Optimum pH Value Research Articles

Optimalisasi Penggunaan Fly Ash Untuk Reduksi Kadar Besi (Fe) Dan Mangan (Mn) Serta Peningkatan pH Dalam Air Asam Tambang

Coal mining activities often result in acid mine drainage (AMD), which can cause environmental pollution if not properly managed. This study aims to evaluate the potential use of fly ash from the Stream Power Plant (PLTU) Tenggarong to mitigate the impacts of AMD, specifically targeting iron (Fe), manganese (Mn), and pH parameters. Acid Mine drainage is formed when sulfide minerals oxidize, producing acidic compounds that can harm the environment. This research focuses on analyzing the ability of fly ash to adsorb iron and manganese from AMD solutions, as well its capability to increase solution pH. Based on the conducted research, the optimum pH value was achieved when using 10 grams and 15 grams of fly ash in the adsorption process. The optimum concentration of iron (Fe) was attained using 10 grams to 15 grams of fly ash, while for manganese (Mn), it was achieved with 20 grams to 25 grams of fly ash. The adsorption process using 25 grams of fly ash showed the highest efficiency in reducing iron (Fe) concentration by 93.78 % and manganese (Mn) concentration by 75.47 %.

Using ion exchange chromatography for the purification of glyoxylate reductase from corn leaves and studying its characteristics

The purpose of this study was to obtain a purified preparation of the studied enzyme from corn leaves and to study its characteristics. In this work, kinetic and regulatory parameters of glyoxylate reductase were calculated for leaves of 14-day-old corn (Zea mays) seedlings grown hydroponically at 25°C. The following methods were used during the study: sample homogenisation, four-step purification including ammonium sulphate for desalting, gel filtration on G-25 columns, and ion exchange chromatography using DEAE-sephacel, as well as electrophoresis on polyacrylamide gels and quantitative analysis of protein. To study the properties of the enzyme, we used electrophoretically homogenous preparations. The influence of pH, substrate concentration, and cofactor on the rate of the enzymatic reaction was determined by a series of measurements with different values of the enzymatic reaction rate. As a result of four-stage purification, we obtained a homogeneous preparation with a specific activity of167 E/mg of protein. Ion exchange chromatography was important for purification; we obtained 1 peak of enzyme activity upon desorption in 104 mM sodium chloride. Studying the properties of glyoxylate reductase showed a significant dependence of activity on pH. The optimal pH value was 6.5 units.

Enhanced stability of papain at extreme pHs and temperatures by its immobilization on cellulose nanocrystals coated with polydopamine

In this investigation, a nano-support containing cellulose nanocrystals – polydopamine (CP) was functionalized with glutaraldehyde (G) and utilized to immobilize papain. The properties of the supports and stabilized enzyme were characterized by TEM, SEM, DLS, Zeta-potential, FTIR, and EDS analyses. The optimal temperature of both papain forms was 60 °C, while the optimal pH value of the stabilized papain shifted from 7 to 8 after immobilization. The immobilized enzyme preparations showed higher stability at 80 and 90 °C and under acidic and alkaline conditions compared to the free enzyme. CPG-papain stability was higher than that of CP-papain. The Km values for free and immobilized papain on CP and CPG were 3.92, 3, and 2.74 mM respectively. Kcat values were 9.05, 15.18, and 11.59 min−1 and catalytic efficiency values were 2.3, 5.05, and 4.23 mM−1.min−1. Additionally, the potential advantages of using a silver nanohydrid support were assessed. Although silver nanoparticles conveyed some catalytic activity to the final biocatalysts, they also caused a decrease in stability and activity of the immobilized papain. Therefore, the non-hybrid supports CP and CPG were more suitable candidates for the immobilization of papain than the hybrid supports.

Recovery of volatile fatty acids from anaerobic fermentation broth of baker’s yeast industry effluent by liquid−liquid extraction

As metabolic intermediates, volatile fatty acids (VFAs) can be recovered by separation and purification and contribute to the economy. It was necessary, however, to investigate the optimization of liquid–liquid extraction (LLE) in this study because of the technical difficulties encountered during the recovery of VFAs. For this reason, the organic solvents diethyl ether, trioctylamine, and toluene were investigated as LLE solvents to extract VFAs from Baker’s yeast industry effluent, which contains high levels of organic matter. An optimal pH value of 3 was determined by a pH scan performed between pH 2.5 and pH 7.5. Principal component analysis (PCA) was used to determine the effects of organic solvents and pH on extraction efficiency. The extraction efficiency was evaluated using the optimal pH and multi-stage extraction experiments. In a three-stage extraction, diethyl ether recovered 82% of the VFAs, making it a promising organic solvent for extracting VFAs from anaerobic fermentation broth. PCA revealed that an opposite correlation between VFA recovery and pH for each organic solvent. Based on the results of the cost analysis, it was determined that the costs of recovering VFAs were reduced by 90% per kilogram.

Bacterial cellulose microfilament biochar-architectured chitosan/polyethyleneimine beads for enhanced tetracycline and metronidazole adsorption

This study investigates the potential applications of incorporating 2D bacterial cellulose microfibers (BCM) biochar into chitosan/polyethyleneimine beads as a semi-natural sorbent for the efficient removal of tetracycline (TET) and metronidazole (MET) antibiotics. Batch adsorption experiments and characterization techniques evaluate removal performance and synthesized adsorbent properties. The adsorbent eliminated 99.13 % and 90 % of TET and MET at a 10 mg.L−1 concentration with optimal pH values of 8 and 6, respectively, for 90 min. Under optimum conditions and a 400 mg.L−1 concentration, MET and TET have possessed the maximum adsorption capacities of 691.325 and 960.778 mg.g−1, respectively. According to the isothermal analysis, the adsorption of TET fundamentally follows the Temkin (R2 = 0.997), Redlich-Peterson (R2 = 0.996), and Langmuir (R2 = 0.996) models. In contrast, the MET adsorption can be described by the Langmuir (R2 = 0.997), and Toth (R2 = 0.991) models. The pseudo-second-order (R2 = 0.998, 0.992) and Avrami (R2 = 0.999, 0.999) kinetic models were well-fitted with the kinetic results for MET and TET respectively. Diffusion models recommend that pore, liquid-film, and intraparticle diffusion govern the rate of the adsorption process. The developed semi-natural sorbent demonstrated exceptional adsorption capacity over eleven cycles due to its porous bead structure, making it a potential candidate for wastewater remediation.

Kinetic and thermodynamic parameters of urease in soils with different fertilization regimes

In recent years the growing demand for food led to intensification of agricultural practices, especially by the excessive use of fertilizers, which increased the environmental pollution. Therefore, pollution control by improving the efficiency of fertilizers and reducing their application is of great interest. Urease is one of the most active hydrolases in soil, having an important role in soil N cycle and being used as an indicator of soil quality. The objective of this study was to assess the urease activity in soils with different fertilization treatment, as well as its kinetic and thermodynamic parameters to better understand its driving factors. The results show a better enzymatic activity in soils treated with combined manure and mineral fertilizers. Soil urease has two optimal pH values, in the neutral and basic domains. Enzymatic activity has a steep increase with the temperature in the interval 45–65°C. The KM values increase with temperature from 11 to 23.5 mM, indicating a lower substrate affinity. The activation enthalpies for enzyme-substrate formation as well as for the rate limiting step are 7.59 and 14.18 kcal/mol respectively. The relationship between urease activity and microbial biomass will be further investigated.

Biotechnological potential of psychrotolerant methylobacteria isolated from biotopes of Antarctic oases.

Ten strains of psychrotolerant methylotrophic bacteria were isolated from the samples collected in Larsemann and Bunger Hills (Antarctica). Most of the isolates are assigned to the genus Pseudomonas, representatives of the genera Janthinobacterium, Massilia, Methylotenera and Flavobacterium were also found. Majority of isolates were able to grow on a wide range of sugars, methylamines and other substrates. Optimal growth temperatures for the isolated strains varied from 6°C to 28°C. The optimal concentration of NaCl was 0.5-2.0%. The optimal pH values of the medium were 6-7. It was found that three strains synthesized indole-3-acetic acid on a medium with L-tryptophan reaching 11-12μg/ml. The values of intracellular carbohydrates in several strains exceeded 50μg/ml. Presence of calcium-dependent and lanthanum-dependent methanol dehydrogenase have been shown for some isolates. Strains xBan7, xBan20, xBan37, xBan49, xPrg27, xPrg48, xPrg51 showed the presence of free amino acids. Bioprospection of Earth cryosphere for such microorganisms has a potential in biotechnology.

Biochemical properties of phytase immobilized and its effect on growth parameters of tomato

AbstractBackgroundPhosphorus (P) is one of the nonrenewable resources of critical importance in agricultural production. P is present in soil in organic and inorganic forms. Phytate constitutes the majority of organic P in soil. Phytate binds strongly to the solid phase of the soil and becomes unavailable for use by plants. Therefore, the soluble phytate‐P ratio in soil is mostly at very low levels. Plants and associated microorganisms secrete organic acids and hydrolyzing enzymes such as phytase to dissolve phytate in the soil. Both the solubility of phytate and phytase activity are limiting properties for the uptake of phytate‐P by plants.AimsOur aim was to evaluate the effects of phytase immobilized on zinc oxide nanoparticles (ZnO Np) on tomato plant (Solanum lycopersicum) growth parameters. In this study, seedling period was analyzed.MethodsIn the study, phytase activity of 13 different bacteria was investigated, and phytase was purified from Lactobacillus kefiri, showing the highest activity, and its biochemical properties were determined. Phytase was immobilized on zinc oxide (ZnO) nanoparticles and characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopes analysis. The effects of ZnONps, immobilized phytase, and free phytase on the growth parameters of tomato plant were investigated. Tomato seeds were soaked with ZnONps, immobilized and free phytase for 30 min at room temperature and sown in pots containing suitable growing medium. Vegetative development of tomato plant, plant height, number of lateral branches, main stem diameter, distance between nodes, number of nodes, main root, and shoot length were determined.ResultsPhytase was partially purified with 7.60% recovery and specific activity of 1758.5 (EU mg−1 protein). Molecular mass of partially purified phytase was approx.72 kD, optimum pH and temperature values were determined as pH 5.0 and 70–80°C, respectively. Immobilized phytase caused a significant increase of 41.1% in plant height, 64.1% in main root, and 36.1% in shoot length in tomato plants compared to the control. In addition, a significant increase was observed in the number of side branches, main stem diameter, distance between nodes, number of nodes, and vegetative growth of the plant.ConclusionsThe results showed that the immobilized phytase enzyme has a positive effect on seedling growth in tomato and can be used in tomato cultivation in the future.

Insights into the photodegradation of decamethylammonium bromide (DDAB) under UV/H2O2 system: Photodegradation kinetic modeling, degradation mechanism and toxicity evaluation

Decamethonium bromide (DDAB), as a class of quaternary ammonium-based disinfectants (QACs), was widely used during the COVID-19 outbreak. The abuse of DDAB is harmful to the health of aquatic organisms. The UV/H2O2 process is popularly utilized for the removal of trace contaminants from aqueous environments. Thus, in this paper, DDAB was selected as the model of QACs, and the degradation kinetics were simulated by Kintecus software. It was indicated that the effect of the degradation efficiency of DDAB was dominated by [·OH]ss. The degradation efficiency of DDAB was greater than 95 % when [·OH]ss was higher than 1.04×10−12 M. The high dosages of H2O2 (>100 μM) and the less concentration of pollutants (<10 μM) were more beneficial to the degradation of DDAB. The high dosages of NOM and CO32- in the system scavenged ·OH and thereby inhibited the degradation of DDAB. The interference of Cl- on the degradation efficiency was negligible. Additionally, the optimal pH value for removing DDAB was between 4 and 7. Besides, the degradation pathway of DDAB was inferred by Density Functional Theory (DFT) and Ultra-high Performance Liquid Chromatography-tandem Mass Spectrometry (UPLC-MS/MS). The results showed that the degradation of DDAB began with C-N bond breaking, then generated aldehydes, underwent demethylation reaction, and finally converted to low molecule weight molecules. The results of Ecological Structure Activity Relationships (ECOSAR) toxicity assessment demonstrated that the toxicity of all the degradation products was significantly low. Overall, this study provides theoretical basis for the removal of QACs in the aqueous environment.

Composite "Crosslinked Polyvinyl Alcohol-Magnetite" as a Stimuli-Responsive Matrix for Optical Methods.

The preparation and application of the composite material "crosslinked polyvinyl alcohol-magnetite" as a sensitive matrix for use in digital colorimetry and optical micrometry methods are discussed. The material was synthesized in the form of spherical granules (for micrometry) and thin films (for digital colorimetry). The obtained composites were characterized by the registration of magnetization curves. It was shown that the amount of grown Fe3O4 particles in the polymer gel is in linear dependence with the iron salt concentrations in the impregnating solutions. The composite granules were applied to determining monosaccharides using optical micrometry. The optimal pH value for the total amount of monosaccharides' determination was 8.6. The study of the analytical response of composite granules and films performed with a low limit of detection (7.9 mmol/dm3) of both glucose and fructose and a possibility of the control of high alcohol contention in water media. The granules were used to determine the total carbohydrate content in samples of natural honey and syrups with high fructose contents, while the films were used to control the alcohol content in hand antiseptics. The results obtained are in good agreement with the data provided by the manufacturers.

Synthesis and Characterization of Cross-Linked Aggregates of Peroxidase from Megathyrsus maximus (Guinea Grass) and Their Application for Indigo Carmine Decolorization.

We present the synthesis of a cross-linking enzyme aggregate (CLEAS) of a peroxidase from Megathyrsus maximus (Guinea Grass) (GGP). The biocatalyst was produced using 50%v/v ethanol and 0.88%w/v glutaraldehyde for 1 h under stirring. The immobilization yield was 93.74% and the specific activity was 36.75 U mg-1. The biocatalyst surpassed by 61% the free enzyme activity at the optimal pH value (pH 6 for both preparations), becoming this increase in activity almost 10-fold at pH 9. GGP-CLEAS exhibited a higher thermal stability (2-4 folds) and was more stable towards hydrogen peroxide than the free enzyme (2-3 folds). GGP-CLEAS removes over 80% of 0.05 mM indigo carmine at pH 5, in the presence of 0.55 mM H2O2 after 60 min of reaction, a much higher value than when using the free enzyme. The operational stability showed a decrease of enzyme activity (over 60% in 4 cycles), very likely related to suicide inhibition.

A novel alcohol dehydrogenase in the hyperthermophilic crenarchaeon Hyperthermus butylicus.

Hyperthermus butylicus is a hyperthermophilic crenarchaeon that produces 1-butanol as an end product. A thermostable alcohol dehydrogenase (ADH) must be present in H. butylicus to act as the key enzyme responsible for this production; however, the gene that encodes the ADH has not yet been identified. A novel ADH, HbADH2, was purified from a cell-free extract of H. butylicus, and its characteristics were determined. The gene that encodes HbADH2 was demonstrated to be HBUT_RS04850 and annotated as a hypothetical protein in H. butylicus. HbADH2 was found to be a primary-secondary ADH capable of using a wide range of substrates, including butyraldehyde and butanol. Butyraldehyde had the highest specificity constant, calculated as k c at/K m, with k cat and apparent K m values of 8.00 ± 0.22 s-1 and 0.59 ± 0.07 mM, respectively. The apparent K m values for other substrates, including ethanol, 1-propanol, 2-propanol, butanol, acetaldehyde, propanal, and acetone, were 4.36 ± 0.42, 4.69 ± 0.41, 3.74 ± 0.46, 2.44 ± 0.30, 1.27 ± 0.18, 1.55 ± 0.20, and 0.68 ± 0.04 mM, respectively. The optimal pH values for catalyzing aldehyde reduction and alcohol oxidation were 6.0 and 9.0, respectively, while the optimal temperature was higher than 90°C due to the increase in enzymatic activity from 60°C to 90°C. Based on its substrate specificity, enzyme kinetics, and thermostability, HbADH2 may be the ADH that catalyzes the production of 1-butanol in H. butylicus. The putative conserved motif sites for NAD(P)+ and iron binding were identified by aligning HbADH2 with previously characterized Fe-containing ADHs.

UV-ARTP combined mutagenesis selection of lignin-degrading strain and enzymatic characterization of the resultant organisms

In this study, we selected a strain JC-28 after mutagenesis in preliminary identification. The Ultraviolet-Atmospheric and Room Temperature Plasma (UV-ARTP) combined mutagenesis time was 60 s for each, resulting in the screening of 6 positively mutated strains. The enzyme activity and lignin degradation rate of these strains were determined. Eventually, two optimal strains, JC-28-UA26 and JC-28-UA12, were identified. Following genetic stability testing, strain JC-28-UA12 was ultimately chosen, exhibiting a 16.18% increase in lignin degradation rate and relatively good genetic stability. The optimal temperatures for the enzymes Lip, Mnp, and Lac of this strain were 40 °C, 40 °C, and 50 °C, respectively, with optimal pH values of 4, 5, and 3, and relatively good stability. Additionally, metal ions Mg2+, Mn2+, and K+ all enhanced the activity of these three enzymes, while Fe2+ and Hg2+ exhibited some inhibitory effects on them. This study provides valuable insights into the breeding of lignin-degrading bacterial strains.

Characterization of Liquid Organic Fertilizer (LOF) Derived from Unmarketable Vegetables and Fruits

The Malaysian government has been challenged with handling unmarketable vegetables and fruit waste that pollutes the environment and emits greenhouse gases, mainly methane and nitrous oxide. These greenhouse gases have been contributing to climate change. In contrast, these wastes consist of high moisture and readily biodegradable nutrients that can serve as the perfect substrate rate for fermentation. The valuable nutrients contained in these wastes can produce liquid organic fertilizers (LOF), which help improve the soil’s physical, chemical, and biological characteristics and reduce the demand for inorganic fertilizers and costs to farmers. In this regard, a study was conducted to produce and characterize LOF derived from unmarketable vegetables and fruit waste. The waste was identified from the nearest wet market, collected, and incubated in containers with a ratio of 1: 2: 0.1 (10 kg unmarketable vegetable and food waste: 20 L water: 1 kg inducer) for 30, 45, and 60 days. The unmarketable vegetables and fruits were fermented using three different types of inducers: yeast (Y), brown sugar (BS), and shrimp paste (SP). Unmarketable vegetables and fruit waste with no inducer were also included as a control. Samples from the produced LOF were taken after 30, 45, and 60 days of fermentation, filtered, and subjected to analysis for pH, electrical conductivity (EC), macro-, and micronutrients. These experiments were laid out in a randomized complete block design (RCBD) with three replications. The highest nitrogen (0.95%), phosphorus (0.31%), potassium (1.68%), copper (0.23 ppm), and manganese (9.03 ppm) were obtained from LOF fermented for 60 days using yeast, indicating that it improved the nutrient availability of agricultural waste. Moreover, this treatment provided optimum pH and EC values for the growth and development of plants. Thus, LOF derived from unmarketable vegetable and fruit waste can be considered an attractive alternative for supplementing chemical fertilizers.

Horseradish Peroxidase Immobilized onto Mesoporous Magnetic Hybrid Nanoflowers for Enzymatic Decolorization of Textile Dyes: A Highly Robust Bioreactor and Boosted Enzyme Stability.

Recently, hybrid nanoflowers (hNFs), which are accepted as popular carrier supports in the development of enzyme immobilization strategies, have attracted much attention. In this study, the horseradish peroxidase (HRP) was immobilized to mesoporous magnetic Fe3O4-NH2 by forming Schiff base compounds and the HRP@Fe3O4-NH2/hNFs were then synthesized. Under optimal conditions, 95.0% of the available HRP was immobilized on the Fe3O4-NH2/hNFs. Structural morphology and characterization of synthesized HRP@Fe3O4-NH2/hNFs were investigated. The results demonstrated that the average size of HRP@Fe3O4-NH2/hNFs was determined to be around 220 nm. The ζ-potential and magnetic saturation values of HRP@Fe3O4-NH2/hNFs were -33.58 mV and ∼30 emu/g, respectively. Additionally, the optimum pH, optimum temperature, thermal stability, kinetic parameters, reusability, and storage stability were examined. It was observed that the optimum pH value shifted from 5.0 to pH 8.0 after immobilization, while the optimum temperature shifted from 30 to 80 °C. K m values were calculated to be 15.5502 and 7.6707 mM for free HRP and the HRP@Fe3O4-NH2/hNFs, respectively, and V max values were calculated to be 0.0701 and 0.0038 mM min-1. The low K m value observed after immobilization indicated that the affinity of HRP for its substrate increased. The HRP@Fe3O4-NH2/hNFs showed higher thermal stability than free HRP, and its residual activity after six usage cycles was approximately 45%. While free HRP lost all of its activity within 120 min at 65 °C, the HRP@Fe3O4-NH2/hNFs retained almost all of its activity during the 6 h incubation period at 80 °C. Most importantly, the HRP@Fe3O4-NH2/hNFs demonstrated good potential efficiency for the biodegradation of methyl orange, phenol red, and methylene blue dyes. The HRP@Fe3O4-NH2/hNFs were used for a total of 8 cycles to degrade methyl orange, phenol red, and methylene blue, and degradation of around 81, 96, and 56% was obtained in 8 h, respectively. Overall, we believe that the HRP@Fe3O4-NH2/hNFs reported in this work can be potentially used in various industrial and environmental applications, particularly for the biodegradation of recalcitrant compounds, such as textile dyes.

Removal of carcinogenic chromium(VI) from effluent of electroplating industry using adsorptive separation

AbstractThe wastewater from an electroplating industry contains chromium VI which is highly carcinogenic at a typical level of 21.5 to 47 mg L−1 which should be reduced to acceptable value of 0.05 mg L−1 for the water to be suitable for drinking purpose. In this study, Tulsion A23 resin was applied as an adsorbent for successful removal of Cr(VI), also dealing with understanding the effect of various parameters on extent of removal of the contaminant. It was elucidated that contact time of 120 min is required for the equilibrium and the optimum pH value was 5 and the optimum resin loading was 4 g L−1 at which 97% Cr(VI) removal was observed. Different adsorption isotherm models were applied and it was elucidated that Langmuir model was the best fit with R2 as 0.99. In the case of kinetic study, pseudo‐second order model was best fitted with higher R2 value. The regeneration of the resin was performed using 3 M NaOH and it was shown that after the three cycles of regeneration, the resin showed 82% Cr(VI) removal. Overall, successful application of Tulsion A23 resin was demonstrated for the removal of Cr(VI) from real effluent for the first time.

Cobalt based bimetallic catalysts for heterogeneous electro-Fenton adapting to vary pH for HEDP and MIT degradation

ABSTRACT Most of the materials studied as catalysts in the electro-Fenton system are variants of iron oxide or iron hydroxide. However, iron-based catalysts often exhibit weak catalytic capabilities under neutral and alkaline conditions. In this work, we synthesized three cobalt based bimetallic oxides, Co2CuOx, Co2AlOx, and Co2NiOx, using hydrothermal method and evaluated them as catalysts for the heterogeneous electro-Fenton system to remove 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and Methylisothiazolinone [2-methyl-4-isothiazolin-3-one] (MIT). Co2NiOx has the highest catalytic degradation activity for HEDP, and Co2CuOx has the best catalytic degradation effect for MIT. Based on characterization results of the catalysts, the reasons for the differences in the pollutant removal efficiency were analysed, and the optimal pH for the three cobalt based oxides to remove HEDP and MIT was investigated. The results showed that the optimal pH values of the three cobalt based bimetallic oxides are not only influenced by the second metal type, but also by the properties of pollutants. Therefore, suitable cobalt based catalysts can be selected based on the different properties of pollutants, or the composition of cobalt based catalysts can be adjusted to meet the different pH requirements of target wastewater. The three cobalt based bimetallic oxides exhibited good degradation of HEDP and MIT under neutral conditions, which to some extent solved the problem of narrow pH range in the practical application of the electro-Fenton process.

Heterologous expression and characterization of mutant cellulase from indigenous strain of Aspergillus niger.

The purpose of current research work was to investigate the effect of mutagenesis on endoglucanase B activity of indigenous strain of Aspergillus niger and its heterologous expression studies in the pET28a+ vector. The physical and chemical mutagens were employed to incorporate mutations in A. niger. For determination of mutations, mRNA was isolated followed by cDNA synthesis and cellulase gene was amplified, purified and sequenced both from native and mutant A. niger. On comparison of gene sequences, it was observed that 5 nucleotide base pairs have been replaced in the mutant cellulase. The mutant recombinant enzyme showed 4.5 times higher activity (428.5 µmol/mL/min) as compared to activity of native enzyme (94 µmol/mL/min). The mutant gene was further investigated using Phyre2 and I-Tesser tools which exhibited 71% structural homology with Endoglucanase B of Thermoascus aurantiacus. The root mean square deviation (RMSD), root mean square fluctuation (RMSF), solvent accessible surface area (SASA), radius of gyration (Rg) and hydrogen bonds analysis were carried at 35°C and 50°C to explore the integrity of structure of recombinant mutant endoglucanase B which corresponded to its optimal temperature. Hydrogen bonds analysis showed more stability of recombinant mutant endoglucanase B as compared to native enzyme. Both native and mutant endoglucanase B genes were expressed in pET 28a+ and purified with nickel affinity chromatography. Theoretical masses determined through ExPaSy Protparam were found 38.7 and 38.5 kDa for native and mutant enzymes, respectively. The optimal pH and temperature values for the mutant were 5.0 and 50°C while for native these were found 4.0 and 35°C, respectively. On reacting with carboxy methyl cellulose (CMC) as substrate, the mutant enzyme exhibited less Km (0.452 mg/mL) and more Vmax (50.25 µmol/ml/min) as compared to native having 0.534 mg/mL as Km and 38.76 µmol/ml/min as Vmax. Among metal ions, Mg2+ showed maximum inducing effect (200%) on cellulase activity at 50 mM concentration followed by Ca2+ (140%) at 100 mM concentration. Hence, expression of a recombinant mutant cellulase from A. niger significantly enhanced its cellulytic potential which could be employed for further industrial applications at pilot scale.

Green Surfactant Assisted-Solidified Floating Organic Drop Micro-Extraction (SA-SFODME) for the Preconcentration of Trace Lead with Determination by Flame Atomic Absorption Spectrometry (FAAS)

Determination of trace lead from environmental samples was carried out by solidified floating organic drop microextraction for preconcentration before analysis by flame atomic absorption spectrometry. The determination of lead from environmental samples, even at trace levels, was possible with an ordinary flame atomic absorption spectrometer (FAAS). The lead formed a hydrophobic complex with the anionic surfactant sodium dodecyl benzene sulfonate (SDBS), and this hydrophobic complex was extracted into the 1-dodecanol drop. Parameters affecting analytical performance have been studied. The optimum pH value was 3.5. The optimum sample volume, SDBS concentration, and extraction solvent volume were 75 mL, 50 mM in dodecanol, and 75 µL, respectively. The optimum extraction time was determined as 30 min, the optimum extraction temperature was 45 °C, the optimum mixing speed was 650 rpm and the ideal extraction phase volume was 0.50 mL. Methanol has been shown to be effective when used as a diluent. Using the optimum conditions, the enhancement factor was 106, and the limit of detection (3s) and precision were 3.3 ng/mL and 2.3% (n = 9,15 ng/mL), respectively. The limit of quantification (LOQ) (10s) was 10 ng/mL and the linear working range was 15-100 ng/mL. The accuracy was evaluated by certified reference material analysis. The optimized method was applied to the determination of Pb(II) from environmental water samples. This method follows the principles of green analytical chemistry.

Rust Prevention Property of a New Organic Inhibitor under Different Conditions.

The corrosion resistance properties of a new type of environmentally-friendly organic inhibitor containing amino ketone molecules are presented in this paper. To evaluate the prevention effect of the inhibitor on corrosion of reinforcement, the electrochemical characteristics of steels in the simulated concrete pore solution (SPS) were investigated under varied conditions of the relevant parameters, including concentrations of the inhibitor and NaCl, pH value, and temperature. The inhibition efficiency of the material was characterized through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and the weight loss of steels. The results reveal a significant improvement in the corrosion resistance of steels with the inhibitor. A maximum resistance value of 89.07% was achieved at an inhibitor concentration of 4%. Moreover, the new organic inhibitor exhibited good corrosion protection capability for steels under different NaCl concentrations. Its inhibition efficiency was determined to be 65.62, 80.06, and 66.30% at NaCl concentrations of 2, 3.5 and 5%, respectively. On the other hand, it was found that an alkaline environment was favorable for an enhanced corrosion prevention effect, and an optimal pH value of 11.3 was observed in this work. Besides, the inhibition efficiencies at different temperatures showed a trend of 25 > 35 > 40 > 20 > 30 °C, with a maximum value of 81.32% at 25 °C. The above results suggest that the new organic material has high potential to be used as an eco-friendly and long-term durable inhibitor for steel corrosion prevention under complex conditions.