Co-contamination of cadmium (Cd) and benzo[a]pyrene (B[a]P) in acidic red soils remains a remediation challenge because single-treatment approaches rarely immobilize metals and degrade organic pollutants simultaneously. We prepared iron-modified biochar (Fe@BC) from corn straw and evaluated it in a 56-day incubation with Cd–B[a]P co-contaminated acidic red soil. Six treatments were compared: blank control (CK), pristine biochar (BC), nano zero-valent iron (nZVI), persulfate alone (PS), Fe@BC alone, and Fe@BC coupled with PS (Fe@BC + PS). Fe@BC decreased exchangeable Cd from 32.4
Contamination from heavy metal ions and effluents from agriculture is one of the most significant environmental restrictions to crops' productivity. In this study, Chitin nanoparticles (ChNPs), Chitosan nanoparticles (CsNPs), Zinc oxide nanoparticles (ZnONPs), and Chitosan/zinc oxide nanocomposites (Cs/ZnO NCs) have been synthesized using Acheta domesticus L. extract. Characterization was carried out using ultraviolet–visible (UV–Vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). According to the results of UV–Vis, the spectra showed characteristic bands within the wavelength range of 296–356 nm, indicating the presence of nanoparticles. FTIR analysis provided information about the functional groups responsible for nanoparticle stability and interaction of chitosan with ZnO, while XRD showed semi-crystallinity of ChNPs and CsNPs and crystallinity of ZnONPs. The particle size varied from 10 to 100 nm using SEM and TEM analysis techniques. After that, the synthesized nanomaterials were examined for their potential to reduce the stress caused by Pb and wastewater in Brassica campestris L. Plants' growth, biomass, chlorophyll, soluble sugars, proteins, phytohormones and electrolytes were decreased due to Pb and wastewater, and on the other hand, oxidative stress was enhanced due to Pb and wastewater. In all tested materials, Cs/ZnONCs demonstrated maximum efficiency in the protection of plants. Under Pb-stressed conditions, Cs/ZnONCs increased shoot and root lengths up to 6.0 and 6.2 cm, respectively, against 2.9 and 3.2 cm of Pb-stressed plants. Furthermore, fresh and dry weights were raised to 0.48 and 0.049 g, respectively, against 0.20 and 0.021 g of Pb-stressed plants. Additionally, Cs/ZnONCs increased the content of soluble sugars and proteins up to 59 and 185 µg/g, respectively, against 22 and 130 µg/g of Pb-stressed plants. Also, chlorophyll a and total chlorophyll content increased from 2.50 and 6.10 mg/g of fresh weight in the presence of Pb stress to 5.30 and 11.80 mg/g of fresh weight, respectively, after Cs/ZnO NCs application. In addition, Cs/ZnONCs improved the concentration of indole-3-acetic acid and gibberellic acid but decreased the level of abscisic acid production. Overall, Cs/ZnONCs showed higher efficacy than the isolated nanoparticles of ChNPs, CsNPs, and ZnONPs and could be a potential nanomaterial to ameliorate Pb and wastewater stress in B. campestris L.
Mixed pollutants, including polycyclic aromatic hydrocarbons (PAHs), pesticides, synthetic dyes and heavy metals, are the primary sources of contamination because they are persistent, toxic and bioaccumulative. They further increase ecological and human health hazards. Traditional single-microbe remediation can be limited due to a lack of substrate selectivity, incomplete mineralisation, formation of toxic intermediates and limited adaptability to changing environmental factors. Microbial consortia, on the contrary, take advantage of metabolic variability, division of labour, syntrophic interactions and greater tolerance to stress. The review has critically analysed the nature and complexity of mixed organic and inorganic pollutants and explained how consortium-based biodegradation works structurally, functionally, and cooperatively. The pollutant-specific degradation mechanisms of PAHs, dyes, pesticides and heavy metals are addressed, and the synergistic action of the most important enzymes, redox processes, and cross-feeding networks leading to effective detoxification has been emphasised. The ability of biofilm-based consortia to enhance metal sequestration, tolerance to toxic shock and stability of the reactor has also been discussed. Recent developments in the field of bioinformatics are discussed to show how gene expression and enzyme production at the community level control the performance of degradation. Lastly, new technologies like AI/ML-informed consortia design, microbiome editing, synthetic biology, hybrid nanomaterial-based microbes and smart bioreactors are outlined as future perspectives for scalable and sustainable remediation of environments contaminated by mixed pollutants.
Cadmium contamination of water poses serious environmental and public-health risks, creating a need for efficient, reusable, and readily recoverable treatment materials. This study developed a magnetic PA6/CNCs–Fe₃O₄ composite from waste polyamide 6 (PA6), cellulose nanocrystals (CNCs), and Fe₃O₄ for Cd(II) removal from aqueous solution. The composite was prepared via in situ co-precipitation and characterised using SEM–EDS, FTIR, XRD, BET, zeta-potential analysis, and VSM. Characterisation confirmed composite formation, retention of the crystalline magnetite phase, mesoporosity, and the presence of Fe₃O₄ nanoparticles, with sufficient magnetic responsiveness for effective separation. Batch experiments evaluated the effects of pH, contact time, initial Cd(II) concentration, adsorbent dosage, and temperature. Under selected conditions of pH 5.0, an initial Cd(II) concentration of 18.97 mg L⁻1, a contact time of 120 min, an adsorbent dosage of 1.0 g L⁻1, and 298 K, the composite achieved an adsorption capacity of 18.62 mg g⁻1 and a removal efficiency of 98.15
The conversion of agricultural residues into high-value materials represents a sustainable pathway for environmental remediation. In this study, rice husk ash (RHA), an abundant agro-industrial by-product, was valorized into high-purity NaY zeolite through a sol–gel-assisted hydrothermal process. The resulting zeolite exhibited a Si/Al ratio of 7, a surface area of 154.4 m2/g, and a micropore size of 1.19 nm. XRD and SEM analyses confirmed the formation of a highly crystalline FAU-type framework with cauliflower-like cubic aggregates ( 2 µm) and rough porous surfaces favorable for ion exchange. Batch adsorption experiments revealed strong pH dependence, with optimal metal uptake at pH 4, achieving removal efficiencies of 91.9
