Modified diatomite for soil remediation and its implications for heavy metal absorption in Calendula officinalis.

BACKGROUND: Among different adsorbents, natural and inorganic compounds such as diatomite are important and advantageous in terms of high efficiency and cost-effectiveness, and function in stabilizing heavy metals in the environment. Calendula officinalis, a plant known as a high accumulator of heavy metals, was cultivated in soil treated with varying concentrations of modified diatomite to demonstrate the efficiency of modified diatomite in stabilizating of heavy metals in soils, RESULTS: The modification of diatomite aimed to enhance Calendula officinalis adsorptive properties, particularly towards heavy metals such as lead (Pb), Zinc (Zn), Chromium (Cr), Nickle (Ni), and Copper (Cu), common contaminants in industrial soils. The experimental design included both control and treated soil samples, with assessments at regular intervals. Modified diatomite significantly decreased the bioaccumulation of heavy metals in contaminated soils except Zn, evidenced by decreased DTPA extractable heavy metals in soil and also heavy metal concentrations in plant tissues. Using 10% modified diatomite decreased 91% Pb and Cu, 78% Cr, and 79% Ni concentration of plants compared to the control treatment. The highest concentration of Zn in plant tissue was observed in 2.5% modified diatomite treatment. Remarkably, the application of modified diatomite also appeared to improve the nutrient profile of the soil, leading to enhanced uptake of key nutrients like phosphorus (P) 1.18%, and potassium (K) 79.6% in shoots and 82.3% in roots in Calendula officinalis. Consequently, treated plants exhibited improved growth characteristics, including shoots and roots height of 16.98% and 12.8% respectively, and shoots fresh and dry weight of 48.5% and 50.2% respectively., compared to those in untreated, contaminated soil. CONCLUSION: The findings suggest promising implications for using such amendments in ecological restoration and sustainable agriculture, particularly in areas impacted by industrial pollution.

Development of a continuous fixed-bed column to eliminate cadmium(II) ions by starch-g-poly(acrylic acid)/cellulose nanofiber bio-nanocomposite hydrogel.

This paper presents an experimental study on continuous adsorptive removal of Cd2+ from the water body using a bio-nanocomposite hydrogel within a fixed-bed column (FBC) system. The bio-nanocomposite hydrogel was synthesized based on starch grafted poly(acrylic acid) (St-g-PAA) reinforced by cellulose nanofibers (CNFs). The effects of processing conditions including pH, flow rate, and initial concentration of Cd2+ on adsorption efficiency were examined. Based on the results, the highest removal efficiency was achieved to be 82.5% at pH of 5, initial concentration of 10 mg L-1, and flow rate of 5 mL min-1. Furthermore, by applying isotherm models, it was uncovered that the Langmuir isotherm model was the most appropriate one, and the maximum adsorption capacity was 40.65 mg g-1. Also, an adsorption process was carried out using the FBC system, and the outcome data were processed using Thomas and Yoon-Nelson models to find the characteristics of the column. In this study, the recovering capacity of the exhausted hydrogel was evaluated. Desorption process efficiencies of batch and continuous operations were obtained to be 91.9% and 90%, respectively.

Bacteriocin activity of various iranian honey-associated bacteria and development of a simple medium for enhanced bacteriocin activity.

PURPOSE: Honey is a promising source of bacterial strains producing metabolites with antimicrobial activity. There is a great variety in the antimicrobial activity of honey from different areas of nature. Therefore, the aim of present study was to investigate the antibacterial activity of Iranian honey from different regions and to optimize the culture condition for the highly potent bacterial isolate. METHODS: Honey samples were collected from ten different regions of Iran and were screened for bacteriocin-producing bacteria. The best bacteriocin-producing strain was characterized and identified by 16S rDNA analysis. One-factor-at-a-time method was used for optimization of culture medium and the yield and time-course of bacteriocin production were compared in both shake flask and bio-reactor. RESULTS: The Bacillus subtilis SB1 that was isolated from Sabalan honey showed potent antibacterial activity with prominent thermal stability. The optimum medium for the bacteiocin production was a yeast extract-based medium. The optimum incubation temperature for bacteriocin production was 34 °C. Bacteriocin production was higher near neutral pH conditions than that produced at acidic or alkaline environment. The results of cell growth and bacteriocin assays revealed that the exponential phase of growth and antibacterial compounds production was started rapidly in bioreactor than flask. CONCLUSIONS: Findings of this study supported the folkloric application of honey against some infectious diseases. B.subtilis SB1 that isolated from Sabalan honey was a potential source for bacteriocins-like compounds. Our studies suggested a simple buffered nitrogen-based medium for SB1 growth and bacteriocin activity in both shake flask and bioreactor.