Solution pH Research Articles

Effects of LED treatments on the growth and nutritional content of lettuce (Lactuca sativa) in a hydroponic vertical farming system

Introduction: LED-integrated hydroponic vertical farming system (HVFS) may address food security challenges arising from urbanisation, while antioxidants in vegetables may prevent cardiovascular disease. This study aimed to explore the LED effects on yield, antioxidant properties, and vitamin C content in Butterhead lettuce (BL) and Italian lettuce (IL). Methods: Three LED combinations were used: 77% red, 14% green, and 9% blue lights (77R:14G:9B); 7% red, 41% green, and 52% blue lights (7R:41G:52B); and 25% red, 67% green, and 8% blue lights (25R:67G:8B). The concentration and pH of nutrient solution in HVFS ranged from 0.878-2.061ppm and 6.0-6.6, respectively, with a 12:12 light-dark cycle. Chlorophyll and anthocyanin contents were measured using chlorophyll and anthocyanin meters, respectively. Total phenolic and vitamin C content were measured using Folin-Ciocalteu colorimetric assay. Total flavonoid and antioxidant activity were determined through aluminium chloride colorimetric assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) colorimetric assay, respectively. Completely randomised design was adapted with three replications. Results: BL exhibited greater yield, anthocyanin and chlorophyll contents, while IL had higher vitamin C content. Significantly (p<0.001) higher yields were produced under 77R:14G:9B and 25R:67G:8B. Significantly higher phenolic (p<0.001) and flavonoid (p=0.003) contents were produced under 25R:67G:8B. Vitamin C was significantly (p=0.037) higher under 25R:67G:8B than 7R:41G:52B. Conclusion: LED treatment with higher proportion of red light generated greater yield, whereas higher proportion of green light gave higher phenolic, flavonoids, and vitamin C accumulation. This study provided preliminary data on boosting crop yield and phytochemical contents, which may improve food self-production and population health.

Selective Determination of Acetaminophen in Presence of Ascorbic Acid at Poly (p-Methoxyphenol) Electrode

In the present work, we discuss the modification of a gold electrode with p-methoxyphenol and its application as a sensor for acetaminophen (ACP) in a phosphate buffer solution (pH = 7.4). The modified electrode was subsequently employed to determine acetaminophen in the presence of ascorbic acid (AA) using differential pulse voltammetry (DPV). The peak positions and relative sensitivity of ACP/AA were influenced by the potential window used during polymerization. For polymerization between 0 and 1.0 V, the peak potentials recorded in the phosphate buffer solution (pH = 7.4) were 488 mV for ACP and 280 mV vs. Ag/AgCl for AA. Furthermore, the effects of pH and electrolyte type on the linearity range and detection limit were investigated. The high selectivity and sensitivity for ACP were attributed to charge discrimination and analyte accumulation. The detection limit for the 3σ-test was determined to be 0.2 nM. This study highlights the potential of the modified gold electrode for selective and sensitive detection of acetaminophen, even in the presence of interfering substances such as ascorbic acid. The optimization of polymerization conditions and the comprehensive analysis of pH and electrolyte effects contribute to the electrode's superior performance.

A comprehensive electrochemical analysis revealing the surface oxidation behavior difference between pyrite and arsenopyrite

This study systematically investigated the surface oxidation behavior differences between pyrite and arsenopyrite under neutral and alkaline pH conditions using various electrochemical measurements. These measurements include open circuit potential (OCP), cyclic voltammetry (CV), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analyses. Key electrochemical parameters have been obtained. The OCP, oxidation potential (Eox), and charge transfer resistance (Rct) of arsenopyrite and pyrite declined as the solution pH increased, but oxidation current density (jox) and carrier concentration (ND) increased, suggesting that a high solution pH is thermodynamically and dynamically favorable for the oxidation of both pyrite and arsenopyrite. Compared to pyrite, arsenopyrite has a higher Fermi level, lower OCP and Eox, a larger jox, and a smaller Rct at the same pH conditions, suggesting that arsenopyrite oxidation has a higher thermodynamic preference and occurs at a faster rate than pyrite oxidation under neutral and alkaline pH conditions. This comprehensive study enhances our understanding of the oxidation difference between pyrite and arsenopyrite and offers important guidance for the pyrite-arsenopyrite flotation separation when using the selective surface oxidation method.

Aqueous benzene, toluene, ethylbenzene and xylene (BTEX) removal using core-shell structure activated carbon ball as a permeable reactive barrier material

Permeable reactive barriers (PRBs) are passive and sustainable treatment systems for remediating the diffusion of contaminant plumes in groundwater. Several conventional reactive materials such as activated carbon (AC) have long been used as reactive media for PRBs. AC, which is known for its high adsorption capability and cost-effectiveness, is commonly used to remove multiple pollutants from groundwater. Unfortunately, among the reactive materials, AC can fill in the barrier and pose practical problems, such as a pressure drop, solid losses during handling, and safe disposal of filled sorbents, because of its low particle strength. In this study, AC balls were prepared using zeolite as the core and powdered AC, quartz, and calcite as the shell. AC ball with excellent mechanical strength and high permeability properties in the form of a core–shell layer is a good alternative to conventional reactive materials. The adsorption characteristics of benzene, toluene, ethylbenzene, and p-xylene (BTEX) from solutions using AC balls were investigated. The adsorption equilibrium is in the order of X>E>T>B. The adsorption capacity for B (4.90 mg/g), T (3.37 mg/g), E (1.16 mg/g) and X (0.46 mg/g) were observed at solution pH=7. To validate the proposed models, batch experiments indicated that the pseudo-2nd-order (11.61 and 10.54 mg/g) and Langmuir models (8.81 and 5.27 mg/g) were the most suitable for describing the kinetics and equilibrium of benzene and toluene, respectively. Regeneration experiments were performed using chemical extraction (methanol) and microwave (MW) heating. When the AC ball was reused six times, the removal efficiency for benzene was maintained above 81% using methanol, whereas that for benzene was increased to 91% using MW. A series of experiments revealed that AC balls have considerable reusability. The AC ball can be effectively used as a medium for the removal of benzene in a continuous flow system such as column and sandbox. Based on these results, AC balls are a potential reactive medium for field-scale PRB practical remediation applications.

Sonochemical Assisted Synthesis of Cr-PTC Metal Organic Framework, ZnO, and Fe3O4 Composite and Their Photocatalytic Activity in Methylene Blue Degradation

Methylene blue pollutants can be treated by photocatalytic methods using metal oxide-based semiconductor materials and metal organic framework (MOF). These two materials are often coupled into a composite to improve their physicochemical properties and catalytic activity. This research focuses on the synthesis of composites based on Cr-PTC MOF, ZnO, and Fe3O4 by the sonochemical method. The obtained composites were characterized and tested for catalytic activity in methylene blue pollutant degradation in an aqueous system under acidic conditions (pH = 5). Our investigation shows that the Cr-PTC@Fe3O4 composite possesses the lowest band gap energy of 1.86 eV and achieves the highest photocatalytic activity in methylene blue degradation at solution pH = 5, with a percent degradation of 84.36%. The sonochemical incorporation of Fe3O4 and Cr-PTC MOF is able to fabricate materials in a short time with better photocatalytic activity in degrading methylene blue than the single materials. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

De Novo Design and Characterization of Amphiphilic Peptides with Basic Side Chains for Tailored Interfacial Chemistries.

Lysine-leucine (LK) peptides have been used as model systems and platforms for 2D material design for decades. LK peptides are amphiphilic sequences designed to bind and fold at hydrophobic surfaces through hydrophobic leucine side chains and hydrophilic lysine side chains extending into the aqueous subphase. The hydrophobic periodicity of the sequence dictates the secondary structure at the interface. This robust design makes them ideal candidates for controlling interfacial chemistry. This study presents the de novo design and characterization of two novel peptides: LRα14 and LHα14, which substitute lysine with arginine and histidine, respectively, in the helical LKα14 sequence. This modification is intended to expand the LK peptide platform to a new basic interfacial chemistry. We explore the stability of the new LRα14 and LHα14 designs with respect to changes in pH and salt concentration in bulk solution and at the interface using circular dichroism (UV-CD) and vibrational sum-frequency generation spectroscopy, respectively. Notably, the structural stability of the peptides remains unaffected across a wide range of pH and ionic strength values. At the same time, the variation of side-chain chemistry leads to a wide spectrum of interfacial water structures. By extension of the LK platform to include arginine and histidine, this study broadens the toolbox for designing tailored interfacial chemistries with applications in material and biomedical sciences.

Freshwater snail flesh (Pomacea paludosa) incubated with bromelain enzyme levels in feed on the carcass quality of Alabio male ducks (Anas plathyrhyncos Borneo)

This study aimed to determine Freshwater snail flesh (Pomacea paludosa) incubated with bromelain enzyme levels in feed on the carcass quality of alabio male ducks. The treatment as ; P0 basal diet + 100% fish meal, P1 basal diet + 75% fish meal + 25% freswater snail flesh incubated bromelain enzym, P2 basal diet + 50% fish meal + 50% freswater snail flesh incubated bromelain enzym, P3 : basal diet + 25 % fish meal + 75% freswater snail flesh incubated bromelain enzym, P4 : basal diet + 100% freswater snail flesh . In each treatment, two male Alabio ducks were taken randomly and then slaughtered. The crude protein, crude fat, moisture, pH, and texture, by taking as many samples as 20 g of sample then mashed for 2 minutes and added 40 ml aquadest. pH measurement is done with pH meter, which was previously calibrated with buffer solution of pH 7.0 and 4.0. Meat tenderness is measured by using the shear warner bratzler tool Instron, , protein,fat and moiture using proximate analysis The result showed that level freshwater snail flesh incubated with bromelain enzym in feed up to 7.5-10% on Alabio male duck diets improved crude protein meat (21.51±0.19 to 23.90±0.40) but decreased meat moisture ( 69.46±0.79 to 62.79±0.27) and decreased crude fat meat (9.55±0.44 to 4.18±0.53). Meanwhile, the tenderness of the meat increased from 3.55% on the control feed to 26.77% on the feed using 7.5-10%.

Study of Insulin Aggregation and Fibril Structure under Different Environmental Conditions

Protein amyloid aggregation is linked with widespread and fatal neurodegenerative disorders as well as several amyloidoses. Insulin, a small polypeptide hormone, is associated with injection-site amyloidosis and is a popular model protein for in vitro studies of amyloid aggregation processes as well as in the search for potential anti-amyloid compounds. Despite hundreds of studies conducted with this specific protein, the procedures used have employed a vast array of different means of achieving fibril formation. These conditions include the use of different solution components, pH values, ionic strengths, and other additives. In turn, this variety of conditions results in the generation of fibrils with different structures, morphologies and stabilities, which severely limits the possibility of cross-study comparisons as well as result interpretations. In this work, we examine the condition–structure relationship of insulin amyloid aggregation under a range of commonly used pH and ionic strength conditions as well as solution components. We demonstrate the correlation between the reaction solution properties and the resulting aggregation kinetic parameters, aggregate secondary structures, morphologies, stabilities and dye-binding modes.

An unexpected degradation pathway of N-hydroxy-5-methylfuran-2-sulfonamide (BMS-986231), a pH sensitive prodrug of HNO, in a prototype formulation solution.

N-hydroxy-5-methylfuran-2-sulfonamide (BMS-986231, Cimlanod) was being developed as a pH-sensitive prodrug of HNO (nitroxyl) for the treatment of acute decompensated heart failure. During a stressed study of Cimlanod in a prototype formulation solution (pH 4.5) at 40°C, a predominant unknown degradant along with three previously identified degradants were observed. The unknown degradant was isolated from the stressed solution via preparative HPLC but totally decomposed during freeze-drying. LC-HRMS analysis of the isolated unknown degradant, prior to freeze-drying, revealed an empirical formula equivalent to the adduct of Cimlanod with SO2 even though SO2 was not added in the prototype formulation solution. The unknown degradant was synthesized from Cimlanod and DABSO ((1,4-diazabiscyclo[2,2,2]octane bis(sulfur dioxide) adduct) and isolated as a crystalline DABCO (1,4-diazabiscyclo[2,2,2]octane) salt for single crystal X-ray structure elucidation. The degradation of Cimlanod increased when the solution was exposed to air, as compared to N2 atmosphere. A plausible mechanism was postulated for the unexpected degradation pathway of Cimlanod. This study provided in-depth stability knowledge of Cimlanod, which will be beneficial to the subsequent stability indicating method development and validation as well as the registrational applications on the content and qualification of impurities in new drug products.

INVESTIGATION OF FACTORS AFFECTING THE SYNTHESIS OF TiO2/HAP COMPOSITE MATERIALS VIA SOL-GEL METHOD

Advanced materials have been of interest in recent years because of their outstanding properties that bring many useful applications to humans, they can be highly compatible with alternative materials. In particular, coating materials on HAp base increase the biocompatibility of HAp. In this study, we synthesize TiO2/HAp composite materials using the sol - gel method. Samples were made under different synthesis conditions in terms of HAp/TTIP ratios: (1:1); (1:1.5); (1:2); (1:2.5); (1:3). Factors affecting the synthesis process, such as the incubation time and pH of the solution, were also investigated. The optimal conditions for the synthesis process are the ratio HAp/TTIP: 1 gram HAp with 2 ml TTIP; stirring time: 16 hours; pH of the gel solution: pH = 0.5, as determined from the analysis of the X-ray diffraction spectrum and SEM surface morphology. The research results are the basis for research on biomedical materials.

Nano‐Enhanced Water Purification: Uncovering the Dye Adsorption Efficiency of Ni‐Zn‐S@Cyclodextrine Nanomaterial

AbstractThis research investigates the synthesis of a hybrid nanomaterial, denoted as Ni‐Zn−S@Cyclodextrine, through a cost‐effective and easy co‐precipitation method. The resulting nanomaterial has been thoroughly characterized and applied for the adsorptive removal of Crystal violet and Congo red dyes from their solutions. The study delves into the thermodynamics and kinetics of the sorption process, as well as helps to propose adsorption mechanism for both the dyes onto the Ni‐Zn−S@Cyclodextrine surface. A comprehensive analysis, encompassing techniques, such as XRD, FTIR, SEM‐EDX, TEM, TGA, Zeta potential, and XPS, have been conducted to explore the structural and morphological attributes of the prepared nanomaterial. Furthermore, key sorption parameters, including adsorbent's dosage, temperature, contact time, and solution pH, have been systematically optimized to achieve maximum efficiency. The TEM images of prepared nanomaterial indicated the particle size ranging between 60–80 nm. Moreover, it exhibited a strong affinity for both the dyes, with a maximum adsorption capacity of 138.20 mgg−1 for Congo red and 129.95 mgg−1 for Crystal violet dyes at 303 K. The thermodynamics of the adsorption process indicated an endothermic and spontaneous nature. Isotherm studies revealed that the data best aligned with the Freundlich isotherm, while the kinetics of the reaction adhered to a pseudo‐second order within the investigated temperature range.

Corn Husk‐Derived Carbon Fused with Iron Oxide as Adsorbent for Cationic Dyes

AbstractThe development of nanomaterials for dye degradation has garnered significant interest due to their efficiency, environmental benefits, and cost‐effectiveness. In this study, a nanocomposite adsorbent composed of α‐Fe2O3 coupled with carbon derived from eco‐friendly corn husk has been developed. This material effectively captured cationic dyes, Methylene Blue (MB) and Malachite Green (MG), from aqueous solutions, including industrial dye effluent from local industry. The synthesized nanocomposite demonstrated rapid removal of MB and MG from the solution without the need for additional oxidizing or reducing agents. The adsorption conditions by varying parameters such as adsorbent dose, contact time, solution pH, initial dye concentration, and temperature have been optimized. Adsorption isothermal studies indicated that the Langmuir isotherm model best explained the adsorption process. Kinetic studies revealed that the adsorption process follows a pseudo‐first‐order model for MB, while the intraparticle diffusion model is more appropriate for MG. Moreover, the nanocomposite exhibited excellent reusability and regenerability for dye adsorption. Our study showcases the effectiveness of the synthesized nanocomposite adsorbent, comprising α‐Fe2O3 integrated with carbon derived from eco‐friendly corn husk using a simple and sustainable methodology, in efficiently removing cationic dyes from textile wastewater. This approach offers a promising solution for environmental remediation.

Effects of chemical solution components on the contact angle of typical minerals in soil: quartz, orthoclase and plagioclase.

Different chemical solutions can significantly change the contact angle (CA) of soil, but few studies have studied the change rule and action mechanism of the CA from the mineral composition of soil essence. In unsaturated soil mechanics, the CA is an important parameter to calculate the wet suction between soil particles in unsaturated soil. When the chemical composition of the soil pore liquid changes, the CA will also change, which will affect the wet suction and other parameters, thus changing the macroscopic mechanical properties of the soil. In this study, the CA of air-solution-mineral phases with different solution components (pH, type and concentration of salt solution) of different minerals (quartz, orthoclase and plagioclase) were measured. The results show that the CAs of quartz, orthoclase and plagioclase all rise first and then drop with the rise of pH. The peak CAs are pH = 5, pH = 4 and pH = 3, respectively. Quartz, orthoclase and plagioclase all have valley values in different concentrations of NaCl and KCl solutions. In CaCl2 solution, only quartz has valley value, while orthoclase and plagioclase increase monotonously. Quartz in soil plays a main role in the influence of soil CA, followed by orthoclase and plagioclase. The CA of different minerals in different chemical solutions is mainly controlled by electric double layer interaction and functional groups interaction. In different salt solution environment, in addition to the above two effects, the mineral CA is also affected by the surface tension.

Rapid precipitation of vanadium from solution using melamine as precipitant with high efficiency

AbstractBACKGROUNDSelective catalytic reduction (SCR) can effectively remove NOx from flue gas in a coal‐fired power plant. As the core of SCR technology, the catalyst has a limited lifespan. The process of reducing acid leaching and roasting water leaching can efficiently extract vanadium and tungsten from spent SCR catalyst. For vanadium recovery in solution, the traditional vanadium precipitation process by NH4Cl has the disadvantages of consuming high precipitant dosage and producing large amounts of waste water.RESULTSThis study focused on the vanadium precipitation process using a solution containing vanadium obtained from adopting some steps to handle the spent SCR catalyst. First, melamine was screened out as the vanadium precipitant. Then, the vanadium precipitation conditions were optimized as follows: solution pH value of 1.0, n(C3H6N6)/n(V) = 0.8, 110 °C and 30 min. Under the best precipitation conditions, the vanadium precipitation efficiency of melamine can reach 99.32%. Finally, the mechanisms of vanadium precipitation by NH4Cl and melamine were discussed, respectively.CONCLUSIONThe results showed that the vanadium precipitation process by NH4Cl followed the chemical reactions between NH4+ and vanadium ions, while the vanadium precipitation process by melamine followed the redox and complexation reactions which essentially belonged to the types of chemical adsorption. The vanadium precipitation product was roasted at 550 °C for 2 h to obtain the vanadium product. The main component of the vanadium product was V2O5, with a purity of 93.27 wt%. The total recovery efficiency of vanadium from spent SCR catalyst was 78.24%. © 2024 Society of Chemical Industry (SCI).

Activation mechanism of CoFe2O4 nanocatalysts on different oxidants and degradation efficiency of butyl xanthate

Owing to the technological limitations associated with beneficiation technology, large amounts of flotation reagents remain in mineral processing wastewater, which is extremely detrimental to humans and the environment. In addition, direct reuse of mineral processing wastewater will adversely affect the entire mine water system. Efficient treatment of residual butyl xanthate from tailing wastewater has recently attracted increasing interest. In this study, we compared the degradation efficiencies of cobalt iron oxide (CoFe2O4) nanoparticles assisted by sulfite-activated advanced processes and persulfate (PDS) and peroxymonosulfate (PMS) advanced oxidation processes on butyl xanthate (BX) for the first time and explored possible reaction mechanisms in various systems. We conducted comprehensive experiments on the acid/alkali washed catalysts using oxidizing agents, obtaining catalysts best adapted to three degradation systems. Results of batch experiments indicated that the BX degradation rate for all the three systems exceeded 95 % within 60 min under their respective optimal conditions and that the best total organic carbon content (TOC) removal rate for these systems was 85.79 %. The effects of key factors, such as catalyst dosage, oxidant dosage, solution pH, and coexisting ions, on BX degradation were investigated. Furthermore, the active free radicals that played a major role in each system were detected via electron paramagnetic resonance (EPR). EPR results indicated that SO3·− and ·O2− were the main active species of the CoFe2O4/sodium sulfite system, ·OH and ·O2− participated in the degradation of BX in the CoFe2O4/PDS system, and ·O2− was present in the CoFe2O4/PMS system. Thus, this study promotes the application of CoFe2O4 with magnetism as a catalyst in wastewater treatment and provides new insights into the effective treatment of organic pollutants in tailing wastewater.

Harnessing Wood Bottom Ash for Efficient Arsenic Removal from Wastewater: Adsorption Mechanisms and Process Optimisation

This study explored the innovative application of wood bottom ash (WBA) as an adsorbent for arsenic (As) removal from wastewater, focusing on the adsorption mechanism and optimisation of the operational conditions. Comprehensive spectroscopic analyses, including FE-SEM/EDS, BET, XRF, XRD, FT-IR, and XPS, were performed to examine the elemental and mineralogical changes in WBA before and after As adsorption. The study assessed the adsorption kinetics and isotherms, revealing that As adsorption reached equilibrium within 48 h, with a maximum capacity of 121.13 mg/g. The adsorption process followed a pseudo-second-order kinetic model and aligned well with the Langmuir isotherm, indicating that the process is governed by chemisorption and occurs as monolayer adsorption. The primary removal mechanism was the surface precipitation of amorphous calcium arsenate. Response surface methodology was employed to analyse and optimise the factors influencing As removal, including solution pH, ionic strength, adsorbent dose and reaction time. The optimal conditions for maximum As removal were pH 7.11, 8.37 mM ionic strength, 9.08 g/L WBA dose, and 2.58 h reaction time. This study offers novel insights into the efficient and cost-effective use of WBA for As removal, highlighting its potential as a sustainable solution for wastewater treatment in developing countries.

Preparation of polymeric aluminum chloride from secondary aluminum dross and its water purification effect

ABSTRACT Aluminum dross is solid waste generated by the aluminum industry. Currently, a large amount of aluminum dross is produced annually year. Aluminum dross, a hazardous waste, contains harmful substances such as aluminum metal, aluminum nitride, fluoride and chlorine salts, which pose a serious threat to human health and also cause damage to the ecological environment. Thus, it is important to recycle secondary aluminum dross and realise its high-value utilisation. Polymeric aluminum chloride (PAC) is a polymer flocculant, at present, China's annual use of PAC in the field of water treatment is about 5 × 105 t, and with the continuous improvement of water purification requirements, the annual use of PAC increased year by year. Here secondary aluminum dross was used as a raw material to prepare PAC by hydrochloric acid (HCl) leaching, followed by the addition of sodium carbonate. The optimal conditions for the acid leaching of secondary aluminum dross for the preparation of PAC were as follows: HCl concentration, 18%; liquid-to-solid ratio, 4.5:1; stirring rate, 200 r/min; reaction temperature, 90 °C; and 60 min. An aluminum leaching rate of 85.5% was obtained under these conditions. The results showed that the acid leachate after adding sodium carbonate, under the conditions of polymerisation temperature of 70 °C, polymerisation time of 6 h, and polymerisation pH value of 3.0, the PAC prepared had an alumina content of 10.19%, salinity of 32.37%, density of 1.32 g/cm3, 1% aqueous solution pH 4.3. The water purification effect of the prepared PAC surpassed that of the commercially available PAC. The utilisation of secondary aluminum dross can reduce the environmental pollution caused by aluminum slag.

Effect of metakaolin on the chloride diffusion properties of alkali-activated slag in an acidic environment

Alkali-activated materials (AAMs) have good resistance to chemical corrosion compared to silicate cements, but the effect of the pH of chloride-containing solutions on the resistance of AAMs to chloride diffusion is not clear. In this paper, the resistance of alkali-activated slag (AAS) with different metakaolin replacement rate to chloride diffusion in HCl/NaCl solution was investigated in terms of mechanical properties, hydration product composition and pore structure. The experimental results show that acidic solutions lead to alkali leaching, and dissolution of gel and hydrotalcite. The capillary pores that appeared in the AAS after the replacement rate of 10% metakaolin resulted in a decrease in the average pore size of the AAS and low depth of chloride diffusion. 30% metakaolin replacement led to a decrease in the diffusion resistance. In HCl solution, the high [AlO4]5− retention corroded layer was observed in the AAS with 30% metakaolin replacement and this layer slowed down the migration rate of [Cl−]. This study shows the promising application of alkali-activated slag/metakaolin in complex chloride solution environments.

Boosted adsorptive removal of eosin yellow dye from aqueous solution with C–ZnO nanoparticles: optimization of process parameters

This study investigates the effectiveness of ultrasound-aided sorption using carbon–doped zinc oxide nanoparticles (C–ZnO NPs) for the removal of eosin yellow dye (EY) from wastewater. Raman spectroscopy was employed to confirm the successful carbon doping in the ZnO lattice, while field emission scanning electron microscopy (FESEM) was used to observe the morphology of the C–ZnO NPs, revealing uniform pseudo-spherical grains with diameters ranging from 20 to 35 nm. The impact of important parameters such as EY base concentration (50–200 mg/L), C–ZnO NPs dose (0.125–1.0 g/L), initial solution pH (2.0–10.0), and reaction time (1–30 minutes) on EY dye removal was investigated to assess the adsorptive potential of C–ZnO NPs. The highest sorption efficiency of 95.90 ± 0.96 % for EY dye was achieved within 20 minutes using C–ZnO NPs dose of 0.50 g/L, a solution pH of 4.0, and at an EY base concentration of 50 mg/L. The adsorption followed pseudo-second-order kinetics and Langmuir isotherm, with a sorption capacity of 232.59 ± 1.36 mg/g. Sono-assisted adsorption outperformed with a performance of 98.96% ± 0.85% as compared with conventional methods like magnetic stirring and overhead stirring, which had a performance of 73.24% ± 1.90% and 78.06% ± 2.0% respectively. C–ZnO is found to be a cost-effective adsorbent due to its low production cost of 31.0 $/kg and high reusability. As a result, this work emphasizes the prospective use of C–ZnO NPs as adsorbent for EY removal from wastewater on account of high sorption efficiency, superior adsorptive performance over ZnO NPs, and its cost effectiveness.

Simple incorporation and calcination of Zn-Al LDH during PEO processing in near-neutral pH solutions

Plasma electrolytic oxidation (PEO) process was employed for preparing oxide coatings on AA2024 aluminum alloy in solutions containing Zn-Al layered double hydroxide (LDH) particles. Sodium hexametaphosphate aqueous solution was selected as the standard solution, based on its almost neutral pH value considered as important for the LDH stability. Different additives to the standard solution were examined including 2-mecaptobenzothiazole (MBT) and different Zn-Al LDH compounds. The formed coatings underwent characterization regarding their morphology, chemical and phase composition, as well as assessment of their photocatalytic and corrosion protection efficiency. Coating thickening and compactness evolution were noted for all coatings with LDH additions to the standard solution. Obtained coatings are well-crystallized featuring γ-Al2O3 and two Zn-containing crystalline phases, namely ZnO and NaZnPO4, originating mainly from the LDH addition to the solution. PEO coatings obtained in this study demonstrated very reasonable photocatalytic activity for immobilized photocatalyst, reaching 51 % after 6 h under UV irradiation. The inclusion of Zn-Al LDH substantially boosted the impedance modules at low frequencies by two orders of magnitude compared to bare AA2024 alloy when exposed to a 3.5 % NaCl solution.