humic acid

Sustainable and green adsorbents for water and wastewater treatment have gained attention worldwide in the last decades. Water contaminated with humic substances (HSs) has become an emerging human health threat due to producing disinfection by-products (DBPs) which react with chlorine and result in carcinogenic materials such as THMs. This study was conducted to remove HSs from aqueous solutions using nano-scale biosorption based on watermelon rind (WR), as a cost-efficient adsorbent. The effects of factors such as time, adsorbent dosage, pH and concentration, and then reaction kinetics and isotherms on the adsorption process were investigated. FTIR, XRD, BET analysis SEM, and also TEM were used to evaluate the structural characteristics of the adsorbent. The characteristics showed that increasing the temperature of thermal oxidation and loading of NH4Cl on the adsorbent surface increases the porosity and surface area, leading to an increase in adsorption performance. Also, given effective factors that increase the time and dose of adsorbent and reduce the initial concentration, The removal efficiency of humic acid (HA) increased with the following conditions: time 45 min and pH=4 and the adsorbent equal to 0.1 gr/L at a concentration of 50 mg/L, the removal efficiency of HSs reached 93.89%. The experiments showed that the adsorption process showed a better match with the pseudo-quadratic synthetic model with a coefficient of determination R²=0.99, while the adsorption isotherm was consistent with the Langmuir adsorption model. Studies have shown that adsorption occurs in a single layer. The thermodynamic parameters show that the process is spontaneous.

The tyrosinase enzyme catalysis monophenols to melanin pigments through the melanogenesis process. For this reason, various inhibitors have been studied for enzyme regulations in melanogenesis abnormalities in both the food and cosmetics industries. In this study, the effect of humic acid (Hu) and fulvic acid (Fu) on the structure, activity, and stability of mushroom tyrosinase (MT) was investigated.

These two organic acids are the main components of soil humus. Assessment of the thermodynamic and structural stability of enzymes was obtained through thechemical and thermal denaturations and (8-anilino-naphthalene sulfonic acid) ANS fluorescence analysis. The Hu and Fu impact on A375 melanoma cancer cell viability was achieved by MTT assay.  

The results of enzyme half denaturation concentration (Cm), melting points (Tm), ΔG0 values and external fluorescence emissions in the presence of Hu and FA proved the reduction of the thermodynamic and structural stability of MT by these compounds. The anti-proliferation effects of the compounds were confirmed by the inhibitory concentrations of 50% (IC50) of 31.5 and 42.7 µM and 12.5 and µM at time points of 24 and 48 hours treatments of the A375 melanoma cell line by Hu and Fu, respectively.

Humic and fulvic acids can be expected to contribute to advancing skin disorder science play a crucial role in tyrosinase related disorders and anti-cancer effects, and good candidates for medical applications.

In sustainable agriculture, reduction of chemical fertilizers- induced environmental pollutions is mainly considered. Therefore, recently application of organic fertilizers particularly their foliar applications received increased attention. Besides, herbal medicine with higher antioxidant activity will be able to limit the formation of free radical species.

Therefore, we aimed to determine the effect of foliar application of organic fertilizers on antioxidant activity and polyphenolic compounds of Marrubium vulgare L. in greenhouse experiment.

In a completely randomized design experiment with three replications that was carried out in 2019, the applied treatments consisted of four levels (0, 250, 500, and 1000 mg L-1) of foliar application of humic and fulvic acids (0, 250, 500, and 1000 mg L-1). Some phenolic compounds including gallic acid, chloregenic acid, coumarin, hesperidin, and eugenol were detected and quantified in the Marrubium vulgare L. extracts.

Application of 250 mg humic acid L-1 resulted in the highest extraction of phenolic compounds, coumarin, reducing this content at a higher applied level and by fulvic acid addition. As such, the foliar application of low concentrations of humic acid before the flowering stage was a useful and effective method to increase the synthesis of phenolic compounds. Among the studied organic acids, the application of 250 mg humic acid L-1 showed the highest antioxidant activities. These compounds can be effective in controlling diseases with free radicals.

Based on the findings of the present research, a more appropriate management of the growth and propagation of medicinal plants and their quality can be applied. In addition, humic substances application reduces the chemical fertilizers used, thereby maintaining the environment.

Soil poisoning with heavy metals is one of the most significant aspects of environmental research. In the soil treated with Thiobacillus, the effect of sulfur granular municipal solid waste (sulfur granular MSW), humic acid, and nano Fe-oxide on reducing Pb absorption by plants was investigated. Treatments consisted of applying sulfur granular MSW (0 and 30 t/ha), spraying humic acid (0 and 1.5 mmol/L), and using nano Fe-oxide (0 and 2% w/w) in the soil contaminated with Pb (0, 600, and 1200 mg/kg-soil). Plants were collected after 5 months, and the Pb content in the soil and plants was estimated by atomic absorption spectroscopy (AAS). The activity of ascorbate peroxidase (APX) and peroxidases (POX) enzymes were also determined. The use of 30 t/ha of sulfur granular MSW in the Pb-polluted soil reduced Pb concentration in the soil and plant by 13.4% and 15.1 %, respectively, while it increased Fe concentration by 15.2% in the plant. Using nano Fe-oxide (2% w/w) in the Pb-contaminated soil (600 and 1200 mg/kg soil) considerably enhanced Fe content in the plant. Pb absorption by plants was dramatically reduced by foliar application of humic acid. According to the findings of this study, the interaction effects of sulfur granular MSW, nano Fe-oxide, and humic acid significantly reduced the Pb absorption by plants. However, the impacts of soil physico-chemical characteristics and the kind of soil pollutant on plant Pb concentration cannot be ignored.

Natural organic matter (NOM) in drinking water sources has always been regarded as a precursor for the formation of trihalomethanes (THMs), haloacetic acids (HAAs), and carcinogenic properties. This study aimed to fabricate and characterize a nanohybrid ultrafiltration membrane (PSF/ZnO) to evaluate its efficiency in NOM removal from water.

Nanohybrid membranes with ratios of 0, 1, 2, 3 and 4% w/w of ZnO nanoparticles (NPs) were fabricated using the phase inversion method and characterized by the contact angle, AFM, FTIR, and SEM analyses. In this study, the effects of initial humic acid (HA) concentration, operating pressure, pH, and filtration time were examined on the HA removal efficiency and pure water flux through the membrane.

The results showed that addition of the ZnO NPs to the PSF membrane reduced the contact angle on the PSF/ZnO nanohybrid membrane’s surface. According to FE-SEM images, increasing the ZnO concentration changed the porous structure of the membranes from a spongy, teardrop shape to a finger-like channel structure. The FTIR analysis revealed an increase in the hydrophilicity of the membrane due to the presence of hydroxyl functional groups in ZnO. AFM images indicated an increase in the surface roughness of nanoparticle-containing membranes. It was found that an increase in the concentration of the ZnO NPs (0-4% w/w) increased HA removal efficiency (43.63-83.4%).

This study demonstrated that the use of the PSF/ZnO nanohybrid membranes increased HA removal efficiency and pure water flux passing through the membrane.

Humic acid (HA) and Fulvic acid (FA) are major members of humic substances, which are extracted from organic sources including soil and peat. The pro-apoptotic and anti-melanogenic effects of HA and FA at the cellular and molecular levels in the A375 human melanoma cell line were examined in this study.  The cytotoxicity effect of HA and FA were evaluated by cell viability assay. Apoptosis and cell cycle were investigated by flow cytometry. Real-time PCR was carried out to measure the expression of BAX, BCL-2, and Tyr genes. Moreover, the changes in nanomechanical properties were determined through atomic force microscopy (AFM).  It was found that HA and FA decrease cell viability with an IC50 value of 50 µg/ml (dose-dependent) for 14 hr, arrested cells in the G0/G1 phase, and increased the sub-G1 phase (induce apoptosis). Based on the AFM analysis, Young’s modulus and adhesion force values were increased, also ultrastructural characteristics of cells were changed. Results of Real-time PCR revealed that HA and FA lead to a decrease in the expressions of BCL-2 and Tyr genes, and increase the BAX gene expression. These results exhibited that HA and FA possess pro-apoptotic effects through increasing the BAX/ BCL-2 expression in A375 cells. These molecular reports were confirmed by cellular nanomechanical assessments using AFM and flow cytometry. In addition, HA and FA inhibited melanogenesis by decreasing the expression of the Tyr gene. It is worthwhile to note that, HA and FA can be regarded to design new anti-cancer and anti-melanogenesis products.

Among water pollutants, Natural Organic Matters (NOMs) are highly important for making problems in water treatment plants.

The main objective of this study was to investigate the efficiency of photocatalytic degradation of humic acid using magnetic nanoparticles (Fe-doped TiO2@Fe3O4) in aqueous solutions.

In the present experiment, Fe-doped TiO2@Fe3O4 nanoparticles were synthesized by the sol-gel method, and SEM, XRD, and DRS analyzes were utilized to characterize the synthesized nanoparticles. The effects of various variables, including pH (3 - 11), initial concentration of humic acid (20 - 80 mg/L), and concentration of nanoparticles (250 - 2000 mg/L) at different reaction times (15 - 60 min) were investigated on the photocatalytic degradation of humic acid.

The maximum degradation efficiency of humic acid at pH 3, the initial humic acid concentration of 5 mg/L, nanoparticle dose of 400 mg/L, and reaction time of 60 min using a 15-W bare UV lamp.

Due to the high efficiency of photocatalytic degradation, it is proposed to use for the removal of humic acid from water resources.

The present study aimed to investigate the effects of salicylic acid (SA), humic acid (HA), and EDTA chelate on the increasing Pb concentration in a plant inoculated with plant growth-promoting rhizobacteria (PGPR). Treatments consisted of applying two levels of EDTA (0 (EDTA0) and 3 (EDTA3) mmol/kg soil) and soil application of HA (0 (HA0) and 200 (HA200) mg/kg soil). In addition, foliar application of SA at the rates of 0 (SA0) and 1.5 (SA1.5) mmol/lit was also sprayed on the inoculated plant with and without PGPR cultivated in the Pb-polluted soil. After 9 weeks, barley plants were harvested and plant Pb concentration was measured using atomic absorption spectroscopy (AAS). The soil Pb concentration and plant Pb biomass was also measured. The least significant difference (LSD) test was used to determine the differences between the means (P=0.05). The results indicated that application of HA or EDTA had significantly (P=0.05) increased the Pb phytoremediation efficiency, as, applying 3 mmol EDTA/kg soil increased the Pb phytoremediation efficiency by 14.1%. In addition, a significant increasing (P=0.05) in plant biomass and Pb phytoremediation efficiency was observed by 12.2 and 13.6%, respectively, in the inoculated plant cultivated in the soil that received the greatest rates of EDTA and HA together with the highest rate of SA foliar application. Plant growth regulators such as SA or humic acid can increase plant resistance to Pb toxicity and help to increase Pb phytoremediation efficiency that is important in environmental studies.

In this study the efficiency of two different morphologies of polysulfone adsorptive membranes was examined for the humic acid removal from contaminated water. Adsorptive membranes with finger-like and sponge-like pore structures were prepared using modified montmorillonite with amino acid. Structure of fabricated membranes was investigated by Field Emission-Scanning Electron Microscopy, pure water flux, porosity and contact angle measurement. The obtained results showed that the addition of modified montmorillonite (MMT) to the membrane with finger-like structure altered the morphology and improved pure water flux, porosity and hydrophilicity. These changes were negligible in PSf with sponge-like structure. In addition, the adsorption property of these membranes for the removal of humic acid (HA) was extensively studied. Adsorption capacity of cellular membrane was higher than the finger-like structure and Freundlich isotherm model was fitted for both of them. Nevertheless, the membrane with finger-like pores provides rapid adsorption of HA respect to cellular structure. It was also found that increasing the pH until pH=8 enhanced HA removal for adsorptive membranes, but increasing the pH above this point was not favorable. The obtained results from the dynamic adsorption revealed that sponge-like and finger-like membranes could generate 100 mL and 50 mL permeate of high quality (<1 ppm HA in water), respectively.

Water scarcity is one of the most serious threats to the sharp decline of yield in different cultivars of pistachio in Iranian orchards. Therefore, attention should be paid to the maximum productivity of water resources and the use of modern agricultural methods to increase water use efficiency.

The purpose of this study was to evaluate the effects of perlite (0 and 10 g kg-1soil), humic acid (0, 7.5 and 15 g kg-1 soil) and irrigation interval (7, 20 and 30 days) on growth parameters of pistachio seedlings. This research was based on a completely randomized factorial design on "Badami Zarand" rootstock under greenhouse conditions. The studied factors included plant height, root length, leaf area, fresh and dry weights of root and shoot and uptake of nutrient elements in leaves. Finally, the statistical analysis of the data was done through a three way factorial ANOVA using the SPSS software, and the means of the data were compared using Duncan’s method.

The results of the study indicate that the application of humic acidin the concentration of15 g kg-1 soil and perlite 10 g kg-1 soil have a significant effect on plant growth and nutrient uptake under drought stress, which is associated with increasing effective roots and water abundance.

The results of the interaction effects showed that the application of humic acid and perlite can efficiently reduce the negative effects of drought stress on pistachio seedlings during irrigation intervals of 30 days, and it also causes more tolerance to stress.

Pistachio (Pistacia vera), as an important agricultural product, normally faces different problems in Iran. Alkalinity is one of the main factors that has detrimental effects on pistachio growth and its production by reducing availability and solubility of essential elements. Using some fertilizers and chelating agents improves the availability and solubility of nutritional elements in the rhizosphere and thereby improves the growth ofplants.

The current research investigated the effect of two bio-fertilizers (humic and fulvic acids) on the growth of pistachio seedlings grown in semi-hydroponic cultures containing either Fe-EDDHA or FeSO4. The pH of culture mediums was adjusted to 6.5, 7.5 and 8.5.

The results indicated that using humic substances (humic and fulvic acids) can increase pistachio dry weight under alkalinity conditions. These findings were remarkable, especially in the presence of Fe-EDDHA versus FeSO4.

Humic substances (as bio-stimulants), especially in the presence of EDDHA, can reduce or compensate some detrimental effects of alkalinity and thereby improve plant growth.

Humic acid is a trihalomethane component in water supplies, causing various health disorders in humans.
This study was performed to examine humic acid adsorption on saturated activated carbon and to evaluate adsorbent regeneration through ultrasonic processes.
In the present study, effects of various parameters, including initial concentration of humic acid, pH, contact time, adsorbent dose, and temperature, on the adsorption stage were investigated. Also, effects of different parameters, such as regeneration time, pH, and number of saturation-regeneration cycles, were studied in the regeneration stage.
The highest percentage of humic acid removal was reported at pH of three and initial humic acid concentration of 10 mg/L. The highest adsorption capacity of activated carbon was 29.7 mg/g at adsorbent dosage of 0.1 g/L and contact time of 10 minutes. The results of thermodynamic experiments showed that removal of humic acid by saturated activated carbon was endothermic. Also, maximum regeneration occurred at pH of 11 and contact time of 60 minutes. Finally, the adsorption capacity of saturated activated carbon changed from 42.94 to 42.14 mg/g after five cycles of saturation and regeneration.
The results of this study showed that activated carbon is an effective adsorbent in the removal of humic acid from water. Also, the ultrasonic process is effective in regeneration of activated carbon, saturated with humic acid.