Green synthesis and characterization of iron oxide nanoparticles for the removal of heavy metals (Cd2+ and Ni2+) from aqueous solutions with Antimicrobial Investigation

Clove and green Coffee (g-Coffee) extracts were used to synthesize green iron oxide nanoparticles, which were then used to sorb Cd²⁺ and Ni²⁺ ions out of an aqueous solution. Investigations with x-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption and desorption (BET), Zeta potential, and scanning electron microscopy were performed to know and understand more about the chemical structure and surface morphology of the produced iron oxide nanoparticles. The characterization revealed that the main component of iron nanoparticles was magnetite when the Clove extract was used as a reducing agent for Fe³⁺, but both magnetite and hematite were included when the g-Coffee extract was used. Sorption capacity for metal ions was studied as a function of sorbent dosage, metal ion concentration, and sorption period. The maximum Cd²⁺ adsorption capacity was 78 and 74 mg/g, while that of Ni²⁺ was 64.8 and 80 mg/g for iron nanoparticles prepared using Clove and g-Coffee, respectively. Different isotherm and kinetic adsorption models were used to fit experimental adsorption data. Adsorption of Cd²⁺ and Ni²⁺ on the iron oxide surface was found to be heterogeneous, and the mechanism of chemisorption is involved in the stage of determining the rate. The correlation coefficient R² and error functions like RMSE, MES and MAE were used to evaluate the best fit models to the experimental adsorption data. The adsorption mechanism was explored using FTIR analysis. Antimicrobial study showed broad spectrum antibacterial activity of the tested nanomaterials against both Gram positive (S. aureus) (25923) and Gram negative (E. coli) (25913) bacteria with increased activity against Gram positive bacteria than Gram negative one and more activity for Green iron oxide nanoparticles prepared from Clove than g-Coffee one.

Modeling heavy metal removal by retention on Laurus nobilis leaves biomass: linear and nonlinear isotherms and design

Heavy metal industries pose a serious threat to the environment. Conventional methods used for heavy metal removal are generally not always low-cost and environmentally friendly. So, researchers focused to investigate alternative biosorbents for the uptake of heavy metal. In this study, Laurus nobilis leaves (LNL) were used as a biosorbent for the uptake of toxic metals such as Pb²⁺ and Cd²⁺ from aqueous solutions. Batch biosorption experiments under varied conditions, such as biosorbent dosage, solution pH, heavy metal concentration, biosorption time, ionic strength, humic acid effect and competitive metal ions (Cd(II), Pb(II), Cu(II) and Zn(II)) were performed. The biomass was characterized using FT-IR spectra and SEM images. The nonlinearized and linearized isotherm models were compared and discussed. A single-stage batch bioreactor system for each heavy metal based on the best fit nonlinear isotherm model also has been presented. The biosorption of Pb(II) on LNL fitted better in the Langmuir model and Cd(II) biosorption fitted better in the Freundlich model by nonlinearized equations. The LNL exhibited the maximum monolayer biosorption capacities (q_max) of 7.1 and 32.5 mg/g for cadmium and lead, respectively. LNL showed great potential especially in Pb(II) uptake. LNL may be promising for heavy metal removal from aqueous environment.