Buffer capacity of humic acid: Thermodynamic approach

Pertusatti, Jonas; Prado, Alexandre G.S.

doi:10.1016/j.jcis.2007.06.006

Cited by 94 publications

(54 citation statements)

References 30 publications

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“…The obtained A 4/6 results (Table 3) for examined humic acids samples are higher than traditional soil humic acids (about 4-5) (Chen et al 1977(Chen et al , 2002Pertusatti and Prado 2007). This fact confirms that examined humic acids present rather a low molecular weight.…”

Section: Resultssupporting

confidence: 70%

“…The first significant temperature range for the transformation of organic matter is attributed to a range of 200 to 400°C and is related to the degradation of less thermally stable structures, generally characterized by a less condensed structure. The loss of mass in this temperature range is attributed to changes such as degradation of carbohydrates, dehydration of aliphatic structures, and decarboxylation of carboxylic groups (Francioso et al 2005;Pertusatti and Prado, 2007;Rotaru et al 2008;Klavins et al 2010;Sirbu et al, 2010). These changes in the DTA graph are reflected in the form of exothermic peaks at a temperature close to 300°C, especially sharp for samples of humic acids obtained using NaOH solutions.…”

Section: Resultsmentioning

confidence: 99%

“…Humic acids obtained from lignite using solutions of Na 2 P 4 O 7 with the highest A 4/6 values should be abundant in carboxyl groups content and low in aromatic structures. More specific information concerning the structure of the HA could be obtained from 13 C NMR spectroscopy (Qiang et al, 1993;Ricca et al 2000;Piccolo 2002;Zbytniewski and Buszewski, 2005;Pertusatti and Prado, 2007;Kwiatkowska-Malina 2009). Figure 1 shows solid-state 13 C NMR spectra of humic acids extracted from lignite using different solutions together with spectra of technical humic acids (KHtech) and their salt (KHsalt) from SigmaAldrich.…”

Section: Resultsmentioning

confidence: 99%

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Evaluation of the possibilities of using humic acids obtained from lignite in the production of commercial fertilizers

Huculak-Mączka

Hoffmann

2018

J Soils Sediments

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Purpose Technological progress and high market demand contributed to a significant interest in the production of fertilizers based on humic acids. The aim of this study was to evaluate the possibilities of using humic acids obtained from lignite in the production of new commercial products. For this purpose, it is necessary to determine the quality standard requirements for such material. Properties of humic acids depend on source of origin as well as method of its extraction. Materials and methods The humic acids were extracted from polish deposit of lignite-Sieniawa Lubuska by alkaline extraction using for this purpose six kinds of extractants: 0.1 M NaOH and 0.25 M NaOH, 0.1 M KOH and 0.25 M KOH, and 0.1 M Na 4 P 2 O 7 and 0.25 M Na 4 P 2 O 7 . The humic samples were used in solid powder form and characterized by UV-Vis spectroscopy, 13 C NMR spectroscopy, fluorescence spectroscopy, and thermal analysis. Results and discussion The determining factor influencing a degree of humic acids extraction from lignite and their structure is type of extractant. The largest efficiency of extraction (about 50%) was obtained with the use of NaOH solutions. All examined humic acids were generally characterized by simple and heterogeneous molecularly structure with low molecular weight and low aromatic polycondensation. Therefore, it can be concluded that humic acids extracted with NaOH and KOH solutions are less condensed than those extracted with Na 4 P 2 O 7 solutions. It can suggest that humic acids obtained from lignite using solutions of Na 4 P 2 O 7 are characterized by a low transformation degree and greater amount of carboxyl groups. Conclusions Low rank coal can be successfully used in agriculture as a rich source of humic acids. Reagent used in their extraction, apart from high efficiency should have a neutral impact on their structure. Studies on the physicochemical properties of humic acids can be helpful in predicting behaviors of such fertilizer components in the environment and in inventing new products taking the principles of sustainable development into consideration.

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Section: Resultssupporting

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of the possibilities of using humic acids obtained from lignite in the production of commercial fertilizers

Huculak-Mączka

Hoffmann

2018

J Soils Sediments

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“…7), which was attributed to the high adsorption capacity of HA by the calcined LDH (data not shown), and the regeneration of adsorption sites on the LDH during the decomposition of adsorbed HA to CO 2 in the process of calcination in air. 37 …”

Section: Parameters Langmuir Ttingmentioning

confidence: 99%

Synergistic effect of humic and fulvic acids on Ni removal by the calcined Mg/Al layered double hydroxide

Fang

Chen

et al. 2015

RSC Adv.

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Discharge of Ni(II) containing wastewater to terrestrial environment can lead to serious pollution issues. This study presents a facile, cost-effective and highly efficient method to rapidly remove Ni(II) from wastewater using a calcined Mg/Al layered double hydroxide (LDH), which is a pioneering investigation of using the calcined LDH to remove the positively charged Ni(II) ions. The kinetic studies showed that the removal of Ni(II) was very rapid with a pseudo first order k of up to 3.6 AE 0.5 h À1 , and maximum removal of Ni(II) was up to 204.2 AE 10.6 mg g À1 . In addition, our results reveal that both humic (HA) and fulvic acids (FA) can strongly bind to the surface of the LDH, which demonstrates that the calcined LDH can effectively remove both cationic and anionic pollutants in a single process. With the increase of pH up to 7.5, the removal of Ni, HA and FA by the calcined LDH are all drastically enhanced. Our study also demonstrated a strong synergetic effect of FA and HA on the Ni(II) removal by the calcined LDH, with a maximum Ni(II) removal of 290.6 AE 16.4 mg g À1 and 480.4 AE 21.3 mg g À1 at pH 7, respectively. The possible mechanism of the Ni(II) removal can be due to the incorporation of Ni into the layered structure by replacing the

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“…They can act as pH regulators and can also influence a contaminant's mobility when adsorbed on their surfaces. 15 Composition, conformation and structure of HA are still ambiguous. HA are sometimes described not only as macromolecules adopting random coil conformation in solution 16 but also as supramolecular structures composed of small entities linked to each other by weak interaction forces.…”

Section: Introductionmentioning

confidence: 99%

Effect of natural organic matter on the disagglomeration of manufactured TiO2 nanoparticles

Loosli

Coustumer

Stoll

2014

Environ. Sci.: Nano

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One major concern in the fate of nanomaterials in aquatic systems is the lack of data on nanomaterial transformations under relevant environmental conditions. The disagglomeration of aggregates composed of manufactured anatase titanium dioxide nanoparticles is investigated here in the presence of alginate and Suwannee River humic acids at varying concentrations using dynamic light scattering and electrophoretic measurements. Stability of TiO 2 nanoparticle agglomerates at typical environmental concentrations of natural organic matter is discussed at a pH value corresponding to the point of zero charge of TiO 2 nanoparticles. In this scenario, the surface charge of TiO 2 is neutralized, allowing the nanoparticles to form large agglomerates. Alginate and Suwannee River humic acids exhibit a negative structural charge under this pH condition and adsorption of both natural polyelectrolytes on the surface of nanoparticle agglomerates leads to disagglomeration and significant redispersion of TiO 2 nanoparticles into fragments. Results indicate that both electrostatic forces and steric interactions play key roles during the disagglomeration process and that the physicochemical properties of natural organic matter are found to influence the kinetics and importance of fragmentation in the disagglomeration process. Most importantly, our data indicate that the presence of natural organic matter at typical environmental concentrations induces significant disagglomeration of large submicron nanoparticle agglomerates. Such a result constitutes an important outcome with regards to the risk associated with manufactured nanoparticles by including the possible transformations of the micron size range structures they can form. Nano impactOne of the main problems in the ecological risk assessment of nanomaterials is the lack of important information on their environmental (bio)physicochemical transformations. The disagglomeration of manufactured titanium dioxide nanoparticles is investigated here in the presence of alginate and Suwannee River humic acids at realistic environmental concentrations. Under such concentration conditions, the adsorption of these compounds is found to induce disagglomeration and significant redispersion of TiO 2 nanoparticles into fragments. Such a result constitutes an important outcome with regards to the risk associated with manufactured nanoparticles by considering one important life-cycle transformation of micron size range structures composed of nanoparticles in aquatic systems.

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Buffer capacity of humic acid: Thermodynamic approach

Cited by 94 publications

References 30 publications

Evaluation of the possibilities of using humic acids obtained from lignite in the production of commercial fertilizers

Evaluation of the possibilities of using humic acids obtained from lignite in the production of commercial fertilizers

Synergistic effect of humic and fulvic acids on Ni removal by the calcined Mg/Al layered double hydroxide

Effect of natural organic matter on the disagglomeration of manufactured TiO2 nanoparticles

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