Removal of Mercury (II) from Aqueous Solution Using Silver Nanocomposite: Synthesis and Adsorption Mechanism

Cutting-edge nanotechnology approaches for efficient mercury remediation: Mechanisms, innovations and future prospects in polluted environments

Mercury contamination poses a significant threat to the environment and human health due to its persistence, bioaccumulation, and toxicity. Conventional remediation methods such as chemical precipitation, coagulation, and membrane filtration often fall short due to limitations like incomplete removal, secondary pollution, and low selectivity. In response, advanced nanomaterials, defined as engineered nanostructures with high surface area, tunable surface chemistry, and exceptional mercury-binding capabilities, have emerged as powerful alternatives. This review critically evaluates five major classes of nanomaterials, such as carbon-based nanomaterials, metal and metal oxide nanoparticles, functionalized polymer nanocomposites, biosynthesized nanoparticles, and hybrid nanomaterials, with a focus on their mercury removal efficiency, regeneration capacity, environmental safety, and real-world applicability. While these materials have been previously reported, this work offers a unique comparative analysis that synthesizes fragmented data across the literature to highlight performance trade-offs and implementation feasibility. Furthermore, nanotechnology-assisted techniques including adsorption, photocatalysis, membrane-based separation, and hybrid treatment systems are systematically reviewed, emphasizing removal efficiencies, operational parameters, and scalability. Among these, hybrid nanomaterials and multifunctional systems demonstrate the highest potential, achieving mercury removal rates exceeding 95 % and offering adaptability to complex contaminated matrices. Rather than introducing new experimental data, this review identifies key research gaps, unresolved challenges such as nanoparticle toxicity and recovery, and the lack of field-scale validation. It concludes with a roadmap to guide future research toward the development of safe, cost-effective, and environmentally sustainable nanotechnology-driven mercury remediation strategies. This work aims to support informed decision-making among researchers, engineers, and environmental policymakers working to mitigate mercury pollution effectively.

Adsorption and desorption ability of divalent mercury from an interactive bicomponent sorption system using hybrid granular activated carbon

The sequestration of heavy metals from multicomponent sorption media has become critical due to the noxious effects of heavy metals on the natural environment and subsequently on human health as well as all life forms. The abatement of heavy metals using bio-adsorbents is one of the efficient and affordable approaches for treating water and wastewater. Therefore, the interactive effect of arsenic [As(III)] ions on the sorption and desorption ability of mercury [Hg(II)] from a binary sorption system was conducted. More so, the impact of reaction time, solution pH, bio-adsorbent particle size, bio-adsorbent dose, initial mono-metal, and binary-metal concentration as well as reaction temperature on the individual and competitive sorption of Hg(II) was explored. The study showed that Hg(II) could be removed effectively from the single-component system and competitively from the aqueous phases by the bio-adsorbent in the coexistence of As(III) species in the bicomponent medium. The adsorptive detoxification of Hg(II) from the monocomponent and bicomponent sorption media showed dependence on all the studied adsorption parameters. The occurrence of As(III) species in the bicomponent sorption medium affected the decontamination of Hg(II) by the bio-adsorbent and the major interactive mechanism was found to be antagonism. The spent bio-adsorbent was effectively recycled using 0.10 M nitric (HNO3) and hydrochloric (HCl) acids solutions and the multi-regeneration cycles showed a high removal efficiency in each cycle. The first regeneration cycle was found to have the highest Hg(II) ions removal efficiencies of 92.31 and 86.88% for the monocomponent and bicomponent systems, respectively. Thus, the bio-adsorbent was found to be mechanically stable and reusable up to the 6.00 regeneration cycle. Therefore, this study concludes that the bio-adsorbent not only has a higher adsorption capacity but also a good recycling performance pointing to good industrial applications and economic prospects.

Highly reusable bentonite clay@biochar@Fe3O4 nanocomposite for Hg(II) removal from synthetic and real wastewater

The present research investigates the performance of bentonite clay@biochar@Fe₃O₄ nanocomposite in removing mercury ions (Hg²⁺) from aqueous media. The physical and structural properties of bentonite clay@biochar@Fe₃O₄ were determined using Brunauer-Emmett-Teller (BET), vibrating-sample magnetometer (VSM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and Raman analyses. The highest uptake efficiency of Hg²⁺ was obtained at pH 6, Hg²⁺ concentration of 10 mg/L, contact time of 80 min, and the composite dose of 1.5 g/L. Under these conditions, the uptake efficiency of bentonite clay@biochar@Fe₃O₄ and bentonite clay was obtained as 98.78% and 97.67%, respectively, which are remarkable values. Also, the q_max values in Hg²⁺ removal using bentonite clay@biochar@Fe₃O₄ and bentonite clay were obtained as 66.66 and 60.98 mg/g, respectively. Moreover, the uptake process of Hg²⁺ ions using bentonite clay@biochar@Fe₃O₄ nanocomposite and bentonite was spontaneous, physical, favorable, and exothermic. Besides, the impact of various divalent ions such as Co²⁺, Cu²⁺, Pb²⁺, Ni²⁺, and Zn²⁺ on the removal efficiency of Hg²⁺ was studied. The results showed that Co²⁺ and Zn²⁺ ions have the highest and lowest interference effect in Hg²⁺ removal, respectively. Also, the reusability of both adsorbents showed that they have high stability and can be used for at least 5 cycles with high uptake efficiency. Additionally, the removal efficiency of chemical oxygen demand (COD), biochemical oxygen demand (BOD₅), Hg²⁺, As³⁺, and As⁵⁺ from real wastewater using bentonite clay@biochar@Fe₃O₄ was obtained as 37.5%, 28.9%, 65%, 60.5%, and 50%, respectively, indicating its remarkable performance.

Boron Adsorption Using NMDG-Modified Polypropylene Melt-Blown Fibers Induced by Ultraviolet Grafting

Boron is in high demand in many sectors, yet there are significant flaws in current boron resource utilization. This study describes the synthesis of a boron adsorbent based on polypropylene (PP) melt-blown fiber using ultraviolet (UV)-induced grafting of Glycidyl methacrylate (GMA) onto PP melt-blown fiber, followed by an epoxy ring-opening reaction with N-methyl-D-glucosamine (NMDG). Using single-factor studies, grafting conditions such as the GMA concentration, benzophenone dose, and grafting duration were optimized. Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and water contact angle were used to characterize the produced adsorbent (PP-g-GMA-NMDG). The PP-g-GMA-NMDG adsorption process was examined by fitting the data with different adsorption settings and models. The results demonstrated that the adsorption process was compatible with the pseudo-second-order model and the Langmuir model; however, the internal diffusion model suggested that the process was impacted by both extra- and intra-membrane diffusion. According to thermodynamic simulations, the adsorption process was exothermic. At pH 6, the greatest saturation adsorption capacity to boron was 41.65 mg·g^-1 for PP-g-GMA-NMDG. The PP-g-GMA-NMDG preparation process is a feasible and environmentally friendly route, and the prepared PP-g-GMA-NMDG has the advantages of high adsorption capacity, outstanding selectivity, good reproducibility, and easy recovery when compared to similar adsorbents, indicating that the reported adsorbent is promising for boron separation from water.