Thermosensitive and Wound-Healing Gelatin-Alginate Biopolymer Hydrogels Modified with Humic Acids

The main goal of the article is the creation and study of thermosensitive and wound-healing gelatin-alginate bio-polymer hydrogels modified with humic acids.Their rheological properties,swelling and contraction behavior were experimentally investigated,elucidated using Fourier transform infrared spectroscopy and used to achieve the physiological melting point,which is necessary for successful drug delivery.It has been shown that in the gelatin-alginate-humic acid biopolymer hydrogels systems,it is possible to obtain a gel-sol transition temperature close to the physiological temperature of 37℃,which is important for drug delivery in the treatment of wounds.By changing the type and concentration of humic acids in the gelatin-alginate hydrogel,it turned out to be achiev-able to regulate the softening time of the gel on the human body in the range from 6 to 20 min,which provides the possibility of controlled prolonged delivery of drugs.Based on the study of the influence of calcium ions on the properties of humic acids and ion exchange,as well as the interaction of humic acids,sodium alginate and gelatin with the formation of tighter gel networks,approaches to regulate the rate of softening of hydrogels at physiological temperature and their swelling,which simulates the absorption of exudate,were proposed and implemented.In addition,low shrinkage of the hydrogel surface due to cross-linking of gelatin-alginate networks when modified with humic acids was experimentally confirmed,which is important for avoiding problems of wound contracture and contour deformations when using dressings for wound healing.Thus,the developed opti-mized innovative biopolymer hydrogels synergistically combine the outstanding properties of natural molecular polymers and humic acids and are promising for the creation of effective medicines for wound healing.

Effects of Three Humic Acid Foliar Fertilizers on Quality and Photosynthetic Characteristics of Hawthorn

[Objectives]To investigate the effects of three foliar fertilizers on photosynthetic characteristics,fruit quality and yield of hawthorn.[Methods]Taking hawthorn foliar fertilization as the reference,the photosynthetic rate,transpiration rate,intercellular CO 2 concentration,stomatal conductance and single fruit weight of hawthorn leaves were measured under different concentrations of foliar fertilizer.[Results]The results showed that the photosynthetic rate,transpiration rate and stomatal conductance of hawthorn leaves increased significantly,while the intercellular CO 2 concentration decreased.Specifically,the fish protein peptide foliar fertilizer performed best,with net photosynthetic rate and transpiration rate increased by 57.22%and 57.51%,respectively.All the three foliar fertilizers significantly reduced the intercellular CO 2 concentration.In addition,fertilization significantly increased the single fruit weight of hawthorn,and the effect of fermented fulvic acid foliar fertilizer was the most significant,with the highest growth rate of 68.49%.[Conclusions]Spraying foliar fertilizer significantly increased the content of Vc,titratable acid,anthocyanin and soluble solids of hawthorn fruit,among which fermented fulvic acid foliar fertilizer had the optimal effect.

Characterization of humic acids extracted from the sediments of the various rivers and lakes in China

The humic acids (HAs) isolated from the sediments of the various rivers,lakes,and reservoirs in China were studied using elemental analyzer,fourier transform infrared (FT-IR),and CP/MAS 13C nuclear magnetic resonance (NMR) spectroscopy.The results showed that the HAs were characterized by some common chemical and physicochemical properties,but they also pose some differences in the C-containing functional groups.The C/N,C/H,O/C,and O/H ratios differ widely for the various HAs,showing that the elemental comp...

Extraction and Characterization of Humic Acids and Humin Fractions from a Black Soil of China

Twenty-three progressive extractions were performed to study individual humic acids (HAs) and humin fractions from a typical black soil (Mollisol) in Heilongjiang Province, China using elemental analysis and spectroscopic techniques. After 23 HA extractions the residue was separated into high and low organic carbon humin fractions. HA yield was the highest for the first extraction and then gradually decreased with further extractions. Organic carbon (OC) of the humin fractions accounted for 58% of total OC …

Complex behaviour of trivalent rare earth elements by humic acids

The complexation behaviours of trivalent rare earth elements (La, Ce, Ho and Yb) by two types of humic acids were investigated under a specified set of conditions. Humic acids show quite different complexation capacities an conditional formation constants with the REEs. Apparently there are two types of binding sites in the functional groups of humic acid, in which the first binding sites have stronger ability than the second. Cerium shows the largest complexation capacities and highest formation constants among the four REEs with two humic acids, this anomaly may be relative to the distribution pattern of the REEs in seawater. The experimental results were comparable to the values of other metals reported and provided the basic data for environmental geochemistry of rare earth elements.

Characteristics of isothermal adsorption and desorption of aluminum ion to/from humic acids

The adsorption and desorption characteristics of Al^3＋ to/from humic acids at different pH, ionic strength, and temperature were studied by the C-25 glucosan-gel chromatography method. The results showed that the maximum adsorption amount （Qmax） and adsorption constant （k） increased, whereas, the absolute value of standard thermodynamic molar free energy change （ΔGm^0） decreased with the increase of pH at constant ionic strength and temperature. With ionic strength increasing from 0 to 0.15 mol/L, Qmax, and k increased and the absolute value of ΔGm^0 decreased at constant pH and temperature. High temperature was unfavorable for the adsorption reaction, as indicated by the dramatic decrease of Qmax and the absolute value of ΔGm^0 with an increase in temperature. The standard thermodynamic molar free energy change （ΔGm^0） and the standard thermodynamic enthalpy change （ΔHm^0） of the adsorption reaction were both negative, suggesting that adsorption reaction was spontaneous and exothermic. The desorption rate of HA-Al^3＋ complex accelerated with the decrease of pH, and a significant linear relationship could be obtained between pH and the desorption rates of Al^3＋ from humic acids. These results demonstrated that the Al^3＋ adsorption reaction was a ＂biphase＂ reaction, and adsorption occurred at both the interior and exterior adsorption sites of humic acids.

Effect of Pig Manure Application on Structural Characteristics of Humic Acids in Brown Soil

The effect of application of pig manure (PM) on the structural characteristics of humic acids (HAs) of brown soil was studied in field and incubation experiments. The results showed that the number-average molecular weights (Mn), the ratios of C/ H, C/ N and O/C, the contents of carboxyl and phenolic hydroxyl groups, the content ofaromatic C, the values of E2, E4and λ Exmax of HAs all decreased; whereas, the contents of alkyl C and O-alkyl C, the ratio of carboxyl to phenolic hydroxyl groups, the degree of oxidation stability, the absorption intensity at 285 mμ (UV), and 2920cm-1 of HAs increased after the application of PM. The above results indicated that the molecular structure of HAs tended to be more aliphatic and simpler after the application of PM.

Electrokinetic chemical characteristics of humic and dannic acids effecting on the natural water and its coagulation

Taking streaming current(SC)as the electrokinetic parameter,this paper demon- strated the electrokinetic chemical characteristics of humic and dannic acids(HA and DA)in sus- pensions including turbid water,coagulated water and HA or DA contained water.Accordingly, the studies were carried out for determining the relationship between streaming current and zeta po- tential ζ(expressed by eleetrophoretie mobility EM)in above water conditions.In addition,the mechanisms of HA effecting on streaming current within or after coagulant addition and the elec- trokinetic detection principles for HA or DA were also investigated on experiments and theoretical analysis.The results indicated that the change of SC like ζ presented meaningful information con- cerning the degree for destabilization of a particulate suspension,and HA or DA in water could re- markably decrease the effect of inorganic coagulant upon streaming current,which is in accordance with their influence on coagulation.

Content and Partial Characterization of Unknown N in Humic Acids

INTRODUCTION Nitrogen is a key component of soil organic matter. Only when we have succeeded in characterizing the major part of organic N-containing compounds will we be able to understand fully the transformation reactions in the soil and to use soil-N more efficiently. However, only about 1/ 4——1/ 2 of the total N in humic acid (HA), one of the major constituents of soil organic matter, can be accounted for as amino acids and amino sugars, and most of the remainder has still to be accounted for. It has been

Extraction and Characterization of Biological Humic Acids from Fermented Furfural Residue

Objective] This study aimed to eliminate the negative effects brought about by continuous, long-term accumulation of sodium ions in soil on soil environ-ment. [Method] Biological humic acids （BHAs） were extracted from fermented furfural residue via alkali-dissolution and acidification. The effects of solid-liquid ratio （mass ratio of fermented furfural residue to water）, alkali concentration, extraction tempera-ture and extraction time on the content of BHA were investigated. Also its structure was characterized by FTIR. [Result] The optimal extraction conditions were as fol-lows： solid-liquid ratio of 1：7, KOH concentration of 6%, extraction temperature of 70℃ and extraction time of 1 h. Under the optimal conditions, the content of BHAs extracted was up to 8.5%. The infrared spectrum analysis indicated that BHA had more types of functional groups and lower molecular weight than commercial humic acid although they had similar structures. [Conclusion] The technique has the ad-vantages of simple operation and good stability, and is suitable for extracting BHAs. BHAs have a good prospect in developing new types of humic acid fertilizers.

Interaction between uranium and humic acid(Ⅰ):Adsorption behaviors of U(Ⅵ) in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) >SHA (HA from the surface) >THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was achieved at a suitable uranium concentration (10 mg·L-1 U(Ⅵ) for SHA and THA, 20 mg·L-1 U(Ⅵ) for FHA), the adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g) ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5-6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.

Characteristics and distributions of humic acids in two soil profiles of the southwest China Karst area

Characteristics and distributions of humic acid(HA) and soil organic matter(SOM) in a yellow soil profile and a limestone soil profile of the southwest China Karst area were systematically investigated to reveal their evolutions in different soils of the study area. The results showed that characteristics and distribution of SOM along the two soil profiles were notably different. Total organic carbon(TOC) contents of soil samples decreased just slightly along the limestone soil profile but sharply along the yellow soil profile. TOCs of the limestone soils were significantly higher than those of the corresponding yellow soils, and C/N ratios of SOMs showed a similar variation trend to that of TOCs, indicating that SOM can be better conserved in the limestone soil than in the yellow soil. The soil humic acids were exhaustively extracted and further fractionated according to their apparent molecular weights using ultrafiltration techniques to explore underlying conservation mechanisms. The result showed that C/N ratios of HAs from different limestone soil layers were relatively stable and that large molecular HA fractions predominated the bulk HA of the top soil, indicating that HA in the limestone profile was protected while bio and chemical degradations were retarded. Combined with organic elements contents and mineral contents of two soils, weconcluded that high calcium contents in limestone soils may play a key role in SOM conservation by forming complexation compounds with HAs or/and enclosing SOMs with hypergene CaCO_3 precipitation.

Study on the action and mechanism of humic acids in Kaschin-Beck disease

Humic acids, especially FA in fractions, contain more oxygen functional groups. In this experiment, on the basis of confirming the action of humic acids on KBD, what was studied is the biological effects of one of main oxygen functional groups, hydroxy group (-OH). The results indicate that inducing pathologic process of KBD, obviously decrease the GSH-Px activity and induce peroxidation membrane injury of tissue. The SOD activity increase in the tissues caused by oxygen functional groups showed that enhancing of free radical reaction should not be neglected.

A characteristic study of humic acids isolated from Arctic fjord sediments

Humic substances are ubiquitous natural materials found in sediments as a product of biochemical transformation reactions representing a significant proportion of organic carbon cycle on earth. This study involves the analysis of humic substances with special emphasis on humic acids(HAs) in sediments collected from the Kongsfjorden System of Arctic region in June, 2017. The characterization of the isolated HAs were done using various spectroscopic techniques viz. UV-visible, Fluorescence, FTIR and NMR. Isolated HAs were also undergone for elemental analysis along with other characterization. The UV spectral analysis results with a lower E4/E6 ratio suggesting the presence of HAs with high degree of aromaticity and condensation. Indications for the presence of hydroxyl, methyl, methylene, carbonyl, carboxyl, phenol, alcohol and amide groups were obtained from the FTIR spectrums of HAs. NMR spectral characteristics also confirm the presence of OH group as well as the presence of CH protons adjacent to C=X, were X can be any electronegative element. This also confirms the presence of carbonyl group which is also evident in the FTIR spectral studies. Presence of aliphatic regions slightly more dominated with long chain and/or alicyclic moieties rather than methyl groups was also inferred from the results of NMR.

The effects of soil sand contents on characteristics of humic acids along soil profiles

It is generally accepted that the compositions and properties of soil organic matter （SOM） are influenced by many factors. In order to reveal the effects of soil texture on characteristics and dynamics of SOM and its sub-fraction, humic acid （HA）, along two soil profiles, a yellow soil profile and a purplish soil profile, under the same climate and vegetation conditions were determined. Results indi- cate that the decomposition and humification degrees of SOM and HA of the purplish soils are higher than those of the corresponding yellow soils indicated by A/O-A ratios of HAs, TOCs and HA yields of bulk soil samples, neverthe- less, the development degree of the purplish soil is lower than that of the yellow soil. The variations of E4/E6 ratios of HAs along the soil profiles indicate the overall molecular sizes of HAs decreased downward along the soil profiles. A/O-A ratios of HAs decreased downward along both the soil profiles indicate that humification processes decrease downward along both the soil profiles. Leaching of SOM shows significant effects on the distribution and character- istics of HAs in the yellow soil profile but the purplish soil profile, which is consistent with the higher hydrophobicity of HAs in purplish soils, shows that the distribution char- acteristics of SOM along the soil profiles are a complex result of the combination of soil texture and characteristics of SOM itself. The remarkably different sand contents are concluded tentatively as one of reasons to the differentdistributions and dynamics of HAs along the soil profiles, however, to profoundly understand the evolution and transport of SOM along soil profiles needs more researches.

Spectroscopic characteristics of two typical soil humic acids in China

Humic acid （HA） is known to be a complex organic compound with varying structural and functional characteristics. In this study, three-dimensional excitation emission matrix fluorescence spectroscopy （3DEEM）, ultraviolet-visible （UV-Vis） and Fourier-transform infrared （FT-IR） were applied to study the fluorescence characteristics and structure of two typical soil HAs in China. The effects of concentration of HA, pH and ionic strength on the fluorescence behaviors were investigated. The results indicate that ionic strength over the range from 0 to 0.05mol L^-1 NaNO3 did not affect the 3DEEM of HA. The concentration of HA and pH of the test solution had obvious effects on the 3DEEM. When the concentration of soil HA was lower than 10mg L^-1, HA has only one obvious fluorescence peak. However, there were several fluorescence peaks for HA in high concentration （≥50mg L^-1）, and its Ex/Em maximum wavelength shifted towards longer wavelength with increasing the concentration of HA. The fluorescence intensity of HA enhanced with the increase of pH, and achieved maximum at pH 10. The effect of pH on the fluorescence intensity of black soil HA （BHA） was the severest and a polycondensation of BHA existed with the change of pH. At the same condition, the fluorescence intensity of red soil HA （RHA） was stronger than that of BHA. At the excitation wavelength of 340nm, the maximum emission peak positions of RHA and BHA were 474 and 504nm at pH 6.0, and their fluorescence quantum yields （QY） were 2.1-2.5% and 1.5-1.9%, respectively. Based on the maximum emission peak positions and fluorescence quantum yield, RHA and BHA can be distinguished.

Effects of urea enhanced with different weathered coal-derived humic acid components on maize yield and fate of fertilizer nitrogen

Humic acid(HA) is a readily available and low-cost material that is used to enhance crop production and reduce nitrogen(N) loss. However, there is little consensus on the efficacy of different HA components. In the current study, a soil column experiment was conducted using the ^(15)N tracer technique in Dezhou City, Shandong Province, China, to compare the effects of urea with and without the addition of weathered coal-derived HA components on maize yield and the fate of fertilizerderived N(fertilizer N). The HA components were incorporated into urea by blending different HA components into molten urea to obtain the three different types of HA-enhanced urea(HAU). At harvest, the aboveground dry biomass of plants grown with HAU was enhanced by 11.50–21.33% when compared to that of plants grown with U. More significantly, the grain yields under the HAU treatments were 5.58–18.67% higher than the yield under the urea treatment. These higher yields were due to an increase in the number of kernels per plant rather than the weight of individual kernels. The uptake of fertilizer N under the HAU treatments was also higher than that under the urea treatment by 11.49–29.46%, while the unaccounted N loss decreased by 12.37–30.05%. More fertilizer-derived N was retained in the 0–30 cm soil layer under the HAU treatments than that under the urea treatment, while less N was retained in the 30–90 cm soil layer. The total residual amount of fertilizer N in the soil column, however, did not differ significantly between the treatments. Of the three HAU treatments investigated, the one with an HA fraction derived from extraction with pH values ranging from 6 to 7, resulted in the best improvement in all assessment targets. This is likely due to the abundance of the COO/C–N=O group in this HA component.

Adsorption characteristics of humic acid-immobilized amine modified polyacrylamide/bentonite composite for cationic dyes in aqueous solutions

Humic acid-immobilized amine modified polyacrylamide/bentonite composite （HA-Am-PAA-B） was prepared and used as an adsorbent for the adsorption of cationic dyes （Malachite Green （MG）, Methylene Blue （MB） and Crystal Violet （CV）） from aqueous solutions. The polyacrylamide/bentonite composite （PAA-B） was prepared by intercalative polymerization of acrylamide with Nabentonite in the presence of N,N＇-methylenebisacrylamide as a crosslinking agent and hexamethylenediammine as propagater. PAA-B was subsequently treated with ethylenediammine to increase its loading capacity for HA. The surface characterizations of the adsorbent were investigated. The adsorbent behaved like a cation exchanger and more than 99.0% removal of dyes was detected at pH range 6.0-8.0. The capacity of HA-Am-PAA-B was found to decrease in the following order： MG〉MB〉CV. The kinetic and isotherm data were interpreted by pseudo-second order rate equation and Freundlich isotherm model, respectively. Experiments were carried out using binary solute systems to assess the competitive adsorption phenomenon. The experimental isotherm data for each binary solute combination of MG, MB and CV were analyzed using Sheindrof-Rebhun-Sheintuch （SRS） （multicomponent Freundlich type） equation.

Ultrafiltration with in-line coagulation for the removal of natural humic acid and membrane fouling mechanism

Experimental and theoretical analysis were made on the natural humic acid removal and the membrane fouling of ultrafiltration （UF） with in-line coagulation. The results showed dissolved organic carbon （DOC） and UV254 removals by the UF with in-line coagulation at pH 7 were increased from 28% to 53% and 40% to 78% in comparison with direct UF treatment respectively. At the same time, the analysis of high performance liquid chromatography showed that UF with coagulation had significant improvement of removal of humic acid with molecular weights less than 6000 Da in particular. Compared to direct UF, the in-line coagulation UF also kept more constant permeate flux and very slight increase oftransmembrane pressure during a filtration circle. Two typical membrane fouling models were used by inducing two coefficients Kc and Kp corresponding to cake filtration model and pore narrowing model respectively. It was found that membrane fouling by pore-narrowing effect was effectively alleviated and that by cake-filtration was much decreased by in-line coagulation. Under the condition of coagulation prior to ultrafiltration at pH 7, the cake layer formed on the membrane surface became thicker, but the membrane filtration resistance was lower than that at pH 5 with the extension of operation time.

Photo-induced transformations of Hg(Ⅱ) species in the presence of Nitzschia hantzschiana,ferric ion,and humic acid

Effects of algae Nitzschia hantzschiana, Fe（Ⅲ） ions, humic acid, and pH on the photochemical reduction of Hg（Ⅱ） using the irradiation of metal halide lamps （λ〉 365 nm, 250 W） were investigated. The photoreduction rate of Hg（Ⅱ） was found to increase with increasing concentrations of algae, Fe（Ⅲ） ions, and humic acid. Alteration of pH value affected the photoreduction of Hg（Ⅱ） in aqueous solution with or without algae. The photoreduction rate of Hg（Ⅱ） decreased with increasing initial Hg（Ⅱ） concentration in aqueous solution in the presence of algae. The photochemical kinetics of initial Hg（Ⅱ） and algae concentrations on the photoreduction of Hg（Ⅱ） were studied at pH 7.0. The study on the total Hg mass balance in terms of photochemical process revealed that more than 42% of Hg（Ⅱ） from the algal suspension was reduced to volatile metallic Hg under the conditions investigated.