pH Level Of Solution Research Articles

Green Synthesis of Flower-Shaped Copper Oxide and Nickel Oxide Nanoparticles via Capparis decidua Leaf Extract for Synergic Adsorption-Photocatalytic Degradation of Pesticides

Green manufacturing of catalysts enables sustainable advanced oxidation processes and water treatment processes for removing trace contaminants such as pesticides. An environmentally friendly biosynthesis process produced high-surface-area CuO and NiO nanocatalysts using phytochemicals in the Capparis decidua leaf extract, which served as a reductant and influenced catalyst shape. Capparis decidua is a bushy shrub, widely distributed in dry and arid regions of Africa, Pakistan, India, Egypt, Jordan, Sudan, Saudi Arabia. The synthesized CuO and NiO nanoparticles were characterized by UV-vis spectroscopy (UV-vis), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) and thermo-gravimetric analysis/differential thermal analysis (TGA/DTA). The produced nanoparticles were spherical and flower-like in shape and have a characteristic face-centered cubic structure of CuO and NiO. Biosynthesized catalysts were photoactive and degraded recalcitrant pesticide Lambda-cyhalothrin (L-CHT). Photocatalytic degradation of L-CHT was affected by the initial L-CHT concentration, solution pH levels between 5 and 9, and photocatalyst concentration. The L-CHT removal percentage attained by CuO photocatalyst (~99%) was higher than for NiO photocatalyst (~89%). The degradation of L-CHT follows a pseudo-first-order kinetic model, and the apparent rate constant (kapp) decreased from 0.033 min−1 for CuO to 0.0084 min−1 for NiO photocatalyst. The novel flower-shaped nanoparticles demonstrated high stability in water and recyclability for removing L-CHT pesticide contamination in water.

Silicene Quantum Capacitance Dependent Frequency Readout to a Label-Free Detection of DNA Hybridization- A Simulation Analysis.

The use of deoxyribonucleic acid (DNA) hybridization to detect disease-related gene expression is a valuable diagnostic tool. An ion-sensitive field-effect transistor (ISFET) with a graphene layer has been utilized for detecting DNA hybridization. Silicene is a two-dimensional silicon allotrope with structural properties similar to graphene. Thus, it has recently experienced intensive scientific research interest due to its unique electrical, mechanical, and sensing characteristics. In this paper, we proposed an ISFET structure with silicene and electrolyte layers for the label-free detection of DNA hybridization. When DNA hybridization occurs, it changes the ion concentration in the surface layer of the silicene and the pH level of the electrolyte solution. The process also changes the quantum capacitance of the silicene layer and the electrical properties of the ISFET device. The quantum capacitance and the corresponding resonant frequency readout of the silicene and graphene are compared. The performance evaluation found that the changes in quantum capacitance, resonant frequency, and tuning ratio indicate that the sensitivity of silicene is much more effective than graphene.

Potentiostatically deposited bimetallic cobalt–nickel selenide nanostructures on nickel foam for highly efficient overall water splitting

The fabrication of efficient electrocatalysts for water splitting is vital for production of clean fuels. Herein, cobalt–nickel selenide (CoNi2Se4) nanostructures were fabricated on a Ni foam substrate using a facile potentiostatic method at different deposition solution pH levels. Nanoparticle-, fluffy-, and flake-like CoNi2Se4 nanostructures were deposited by changing the aqueous solution pH to 2.0, 2.5, and 3.0, respectively. The desired flake-like CoNi2Se4 electrode fabricated at pH 3.0 presented the best electrocatalytic performance of all CoNi2Se4 nanostructures in this study and required overpotentials as low as 244 and 184 mV to deliver a current density of 10 mA cm−2 for the OER and HER in 1.0 M KOH, respectively. Furthermore, the electrodes presented long-term stability over 20 h at current densities of 10 and −10 mA cm−2. Besides, this bifunctional flake-like CoNi2Se4 electrocatalyst delivered outstanding overall water splitting performance and required an external potential of 1.63 V to deliver a current density of 10 mA cm−2.

Adsorption of Co2+ and Sr2+ from aqueous solution by chitosan grafted with EDTA

The adsorptive removal of Co2+ and Sr2+ from water and wastewater is of great importance for environmental protection. Herein, a cost-effective and efficient adsorbent was reported for both nuclides removal, whilst their adsorption behavior and mechanism were also explored. In single-component systems, the maximum adsorption capacity was estimated to be 61.0 mg g−1 for Co2+ and 8.8 mg g−1 for Sr2+. Over the pH range of 3–7, adsorption capacity of both nuclides was less affected by solution pH level. In Co2+/Sr2+ co-existing system, EDTA-chitosan presented a higher adsorption capacity and affinity towards Co2+ than Sr2+. In multi-components system, EDTA-chitosan was an efficient broad-spectrum adsorbent for many types of metal ions even at a low pH level (pH=1.2). Furthermore, its adsorption affinity was affected by the nature of grafting EDTA fragments and the remaining chitosan fragments. Coordination and electrostatic interaction played a vital role in adsorption process. Above all, EDTA-chitosan is an efficient adsorbent for the adsorptive removal of heavy metal from water and wastewater.

Functionalized Stink Bean Pod (Parkia speciosa) Powder for Adsorption of Reactive Dye

The potential of agricultural waste materials for removing synthetic dye, Remazol Brilliant Blue R (RBBR) and Remazol Brilliant Violet 5R (RBV5) from aqueous solution were investigated. Water pollution is one of the major environmental issues; dyes have contributed enormous damage to water bodies and greatly impact human health due to high toxicity and carcinogenic by nature. Agricultural wastes are sustainable adsorbents and generally low cost, which has the potential to replace traditional activated carbon. Therefore, this study investigated the removal of RBBR and RBV5 dye from the aqueous solution by adding adsorbent through adsorption. Stink bean pod (Parkia speciosa) was selected as the main adsorbent of this study. The experiment was carried out to study the effect of different initial dye concentration, adsorbent dosage, contact time, and pH level of dye solution. The results have shown that different parameters can affect the removal rate and adsorption capacity of adsorbents in different ways. The adsorption of dye from aqueous solution onto adsorbent was assessed using Fourier Transform Infrared Spectroscopy (FTIR) to determine the functional groups of adsorbent before and after the adsorption process. The FTIR results show that the functional group would affect the removal rate and adsorption capacity of adsorbents. The present study indicates that 83.35% of RBBR with the adsorption capacity of 1.23 mg/g was removed by a 3 g stink bean pod. In comparison, 80.07% of RBV5 with the adsorption capacity of 1.22 mg/g was removed by a 3 g stink bean pod. Design-Expert software was used to generate the equation, which represents the behavior for the adsorption of RBBR and RBV5 dye. The results proved that stink bean pod was promising material as an alternative adsorbent for the removal of dye from aqueous solution.

Comparison of micro and nano MgO-functionalized vinasse biochar in phosphate removal: Micro-nano particle development, RSM optimization, and potential fertilizer

The present study is conducted to synthesize vinasse-derived biochar, followed by modification with Micro and Nano MgO in an attempt to assess their effects on the phosphate (P) removal from aqueous medium. Based on the characterization results of modified biochars and adsorption capacities, Nano-MgO Functionalized ones have proven to be more capable in P removal, with the specific surface areas of 119.98–125.41 m2/g and maximum P adsorption capacity of 188.67 mg/g. The dependencies of adsorption on initial P concentration (50–350 mg/L), contact time (5–90 min), and solution pH level (3–11) were investigated by 20 experiments designed via CCD-based RSM. The regression analysis showed a good fit of the experimental data to the second-order polynomial model with coefficient of determination (R2) value of 0.9916 and model F-value of 131.82. The optimum conditions of pH (7.00), contact time (75 min), and initial P concentration (250 mg/L) were recorded from desirability function. Based on the thermodynamic analysis, the adsorption process was spontaneous and exothermic in nature. In addition, the isotherm and kinetic studies indicated that the Freundlich and the pseudo-second order are the best fitted models for the P adsorption. Further, the P removal efficiency declined slightly in the presence of other co-existed anions, while acted relatively selective towards P. Finally, the P-loaded biochar could be properly regenerated by 1.0 M HCl solution, and the pot experiments proved its applicability as a P fertilizer substitute, increasing the plant growth rate – averagely, the height by 40 % and the dry mass by 59 %.

Finite Element Modelling and Experimental Validation of the Enamel Demineralisation Process at the Rod Level

In the past years, a significant amount of effort has been directed at the observation and characterisation of caries using experimental techniques. Nevertheless, relatively little progress has been made in numerical modelling of the underlying demineralisation process.The present study is the first attempt to provide a simplified calculation framework for the numerical simulation of the demineralisation process at the length scale of enamel rods and its validation by comparing the data with statistical analysis of experimental results.FEM model was employed to simulate a time-dependent reaction-diffusion equation process in which H ions diffuse and cause demineralisation of the enamel. The local orientation of the hydroxyapatite crystals was taken into account. Experimental analysis of the demineralising front was performed using advanced high-resolution synchrotron X-ray micro-Computed Tomography. Further experimental investigations were conducted by means of SEM and STEM imaging techniques.Besides establishing and validating the new modelling framework, insights into the role of the etchant solution pH level were obtained. Additionally, some light was shed on the origin of different types of etching patterns by simulating the demineralisation process at different etching angles of attack.The implications of this study pave the way for simulations of enamel demineralisation within different complex scenarios and across the range of length scales. Indeed, the framework proposed can incorporate the presence of chemical species other than H ions and their diffusion and reaction leading to dissolution and re-precipitation of hydroxyapatite. It is the authors’ hope and aspiration that ultimately this work will help identify new ways of controlling and preventing caries.

Forms and mobility of heavy metals/metalloids in sewage-irrigated soils in the North China Plain

Heavy metal/metalloid pollution in sewage-irrigated soils (SIS) is one of the major environmental issues in China. Mobility of heavy metals/metalloids in the contaminated soils and their potential threats to groundwater are needed to be understood. This study investigated impacts of organic matter, solution pH, and water level on forms and migration of heavy metals/metalloids (As, Cr, Cu, Pb, and Cd) in the contaminated soils from a typical sewage-irrigated area in the North China Plain (NCP). Based on extensive field measurements, two sewage-irrigated sites and a non-sewage-irrigated site were selected in the study area. Soil samples were collected every 10 cm in a profile (no more than 1 m) from each site. The release and mobility of heavy metals/metalloids in the SIS were investigated using column experiments with two leaching stages (stage I: low water level; stage II: high water level). Deionized water, synthesized acid rain, and poultry manure extractant were used as influents for different columns to stimulate leaching of rainfall, acid rain, and compost leachate, respectively. Soil samples before and after leaching were subjected to sequential extraction for 7 target phases, evaluating the impacts of three leaching conditions on forms of heavy metals/metalloids in soils at different depths. Results revealed that more As and Cu were mobilized in the column with a compost leachate as the influent than the columns with organic matter-free influents, resulting from reductive dissolution, complexation, and desorption. Cr and Pb concentrations were higher in effluents from the column with low pH influent (acid rain) than those from near-neutral pH influents (rainfall and compost leachate). Proton-promoted desorption and dissolution of very amorphous Fe oxides was the major cause for mobilized Cr and Pb in porewater. Moreover, decrease in dissolved oxygen (DO) was observed with the increase in water level in the column, triggering microbial respiration of Fe/Mn oxide reductions in the presence of bioactive dissolved organic matter, which elevated concentrations of porewater heavy metals/metalloids. This study suggested that sewage irrigation significantly increased heavy metal/metalloid contents associated with labile and bioavailable fractions in the SIS, and both the compost leachate and low pH solution should enhance the mobility of heavy metals/metalloids in the SIS and potentially contaminate groundwater.

Investigation of Structure, Optical, and Electrical Properties of CuS Thin Films by CBD Technique

Copper Sulfide (CuS) thin films were deposited onto a glass substrate using the Chemical Bath Deposition (CBD) technique. The chemical bath Precursors were made up of CuSO4, SC(NH2)2, and C4H6O6. Different parameters have been considered to specify the optimum conditions for fabricating CuS thin films, such as solution temperature, deposition time, pH level, and different precursor concentrations. It has been found that the optimum deposition time is 20 min at temperature 80 °C and pH = 11. The optimum precursor concentrations were 0.15 M, 0.2 M, and 0.1 M of CuSO4, SC(NH2)2, and C4H6O6, respectively. The structural properties of the thin film were studied using X-ray diffraction (XRD), and a single peak was observed for the thin film made at optimum conditions, while all other cases were amorphous. It is obvious from the optical characterization that the transmission spectra show a red-shift for the cases of increasing deposition time, bath temperature, C4H6O6 concentration, and pH. For the case of increasing CuSO4, blue shifts in the transmission spectra were observed. The energy band gap, resistivity, and activation energy of CuS thin films under optimum conditions are 2.35 eV, 0.7 Ω·cm, and 0.0152 eV, respectively.

PH Level of Pore Solution in Alkali-Activated Fly-Ash Geopolymer Concrete and Its Effect on ASR of Aggregates with Different Silicate Contents

Durability has always been a major concern in concrete-based infrastructures. Alkali–silica reaction (ASR) is the result of a chemical reaction between hydroxyl ions in pore water and silica from aggregates and cement of the concrete matrix. Geopolymer is a type of alkaline reactivated binder which can be synthesized by a polycondensation reaction of geopolymeric precursors and alkali polysilicates. Due to the alkaline solution brought in by alkali polysilicates, it is intuitive that a higher alkaline concentration in pore solutions of geopolymer concrete will adversely affect long-term performance. This study researched the preceding hypothesis and reports the finding of an experimental investigation of alkali–silica reaction between reactive aggregates and the geopolymer matrix. Specimens were prepared using Class C fly ash with a high CaO content and three types of aggregates (granite, carbonate, and gravel), each with different alkaline activator ratios and Na2O doses. Each aggregate also had different percentages of silicate and aluminum content. Mechanical testing of potential resistivity of the aggregates was performed via length change. Pore solution of the hardened geopolymer concrete was extracted and the pH value of the pore solution was determined. Results suggest that the extent of ASR reaction based on the presence of all three types of aggregates in fly ash–based geopolymer concrete is substantially smaller than that of ordinary portland cement (OPC)-based concrete. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) tests also revealed that the amount ASR gel formed in geopolymer is less than that formed in ordinary portland cement concrete. Hence, utilizing ASR vulnerable aggregates in the production of geopolymer concrete might be permissible.

Amorphous High-Surface-Area Aluminum Hydroxide-Bicarbonates for Highly Efficient Methyl Orange Removal from Water.

Amorphous high-surface-area aluminum hydroxide-bicarbonates were synthesized starting from AlCl3, base, and bicarbonate in water. Composites with a chemical formulas of [Al13O4(μ-OH)24(H2O)6.5(OH)5.5](HCO3)1.5 (I-NaOH) and [Al13O4(μ-OH)24(H2O)6(OH)6](HCO3) (I-NH3) were obtained by the use of NaOH/NaHCO3 and NH3/NH4HCO3 as base/bicarbonate, respectively. The surface area of the composites was highly dependent on the pH level of the synthetic solution, and composites with high surface areas (ca. 200 m2 g-1) were obtained around pH 7-8. Pore-size distributions determined from the N2 adsorption isotherms showed that I-NH3 and I-NaOH possess mainly large (pore radius rp > 3 nm) and small (rp < 3 nm) pores, respectively, despite similar surface areas. While SEM images showed that both I-NH3 and I-NaOH were aggregates of nanoparticles, the particles were more fused in I-NaOH, which is in line with the existence of small pores and the use of a stronger base (NaOH), which would facilitate the dehydration condensation reaction. The composites were applied as adsorbents to remove methyl orange (MO) from water. The time course of MO adsorption was readily fitted with a pseudo-second-order model, and over 90% MO removal was attained within 10 min with I-NH3, while I-NaOH showed much less MO removal (26%). The MO adsorption isotherm of I-NH3 was reproduced with a Langmuir model with an adsorption capacity of 154 mg g-1. Notably, the aluminum hydroxide-bicarbonates could not absorb methylene blue, which is a cationic dye, while anions (MO and PO43-) were readily absorbed. Solid-state 27Al MAS NMR spectra showed that the concentration of 5-coordinated aluminum species, which may serve as guest binding sites, was higher for I-NH3. These results show that electrostatic interaction between anionic MO and coordinatively unsaturated 5-coordinated cationic aluminum species and the large external surface area of I-NH3 contribute to the highly efficient MO adsorption.

Fabrication and performance evaluation of A shaped frame hydroponic system for leafy garlic

Present study was carried out for Fabrication and Performance Evaluation of A Shaped frame Hydroponic System under Protected Structures at the Centre of Excellence on Protected Cultivation and Precision Farming (CoE-PCPF), College of Agriculture, IGKV, Raipur (C.G.) during the year 2017-18. The experiment was laid out with three treatments T1 (A-frame PVC pipe), T2 (A-frame UPVC pipe), T3 (A-frame CPVC pipe), of hydroponic system. The transplanting of seedlings of leafy garlic was done in perforated net pots with a media of coco-pit and vermiculite in 3:1 proportion and clay pellets. Irrigation was applied to the crop by ebb flow technique. The pH and EC of the hydroponic solution were maintained in the range of 5.5 to 6.5 and 1.5 to 2.5 dS/m respectively in the tank. Hydroponic system in the present study has been fabricated with the help of locally available material which reduced cost of construction substantially. Effects of material on the growth of plants, EC and pH level of nutrient solution have also been studied and it is found that material has a very little or no effect on the growth as well as EC and pH aspects of nutrient solution at least in the first year of cultivation which might be changed in later years. Appearance wise good and moderately costlier UPVC pipes can be a better option for the design and construction of commercial hydroponic systems. Cost analysis of fabricated hydroponic Structure was also done.

The Characterization of Nanofet Sensor with Extended Sensing Electrode and Reference Electrode for Biosensor Application

Biosensors based on nano field-effect transistor(nanoFET) have been studied to detect from pH to biomolecules and anion in the air because its potential for label-free detection, rapid response time, low-cost and miniaturization [1-3]. The nanoFET sensor detect target species with a conductance change of nanochannel that is induced by the adsorption of charged substance or the surface potential of the sensing gate electrode. However, the sensing area on top of the nanochannel area is very small, the probability of binding of target molecules on the sensing surface of the device is very low. Therefore, we employ an electrically extended sensing electrode in order to improve adsorption probability of the charged substances and detection sensitivity. Here, we analyzed the behavior of the nanoFET sensor with an extended gate electrode and a reference electrode using pH solution of difference pH levels. It is a fundamental study to understand the behavior of nanoFET sensor with extended gate as biosensors, and it is necessary before applying it to various solution environment.Figure 1 shows the schematics of the nanoFET sensor with the extended gate electrode for pH level sensing of solution. The top gate electrode and the bottom substrate gate of the nanoFET sensor are electrically interconnected with the extended external electrode in order to increase the sensing area. The Ids-Vg characteristics of the nanoFET sensor with extended gate electrode, which is obtained by the voltage sweeping of the gate (Vg) as shown in Figure 2. The threshold voltage of the device is approximately -2.5 V. The electrode of an indium tin oxide(ITO) glass and a Ag/AgCl wire are used for the extended sensing gate electrode and the reference electrode. The connection for gate electrode and the reference electrode are compared with three cases of ITO-Ag/AgCl, Ag/AgCl-ITO and ITO-ITO respectively to compare pH response with the Ids-Vg sweep characteristics of the nanoFET sensor. In the pH sensing experiment, about 50 μL-solution having 4, 7 and 9.2 pH level are used, and it is dropped to a micro well on the extended sensing gate electrode as shown in Figure 1. Figure 3 shows Ids-Vg measurement results of varying the pH level on solution for the three connection cases of extended sensing gate electrode and reference electrode using the same device. Figure 3(a) shows Ids-Vg curve is shifted to the right side as the pH level rises in case of the reference electrode is the Ag/AgCl wire and the extended sensing gate electrode is the ITO glass. The response to pH level is shifted to left side as shown in Figure 3(b) when the electrode connection is reversed for the reference electrode and the extended sensing gate electrode with the ITO glass and the Ag/AgCl wire, respectively. In particular, it is confirmed that the nanoFET device don’t respond to the pH change of solution when both the reference electrode and the extended sensing gate electrode are the ITO glass. We finally conclude that the nanoFET sensor with the extended sensing gate electrode is affected by the surface potential in electrolyte solution induced by varying pH level. The equivalent circuit model of the nanoFET sensor is the series interconnection of two opposing electrolytic capacitors and the MOS capacitor of nanoFET device to the applied gate voltage as shown in Figure 4. Therefore, the nanoFET sensor with the extended gate electrode may not respond to the pH change or ion concentration in electrolyte solution when the interface of liquid-reference electrode is equal to interface of liquid-sensing electrode.In this study, we demonstrated experimentally the working principles of the nanoFET sensor with the extended gate electrode with the response to pH level of liquid solution. We found that the equivalent circuit model is the series connection of two opposing electrolytic capacitors in liquid solution and the MOS capacitor of the nanoFET device. The results suggest that the proper reference electrode should be utilized to measure the pH levels in liquid solution of nanoFET sensor and the other adequate reference electrode might be used to remove the effects induced by pH noise for the biosensor application such as immunosensors.This work was financially supported by the research funds (Grant No. 10076874 and No. 10077599) of the Ministry of trade, Industry and Energy, Korea[1]Matti Kaisti, Detection principles of biological and chemical FET sensors, Biosensors and Bioelectronics, 98 (2017)[2]Benjamin M. Lowe et al. Field-effect sensors-from pH sensing to biosensing: sensitivity enhancement using streptavidin-biotin as a model system, Analyst 142 (2017)[3]K.-N. Lee et al. Chemical gating experiment of a nano-field-effect transistor sensor using the detection of negative ions in air, Sens. Actuators, B 236 (2016) Figure 1

Structural, morphological, magnetic and spectral studies of Bi3+ substituted YFeO3 Nano-powders: Obtained by sol-gel synthesis

Nano powders of Bismuth substituted Yttrium ferrite have been synthasized by standard Sol-Gel method with maintaining the pH level of solution at 9 on the pH scale. The X-ray diffraction spectra concludes that these materials are well crystallized and lie in the desired single orthorhombic phase. Scanning Electron Microscopy (SEM) measurement suggests that each sample possesses a certain degree of homogeneity which follow increasing trend with enhanced doping concentration. EDAX measurement confirms the successful substitution of Bismuth for Yttrium cation site and also varify that the chemical compositions are in appropriate molar ratio which is consistant with the desired stoichiometry. Hysteresis loop recorded at 300 K indicates the anti-ferromagnetic nature of the prepared samples. The high value of coercivity (14 kOe to 24 kOe) predict their use in magnetic storage devices. The FT-IR spectra recorded in the fingerprint region (800 cm−1 to 400 cm−1) are showing various metal oxide bonds observed in the form of absorption bands.

The Role of Surface Properties on Protein Aggregation Behavior in Aqueous Solution of Different pH Values.

This study aimed to investigate the effect of pH-mediated surface properties of bovine serum albumin (BSA) on protein aggregation and the changes of protein structure and colloidal stability at different solution pH levels. The hydrophobicity of BSA surface was characterized by endogenous fluorescence spectroscopy, fluorescence quenching of acrylamide, and fluorescence probe. The results showed that the hydrophobicity of BSA surface was similar at pH5, 6, 7.4, followed by pH4, 8, 9, 10, and finally by pH3 and 11 with strong acidity and alkalinity. The positive charge on the BSA surface was increased gradually with the decrease of solution pH, while the negative charge on protein surface was increased gradually with the increase of solution pH. The degree of protein aggregation was examined by turbidimetry, flow cytometry, and SDS-PAGE. The results showed that the oscillating aggregation of BSA did not change with the solution pH, but was partially dependent on the relative contribution of electrostatic and hydrophobic interactions between the protein molecules. In addition, the secondary structure, conformational stability, unfolding degree, and colloidal stability of proteins were investigated by circular dichroism, fluorescence spectroscopy, protein pulse hydrolysis, and dynamic light scattering, respectively. The results suggested that the solution pH could change the structure and stability of the protein at different levels. Solution pH has distinct effects on the structural stability of protein at different levels. The change of protein surface properties mediated by solution pH is related to protein aggregation.

Conversion synthesis of manganese sulfate residue into iron hydroxide adsorbent for Cu(II) removal from aqueous solution.

Manganese sulfate residue (MSR) is a by-product derived from the manganese sulfate production process. In this study, an iron hydroxide adsorbent was prepared from MSR using the hydrothermal conversion method. The adsorbent was characterized and used to remove copper(II) ions from aqueous solution. Batch experiments were performed to investigate the adsorption efficiency of copper ions at different contact times, initial concentrations, solution pH levels, and reaction temperatures. Adsorption equilibrium was observed in 3h, and the best pH was under natural conditions (pH ∼ 5.5). Increasing the initial Cu2+ concentration and reaction temperature can increase the adsorption quantity. The adsorption capacity of iron hydroxide at an initial concentration of 50mgL-1 was 14.515mgg-1 Cu(II) under the conditions of a nature pH and room temperature. According to the adsorption data, the pseudo-second-order model can describe the adsorption kinetics of copper ions well, and the Freundlich model provides an excellent fit to the adsorption isotherm. XRD and FTIR were applied to characterize the raw materials and adsorbents to reveal the adsorption mechanism. The results suggest that the adsorbent converted from MSR is a promising material for the removal of Cu(II) in aqueous solutions.

Solvent Extraction of Copper and Zinc from Sulfate Leach Solution Derived from a Porcelain Stone Tailings Sample with Chemorex CP-150 and D2EHPA

This research investigates the extraction behavior of copper and zinc from the sulfate leachate of a porcelain stone tailings sample with Chemorex CP-150 and D2EHPA in detail. The findings demonstrated that Chemorex had greater ability and selectivity in the extraction of copper, while D2EHPA was better in the extraction of zinc. 97.88% copper and 78.2% zinc were extracted, respectively, with Chemorex and D2EHPA within 10 min contact time at an 1:1 aqueous/organic ratio, 10% (v/v) extractant concentration, and ambient temperature. The appropriate solution pH levels for Chemorex and D2EHPA were found to be 2.5 and 2, respectively. Also, a McCabe–Thiele diagram was drawn and one single-step extraction for copper and a two-stage process for zinc were needed to achieve the highest extraction efficiency. Additionally, the mechanism study indicated the association of ~ 1.5 and 1 mol of Chemorex CP-150 and D2EHPA for the extraction of one mole of Cu and Zn from the leach solution. Moreover, thermodynamic parameters, including ΔH, ΔG and ΔS were found to be 65.29 kJ/mol, 9.83 kJ/mol, and 186.14 J/mol K for copper and − 18.71 kJ/mol, 17.80 kJ/mol, and − 122.53 J/mol K for zinc, respectively, indicating that the extraction process was endothermic for copper and exothermic for zinc. The effect of contact time, pH, and extractants concentration on the extraction efficiency of Cu and Zn by Chemorex CP-150 and D2EHPA and also the number moles required for extractants

Mechanoresponsive Alignment of Molecular Self-Assembled Negatively Charged Nanofibrils.

Inspired by the mechanoresponsive orientation of actin filaments in cell, we introduce a design paradigm of synthetic molecular self-assembling fibrils that respond to external mechanical force by transforming from a macroscopically disorder state to a highly ordered uniaxial aligned state. The incorporation of aromatic-containing amino acids and negatively charged amino acids lead to self-assembly motifs that transform into uniform nanofibrils in acidic solution. Adjusting the pH level of aqueous solution introduces optimal negative charge to the surface of self-assembling nanofibrils inducing long-range electrostatic repulsion forming a nematic phase. Upon external mechanical force, nanofibrils align in the force direction. Via evaporation casting in capillary confinement, the solvated synthetic self-assembling nanofibrils transform into scalable lamellar domains. Adjusting capillary geometry and drying procedure offers further parameters for tuning the mesoscale alignment of nanofibrils generating a variety of interference colors. The design paradigm of mechanoresponsive alignment of self-assembled nanofibrils as an addition of nanofabrication techniques is potentially employable for realizing biomimetic optical structures.

Nitrogen Fertilizer Programs for Organic Flue-Cured Tobacco (Nicotiana Tabacum L.) Seedling Production

Certified organic flue-cured tobacco (Nicotiana tabacum L.) production has experienced significant expansion in the United States. Despite this expansion, there is very little information available that outlines organic nitrogen (N) programs for seedling production. To develop grower recommendations, research was conducted to evaluate the effects of a Peruvian seabird guano (SG), sodium nitrate (SN), or a combination of the two (SN_SG) in a float system on float water chemistry and seedling vigor. A conventional treatment (Conv; SQM Ultrasol Premium) was included for comparison. A greenhouse study was conducted twice between June 2016 and January 2017. Nitrogen fertilizer treatments were applied to tobacco float system water twice during the germination and growth of tobacco transplants. Float system water was collected every 5 days and analyzed for N forms, pH, dissolved oxygen, and bicarbonate. At the end of each experiment, transplant dimensions were measured and percent of usable plants collected. Float water bicarbonate concentration was &amp;lt;1 meq L−1 in treatments absent of SG for the duration of the study, but were in excess of 12 meq L−1 25 days after seeding (DAS) when SG was the exclusive N source. Despite high ammonium and bicarbonate concentrations with SG, neither factor negatively impacted seedling growth. Both SG and SN_SG produced as many usable plants as Conv; however, seedling height and diameter tended to be lower in SG compared to the other two treatments. No usable transplants were produced when SN was the sole fertility source, likely because of lack of nutrients other than N. Furthermore, many of the organic fertility products require biological activity to mineralize organic N to a plant-available form. This activity can have potentially detrimental outcomes on float system solution pH, dissolved oxygen, and bicarbonate levels.

A comparison of cation exchange capacity of organic soils determined by ammonium acetate solutions buffered at some pHs ranging between around field pH and 7.0

Cation exchange capacity (CEC) and exchangeable cations are among two of the most important measures for determining soil characteristics and soil quality. There are various methods of measuring CEC, including the ammonium acetate method of Schollenberger and Dreibelbis (1930) which is buffered at pH 7.0 and the barium chloride-triethanolamine method of Mehlich (1938) which is buffered at pH 8.2. These CEC measurements can result in values very different from the CEC of the soil at its field pH (effective CEC or CECe), especially in acidic soils, such as organic soils, with pH-dependent CEC. Therefore, the focus of this article is the comparison of CEC of organic soils obtained using the different pH level of the extraction solution. Five organic soil and two mineral soil samples were used in this experiment. The variables tested were CEC and exchangeable cations using ammonium acetate solutions buffered at several pHs; field pHs (acidic) of 3.8, 4.2, 4.8 and neutral (7.0). Each soil sample and pH level were replicated three times. The decomposition rate of the five organic soil samples was determined using the pyrophosphate color method, which proved to be sapric. The results indicated a positive relationship between pH and CEC value, the higher the pH buffer the much higher the CEC measured. There was a considerable difference of CEC values produced from the varying pHs of extraction solution. However, the pH of the extraction had no substantial effect on measured exchangeable cations.