Synergetic effect of green synthesized reduced graphene oxide and nano-zero valent iron composite for the removal of doxycycline antibiotic from water.

In this work, the synthesis of an rGO/nZVI composite was achieved for the first time using a simple and green procedure via Atriplex halimus leaves extract as a reducing and stabilizing agent to uphold the green chemistry principles such as less hazardous chemical synthesis. Several tools have been used to confirm the successful synthesis of the composite such as SEM, EDX, XPS, XRD, FTIR, and zeta potential which indicated the successful fabrication of the composite. The novel composite was compared with pristine nZVI for the removal aptitude of a doxycycline antibiotic with different initial concentrations to study the synergistic effect between rGO and nZVI. The adsorptive removal of bare nZVI was 90% using the removal conditions of 25 mg L-1, 25 °C, and 0.05 g, whereas the adsorptive removal of doxycycline by the rGO/nZVI composite reached 94.6% confirming the synergistic effect between nZVI and rGO. The adsorption process followed the pseudo-second order and was well-fitted to Freundlich models with a maximum adsorption capacity of 31.61 mg g-1 at 25 °C and pH 7. A plausible mechanism for the removal of DC was suggested. Besides, the reusability of the rGO/nZVI composite was confirmed by having an efficacy of 60% after six successive cycles of regeneration.

Recent developments in alginate-based adsorbents for removing phosphate ions from wastewater: a review.

The huge development of the industrial sector has resulted in the release of large quantities of phosphate anions which adversely affect the environment, human health, and aquatic ecosystems. Naturally occurring biopolymers have attracted considerable attention as efficient adsorbents for phosphate anions due to their biocompatibility, biodegradability, environmentally-friendly nature, low-cost production, availability in nature, and ease of modification. Amongst them, alginate-based adsorbents are considered one of the most effective adsorbents for removing various types of pollutants from industrial wastewater. The presence of active COOH and OH- groups along the alginate backbone facilitate its physical and chemical modifications and participate in various possible adsorption mechanisms of phosphate anions. Herein, we focus our attention on presenting a comprehensive overview of recent advances in phosphate removal by alginate-based adsorbents. Modification of alginate by various materials, including clays, magnetic materials, layered double hydroxides, carbon materials, and multivalent metals, is addressed. The adsorption potentials of these modified forms for removing phosphate anions, in addition to their adsorption mechanisms are clearly discussed. It is concluded that ion exchange, complexation, precipitation, Lewis acid-base interaction and electrostatic interaction are the most common adsorption mechanisms of phosphate removal by alginate-based adsorbents. Pseudo-2nd order and Freundlich isotherms were figured out to be the major kinetic and isotherm models for the removal process of phosphate. The research findings revealed that some issues, including the high cost of production, leaching, and low efficiency of recyclability of alginate-based adsorbents still need to be resolved. Future trends that could inspire further studies to find the best solutions for removing phosphate anions from aquatic systems are also elaborated, such as the synthesis of magnetic-based alginate and various-shaped alginate nanocomposites that are capable of preventing the leaching of the active materials.

Novel Biogenic Synthesis of a Ag@Biochar Nanocomposite as an Antimicrobial Agent and Photocatalyst for Methylene Blue Degradation.

The conventional synthesis of nanomaterials employing physical and chemical methods usually requires high cost and toxic chemicals. Thus, a facile, ecofriendly, cost-effective, novel, and sustainable route for the synthesis of a silver-loaded biochar nanocomposite (Ag@biochar) using Chenopodium ambrosioides leaf extract and biomass is reported for the first time in this study to advocate many of the principles of green chemistry such as safer solvents and auxiliaries. UV spectroscopic analysis at 420 nm indicated the formation of silver nanoparticles (AgNPs). The band gap energy of Ag@biochar was 1.9 eV, confirming its potential use as a photocatalyst. Ag@biochar was found to be photoluminescent at 425 nm. AgNPs on the surface of biochar were predominantly spherical with a size range of 25-35 nm and a surface area of 47.61 m2/g. A zeta potential of -5.87 mV designated the stability of Ag@biochar. Testing the photocatalytic potential of Ag@biochar to remove methylene blue from wastewater demonstrated its high removal efficiency that reached 88.4% due to its high efficiency of electron transfer confirmed via electrochemical impedance spectroscopy analysis and retained 70.65% after six cycles of reuse. Ag@biochar was shown to be a powerful broad-spectrum antimicrobial agent as it completely prevented the growth of Escherichia coli and also inhibited the growth of Pseudomonas aeruginosa, Klebsiella pneumoniae, Bacillus subtilis, and Candida albicans with the inhibition zones of 19, 18, 22, and 16 mm, respectively.

Green Synthesis of Nano-Zero-Valent Iron Using Ricinus Communis Seeds Extract: Characterization and Application in the Treatment of Methylene Blue-Polluted Water.

In this study, the removal of methylene blue dye (MB) from aqueous solution was examined using a novel green adsorbent to overcome the obstacles encountered in chemical methods. Ricinus communis (RC) aqueous seeds extract was herein used as a reducing and capping agent to synthesize a novel nano-zero-valent iron (RC-nZVI) for the adsorption of harmful MB. Structural and morphological characterization of the synthesized RC-nZVI were performed using several techniques, e.g., steady-state absorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and zeta potential. The maximum efficiency of the removal was 96.8% at pH 6 and 25 °C. According to the kinetics study results, the adsorption process obeys the pseudo-first-order model. The experimental equilibrium data were fitted to the Freundlich isotherm model, the maximum adsorption capacity reached was 61.37 mg·g-1, and the equilibrium parameters were determined. The synthesized RC-nZVI possesses good reusability and can be considered as a potential economic and environmentally friendly adsorbent.