Humic Acid Sodium Research Articles

Research on COD parameter in water based on the combination of UV absorption photometry and laser spectroscopy

Chemical Oxygen Demand (COD) is widely utilized as a representative and required measurement indicator of water pollution as well as water quality monitoring. The spectral technology is an important development direction in water quality detection. In this paper, a novel COD monitoring instrument is designed based on ultraviolet (UV) absorption photometry and laser spectroscopy. The instrument consists of CODcr and CODmn detection modules. The CODcr module is based on the Lambert-Beer law to measure UV absorption of organic matter in water, which can be used to measure the COD parameter in high concentration organic pollution in water. The CODmn module is based on the ratio method of fluorescence and Raman to analyze the spectral signals generated by the laser-excited water body, which can determine the COD parameter in low contaminated water. By analyzing the CODcr and CODmn parameters together, the comprehensive evaluation of organic pollutants in water can be realized. In the experiment, the CODcr and CODmn modules are respectively calibrated with the potassium hydrogen phthalate (KHP) solution as well as the mixed solution of humic acid sodium and glucose. Then the stabilities of the two detection modules are tested, and the detected result drifts are stable within six days. In addition, to verify the reliability of measuring results in complex environments, we test the instruments at 10 monitoring sites of the Sow River in Weihai city. The results of on-site monitoring are highly consistent with those of national standard method. The study result shows that the instrument developed in this paper can measure both CODcr and CODmn simultaneously, which can expand the COD detection range, and provide a new method for the comprehensive detection of organic pollutants in water.

Activation of peroxymonosulfate by Fe,N co-doped walnut shell biochar for the degradation of sulfamethoxazole: Performance and mechanisms

Fe and N co-doped walnut shell biochar (Fe,N-BC) was prepared through a one-pot pyrolysis procedure by using walnut shells as feedstocks, melamine as the N source, and iron (III) chloride as the Fe source. Moreover, pristine biochar (BC), nitrogen-doped biochar (N-BC), and α-Fe2O3-BC were synthesized as controls. All the prepared materials were characterized by different techniques and were used for the activation of peroxymonosulfate (PMS) for the degradation of sulfamethoxazole (SMX). A very high degradation rate for SMX (10 mg/L) was achieved with Fe,N-BC/PMS (0.5 min−1), which was higher than those for BC/PMS (0.026 min−1), N-BC/PMS (0.038 min−1), and α-Fe2O3-BC/PMS (0.33 min−1) under the same conditions. This is mainly due to the formation of Fe3C and iron oxides, which are very reactive for the activation of PMS. In the next step, Fe,N-BC was employed for the formation of a composite membrane structure by a liquid-induced phase inversion process. The synthesized ultrafiltration membrane not only exhibited high separation performance for humic acid sodium salt (HA, 98%) but also exhibited improved self-cleaning properties when applied for rhodamine B (RhB) filtration combined with a PMS solution cleaning procedure. Scavenging experiments revealed that 1O2 was the predominant species responsible for the degradation of SMX. The transformation products of SMX and possible degradation pathways were also identified. Furthermore, the toxicity assessment revealed that the overall toxicity of the intermediate was lower than that of SMX.

Assessment of the Relationship Between Humic Acid Contents and Trace Elements of Some Agricultural Soils in Diyarbakır Region by Multivariate Statistical Methods

There are important relationships between humic acid (HA) and the bioavailability, reactions and mobility of trace elements in the soil. For this reason, soils are tried to be improved chemically, biologically and physically with HA applications. In this study, the relationship of humic acid contents of 118 agricultural soil samples from Diyarbakır region with some trace elements (Al, As, Ba, Be, Cd, Fe, Mn, Pb, Sb, Sn, Se, V and P) was evaluated by multivariate statistical analysis. After the soil samples were solubilized by the microwave wet digestion method, the element contents were determined with the ICP OES (Inductively Coupled Plasma Optical Emission Spectrometer) device. SRM NIST 2586 was used as SRM (Standard Reference Material) for the accuracy of the method. Recovery values were found between 91.6% and 105.9% as a result of the analysis. Humic acid was extracted from soils by the International Society for Humic Substances (IHSS) method and determined using a shaker and centrifuge device. For the accuracy of the method, it was tested with Humic Acid Sodium Salt (HA-Na). Pearson correlation and partial correlation analysis were applied to the obtained data set. In addition, multivariate statistical analyses such as multiple regression HCA (Hierarchical Cluster Analysis) and PCA (Principal Component Analysis) were applied. Multiple regression analysis was performed according to the Step-wise method. Manganese and P (p< 0.01) were significant when HA was taken as the dependent variable. According to the Pearson correlation coefficient, the correlation between HA and As (r = -0.282**) in soil was negative and significant, while Fe (r = 0.185*), Mn (r = 0.273**)), Sn (r = 0.242*), Se (r = 0.325**) and P (r = 0.315**) were determined as positive and significant. In clustering and PCA analysis, HA, P Mn and Fe were found to be in the same group. The analyses have shown that HA has a positive effect on the plant nutrients in the soil.

Synthesis and mechanism study of an environmentally friendly filtrate reducing agent from humic acid and organic silicon

AbstractIn this study, organic silicon was introduced to humic acid for the first time, and set the novel polymer NaHm/AMPS/AM/TSP‐L12 (HASSi) as an environmentally friendly filtrate reducing agent, which was developed by using silica modified material (TSP‐L12), sodium humic acid (NaHm), 2‐acrylamido‐2‐methylpropanesulfonic acid sodium (AMPS), and acrylamide (AM) as raw materials. The molecular structure, chemical composition of HASSi has been investigated and results show that HASSi shows the chemical structure was conformed to the molecular design. Differential scanning calorimetry–thermogravimetric analysis results illustrate that thermal decomposition temperature of HASSi under nitrogen was 250°C. Though temperature resistance evaluations, HASSi could withstand temperature up to 230°C. Salt and calcium resistance evaluations confirmed its resistance of NaCl could reach up to 5% and CaCl2 to 0.5%. The filtrate reduce mechanism of HASSi was investigated through various methods, including scanning electron microscope analysis of HASSi aqueous solution, microstructure of filter cake, measurements of zeta potential, and particle size distribution, results showed that HASSi participation in the formation of mud cakes and illustrated an excellent filtration reduction effect. In addition, HASSi was identified as an environmentally friendly filter loss reducing agent through environmental performance evaluation, which shows a great application prospect in oilfield.

Low-pressure ultraviolet-H2O2 photolysis for restoring the anodic stripping voltammetry signal: a new strategy for the detection of heavy metal ions in complex organic matter.

A new strategy based on low-pressure ultraviolet (LPUV)-H2O2 advanced oxidation photolysis for the quantitative determination of organic heavy metal ions (HMIs) in soil was proposed for the efficient, low-cost, accurate, and green detection of Pb(II) and Cd(II) in soil extracts by breaking the complexation of HMIs and organic matters, consequently restoring the ASV signals of target HMIs. The key parameters of the proposed LPUV-H2O2 photolysis system for the restoration of stripping responses were optimized; the conversion of organic matter to inorganic matter during the photolysis was investigated by total organic carbon (TOC); the degradation kinetics of humic acid sodium (HAS) was measured by UV-vis spectroscopy (UV); the pathway of HAS converted to small molecule organics during degradation was observed by fluorescence spectroscopy (FS); additionally, Fourier transform infrared spectroscopy (FTIR) was used to study the complexation between HAS and HMIs. The results showed that the stripping signals of target HMIs in the simulated soil samples can be restored to nearly 100% with a good repeatability, and the restoration ratio of the stripping signal fluctuated within 10%. And the feasibility of the proposed method for the accurate detection of HMIs in the real soil samples was verified; the results showed that 93.7% of Cd(II) and 92.5% of Pb(II) in real soil extracts were detectable.

Strategy for enhancing Cr(VI)-contaminated soil remediation and safe utilization by microbial-humic acid-vermiculite-alginate immobilized biocomposite

Bioreduction is an efficient approach to in-situ remediate Cr(VI)-contaminated soil, but further strengthening methods are still urgently needed. Herein, a novel immobilized biocomposite (B-HA-VE-SA) was successfully synthesized by embedding a efficient strain Bacillus sp. CRB-7 with humic acid (HA) combined vermiculite (VE) and sodium alginate (SA). The performance and enhancement mechanism of the immobilized biocomposite on remediating Cr(VI)-contaminated soil were also investigated by analyzing the whole-genome of CRB-7, Cr(VI) detoxification, soil microecological regulation, and subsequent crop growth response. Genomic annotation demonstrated that CRB-7 contains multiple genes contributed to Cr(VI) tolerance, Cr(VI) reduction and other metals resistance. Results showed that embedded CRB-7 biocomposites exhibited more effective reduction of Cr(VI) in soil compared with control and free CRB-7 treatment, especially B-HA-VE-SA achieved the highest Cr(VI) removal efficiency (96.18%) and the residual Cr proportion (49.04%) via multiple mechanisms including carrier effects, nutrient sustained-release, and electron-shuttle effect enhanced the bioremediation process. Furthermore, the synergies of CRB-7 and immobilizers (HA, VE and SA) significantly improved soil microecology (soil enzyme activities, microbial quantity and diversity), and engendered the evolution of microbial community composition and functional pathways. Consequently, pot experiments (Brassica napus L.) verified the plant-growth-promoting (12.00–18.00% and 43.82–69.00% higher in emergence rate and biomass) and Cr-accumulation-reducing effects (19.47–91.09% and 29.11–89.80% lower in root and aerial parts) of free and immobilized CRB-7. Taken together, these findings highlighted the superiority of B-HA-VE-SA in simultaneous remediation, microecological improvement and safe utilization of Cr(VI)-contaminated soil.

SALTING-IN AND SALTING-OUT EFFECTS OF POLYPHENOLS, AROMATIC COMPOUNDS, AND AMINO ACIDS ON POLY (N-ISOPROPYLACRYLAMIDE) AND EGG WHITE AQUEOUS SOLUTIONS

Introduction. Understanding the biophysical phenomena related to the Hofmeister series or cosmotropic/chaotropic properties of ions requires experimental data on specific ion effects of large organic molecules.Problem Statement. Specific ion effects are of significant importance for biophysics and medicine. It is interesting to find out if additives with biologically relevant anions can interact with proteins and avoid aggregation.Purpose. The purpose of this research is to study the stabilizing/destabilizing effects in Poly(N-isopropylacrylamide) (PNIPAM)/water, hen egg white/water systems under influence of substances of various classes of different hydrophobia.Materials and Methods. Materials: sodium salts: salicylate, ferulate, benzoate, vanillate, cinnamate; humic acid sodium salt, hydroxy-sodium benzoate, glycine, L-alanine, sodium L-glutamate, D-(—)-quinnic acid, PNIPAM, egg white. Methods: measurement of the transition temperature (TT) of PNIPAM/water and the denaturationtemperature of the egg white / water systems.Results. Ion-specific effects have been studied with the use of models based on the research of the transition temperature (TT) evolution of binary PNIPAM / water mixtures (for heating from 0 to 35°C) and the denaturation temperature of the egg white / water (for heating from 48 to 65°C). The dependences of these temperatureson the content of substances that occur in live nature have been received at pH = 7.4.Conclusions. The results have shown the tendencies of the additive solubilizing effects on PNIPAM and egg white. The majority of substances studied has the salting-out effect on PNIPAM / water in the order NaBz ~ NaCinn < L-NaGlu ~ NaFer. For NaSal and NaHum; the salting-in effect has been established. For the egg white, all additives show the salting-in effect. In PNIPAM and egg white systems, NaBz and L-NaGlu demonstrate the opposite effects. The results have been compared with the ones for binary mixtures of water/di-propylene glycolpropyl ether (DPnP).

Acid-free protocol for extracting pollen from Quaternary sediments

Quaternary palynology commonly requires the use of acids such as hydrofluoric acid (HF), sulphuric acid (H2SO4), and hydrochloric acid (HCl) to extract pollen grains and spores. In some countries, restricted access to these acids makes fossil pollen studies challenging. Here, we propose an alternative pollen processing technique that does not require the use of acids. The methodology is mainly based on the use of potassium hydroxide (KOH) as a humic acid remover, sodium metaphosphate (NaPO3) and sodium pyrophosphate (Na4P2O7) as a deflocculant, and zinc chloride (ZnCl2) as a precursor for the flotation of the pollen grains. The techniques were tested and compared with a well-established and widely applied technique in palynology laboratories, which requires acids. For testing the techniques, 0.5 cm3 of samples from three different sedimentary environments (peat, lake, and swamp) in Brazil were used. The technique using sodium metaphosphate was successful because the structure of the fossil pollen grains and spores showed no retention of extraneous organic matter, thus facilitating their morphological identifications. The pollen grain concentrations for the sample were equivalent to the treatment with acids. This protocol was developed to allow broader, safer, and cheaper access to palynological research, as the impediments represented by restrictions on reagent controls do not apply. This protocol also respects environmental protection policies.

Brown carbon's emission factors and optical characteristics in household biomass burning: developing a novel algorithm for estimating the contribution of brown carbon

Abstract. Recent studies have highlighted the importance of brown carbon (BrC) in various fields, particularly relating to climate change. The incomplete combustion of biomass in open and contained burning conditions is believed to be a significant contributor to primary BrC emissions. So far, few studies have reported the emission factors of BrC from biomass burning, and few studies have specifically addressed which form of light-absorbing carbon, such as black carbon (BC) or BrC, plays a leading role in the total solar light absorption by biomass burning. In this study, the optical integrating sphere (IS) approach was used, with carbon black and humic acid sodium salt as reference materials for BC and BrC, respectively, to distinguish BrC from BC on filter samples. A total of 11 widely used biomass types in China were burned in a typical stove to simulate the real household combustion process. (i) Large differences existed in the emission factors of BrC (EFBrC) among the tested biomass fuels, with a geometric mean EFBrC of 0.71 g kg−1 (0.24–2.09). Both the plant type (herbaceous or ligneous) and burning style (raw or briquetted biomass) might influence the value of EFBrC. The observed reduction in the emissions of light-absorbing carbon (LAC) confirmed an additional benefit of biomass briquetting in climate change mitigation. (ii) The calculated annual BrC emissions from China's household biomass burning amounted to 712 Gg, higher than the contribution from China's household coal combustion (592 Gg). (iii) The average absorption Ångström exponent (AAE) was (2.46±0.53), much higher than that of coal-chunk combustion smoke (AAE=1.30±0.32). (iv) For biomass smoke, the contribution of absorption by BrC to the total absorption by BC+BrC across the strongest solar spectral range of 350–850 nm (FBrC) was 50.8 %. This is nearly twice that for BrC in smoke from household coal combustion (26.5 %). (v) Based on this study, a novel algorithm was developed for estimating the FBrC for perhaps any combustion source (FBrC=0.5519ln⁡AAE+0.0067, R2=0.999); the FBrC value for all global biomass burning (open+contained) (FBrC-entire) was 64.5 % (58.5 %–69.9 %). This corroborates the dominant role of BrC in total biomass burning absorption. Therefore, the inclusion of BrC is not optional but indispensable when considering the climate energy budget, particularly for biomass burning emissions (contained and open).

Investigations on the fouling characteristic of humic acid and alginate sodium in capacitive deionization

Abstract Capacitive deionization (CDI) has been investigated for brackish water desalination, selective removal of ions, and water softening. We used humic acid (HA) and alginate sodium (SA) to simulate different kinds of natural organic matter to investigate the fouling phenomena during CDI operation. Adsorption amount and energy efficiency were studied. Results showed that both SA and HA could decrease the removal of NaCl during CDI operation. There existed a slight decrease of energy consumption in SA solutions which was opposite to that in HA solutions. HA can compete with ions adsorbed by electrodes and attach to electrodes adhesively, resulting in co-ion repulsion. SA is not sensitive to electrical field and its fouling is not obvious. The amount of adsorbed Mg2+ would increase from 0.927 mg/g to 1.508 mg/g in ten cycles' operation and the increment of Ca2+ was from 1.885 mg/g to 2.878 mg/g in SA solutions. This increase of adsorption was due to the complexation between SA and cations. Simultaneously, energy consumption was decreased. In HA solutions, energy consumption of Mg2+ and Ca2+ adsorption increased. In ten cycles' operations, both HA and SA could reduce the efficiency of CDI operation. The types of organic substances are important factors in fouling of CDI electrodes.

Effects of Dietary Supplementation of Humic Acid Sodium and Zinc Oxide on Growth Performance, Immune Status and Antioxidant Capacity of Weaned Piglets.

Simple SummaryWeaning of piglets can destroy the piglet’s intestinal health and immune function, leading to diarrhea and a reduction in growth rate eventually. Considering drug resistance and residues, new alternatives, such as sodium humate (HNa), have attracted considerable research interest over recent decades. Our study was designed to explore the effect of HNa on the growth performance, diarrhea rate, antioxidative, inflammation, and immunity of weaned piglets and the possibility of HNa replacing antibiotics and zinc oxide. The obtained results indicate that HNa reduces stress, protects the intestinal barrier, and improves the performance of weaned piglets.At present, the widespread use of high-dose zinc oxide and antibiotics to prevent post-weaning diarrhea (PWD) in piglets has caused serious environmental problems. To solve this problem, we studied the effect of HNa as a substitute for zinc oxide (ZnO) and antibiotics on the growth performance, immune status, and antioxidant capacity of piglets. Seventy-two weaned piglets (body weight = 7.42 ± 0.85 kg, 26-d-old) were distributed in a randomized 2 × 3 factorial design (two sexes and three treatments) with six replicates of four piglets each. The three treatments were the control diet (basic diet), HNa diet (basic diet + 2000 mg/kg sodium humate), and ZoA group (basic diet + 1600 mg/kg zinc oxide + 1000 mg/kg oxytetracycline calcium). ANOVA and Chi-square tests were applied to compare the means (p < 0.05) between treatments. The results showed that body weight at 16 and 30 d and the average daily gain of piglets fed with HNa or ZoA were significantly higher (p < 0.05) than the control group. Supplementing HNa or ZoA significantly increased (p < 0.05) the level of immunoglobulin M and G, and reduced (p < 0.05) the concentration of inflammatory factors such as tumor necrosis factor-alpha (TNF-α), interleukins IL-6 and IL-1β, myeloperoxidase (MPO), and diamine oxidase (DAO). Furthermore, dietary HNa or ZnO significantly reduced (p < 0.05) the level of total antioxidant capacity (T-AOC) and malondialdehyde (MDA) compared with the control group. ZoA treatment showed an upward trend of IgA level and a downward trend of the concentration of lipopolysaccharide (LPS) and catalase (CAT). Overall, the study demonstrated that the addition of HNa in the diet partially replaced antibiotics and ZnO to improve the growth performance, immune function, and antioxidant capacity of weaned piglets, and maintained a good preventive effect on piglet diarrhea.

Solubilization mechanism of diesel in saponin micelle for contaminated montmorillonite washing

Abstract The biosurfactant was used to remove diesel from contaminated montmorillonite, which was enhanced by humic acid sodium salt (HASS) addition or microbubbles resulted from sonication. It was found that montmorillonite exhibited strong adsorption for saponin, causing the effective critical micelle concentration shift of saponin from 0.2 g L−1 to 0.6 g L−1. The washing efficacy (diesel removal) with 0.6 g L−1 saponin and 2% HASS (HASS/saponin ratio = 2%) increased 14.9 % compared to the control condition (without HASS), whereas the diesel removal with microbubble enhancement (25 min sonication) increased 15.2 % compared to the control condition. Bright-field microscopy, microscope, DLS, PSS, and TEM were used to measure the size of micelles and count micelle numbers. In the addition of 2% HASS, the mean diameter of saponin micelles decreased from 824.9 ± 12.3 nm to 91.3 ± 7.6 nm, and the number of micelles increased from 42,000 to 110,000 at saponin solution of 0.3 g L−1. The hydrophobic core volume increased accordingly. HASS molecule might cause the extension of hydrophobic interior space in micelles to solubilize the hydrocarbon contaminant. In addition to micelles solubilization, the microbubbles enhancement washing process increased the diesel removal by floatation, cavitation in sonication.

Hydroxyl radical scavenging factor measurement using a fluorescence excitation-emission matrix and parallel factor analysis in ultraviolet advanced oxidation processes

The performance of the UV/H2O2 advanced oxidation process (AOP) is dependent on water quality parameters, including the UV absorbance coefficient at 254 nm and hydroxyl radical (•OH) water background demand (scavenging factor, s−1). The •OH scavenging factor represents the •OH scavenging rate of the background substances in the water matrix, and it is known to be one of the key parameters to predict the performance of the UV/H2O2 process. The •OH scavenging factor has been determined experimentally by using a probe compound such as pCBA and rhodamine B. The experimental method has been validated to accurately predict the micropollutants removal in the UV/H2O2 process, but there is a need for an easier and simple method of determining the OH scavenging factor. We evaluated the alternative method to analyze the •OH scavenging factor using fluorescence excitation-emission matrix and parallel factor analysis (F-EEM/PARAFAC). The correlation between •OH scavenging factor and the spectroscopic characteristics and structure of different organic matter types was evaluated. Organic matter was characterized using a fluorescence excitation-emission matrix, parallel factor analysis, and liquid chromatography-organic carbon detection. Second-order reaction rates of humic acid sodium salt, sodium alginate, Suwannee River humic acid and bovine serum albumin were calculated as 1.30 × 108 M−1 s−1, 1.39 × 108 M−1 s−1, 1.03 × 108 M−1 s−1, and 3.17 × 107 M−1 s−1, respectively. Results of PARAFAC analysis, the ratio of humic and fulvic fluorescence component 2 to terrestrial humic-like fluorescence component 1 (C2/C1), and •OH scavenging factor showed high linearity. A predictive model, which combines with the F-EEM/PARAFAC method, predicted the optimal UV and H2O2 dose to achieve target compound removal.

Hexafluoroisopropanol-alkanol based high-density supramolecular solvents: Fabrication, characterization and application potential as restricted access extractants

Hexafluoroisopropanol-alkanol (C6–C12) supramolecular solvents were proposed and their application potential as restricted access extraction solvents was assessed. Hexafluoroisopropanol acts as alkanol reverse micelle-forming agent and density-regulating agent for the supramolecular solvent synthesis. The formation of supramolecular solvent only needs a small percentage of hexafluoroisopropanol (<10% v/v for alkanol <5% v/v) and is almost not affected by the pH (2-11) and low ionic strength (NaCl <3%, w/v) of aqueous medium. The supramolecular solvents have higher density than water and consist of reversed micellar aggregates with irregular mesh structures and hydrophilic inner cavities, and the hydrophilic cavity size is obviously dependent on the hexafluoroisopropanol amount in the bulk system but almost not relevant to the alkanol amount. The hydrogen-bond and hydrophobic interactions of hexafluoroisopropanol with alkanol and the hydrogen-bond force between hexafluoroisopropanol and water play crucial roles in the formation of supramolecular solvent. The supramolecular solvents not only do not or slightly dissolve macromolecules (proteins, polysaccharides, and humic acid sodium), but also can effectively exclude them in extraction procedure; meanwhile, they can extract small molecules from complex samples with high extraction rate (even near 100% through optimization). The extraction mechanism involves the hydrophilic inner cavity size of supramolecular aggregates and the interactions (hydrogen-bond, hydrophobic) between supramolecular solvent and analytes. The suitability of supramolecular solvents as extractants was evaluated by extracting and determining chlorophenols in real water samples, coupled with high performance liquid chromatography-ultraviolet detector. The enrichment factors of 72–147 were obtained. Limits of detection were from 0.38 to 0.57 ng mL−1. The recoveries ranged from 96.0 to 107.9%, and intra-day and inter-day precisions were less than 4.0%. The novel hexafluoroisopropanol-alkanol supramolecular solvents have promising potential as restricted access extractants.

Enhancement of auxiliary agent for washing efficiency of diesel contaminated soil with surfactants.

We used five types of surfactants assisted with sodium salts, including sodium tartrate (ST), sodium chloride (SC), and humic acid sodium (HAS) as auxiliary agents for soil washing to remove diesel from contaminated soil. Decontamination enhancement of diesel polluted soil washing with biosurfactant and H2O2 was examined, which showed higher effectiveness for newly contaminated soil. An increase in temperature and sodium salt addition exhibited a profound enhancement in diesel removal from aged contaminated soils. Compared to ST and SC, HAS exhibited a higher removal efficiency with saponin washing for aged diesel contaminated soil by lowering surface tension, shifting zeta potential, and increasing the number of micelles. Phytotoxicity experiments showed no significant inhibition of germination of lettuce, arugula, and cucumber with 0.2 g L−1 saponin incubation. Conversely, there was a promotion on the root extension of lettuce and cucumber except for arugula. Similarly, the addition of 2% HAS (wight of saponin) improved on root growth of lettuce, arugula, and cucumber, increasing by 25%, 5%, and 22% at the period of 14 d, respectively. Because of excellent removal efficiency and non-toxicity, enhanced wash with saponin and HAS might be considered in the future design of full-scale remediation processes of diesel contaminated soil.

Adsorption of polymers onto iron oxides: Equilibrium isotherms

The interactions of polymers (corn starch, dextrin from maize starch, humic acid sodium salt and sodium carboxymethyl cellulose) with iron oxides (hematite and magnetite) have been investigated by measuring adsorption isotherms and by electrophoresis. According to the electrophoresis measurements at pH 7 both iron oxides present negative surface charge and positive at pH 5. The equilibrium adsorption isotherms were then determined at pH 7 for all the adsorbates except for humic acid which was studied at pH 5, due to its anionic characteristics. The equilibrium data of both iron oxides were studied using Freundlich and Langmuir models and it was found to best fit to the Freundlich one. The values for Freundlich constants indicate that the mechanism that contributes most to the adsorption process in all experiments was the hydrogen bonding. However, the coexistence of more than one adsorption mechanism is what best explains the process itself, in addition to explaining the differences found amongst theories over the years.

Hümik Asit/Kuversetin Kaplı Fe3O4 Manyetik Nanoparçacıklar ile Cu2+ ve Ni2+ Metallerinin Adsorpsiyon Yöntemiyle Giderimi

Removal of metals and heavy metals from industrial wastewaters is a serious concern for water systems. In this study, environmentally friendly natural polymer coated, cost-effective, easy to operate HA/QR magnetic nanoparticles were suggested to overcome this problem, for the first time in literature. Fe3O4 magnetic nanoparticles were synthesized with co-precipitation technique and a core-shell structure was obtained with humic acid sodium salt (HA) solution. At the second step of the procedure, synthesized magnetic nanoparticles were coated with quercetin solution. Scanning electron microscopy (SEM), X-Ray diffraction (XRD) and particle size analyses were performed to enlighten and characterize the structure. The newly synthesized nanoparticles were used for the batch-wise adsorption of copper and nickel metals, successfully. Maximum adsorption capacities were calculated as 14.61 mg/g for copper and 28.30 mg/g using 0.03 g adsorbents, at pH=7. Adsorption isotherms were evaluated and it was concluded that adsorption equilibrium fitted to both Langmuir and Freundlich isotherm models, better correlated with Langmuir isotherm model.

Green fabrication of SH‐modified GO composite for heavy metal ions removal in aqueous solution

Humic acid (HA) sodium salt (SH)-modified graphene oxide (GO) composite, which could snatch Pb (II), Cd (II) and Cu (II) effectively from aqueous solution, was fabricated by a green hydrothermal method. Here, the morphology and structure of as-synthesised SH–GO composite was presented through scanning electron microscopy, Roman spectra, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermal gravimetric analysis. Owing to the introduction of cheap and readily available HA sodium salt, the adsorption capacity of SH–GO toward heavy metals was improved obviously, and the corresponding removal behaviours were further investigated in detail. Besides, the adsorption results were in good agreement with Langmuir isotherm and the pseudo-second kinetic model, where the thermodynamic parameters revealed the adsorption process was spontaneous and endothermic in essence. Adsorption–desorption result showing its stable adsorption capacity confirmed its great potential as adsorbent for removal of heavy metal ions from aqueous solution.

Optical Properties of Humic Material Standards: Solution Phase and Aerosol Measurements

Aerosols generated from aqueous samples of readily obtainable humic material standards are often used as proxies for organic particulates found in the atmosphere in various investigations, such as consideration of radiative forcing effects. Here, we present results for the retrieved complex index of refraction, m = n + ik, at a wavelength of 403 nm for aerosols prepared from six humic material standards using a calibrated cavity ring-down spectrometer: a humic acid sodium salt, Pahokee peat humic and fulvic acids, Elliott soil humic and fulvic acids, and Suwannee river fulvic acid. In addition, we have conducted UV–vis spectrometric studies to measure the mass absorption coefficients, molar absorptivities, and absorption Angstrom exponents of bulk aqueous solutions of the humic materials. We find clear differences between the humic acid (HA) and fulvic acid (FA) samples with the HA having larger values for the imaginary part of the refractive index, k. The mean value for the HA samples is k = 0.170 while ...

Effects of dietary humic acid on growth performance, haemato-immunological and physiological responses and resistance of Rainbow trout,Oncorhynchus mykisstoYersinia ruckeri

This study investigated the effects of dietary humic acid sodium salt on growth performance, haemato-immunological and physiological responses, and resistance of rainbow trout, Oncorhynchus mykiss to Yersinia ruckeri. The experimental fish were divided into four groups; three of them were fed with humic acid incorporated diets (0.3% H3, 0.6% H6, 1.2% H12) and an additive free basal diet served as the control. Growth performance and haematological parameters of rainbow trout were not affected by humic acid supplemented diets (p > 0.05). However, dietary humic acid especially with 0.6% incorporation significantly increased stomach pepsin, intestinal trypsin and lipase activities p < 0.05. Following 60 days of feeding trial, fish were challenged with Yersinia ruckeri for 20 days. At the end of the challenge period, significantly higher (p < 0.05) survival rates were found in the 6% humic acid group compared to all other experimental treatment. Thus humic acid might replace antibiotics in diets for rainbow trout to control yersiniosis.