Eco-friendly nanoparticles: mechanisms and capacities for efficient removal of heavy metals and phosphate from water using definitive screening design approach.

Can nano-zero-valent iron, synthesized using oak leaf extract, be the key solution for water preservation, efficiently removing heavy metal ions and phosphate anions simultaneously? This research unveils how this technology not only promises high efficiency in the remediation of water resources, but also sets new standards for environmentally friendly processes. The high antioxidant capacity and high phenol content indicate suggest the possibility of oak-nZVI synthesis using oak leaf extract as a stable material with minimal agglomeration. The simultaneous removal of Cd and phosphates, as well as and Ni and phosphates was optimized by a statistically designed experiment with a definitive screening design approach. By defining the key factors with the most significant impact, a more efficient and faster method is achieved, improving the economic sustainability of the research by minimizing the number of experiments while maximizing precision. In terms of significance, four input parameters affecting process productivity were monitored: initial metal concentration (1-9 mg L-1), initial ion concentration (1-9 mg L-1), pH value (2-10), and oak-nZVI dosage (2-16 mL). The process optimization resulted in the highest simultaneous removal efficiency of 98.99 and 87.30% for cadmium and phosphate ions, respectively. The highest efficiency for the simultaneous removal of nickel and phosphate ions was 93.44 and 96.75%, respectively. The optimization process fits within the confidence intervals, which confirms the assumption that the selected regression model well describes the process. In the context of e of the challenges and problems of environmental protection, this work has shown considerable potential and successful application for the simultaneous removal of Cd(II) and Ni(II) in the presence of phosphates from water.

Integrated application of green zero-valent iron and electrokinetic remediation of metal-polluted sediment.

In recent years, more focus has been placed on integrated metal removal processes. Electrokinetic (EK) treatment is superior to other technologies because it can be applied to a variety of mediums. Green nanoparticles, on the other hand, have the potential to significantly reduce pollutant concentrations in a short period of time. In this study, we investigated the possibility of combining green zero-valent iron (nZVI) with EK on Cd and Zn-contaminated sediment. For green synthesis, extracts of dry leaves of mulberry (ML-nZVI) and oak (OL-nZVI) were used, both abundantly present in the Republic of Serbia. The results show that, despite the fact that their availability was greatly reduced, the metals were concentrated and stabilized to a significant extent in the middle of the EK cell (z/L 0.5) after all treatments. When the results were compared, OL-nZVI proved to be a more effective nanomaterial even with smaller doses of OL-nZVI, which is important in terms of achieving better economic benefits. This study identified green nano zero-valent iron as a powerful tool for metal removal when combined with electrokinetic (EK) treatment, which improves green nZVI longevity and migration. This study of the combined green nZVI-EK remediation treatment, in particular, will have an impact on future research in this field, given the achieved efficiency.

"Green" nZVI-Biochar as Fenton Catalyst: Perspective of Closing-the-Loop in Wastewater Treatment.

In the framework of wastewater treatment plants, sewage sludge can be directed to biochar production, which when coupled with an external iron source has the potential to be used as a carbon-iron composite material for treating various organic pollutants in advanced oxidation processes. In this research, "green" synthesized nano zero-valent iron (nZVI) supported on sewage sludge-based biochar (BC)-nZVI-BC was used in the Fenton process for the degradation of the recalcitrant organic molecule. In this way, the circular economy principles were supported within wastewater treatment with immediate loop closing; unlike previous papers, where only the water treatment was assessed, the authors proposed a new approach to wastewater treatment, combining solutions for both water and sludge. The following phases were implemented: synthesis and characterization of nano zero-valent iron supported on sewage sludge-based biochar (nZVI-BC); optimization of organic pollutant removal (Reactive Blue 4 as the model pollutant) by nZVI-BC in the Fenton process, using a Definitive Screening Design (DSD) model; reuse of the obtained Fenton sludge, as an additional catalytic material, under previously optimized conditions; and assessment of the exhausted Fenton sludge's ability to be used as a source of nutrients. nZVI-BC was used in the Fenton treatment for the degradation of Reactive Blue 4-a model substance containing a complex and stable anthraquinone structure. The DSD model proposes a high dye-removal efficiency of 95.02% under the following optimal conditions: [RB4] = 50 mg/L, [nZVI] = 200 mg/L, [H2O2] = 10 mM. pH correction was not performed (pH = 3.2). Afterwards, the remaining Fenton sludge, which was thermally treated (named FStreated), was applied as a heterogeneous catalyst under the same optimal conditions with a near-complete organic molecule degradation (99.56% ± 0.15). It could be clearly noticed that the cumulative amount of released nutrients significantly increased with the number of leaching experiments. The highest cumulative amounts of released K, Ca, Mg, Na, and P were therefore observed at the fifth leaching cycle (6.40, 1.66, 1.12, 0.62, 0.48 and 58.2 mg/g, respectively). According to the nutrient release and toxic metal content, FStreated proved to be viable for agricultural applications; these findings illustrated that the "green" synthesis of nZVI-BC not only provides innovative and efficient Fenton catalysts, but also constitutes a novel approach for the utilization of sewage sludge, supporting overall process sustainability.

Gender-specific differences in hemodialysis patients: a multicenter longitudinal study from Serbia.

PURPOSE: The study was undertaken with the aim to determine gender-specific differences in incident hemodialysis (HD) patient and their changes over time. METHODS: The retrospective longitudinal closed cohort study involved 441 incident patients starting HD in 2014 and followed for 1-59 (median 43, IQR 40) months. Demographic, clinical data, treatment characteristics, laboratory findings and outcome were abstracted from the patients' medical records. RESULTS: The relative number of males on HD was about twice that of females throughout the five years investigated. At the beginning of the study, no significant differences were found in the main demographic and clinical characteristics except that diabetes was more often the underlying disease in men than in women. Systolic blood pressure decreased over time significantly more in females than in males. Throughout the study spKt/V was significantly higher in females than in males, but it increased in patients of both genders. There were no gender differences for comorbidities, vascular access and the majority of laboratory findings except for higher serum levels of creatinine and CRP in men than in women. Relatively more females were treated with erythropoiesis stimulating agents and phosphate binders than males. Age and malignancy were selected as significant predictors of mortality for both genders, and, in addition, polycystic kidney disease, serum level of albumin and CRP for men, but spKt/V for women. CONCLUSION: Some significant gender differences were observed throughout, while others appeared during the study but none of them were due to gender inequalities in the applied treatment.

A cost effective method for immobilization of Cu and Ni polluted river sediment with nZVI synthesized from leaf extract.

This study investigates the performance of oak (OL) and mulberry (ML) leaves for synthesized of nanoscale zero-valent iron (nZVI), in immobilizing Cu and Ni in contaminated sediment. Characterization of synthesized Fe nanoparticles from oak and mulberry leaf extracts demonstrated that they are nontoxic and stabile nanomaterials for application in the sediment remediation. Effectiveness of stabilization process was performed by microwave-assisted sequential extraction procedure (MWSE) and single-step leaching tests which have been applied to evaluate the metal extraction potential. This research showed that OL-nZVI and ML-nZVI were effective in transforming available Cu and Ni to stable fraction. The maximum residual percentage of Cu increased by 76% and 73%, and for Ni 81% and 80%, respectively, with addition of 5% OL-nZVI and 5% ML-nZVI. Used single-step leaching tests (Toxicity Characteristic Leaching Procedure-TCLP and German standard test- DIN) indicated that all stabilized samples can be considered as non-hazardous waste, as all leached metal concentrations met the appropriate set criteria. Cost analysis showed that the operating cost for contaminated sediment treatment with green synthesized nZVI are 50.37 €/m3/per year. This work provides a new insight into the immobilization mechanism and environmental impact of Cu and Ni in contaminated sediment and potential way of treatment with OL-nZVI and ML-nZVI. Generally, nZVI can be an effective and versatile tool for stabilization of sediment polluted with toxic metals.

Long-term application of stabilization/solidification technique on highly contaminated sediments with environment risk assessment.

After dredging of contaminated sediment, additional remediation technique is required before its final disposal. For this purpose, this research was based on the long-term stabilization/solidification (S/S) process of highly contaminated sediment (dominantly by heavy metals) from a European environmental hot spot, the Great Backa Canal. Due to optimisation of remediation techniques, this sediment is treated with selected immobilization agents: kaolinite, quicklime and Portland cement. The use of pseudo-total metal content (selected priority substances: Cr, Ni, Cu, Cd, Zn, Pb and As) in untreated sediment, determined that sediment urgently requires remediation. Short-term (after 7 and 28 days) and long-term (after 7 years) monitoring were done in order to estimate the concentrations of metals and effect on biota from S/S mixtures during this processes. The environmental risk assessment encompassed the application of several appropriate analytical methods: the pseudo-total metal content, the German standard leaching test - DIN 3841-4 S4 and Toxicity Characteristic Leaching Procedure - TCLP test leaching tests and sequential extraction procedure (BCR) on S/S mixtures, testing the aging process and toxicity effects. After simulating real environmental conditions using all tests in all three mixtures, metals do not exceed the prescribed limit values and as such S/S mixtures are classified as non-hazardous waste. Sequential extraction procedure showed that the highest percentage of metals are in the residual phase, bound to silicates and crystalline structure. After 7 years of S/S mixture aging, kaolinite showed the highest binding capacity that was reflected in the content of metals in the residual phase (34.8% of Ni to 77.6% of Cr). DIN and TCLP leaching tests confirmed that the exchangeable phase has a minor effect on the environment. Accordingly, this remediation technology could be well applied for final disposal of this and similar extremely contaminated sediment dominantly with inorganic pollutants.

Distribution and ecological risk assessment of organic and inorganic pollutants in the sediments of the transnational Begej canal (Serbia-Romania).

This research is designed to determine the level and types of pollution in the highly contaminated sediments of the international Begej canal in Timis district, Romania and north-eastern Serbia. The cross-border canal stretch investigated is currently not navigable, but represents an important waterway between the Danube River in Serbia and the city of Timisoara. Surface sediments were monitored annually from 2008 to 2016 at 36 representative sampling locations, with a wide range of analyses, including eight heavy metals of long-term monitoring concern (Ni, Zn, Cd, Cr, Cu, Pb, As and Hg) and the 16 USEPA PAHs. The purpose of this study was to determine the diversity and impact of anthropogenic and natural sources of pollution at the pollution hot spots on the canal: at the Itebej lock (near the border with Romania) and downstream at the Klek lock. Sediment quality and ecological risk were assessed in order to determine pollutants of concern. Several multi-proxies were applied (e.g. geo-accumulation index (Igeo), ecological risk index (RI) and total benzo[a]pyrene equivalent (B[a]Peq)). To determine and predict trends, multivariate statistical methods (factor analysis of principal component analysis (PCA/FA)) were carried out on the organic and inorganic parameters analysed. In the near-border region, acute and significant ecological impacts were observed. The heavy metals Hg, Cr, Pb, Cu and Zn, and the carcinogenic PAH dibenzo[a,h]anthracene, were historically the most frequently detected harmful substances to biota in this and the wider Pannonia region. This is the first long-term study to quantify and derivate the most frequently detected harmful substances of concern for this and similar sites in the wider region, and is additionally supported by significant national and similar environmental data from previous studies in the region.

Compliance with guidelines and predictors of mortality in hemodialysis. Learning from Serbia patients.

OBJECTIVES: The aims of the study were to determine the percentage of patients on regular hemodialysis (HD) in Serbia failing to meet KDOQI guidelines targets and find out factors associated with the risk of time to death and the association between guidelines adherence and patient outcome. METHODS: A cohort of 2153 patients on regular HD in 24 centers (55.7% of overall HD population) in Serbia were followed from January 2010 to December 2012. The percentage of patients failing to meet KDOQI guidelines targets of dialysis dose (Kt/V>1.2), hemoglobin (>110g/L), serum phosphorus (1.1-1.8mmol/L), calcium (2.1-2.4mmol/L) and iPTH (150-300pg/mL) was determined. Cox proportional hazards analysis was used to select variables significantly associated with the risk of time to death. RESULTS: The patients were on regular HD for 5.3±5.3 years, dialyzed 11.8±1.9h/week. Kt/V<1.2 had 42.4% of patients, hemoglobin <110g/L had 66.1%, s-phosphorus <1.1mmol/L had 21.7% and >1.8mmol/L 28.6%, s-calcium <2.1mmol/L had 11.7% and >2.4mmol/L 25.3%, iPTH <150pg/mL had 40% and >300pg/mL 39.7% of patients. Using Cox model (adjustment for patient age, gender, duration of HD treatment) age, duration of HD treatment, hemoglobin, iPTH and diabetic nephropathy were selected as significant independent predictors of time to death. When targets of five examined parameters were included in Cox model, target for KtV, hemoglobin and iPTH were found to be significant independent predictors of time to death. CONCLUSION: Substantial proportion of patients examined failed to meet KDOQI guidelines targets. The relative risk of time to death was associated with being outside the targets for Kt/V, hemoglobin and iPTH.