scholarly journals Characterization of Ultrafiltration-Fractionated Humic Acid Derived from Chinese Weathered Coal by Spectroscopic Techniques

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2030
Author(s):  
Shuiqin Zhang ◽  
Liang Yuan ◽  
Yanting Li ◽  
Bingqiang Zhao
Keyword(s):  
Molecular Weight ◽  
Humic Acid ◽  
Atomic Ratio ◽  
Raw Material ◽  
Spectroscopic Techniques ◽  
Acid Fraction ◽  
Aromatic Rings ◽  
Xps Spectra ◽  
Weathered Coal ◽  
Degree Of Aromaticity

Weathered coal is a widely used raw material of farm-oriented humic acid in China, while the high heterogeneity impedes its sufficient utilization. In this study, we fractionated the humic acid derived from Chinese weathered coal by ultrafiltration, and three fractions with the molecular range of ≥100 kDa, 10–100 kDa, ≤10 kDa were obtained. Subsequently, the chemical and spectral properties of the fractions were characterized by elemental analysis, potentiometric titration, Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and X-ray photoelectron (XPS) and other spectroscopy. The results showed that more than 60% of humic acid by weight was concentrated in the molecular range higher than 100 kDa, while only 3.25% was assigned to that with molecular weight lower than 10 kDa. The humic acid fraction with molecular weight higher than 100 kDa showed more carbon content, lower H/C atomic ratio, while higher E4/E6 ratio, more aromatic structure in FTIR, 13C NMR, and XPS spectra, indicating a higher degree of aromaticity and stronger hydrophobicity. Conversely, there were more carboxyl groups and aliphatic structures, while fewer condensed aromatic rings for the humic acid fraction with molecular weight less than 100 kDa. These differences provide a baseline for the better utilization of weathered coal.

scholarly journals Removal of Cd(II) from Water by HPEI Modified Humin

2020 ◽  
Vol 12 (19) ◽  
pp. 7931
Author(s):  
Sanmei Li ◽  
Mingda Wu ◽  
Linghong Lu ◽  
Jiabao Zhu
Keyword(s):  
Humic Acid ◽  
Adsorption Capacity ◽  
Low Cost ◽  
Raw Material ◽  
Flame Atomic Absorption Spectroscopy ◽  
X Ray ◽  
Adsorption Performance ◽  
Flame Atomic Absorption ◽  
Weathered Coal ◽  
Cost Treatment

Humin is the waste residue from the process of preparing humic acid, which accounts for a large proportion of the raw material (weathered coal humic acid). Its Cd(II) adsorption performance is far inferior to that of humic acid. How to regenerate humin is of great significance to the low-cost treatment of Cd(II) pollution in wastewater. In this study, humin was modified by hyperbranched polyethyleneimine to enhance the adsorption capacity for Cd(II). Fourier transform infrared spectroscopy and the X-ray photoelectron spectrometer showed that hyperbranched polyethyleneimine was grafted to the surface of humin. Flame atomic absorption spectroscopy showed that the saturated Cd(II) adsorption capacity of the modified humin was increased to 11.975 mg/g, which is about 5 times than that of humin and is also higher than that of humic acid. The adsorption kinetics, adsorption isotherm, and thermodynamic properties of humic acid, humin, and modified humin were also studied. This study may provide a foundation for research utilizing natural resources to reduce heavy metal pollution in the environment.

Photocatalytic oxidation of humic acid and its effect on haloacetic acid formation potential: a fluorescence spectrometry study

2012 ◽  
Vol 65 (9) ◽  
pp. 1548-1556 ◽  
Author(s):  
Yan Xiaoju ◽  
Bao Ruiling ◽  
Yu Shuili ◽  
Li Qiongfang ◽  
Chen Wei
Keyword(s):  
Molecular Weight ◽  
Humic Acid ◽  
Photocatalytic Oxidation ◽  
Molecular Conformation ◽  
Oxidation Process ◽  
Fluorescence Spectrometry ◽  
Raw Water ◽  
Aromatic Rings ◽  
Formation Potential ◽  
Large Molecular Weight

By fluorescence spectrometry method, molecular conformation changes of humic acid (HA) during the photocatalytic oxidation process were studied. Haloacetic acids formation potential (HAAFP) changes during the oxidation process were also measured. The results indicated that aromatic rings of HA decreased and conjugated double bonds were destroyed at the beginning of the process. Meanwhile, organic matter with large molecular weight decomposed into intermediates with smaller molecular weight, such as tryptophan and tyrosine. HA can be degraded almost completely, but not be mineralized thoroughly. Structures of the intermediates were changing during the oxidation process. Molecular structure transformation of HA led to the fluctuation tendency of the HAAFP changes during the photocatalytic oxidation process. HAAFP increased to 1.22 times that in raw water after 30 min of ultraviolet (UV) radiation, and decreased to 0.66 times that in raw water after 60 min of photocatalytic oxidation.

Advances on the Pharmacology Research of Active Component in Humic Acid

2011 ◽  
Vol 138-139 ◽  
pp. 1221-1227 ◽  
Author(s):  
Xia Ping Zhou ◽  
Xing Ming Fan ◽  
Yi Chao Zhang
Keyword(s):  
Molecular Weight ◽  
Humic Acid ◽  
Fulvic Acid ◽  
Complex Compounds ◽  
Raw Material ◽  
Hydroxyl Group ◽  
Molecular Weight Determination ◽  
Bioactive Substances ◽  
Selective Degradation ◽  
Slow Progress

The humic acids in young coal are complex compounds of aromatic-fatty group organic acid with content of functional groups like carboxy, phenolic hydroxyl group, benzoquinonyl, alcohol group , ketone group etc. The pharmacology research of humic acid advanced in slow progress as a result of composition complexity and raw material multiplicity. At first it was analysed that terpene, steroids and other bioactive substances existed in natural humic having effects on antibacterial, antiviral, antitumor and microcirculation improvement. A new way of molecular weight determination for fulvic acid was established by modification of cryoscopic constant which was proved by the detection of capillary electrophoresis and LC-MS then. In terms of Fulvic acid which molecular weight of 300-500, pharmacology of humic acid （FA/HA）- pyrones, humic acid (FA)- catechin, humic acid (FA)-saccharide metabolism of insulin, humic acid (FA)-allantoin-glycoconjugates,humic acid (FA)-glycyron-glycoconjugates which are prepared through selective degradation and branching modification were illustrated with similar pharmacophore (functional group) of Terpenoids, steroids by MTT experiment and flow cytometer.

Low Molecular Weight Microfibers with Light Sensing Properties

2017 ◽  
Vol 54 (4) ◽  
pp. 655-658
Author(s):  
Andrei Bejan ◽  
Dragos Peptanariu ◽  
Bogdan Chiricuta ◽  
Elena Bicu ◽  
Dalila Belei
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
Aromatic Rings ◽  
X Ray ◽  
Force Microscopy ◽  
Light Sensing ◽  
Sensing Applications ◽  
Atomic Force ◽  
Low Molecular Weight Compounds

Microfibers were obtained from organic low molecular weight compounds based on heteroaromatic and aromatic rings connected by aliphatic spacers. The obtaining of microfibers was proved by scanning electron microscopy. The deciphering of the mechanism of microfiber formation has been elucidated by X-ray diffraction, infrared spectroscopy, and atomic force microscopy measurements. By exciting with light of different wavelength, florescence microscopy revealed a specific optical response, recommending these materials for light sensing applications.

Characteristics of fouling due to clay-organic substances in potable water treatment by ultrafiltration

1996 ◽  
Vol 34 (9) ◽  
pp. 157-164 ◽  
Author(s):  
Kim C.-H. ◽  
M. Hosomi ◽  
A. Murakami ◽  
M. Okada
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Humic Acid ◽  
Fulvic Acid ◽  
Size Distribution ◽  
Ultrafiltration Membrane ◽  
Organic Substances ◽  
Decomposition Products ◽  
Microbial Decomposition ◽  
Fouling Materials

Effects of clay on fouling due to organic substances and clay were evaluated by model fouling materials and kaolin. Model fouling materials selected were protein, polysaccharide, fulvic acid, humic acid and algogenic matter (EOM:ectracellular organic matter, microbial decomposition products) and kaolin was selected as the clay material. Polysulfone membrane (MWCO(Molecular Weight Cut-Off) 10,000, 50,000 and 200,000) was used as an ultrafiltration membrane. In particular, the flux measurement of solutions containing algogenic matter used an ultrafiltration membrane of MWCO 50,000. The flux of protein and polysaccharide with coexistence of kaolin increased in the case of the ratio of MW/MWCO being greater than one, but did not increase in the case of the MW/MWCO ratio being below one. In contrast, the flux of fulvic acid and humic acid with coextence of kaolin decreased regardless of the ratio of MW/MWCO. The addition of dispersion agent and coagulant in the organic substances and kaolin mixture solution changed the size distribution of kaolin, and resulted in a change of the flux. EOM and microbial decomposition products decreased with the increase of the fraction of organic matter having molecular weight more than MWCO of membrane. The flux of the algogenic organic matter with coexistence of kaolin decreased with the increase of the amount of kaolin. It was suggested that the decline of the flux with coexistence of kaolin was due to the change of the resistance of the kaolin cake layer corresponding to the change in kaolin size distribution with charge.

Removal of Hydrophobic and Hydrophilic Constituents by Anion Exchange Resin

1999 ◽  
Vol 40 (9) ◽  
pp. 207-214 ◽  
Author(s):  
J.-P. Croué ◽  
D. Violleau ◽  
C. Bodaire ◽  
B. Legube
Keyword(s):  
Molecular Weight ◽  
Anion Exchange ◽  
Water Source ◽  
Atomic Ratio ◽  
Size Exclusion ◽  
Salting Out ◽  
Anion Exchange Resins ◽  
Hydrophilic Character ◽  
Exchange Resins

The objective of this work was to compare the affinity of well characterized NOM fractions isolated from two surface waters with strong (gel matrix and macroporous matrix) and weak anion exchange resins (AER) using batch experiment conditions. The structural characterization of the fraction of NOM has shown that the higher the hydrophilic character, the lower the C/O atomic ratio, the lower the SUVA, the lower the aromatic carbon content and the lower the molecular weight. In general (not always), strong AER was more efficient to remove DOC than weak AER. For the same water source (Suwannee River), the higher the molecular weight of the NOM fraction, the lower the affinity with AER. Increasing the ionic strength favored the removal of the hydrophobic NOM fraction (“salting out” effect) while increasing the pH apparently reduced the removal of the hydrophilic NOM fraction. Results were discussed in terms of size exclusion, adsorption, anion exchange and also hydrophobic/hydrophilic repulsion.

scholarly journals Manufacturing PLA/PCL Blends by Ultrasonic Molding Technology

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2412
Author(s):  
Inés Ferrer ◽  
Ariadna Manresa ◽  
José Alberto Méndez ◽  
Marc Delgado-Aguilar ◽  
Maria Luisa Garcia-Romeu
Keyword(s):  
Molecular Weight ◽  
Crystallization Rate ◽  
Raw Material ◽  
Small Particle Size ◽  
Polymer Mixtures ◽  
Crystallinity Degree ◽  
Correct Determination ◽  
Production Stages ◽  
Process Speed

Ultrasonic molding (USM) is a good candidate for studying the plasticization of polymer mixtures or other composite materials due to either the little amount of material needed for processing, low waste or the needed low pressure and residence time of the mold. Thus, the novelty of this research is the capability of USM technology to process PLA/PCL blends and their corresponding neat materials, encompassing all the production stages, from raw material to the final specimen. The major findings of the work revealed that the thermal properties of the blends were not affected by the USM process, although the crystallinity degree experienced variations, decreasing for PLA and increasing for PCL, which was attributed to the crystallization rate of each polymer, the high process speed, the short cooling time and the small particle size. The employed ultrasonic energy increased the molecular weight with low variations through the specimen. However, the degradation results aligned with the expected trend of these material blends. Moreover, this study also showed the effect pellet shape and dimensions have over the process parameters, as well as the effect of the blend composition. It can be concluded that USM is a technology suitable to successfully process PLA/PCL blends with the correct determination of process parameter windows.

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