation separation of polystyrene and polyvinyl chloride based on heterogeneous catalytic Fenton and green synthesis of nanoscale zero valent iron (GnZVI)

It arises sharp concern that waste plastics entrain hazardous substances and accumulate in living organisms, endangering the environment and human health. To achieve clean plastic management and obtain qualified recycled products, separation deserves intensive research in preference to other technologies in plastic recycling. In this research, we proposed a novel flotation separation of binary plastic mixtures, polystyrene (PS) and polyvinyl chloride (PVC), based on heterogeneous advanced oxidation technology (AOT) and the green synthesis of nanoscale zero valent iron (GnZVI). The optimal conditions for separating PVC and PS (PS as a sinking plastic) are 1.5 mM H2O2, H2O2/Fe0 molar ratio 40:1, treatment time 300 s, room temperature, and pH 6. We revealed the oxidation mechanisms of PS after AOT treatment through extensive characterizations, such as scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance spectroscopy (NMR). Surface-incorporated oxygenated functions, such as hydroxyl (C–OH) and carboxyl groups (OC–O), are introduced on PS through the scission of backbone chain and the addition of hydroxyl and hydroperoxy radicals, increasing the hydrophilicity of PS. Besides, we established a novel pretreatment kinetics based on flotation percentage and treatment time to research the flotation behavior of PS, providing a new research perspective for plastic flotation. With the characteristics of low reagents dosage, short treatment time, mild temperature, and slight pollution, the proposed flotation process is an applicable separation technology for plastic recycling.

Intelligent Setting Method of Reagent Dosage Based on Time Series Froth Image in Zinc Flotation Process

It is well known that the change of the reagent dosage during the flotation process will cause the froth image to change continuously with time. Therefore, an intelligent setting method based on the time series froth image in the zinc flotation process is proposed. Firstly, the sigmoid kernel function is used to estimate the cumulative distribution function of bubble size, and the cumulative distribution function shape is characterized by sigmoid kernel function parameters. Since the reagent will affect the froth image over a period of time, the time series of bubble size cumulative distribution function is processed by the ELMo model and the dynamic feature vectors are output. Finally, XGBoost is used to establish the nonlinear relationship modeling between reagent dosage and dynamic feature vectors. Industrial experiments have proved the effectiveness of the proposed method.

Efficient inactivation of antibiotic resistant bacteria and antibiotic resistance genes by photo-Fenton process under visible LED light and neutral pH

Antibiotic resistance has been recognized as a major threat to public health worldwide. Inactivation of antibiotic resistant bacteria (ARB) and degradation of antibiotic resistance genes (ARGs) are critical to prevent the spread of antibiotic resistance in the environment. Conventional disinfection processes are effective to inactivate water-borne pathogens, yet they are unable to completely eliminate the antibiotic resistance risk. This study explored the potential of the photo-Fenton process to inactivate ARB, and to degrade both extracellular and intracellular ARGs (e-ARGs and i-ARGs, respectively). Using Escherichia coli DH5α with two plasmid-encoded ARGs (tetA and blaTEM-1) as a model ARB, a 6.17 log ARB removal was achieved within 30 min of applying photo-Fenton under visible LED and neutral pH conditions. In addition, no ARB regrowth occurred after 48-h, demonstrating that this process is very effective to induce permanent disinfection on ARB. The photo-Fenton process was validated under various water matrices, including ultrapure water (UPW), simulated wastewater (SWW) and phosphate buffer (PBS). The higher inactivation efficiency was observed in SWW as compared to other matrices. The photo-Fenton process also caused a 6.75 to 8.56-log reduction in eARGs based on quantitative real-time PCR of both short- and long amplicons. Atomic force microscopy (AFM) further confirmed that the extracellular DNA was sheared into short DNA fragments, thus eliminating the risk of the transmission of antibiotic resistance. As compared with e-ARGs, a higher dosage of Fenton reagent was required to damage i-ARGs. In addition, the tetA gene was more easily degraded than the blaTEM-1 gene. Collectively, our results demonstrate the photo-Fenton process is a promising technology for disinfecting water to prevent the spread of antibiotic resistance.

Ultrasound-assisted electrochemical treatment for phenolic wastewater.

With the rapid development of industry, especially the rapid rise of the chemical industry, the problem of water pollution is becoming more and more serious. Among them, the discharge of organic pollutants represented by phenolic substances has always been at the forefront. In this paper, ultrasound-assisted electrochemical treatment for phenolic wastewater is investigated. The effects of ultrasonic frequency, current, pH value and the amount of fly ash-loaded titanium TiO2-Fe3+ particles on phenol removal from phenol-containing wastewater are investigated. The experimental results demonstrate that the removal rate of phenol in phenol-containing wastewater is the best when ultrasonic frequency is 45kHz, power is 200W, the current is 1.2 A, pH is 5 and the dosage of fly ash-loaded titanium TiO2-Fe3+ particles is 3g. In addition, microwave-assisted-Fenton reagent treatment for phenol wastewater is investigated. The effects of Fenton reagent dosage, initial pH value, microwave power density and radiation time on phenol degradation rate are investigated. The results show that microwave can accelerate the reaction rate, reduce the number of metal ions, save the process cost and reduce the difficulty of post-treatment. Finally, the research status of phenol wastewater treatment technology at the present stage is reviewed, and the future development direction is discussed.

Fuzzy association rule-based set-point adaptive optimization and control for the flotation process

Froth flotation is a complicated process which is difficult to establish its first-principle model. Due to the fluctuations in the grade of raw ore, adaptively adjusting the set-points is extremely important in the flotation process. The inappropriate set-points easily lead to the instability of the process. This paper presents a fuzzy association rule-based set-point adaptive optimization and control strategy for the antimony flotation process without knowing the system model. Firstly, a fuzzy neural network is constructed as a soft-sensor to estimate the feed grade online because of the lack of efficient measurement equipment. Then, fuzzy association rule is used to mine the hidden relationship between the feed grade with reagent dosages and the optimal set-points. Through data mining from the quantitative database, the fuzzy inference system generates the optimal set-points. To implement satisfactory tracking performance, predictive controller is used to compute the control inputs. Because the system dynamics is unknown, long short-term memory network model is established to predict the future behaviors of the process. Finally, simulations and experiments are carried out to demonstrate the effectiveness of the proposed strategy. Compared to the manual manipulation, which is widely used in flotation processes, our control strategy achieves a better control performance, and the concentrate grades are more in line with the process requirement.

Optimization of management choices of clariflocculation process by means of qualitative multi-criteria analysis.

Every year ship traffic produces tons of liquid waste mainly consisting of bilge water and of washing water of tankers' tanks. The latter are called slop waters and are characterized by high salinity and by the presence of recalcitrant pollutants mainly of hydrocarbon origin: these characteristics promote the use of chemical-physical rather than biological treatment. In particular, in the present study the slop waters were subjected to a clariflocculation treatment by means of batch tests. This treatment involves the dosage of specific chemical reagents (coagulants and flocculants) added to water at different stages of the process. In order to establish the optimal reagents' type and dose, also considering the operating costs, the proposed study presents a frequency analysis belonging to the family of multi-criteria exploration. The application of this methodology to examine the validity of the different process alternatives has allowed the inclusion of, in a single assessment, both economic and extra-economic (measurable only in qualitative terms) procedures. Thanks to this qualitative and quantitative method, it was therefore possible to order the different treatment alternatives analyzed, identifying the one that allows optimizing the wastewater management, for a conscious choice of the most suitable solution to the problem.

Optimization of Preparation Method of Molecularly Imprinted Microspheres by Uniform Design

This work presented a simple and effective method for the preparation of molecularly imprinted microspheres (MIMPs) through multi-step swelling polymerization. To prepare carbofuran MIMP with a uniform size, the experiment of optimizing the dosage of reagents which used during synthesis based on uniform design (UD) method was performed. Six kinds of factors, namely methacrylic acid (MAA, functional monomer), ethylene glycol dimethacrylate (EGDMA, cross linker), polyvinyl alcohol (PVA, dispersant), dibutyl phthalate (DBP, sweller), polymerization temperature and polymerization speed were taken into account based on UD to perform the optimization experiment. The micromorphology of MIMP was characterized by scanning electron microscopy (SEM) and it showed that the particle sizes were between 6-8 μm. The results indicated that MIMP possessed good selectivity and specificity for carbofuran, which was an excellent material for adsorption and testing of carbofuran residues in food and environment.

RESEARCH ON THE EFFICIENCY OF USE OF NATURAL POLYMER FLOCCULANTS IN THE PROCESS OF WATER SOLUTION PURIFICATION

Natural flocculants are studied in the processes of water solution purification using the method of Jar-test. Experimental part of the work involves the research of different flocculants for the purification of colored water. The aim of this study is to determine the efficacy and optimal doses of flocculants in combination with aluminum sulfate. The flocculants such as chitosan, sodium alginate, starch and polyacrylamide are used for researching. As a coagulant, Al2(SO4)3·18H2O with a concentration of 10 % is used. It has been established that chitosan is the most effective flocculation reagent. It is explored that such factors as the dosage of reagents, chemical nature of links and the composition of polymer macromolecules, physical and chemical parameters of the process and the concentration of reagents influence the flocculation process. The optimal conditions for carrying out the process of flocculation are established

Recovery of clean coal from blast furnace dusts by flotation column

The paper presents the results of the study on recovery of clean coals from blast furnace dusts of the Cao Bang Iron Steel plant. The study has explored the effects of the most important operating parameters on the coal flotation performance including flotation reagent dosage, solid concentration, froth wash-water rate, flotation time and the froth thickness. The results of the study showed that using a combination of a rougher and a cleaning flotation operations at respectively collector dosage, solid concentration, flotation time, froth wash-water rate and froth thickness of 1000 g/t, 100 g/l, 10 minutes and 1.5 l/minute and 450 mm, has obtained a clean coal product with the yield, ash content and combustible matter recovery respectively of 44.90%, 19.15% and 77.63%. The clean coal has met the quality strandards requirements of the fuel for sintering.

СЕЗОННЫЕ ИЗМЕНЕНИЯ СОДЕРЖАНИЯ ПРОТИВОГОЛОЛЕДНЫХ СРЕДСТВ В ДЕРНОВО-ПОДЗОЛИСТОЙ ПОЧВЕ В ЛАБОРАТОРНОМ И ПОЛЕВОМ ЭКСПЕРИМЕНТАХ

Противогололедные средства (ПГС), применяющиеся для борьбы с ледяными и снежными отложениями в городах, являются одним из наиболее вредных антропогенных факторов. Значительное число работ по данной тематике посвящено воздействию на окружающую среду технической соли, в то время как реагентам нового поколения уделяется недостаточно внимания. В статье представлены результаты изучения сезонной динамики содержания водорастворимых солей ПГС нового поколения в дерново-подзолистой почве в условиях полевого и лабораторного экспериментов. Сопоставлены 9 ПГС, применяемых в Санкт-Петербурге – хлоридные, ацетатные и формиатные реагенты. Лабораторные опыты показали, что высокие дозы хлоридных реагентов увеличивали содержание солей в почвах до отметок, соответствующих слабому засолению (максимальные показатели – 3,96 мСм/см), потенциально опасному для растений и почвенных микроорганизмов. В полевых условиях с течением времени степень засоления почвы уменьшалась – соли ПГС вымывались из верхних горизонтов с выпадающими осадками. К концу вегетационного сезона максимальные показатели не превышали 0,29 мСм/см, что соответствовало фоновым значениям. Следовательно, снижалась токсичность загрязненных почв для растений и микроорганизмов. По результатам исследований определены наименее экологически вредные ПГС средства. К ним относятся ацетатные и формиатные реагенты «Нордвэй» и «Clearway». Хлориды магния («Бишофит») оказались менее опасными среди реагентов хлоридной группы. Также рекомендованы допустимые дозы ПГС на городских улицах. В Северо-Западном регионе сравнительно безопасной можно считать дозу 50 г/м2.

Rapid on-chip quantification of ammonia nitrogen based on a ‘flow and react’ mechanism

ABSTRACT Ammonia nitrogen pollution comes from a variety of sources, resulting in a wide distribution of concentrations and forms of existence across different samples. The on-site rapid detection of ammonia nitrogen in water is of great importance especially in unexpected water pollution accidents. In this paper, an inexpensive and portable microfluidic chip for the quantitative detection of ammonia nitrogen in water was developed. Solid reagents specific to ammonia nitrogen was pre-loaded in the microchannels and then liquid sample was introduced to initiate reactions that generated optical signals. A novel ‘flow and react’ regime replying on accelerated dissolution and reaction was proposed, shortening reaction time and reducing reagent dosage significantly. Ammonia nitrogen concentration in the range of 0.3–10 ppm was determined successfully within 5 min with this chip and a fibre spectrophotometer.

Efficient degradation, mineralization and toxicity reduction of sulfamethoxazole under photo-activation of peroxymonosulfate by ferrate (VI)

The photodegradation of sulfamethoxazole (SMX) based on activation of peroxymonosulfate (PMS) with ferrate (VI) (Fe(VI)) was investigated for the first time. The role of the reagents under different light sources and the effects of reagent dosages as well as solution pH on the SMX degradation were revealed. Besides, the SMX degradation, mineralization, the reaction mechanism, and the toxicity of the degradation products to Artemia salina under various treatment processes with one-off or stepwise dosing of reagents were determined. SMX of 0.1 mM can be completely removed in 8 min under optimal conditions. A mathematic model was proposed to describe the two stage reactions, and the initial decay rate as well as the maximum oxidation capacity were calculated accordingly. Fe(VI) played a dominant role in initial degradation while radicals including SO4− and OH contributed to continuous degradation. Compared to one-off dosing, stepwise addition of reagents slowed down SMX degradation, while stepwise introduction of Fe(VI) enhanced the mineralization efficiency. The proposed degradation pathways include hydroxylation, carboxylation, nitration and so on. The adverse effect of SMX solution to the feeding of Artemia Salina was abated after treatment. The results from this study demonstrate a good potential of using UVA/Fe(VI)/PMS in treatment of antibiotics in aqueous phase.

Influence of Acetylated Annealed Starch on the Release of β-Escin from the Anionic and Non-Ionic Hydrophilic Gels.

Naturally sourced products introduced to human nutrition and rediscovered for therapy include polysaccharides from potatoes. The starch may obtain unique properties via acetylation with acetic anhydride at 13 cm3/100 g of starch as the basic dose of reagent used in industrial conditions. The hydrogel formulation was applied as a carrier for escin included in the dry extract of Aesculus hippocastanum. Six hydrogels were evaluated (methylcellulose, polyacrylic acid-Carbopol 980 NF and polyacrylate crosspolymer 11—Aristoflex Velvet) with various concentrations of the modified starch. The kinetic studies of in vitro β-escin release were carried out in purified water at 37 ± 0.5 °C using a paddle apparatus at 50 rpm and a time period of 7 h. The criterion for the most suitable model was based on a high correlation coefficient of evaluated release profiles. The addition of modified annealed acetylated potato starch resulted in prolongation of β-escin release.