International Journal of Phytoremediation最新文献

Biochar is a novel approach to remediating heavy metal-contaminated soil. Using various organic amendments like phyllosilicate-minerals (PSM), compost, biochar (BC) and sulfur-modified biochar (SMB), demonstrates superior adsorption capacity and stability compared to unmodified biochar (BC). The adsorption mechanisms of SMB are identified for its potential to increase soil-pH and reduce available cadmium (Cd). The study reveals the potential of BC and SMB in immobilizing Cd in contaminated soil. SMB demonstrated the highest adsorption capacity for Cd, followed by BC, PSM, and compost, with capacities ranging from 7.47 to 17.67 mg g^-1. Both BC and SMB exhibit high adsorption capacities (12.82 and 17.67 mg g^-1, respectively) and low desorption percentages (4.46-6.23%) at ion strengths of 0.01 to 0.1 mol-L^-1 and pH levels ranging from 5 to 7. SMB showed a higher adsorption capacity (17.67 mg g^-1) and lower desorption percentage (4.46-6.23%) compared to BC. The adsorption mechanism involves surface-precipitation, ion exchange, and the formation of Cd(OH)₂ and CdCO₃ precipitates, as well as interactions between Cd and organic sulfur, leading to more stable-Cd and CdHS⁺ compounds. Adding 1% SMB increased soil pH and significantly reduced available Cd, demonstrating its potential for pollutant remediation. The study underscores the promise of SMB in providing a sustainable solution for Cd-contaminated soil remediation.

Soil heavy metal contamination and sludge disposal have become globally environmental issues problems of great concern. Utilizing sludge pyrolysis to produce biochar for remediating heavy metal-contaminated soil is an effective strategy to solve these two environmental problems. In this study, municipal sewage sludge and papermaking sludge were used as feedstock to prepare co-pyrolyzed biochar, which was then applied to reduce the toxicity of Cd in soil. The results indicated that the application of co-pyrolyzed biochar significantly increased soil pH, CEC, and enzyme activity, while decreasing the content of available Cd in the soil. Following the application of 3% co-pyrolyzed biochar, the proportion of acid-soluble Cd in the soil decreased to below 46%, as the biochar facilitated the conversion of leachable acid-soluble Cd to stable oxidizable and residual forms through precipitation and complexation. The DFT computational results indicate that the aromatics in co-pyrolyzed biochar can adsorb Cd ions through cation-π interactions, while carboxyl, hydroxyl, aldehyde, and amide groups can provide more electrons for the adsorption of Cd ions, resulting in stronger adsorption capacities. The study findings provide a feasible solution for the resourceful treatment of sludge and the remediation of heavy metal-contaminated soil.

Phytoextraction using natural cadmium (Cd) hyperaccumulators, notably Sedum alfredii and Sedum plumbizincicola, represents an economical and efficient approach for soil Cd purification. However, achieving high phytoremediation efficiency necessitates a comprehensive understanding of the mechanisms underlying Cd tolerance and accumulation in these plants. This review summarizes key mechanisms, encompassing Cd activation in the rhizosphere, uptake and transport in the roots, translocation via the xylem, and Cd tolerance. Additionally, physical, chemical, and biological strategies for enhancing phytoremediation efficiency are overviewed and compared. Despite advancements, disparities persist between field and laboratory research, posing certain limitations to the application of natural hyperaccumulators for large-scale phytoextraction or specific soil types. To address these challenges, we propose combining novel hyperaccumulating-like biomaterials with intelligent agriculture to achieve large-scale precision phytoremediation. Furthermore, we aim to draw attention to strategies for enhancing the phytoextraction potential of non-hyperaccumulator plants with high biomass production and stimulate further research into phytoextraction-inducing substances.

The increasing prevalence of cadmium (Cd)-contaminated agricultural soils threatens the safe production of maize (Zea mays L.). To decrease the Cd accumulation in maize, a pot experiment was conducted to study the effects of humic acid on the growth and Cd uptake of maize seedlings. Cd treatment led to a decrease in biomass and photosynthetic pigment content in maize seedlings, as well as an increase in the activities of antioxidant enzymes. Under Cd stress, the application of humic acid resulted in an increase in biomass, photosynthetic pigment content, and antioxidant enzyme activity in maize seedlings. Additionally, the application of humic acid led to a decrease in root Cd content and an increase in shoot Cd content and translocation factor in maize seedlings under Cd stress. Compared to Cd treatment, humic acid reduced root Cd content by 14.63% and increased shoot Cd content by 12.81%. Furthermore, the carotenoid content, translocation factor, chlorophyll a + b content, and chlorophyll a content were strongly associated with shoot Cd content under Cd stress. Therefore, the application of humic acid can enhance growth, inhibit Cd uptake in roots, and promote Cd translocation from roots to shoots of maize seedlings under Cd stress.

The increasing demand for sustainable, robust, and cost-efficient arsenic (As) treatment techniques strengthens the implementation of new constructed wetland (CW) designs like aerated CWs in the agricultural sector. The aim was to assess and contrast the influence of various aeration rates on As elimination in subsurface flow CW utilizing Pennisetum purpureum plants for treating As-polluted sand. This study consisted of an experiment with 16 subsurface flow CW, operating at different As concentrations of 0, 5, 22, and 39 mg kg^-1 and aeration rates of 0, 0.18, 1, and 2 L min^-1. The highest elimination of As from treatment sand in the subsurface flow CWs was 96.19 ± 3.09%, 93.95 ± 2.17%, and 91.91 ± 1.92% for 5, 22, and 39 mg kg^-1 As, respectively, at 0.18 L min^-1 aeration. A negative influence of As pollution on growth was detected in the 0, 1, and 2 L min^-1 aeration but Pennisetum purpureum grows well in polluted sand with 0.18 L min^-1 aeration. Bacterial population and different enzyme activity showed statistically significant differences with 0, 0.18, 1, and 2 L min^-1 aerations at all As levels. These results suggest that this treatment can be used for As phytoremediation in anthropogenically polluted environments due to its high capability to uptake As.

The synergistic application of calcium (Ca) and magnesium (Mg) was investigated to mitigate cadmium (Cd) uptake and translocation in rice grown in Cd-contaminated soil. A pot experiment was conducted using different Ca:Mg molar ratios (Ca1:Mg2, Ca2:Mg1, and Ca1:Mg1) to evaluate their effect on Cd uptake. The results showed that the Ca1:Mg1 treatment achieved the highest reduction in grain Cd content (54.7%, p < 0.05), followed by Ca2:Mg1 (47.6%), and Ca1:Mg2 (40.7%), all below China's National Food Safety Standard (0.2 mg kg^-1). Significant reductions were also observed in roots, stems, and leaves (p < 0.05). Ca1:Mg1 minimized Cd translocation by decreasing stem-to-grain transfer by 61.0% and xylem sap Cd by 50.1% (p < 0.05). It also reduced mobile Cd fractions in roots (F_E from 25% to 18%, F_Di from 44% to 37%) and increased DCB-extractable Fe (DCB-Fe) on roots, enhancing Cd immobilization. Ca:Mg treatments raised soil pH by 23.6-25.7% (p < 0.05), shifting Cd from bioavailable forms (F_EX reduced by 9.3%, F_CB by 17.8%) to more stable forms (F_Fe/Mn increased by 15.5%, F_OM by 1.9%). Strong negative correlations (p < 0.05, 0.01) between soil pH, DCB-Fe, Ca, Mg_TF, F_Fe/Mn, and grain Cd indicating their effect in reducing Cd uptake.

This study introduces a sustainable biological approach for synthesizing silver nanoparticles (AgNPs) using Conocarpus seeds, aimed at improving the adsorption and photocatalytic degradation of methylene blue (MB) in wastewater treatment. The photocatalytic efficiency of AgNPs, synthesized under varying concentrations of silver nitrate (AgNO₃) and pH levels, was evaluated, together with the effectiveness of a photocatalytic reactor. The synthesized samples were characterized using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, and atomic force microscopy (AFM). Results showed that MB degradation occurred quickly within the first 50 min, achieving a 99.60% removal efficiency via adsorption and photocatalytic degradation under optimal conditions (pH = 3, 1 g sample) after 1 h. The maximum adsorption capacity reached 49.80 mg·g^-1. Furthermore, the AgNPs demonstrated a significant degradation rate of 99.76% within 2 h under UV light, highlighting the synergistic effects of AgNPs in enhancing both adsorption and photocatalysis. This study not only accentuates the potential of Conocarpus seeds as an eco-friendly precursor for AgNP synthesis but also highlights the applicability of AgNPs in wastewater treatment.

Chickpea (Cicer arietinum L.) productivity is hindered by biotic and abiotic stresses, particularly heavy metal toxicity. The pot experiment was carried out at the botanical garden of The Islamia University of Bahawalpur, Bahawalpur-Pakistan. The experimental treatments comprised of following details: T0 = Control + 0 µM MT, T1 = Control + 15 µM MT, T2= Control + 30 µM MT, T3 = 100 µM Cd + 0 µM MT, T4 = 100 µM Cd + 15 µM MT and T5 = 100 µM Cd + 30 µM MT. A completely randomized design (CRD) with three replicates was used. Cd stress significantly reduced shoot fresh (51.3%) and dry weight (50.4%), total chlorophyll (53.6%), and shoot Ca²⁺ (56.6%). However, it increased proline (38.3%), total phenolics (74.2%), glycine betaine (46.4%), TSS (67.7%), TSP (50%), SOD (49.5%), POD (107%), and CAT (74.2%). Conversely, 30 µM MT improved shoot fresh (78.5%) and dry weight (76%), total chlorophyll (47%), SOD (26.5%), POD (35.8%), CAT (27.8%), proline (19%), TSS (24.5%), TSP (25.8%), and shoot Ca²⁺ (56.6%). Results indicated that MT enhanced photosynthetic pigments and antioxidant activities, maintained ion homeostasis, and reduces reactive oxygen species. Desi variety performed better than Kabuli, and 30 µM MT application effectively mitigated Cd toxicity.

Due to a lack of high-quality water, farmers have been compelled to use sewage water for irrigation, contaminating agricultural soils with multiple heavy metals. For the remediation of contaminated soil, plant growth-promoting rhizobacteria (PGPR), pressmud (PM), and iron (III) oxide were used to improve the growth and phytostabilization potential of chickpea grown in contaminated soil. Contaminated soil was collected from a nearby field, receiving sewage and factory water over the last 60 years. Chickpea seeds were inoculated with metal-tolerant (lead and cadmium) rhizobacterial and rhizobial strains. It was observed that combined application of rhizobia, rhizobacteria, iron oxide, and pressmud improved shoot fresh weight (87%), root fresh weight (47.9%), root length (47.9%), nodules plant^-1 (2.58 folds), photosynthetic rate (63%) and grain yield (39%) of chickpea as compared to respective untreated control in contaminated soil. Moreover, a significant decrease in the lead (75.8 and 68.1%) and cadmium (81 and 72%) concentrations due to the combined application of rhizobacteria, rhizobia, iron oxide, and pressmud was observed in shoot and root of chickpea than respective control, respectively. It can be concluded that the contaminated soil with mixed metals can be remediated, and the growth and yield of chickpea can be improved.

The article details a feasibility study of removing Brilliant Green (BG), a mutagenic dye from an aqueous solution by adsorption using low-cost coriander seed spent as a by-product in the nutraceutical industry. The study includes an analysis of the parameters that affect the adsorption process. The variables that have been identified include pH, dye concentration, process temperature, adsorbent amount, and particle size of the adsorbent. To obtain information on the adsorption process and to design the mechanism of the adsorption system on experimental equilibrium, 10 isotherm models, namely, Langmuir, Freundlich, Jovanovic, Dubinin-Radushkevich, Sips, Redlich-Peterson, Toth, Vieth-Sladek, Brouers-Sotolongo, and Radke-Prausnitz were applied. It was discovered that the experimental adsorption capacity, q_e, was roughly 110 mg g^-1. The result has a maximum adsorption of 136.17 mg g^-1 as predicted by Dubinin-Radushkevich isotherm. Diffusion film models, Dumwald-Wagner and Weber-Morris models, and pseudo-first- and second-order models, were used to determine the adsorption kinetics. It was realized that the adsorption kinetics data fit into a pseudo-second-order model. Thermodynamic analysis with a reduced enthalpy change suggests a physical process. The values of the thermodynamic parameters ΔG⁰, ΔH⁰, and ΔS⁰ demonstrated an endothermic and nearly spontaneous process of adsorption. The small valuation of ΔH⁰ specifies that the process is physical. FTIR spectroscopy and SEM imaging were used to confirm that the BG dye had been adsorbing on the adsorbent surface. The study concludes that NICSS is an effective adsorbent to extract BG dye from wastewater solutions, offers insights into numerous dye and adsorbent interaction possibilities and indicates that the process can be scaled to fit into the concept of circular economy.