Adsorption Potential, Speciation Transformation, and Risk Assessment of Hg-, Cd-, and Pb-Contaminated Soils Using Biochar in Combination with Potassium Dihydrogen Phosphate.

The objective of this study is to develop a remediation technology for composited heavy metal-contaminated soil. Biochars (BC300, BC400, and BC500) derived from corn were combined with potassium dihydrogen phosphate (KH2PO4) to immobilize and remove heavy metal ions, including mercury (Hg2+), cadmium (Cd2+), and lead (Pb2+). The adsorption kinetics of metal ions in aqueous solutions with different concentrations was tested, and the fitting effects of the two models were compared. The findings demonstrate that the joint application of biochar and KH2PO4 could markedly enhance the immobilization efficacy of Pb2+, whereas the utilization of KH2PO4 on its own exhibited a more pronounced immobilization impact on Cd2+. Furthermore, the present study underscores the shortcomings of various remediation techniques that must be taken into account when addressing heavy metal-contaminated soils. It also emphasizes the value of comprehensive remediation techniques that integrate multiple remediation agents. This study offers a novel approach and methodology for addressing the intricate and evolving challenges posed by heavy metal contamination in soil. Its practical value and potential for application are significant.

Fly ash treatment via conventional and microwave-assisted organic acid leaching: kinetics and life cycle assessment.

Heedless disposal of oil-based fly ash contributes to the contamination of the air, water, and soil. Acid leaching of industrial solid wastes is recognized as a versatile, cost-effective, and environmentally friendly solid waste treatment approach. The present study investigated the viability of conventional leaching (CL) and microwave-assisted leaching (MAL) of predominant heavy metals from Mazut-burnt fly ash. For this purpose, the practicality of four organic acids with various specifications (ascorbic, gluconic, citric, and oxalic acids) on the dissolution efficiency of fly ash components was examined. Utilization of oxalic acid led to achieving full V recovery, complete Fe removal, and Ni enrichment in the residue in both CL and MAL setups. The Ni content of the sample was enriched from 6% in the calcinated sample to 23.7% in the oxalic acid leaching residue. Using citric acid resulted in the co-extraction of V, Ni, and Fe with nearly 70% V, 50% Ni, and 89% Fe dissolved in CL. The dissolution efficiencies were slightly lower in MAL. Oxalic acid was selected as the most promising organic acid reagent for fly ash treatment, so its CL kinetics was studied and defined by the shrinking particle model. The model showed that the controlling steps in the leaching of V differ over time, changing from a chemical reaction before 60 min to fluid film diffusion or mixing afterward. The kinetic study proved MAL as an effective technique in overcoming the leaching kinetic barriers. A life cycle assessment study was conducted to determine the environmental impacts of the proposed process. Accordingly, the MAL using oxalic acid was the most environmentally friendly process among the studied ones, and the utilization of microwaves leads to the reduction of the leaching processes' environmental impacts by decreasing the processing time.

Reducing CO/NO and absorbing heavy metals in self-sustained smouldering of high-moisture sludge by regulating inert media with low-cost natural zeolite.

Smouldering is a low-energy, low-cost, effective treatment technology for sludge with high moisture. However, combustible gas and pollution in the flue gas limit the low-cost operation. This work proposes a novel method to in-situ reduce gas emissions (CO, NO, VOCs) and absorb heavy metals by regulating inert media with low-cost natural zeolite in self-sustained smouldering of sludge, and the effect of natural zeolite blending ratio on the performance is deeply investigated by fixed-bed and smouldering experiments. Fixed-bed experiments show that adding natural zeolite contributes to the sludge reaction owning to the confined catalysis with porous structure, as observed by the more rapid oxygen consumption, lower CO/NO concentrations. Moreover, smouldering experiments demonstrate that the endothermic dehydroxylation and dehydroxylation processes of the pure natural zeolite decreases the smouldering temperature and the propagation velocity, reduces the pyrolysis layer, but adding natural zeolite significantly reduces the concentrations of CO/NO/VOCs in the flue gas. Furthermore, higher heavy element content in the post-reaction natural zeolite is observed, indicating that the inorganic minerals in natural zeolite can effectively absorb the heavy elements. Taking reaction intensity, CO/NO/VOCs reduction and heavy element absorption into account, adding a small amount of natural zeolite (Sand: Natural-zeolite = 2.90:0.10) may be reasonable with obtaining good performance. Finally, the organic components in condensable liquids of the smouldering flue gas are deeply analyzed, and the main components is 36.7% for amides and 23.41% for nitrogen-containing heterocyclic compounds. This work can provide a possible pathway and useful information for the low-cost application of the sludge smouldring technology.

A circular economy approach to drinking water treatment residue management in a catchment impacted by historic metal mines.

Drinking water treatment residues (DWTR) from mining areas which remove and contain potentially toxic elements (PTE) could still potentially be used as a soil amendment to restore contaminated sites in the same catchment, thus eliminating waste and reducing the chemical and physical mobility of the pollutants. To assess this restorative and regenerative approach to DWTR management, field and pot trials were established with soils from a historic Pb-Zn mine site in the North East of England, amended with either local DWTR or the nearest available municipal green waste compost (GWC). Soils from the mine site were found to have very low levels of nutrients and very high levels of PTE (Pb and Zn > 13, 000 mg/kg). The perennial grass species Phalaris arundinacea, known for many ecosystem service benefits including soil stabilization, was used throughout this study. The application of the BCR sequential extraction to soils amended with the DWTR in the pot trials found a significant decrease in the bioavailability of Pb and Cu (p < 0.05) after plant growth when compared with an unamended control. The field trial involved 648 pre-grown grass plants planted-out into mine soils amended with either DWTR, GWC or a mixture (MIX) of the two, all at rates of 25-30% w/w. Both amendments and the MIX had significant positive effects on biomass production compared to the unamended control in the following order GWC > MIX > DWTR (p < 0.05). Results of the elemental analysis of biomass from the field trial were generally ambiguous and did not reflect the decreased bioavailability noted in the pot trials using the BCR procedure. Pot trials, however, showed increases in plant growth and decreases in concentrations of Cr, Cu, Pb and Zn in above ground biomass following the application of both amendments. Further work should involve the testing of a mixture of DWTR and other soil amendments to enhance plant growth. The success of these trials should provide confidence for those working in drinking water treatment and catchment management to reuse the waste residues in a circular economy and a sustainable way that could improve water quality over time.

Phosphorus recovery from sewage sludge ash (SSA): An integrated technical, environmental and economic assessment of wet-chemical and thermochemical methods.

Incineration is a promising disposal method for sewage sludge (SS), enriching more than 90% of phosphorus (P) in the influent into the powdered product, sewage sludge ash (SSA), which is convenient for further P recovery. Due to insufficient bioavailable P and enriched heavy metals (HMs) in SSA, it is limited to be used directly as fertilizer. Hence, this paper provides an overview of P transformation in SS incineration, characterization of SSA components, and wet-chemical and thermochemical processes for P recovery with a comprehensive technical, economic, and environmental assessment. P extraction and purification is an important technical step to achieve P recovery from SSA, where the key to all technologies is how to achieve efficient separation of P and HMs at a low economic and environmental cost. It can be clear seen from the review that the economics of P recovery from SSA are often weak due to many factors. For example, the cost of wet-chemical methods is approximately 5∼6 €/kg P, while the cost of recovering P by thermochemical methods is about 2∼3 €/kg P, which is slightly higher than the current P fertilizer (1 €/kg P). So, for now, legislation is significant for promoting P recovery from SSA. In this regard, the relevant experience in Europe is worth learning from countries that have not yet carried out P recovery from SSA, and to develop appropriate policies and legislation according to their own national conditions.

Experimental, Grand canonical Monte Carlo, and Density Functional Theory studies for comparing halloysite and kaolinite on heavy metals fate during pyrolysis of solid waste.

In this study, we utilized low-cost halloysite (Hal) for the first time to enhance the solid-phase enrichment and stability of heavy metals (HMs) during solid waste pyrolysis through experimental and theoretical methods, and compared with kaolinite (Kao). Experimental results demonstrated that Hal was superior to Kao in improving the solid-phase enrichment of HMs. Specifically, the solid-phase enrichment of Cd increased by 32.6 % (500 °C) and 25.94 % (600 °C), while that of Pb and Zn increased by 17.37 %/16.83 % and 19.82 %/22.37 % (700/800 °C), respectively. Adding Hal reduced the proportion of HMs in the unstable fraction (F1 + F2), consequently lowering the environmental risk of biochar and the extractable state of HMs. Through Grand canonical Monte Carlo and Density Functional Theory (DFT) simulations, we analyzed the adsorption amounts, adsorption sites, and adsorption mechanisms of Cd/Pb compound on Hal/Kao surfaces, revealing that the primary factor influencing the adsorption performance of Hal and Kao was the difference in specific surface area. The adsorption amounts of HMs by Hal were significantly higher than Kao and decreased with increasing temperature, while the difference in adsorption performance caused by structural bending was negligible. The DFT results indicated that Cd and Pb monomers were stabilized by establishing covalent bonds with OH or reactive O atoms on the Al-(001) surface, whereas the covalent bonds with ionic bonding properties formed between Cl atoms and unsaturated Al atoms played a crucial role in stabilizing HM chlorides. Furthermore, the adsorption energy of Hal on HMs increased with the removal rate of OH. Our study highlights the potential of Hal in stabilizing HMs during pyrolysis without requiring any modifications, thereby avoiding the generation of modified waste solutions and unnecessary cost loss.

Assessment of heavy metals and macromineral in frequently used medicinal plants from Algerian Sahara traditional ethnopharmacopeia.

In this study, a total of 15 elements, both physiological and causing toxic effects, have been determined in 9 medicinal plants collected from their natural environment in the Algerian Sahara regions. The concentrations of elements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) after acid digestion and by the X-ray fluorescence spectrometry (XRF). By analyzing the spiked test and the reference materials, the accuracy of the measurements was determined. Our findings show differences in elements composition and concentration between the species under investigation, indicating differences in physiological function of the plant as a result of elemental interactions within it. The elements were quantified (in µg/g): Br (0.04-5.44), Cd (1.21-1.34), Co (1.12-64.35), Cr (1.51-59.05), Cu (1.81-9.28), Fe (94.26-668.55), Mn (16.34-70.77), Ni (1.5-53.64), Pb (1.18-2.55), Zn (1.21-310.80) and (in mg/g): Ca (4.23-4.70), Cl (21.98-117.91), P (28.92-30.49), S (4.15-11.95), Si (1.99-2.36). Mean element levels in medicinal plants were established in decreasing order as follows: Zn>Mn>Cu>Cr>Ni>Pb>Cd>Co. Except for nickel, which reached 53.64µg/g in the Capparis spinosa L species, heavy metal concentrations were found to be low in all samples. Based on traditional use, we can cautiously conclude that these medicinal plants pose no risk to users.

Clinoptilolite based zeolite-geopolymer hybrid foams: Potential application as low-cost sorbents for heavy metals.

Clinoptilolite based zeolite-geopolymer foams (abbreviated as CFs) were prepared from natural clinoptilolite and calcined clinoptilolite, using H2O2 solution as pore former through a straightforward process. Natural clinoptilolite and CFs are characterized by analytical techniques including optical microscope, XRF, FTIR, XRD, BET, MIP and SEM. The obtained CFs possesses micropores of zeolite and meso/macropores of geopolymer matrix. The porosities range from 66.7 to 69.5%. Clinoptilolite (partially dissolved) and impurity minerals (montmorillonite, illite and albite) contribute to the formation of geopolymer. CFs shows a good static sorption performance for toxic heavy metals at pH = 5 and sorption time of 24 h. Results show that the adsorption amount of CFs for Cr3+, Pb2+, Ni2+, Cu2+ and Cd2+ in the 50 mg/L working solutions are 6.21 mg/g, 6.11-6.13 mg/g, 5.92-6.07 mg/g, 5.53-5.93 mg/g and 5.44-5.79 mg/g, respectively. In addition, CFs could reach a high removal rate (Cr removal rate >80% and Cd > 60%) for different heavy metals after three cycles. The elimination order of toxic metals is Cr3+ > Pb2+ > Ni2+ > Cu2+ > Cd2+. The sequence is in accordance with Hard-Soft-Acid-Base principle, it is also related to the speciation and the ionic radii of the hydrated metal ions. This research provides a feasible approach for preparation of promising foams sorbent based on natural zeolite for wastewater management.

Ecotoxicological Assessment of Heavy Metal and Its Biochemical Effect in Fishes.

Level of toxic heavy metal concentration like lead (Pb), chromium (Cr), cadmium (Cd), iron (Fe), copper (Cu), zinc (Zn), and nickel (Ni) in thirty-six soft and hard organs and their impact on lipid profile of Hypophthalmichthys molitrix and Catla catla fish species inhibiting in Tanda Dam reservoir were investigated. The heavy metal concentrations in water, sediment, and fish of the different regions in the reservoir were determined with atomic absorption spectrophotometer. Lipid profile was carried out by AOAC official methods. The results showed that Pb was dominant among all the heavy metals in six organs, and its maximum concentration of Pb (22.5 mg kg-1 and 32.9 mg kg-1) was observed in scales in Hypophthalmichthys molitrix and tail of Catla catla, respectively. The maximum concentrations of Cd were observed in the head, scales, fins, and gills of Catla catla. The bioaccumulation of heavy metals was significantly different at (p ≤ 0.01) within the organs and between the fish species. The lipid concentration was minimum in those organs where the concentrations of heavy metals were maximum. It is clear from the findings that heavy metal accumulation reduces the lipid content of fish. It is inevitable to monitor the Tanda Dam reservoir to safeguard human health.

Shaping polyelectrolyte composites for heavy metals adsorption from wastewater: Experimental assessment and equilibrium studies.

Design of core/shell composite microparticles for loading/release of organic/inorganic pollutants is of great interest in wastewater treatment. As compared to the classic layer-by-layer strategy, the new approach presented in this study introduced higher organic shell amounts in one-pot deposition step, with less material and energy consumption and lack of toxic by-products formation. Herein, one weak polycation (polyethyleneimine) and two weak polyanions were directly deposited onto silica surface through precipitation of an in-situ formed interpolyelectrolyte coacervate, followed by selective crosslinking with glutaraldehyde and extraction of polyanion chains, confirmed by electrokinetic measurements and FTIR spectra of composites. Twelve composite sorbents were synthesized and tested for adsorption of cadmium, as model heavy metal ion. It was demonstrated that the high sorption occurred onto four newly synthesized composites which is correlated to the deposited shell amount, dependent on the deposition method, polyanion nature and crosslinking ratio. The Cd2+ sorbed amount increased with the polyelectrolyte deposited amount and with the accessibility toward active sorption site, less cross-linked composite shells sorbing higher amounts as compared to strong cross-linked shells, the molar ratio [active site]:[Cd2+] ranging from 16:1 to 26:1. The best fitting of four isotherm (Langmuir, Freundlich, Sips and Toth) and four kinetics (pseudo-first order, pseudo-second order, modified Freundlich and Elovich) models was assessed by the sum of normalized errors, based on different nonlinear regression error functions, and by the Hannah-Quinn information criterion. In general, the best agreement with the experimental data was found for Toth isotherm and the pseudo-second order kinetic model. Efficient regeneration of the sorbents was possible at least three times. The competitive effect of Pb2+ and Ni2+ ions was also studied in simulated and real systems. Silica composite sorbents with polyethyleneimine chains as major component of the shell could be very promising in wastewater treatment processes.

Synergistic optimization of syngas quality and heavy metal immobilization during continuous microwave pyrolysis of sludge: Competitive relationships, reaction mechanisms, and energy efficiency assessment.

To realize the efficient resource utilization of sewage sludge, this work explored the competitive relationship and reaction mechanisms between syngas quality optimization and heavy metals (HMs) immobilization. The results showed that continuous microwave pyrolysis (CMP) technology with an instantaneous temperature increase could shorten the pyrolysis time, and the biogas yield and syngas concentration reached 51.68 wt% and 83.6 vol%, respectively. Although a higher pyrolysis (750 °C) temperature could optimize the syngas quality, the HMs immobilization efficiency was reduced due to the deep pyrolysis of the biochar. The moderate pyrolysis temperature (650 °C) facilitated the rapid formation of biochar with abundant surface functional groups and pore structure, thus enhancing HMs immobilization. Furthermore, the HMs could also form more stable crystalline compounds with inorganic components (SiO2, Al2O3, inorganic sulfur). By optimizing the process parameters, the risk factor of HMs in the sludge decreased from 117.36 to 62.5 while obtaining high-quality syngas. The energy utilization efficiency of microwave pyrolysis also increased significantly from 11.20% to 82.01%. This work provided new insight into the efficient resource utilization and environmentally friendly treatment of sludge, and demonstrated that CMP technology has significant potential for future industrial applications as an alternative to traditional pyrolysis.

Leaching assessment of cemented bauxite tailings through wetting and drying cycles of durability test.

Disposal of mine tailings can cause negative environmental effects by releasing contaminants to surface and underground water. Alkali activation is a promising technique for immobilizing metals in stabilization/solidification of these wastes. This study evaluates the leaching behavior of cemented bauxite tailings (BT) submitted to weathering conditions. The alkali-activated binder was composed of sugar cane bagasse ash, carbide lime, and sodium hydroxide solution. Comparisons of the durability and leaching behavior of BT stabilized with alkali-activated binder and high initial strength Portland cement were performed. The durability results for alkali-activated were similar to the Portland cement, showing an average difference of 16%. Portland cement showed favorable results in the encapsulation of heavy metals like Cd and Hg, while the alkali-activated cement on Al, Cr, and Se. For Ba, Fe, Mn, and Zn immobilization, both types of cement presented an equal performance. The durability and leaching behavior of stabilized bauxite tailings is governed by the cement content and porosity of the blends, as well as their pH.

Recent advances in nanomaterials-based electrochemical immunosensors and aptasensors for HER2 assessment in breast cancer.

Human epidermal growth factor receptor 2 (HER2) is one of the key molecular targets in breast cancer pathogenesis. Overexpression and/or amplification of HER2 in approximately 15-20% of breast cancer patients is associated with high mortality and poor prognosis. Accumulating evidence shows that accurate and sensitive detection of HER2 improves the survival outcomes for HER2-positive breast cancer patients from targeted therapies. The current methods of clinical determination of HER2 expression levels are based on slide-based assays that rely on invasively collected primary tumours. Alternatively, ELISA-based detection of the shredded HER2 extracellular domain (HER2-ECD) of has been suggested as a surrogate method for monitoring disease progress and treatment response in breast cancer patients. In the past decade, biosensors have emerged as an alternative modality for the detection of circulating HER2-ECD in human serum samples. In particular, electrochemical biosensors based on nanomaterials and antibodies and aptamers have been increasingly developed as promising tools for rapid, sensitive, and cost-effective detection of HER2-ECD. These biosensors harness the high affinity and specificity of antibodies and aptamers, and unique conductive properties, biocompatibility, large surface area, and chemical stability of nanomaterials for selective and sensitive assessment of the HER2. This review provides an overview of the recent advances in the application of nanomaterials-based immunosensors and aptasensors for detection of circulating HER2-ECD. In particular, various electrochemical techniques, detection approaches, and nanomaterials are discussed. Further, analytical figures of merit of various HER2 immunosensors and aptasensors are compared. Finally, possible challenges and potential opportunities for biosensor-based detection of HER2-ECD are discussed.

Heavy metals drinking water contamination and health risk assessment among primary school children of Pakistan.

The purpose of this study was to characterize the concentrations of lead (Pb), cadmium (Cd), manganese (Mn), and Fe (Fe) in drinking water sources in primary schools in Sindh Province, Pakistan and to quantify potential health risks among those school children. We conducted a representative, cross-sectional study among 425 primary schools in Sindh province of Pakistan. We used risk assessment models to estimate the metal index, pollution index, lifetime cancer risk, and hazard quotient index. Across the 425 sampled schools, the levels of heavy metals in the drinking water often exceeded the WHO permissible limits (67% of schools exceeded Pb limit, 17% for Cd, 15% for Fe). The average incremental lifetime cancer risk (ILCR) for Pb exceeded tolerable limits in all of the districts under study. The findings, particularly for Pb, are of concern, as Pb may negatively influence children's growth, development, school performance, and long-term health.

Heavy Metals Detection with Paper-Based Electrochemical Sensors.

This Feature summarizes recent works in paper-based potentiometry and voltammetry in heavy metal determination. Interactions of paper substrates with heavy metals, influence on the sensing response, and modification methods applied to paper substrates to improve the performance of recently developed electrochemical sensors are discussed. Since the rekindling of interest in paper-based analytical devices, methodologies and electrode designs for heavy metal determinations are highlighted. Promising aspects of the use of these sensors for samples containing solids and the increased versatility of the use of paper in analytics offers the possibility of increased acceptance of these low-cost platforms.

Assessment of the concentrations and health risk of some heavy metals in cowpea (Vignus unguiculata) in Gwagwalada, Nigeria.

Cowpea (Vignus unguiculata) is a source of plant protein that is widely consumed by the Nigerian populace. The aim of the study was to evaluate the health risk of heavy metals in two cowpea types sold in Gwagwalada Market, Nigeria. The concentrations of five heavy metals nickel (Ni), cadmium (Cd), manganese (Mn), cobalt (Co), and chromium (Cr) were assessed in the cowpea types. Samples of each type were randomly purchased and the heavy metal concentrations (mg/kg) were analyzed with an atomic absorption spectrophotometer. The concentrations of the heavy metals in mg/kg dry weight of the brown type were as follows: Ni (2.45 ± 0.87), Cd (0.26 ± 0.10), Mn (9.11 ± 1.80), and Co (1.67 ± 0.20), while the concentrations for the white type were: Ni (4.55 ± 1.21), Cd (0.27 ± 0.13), Mn (9.17 ± 1.50), and Co (1.09 ± 0.15). The level of Cr was below detection in all the samples analyzed. However, the levels of Ni, Mn, and Co investigated were all below the permissible limits set by FAO/WHO. The Cd concentrations of both cowpea types exceeded the FAO/WHO permissible limit of 0.2 mg/kg for cowpea. Determined heavy metal concentrations were used for potential health risk assessment in adults and children. The target hazard quotient and hazard index were >1 for Co, while the target cancer risk of Ni subsulfide for the cowpea types exceeded 10-4, and these results are causes for concern. It is recommended that the concentrations of the heavy metals in cowpea sold in Nigerian markets should be monitored regularly in order to avert their detrimental effects on consumers.

Assessment of the potential ecological and human health risks of heavy metals in Ahvaz oil field, Iran.

The potential hazard to human health from exposure to heavy metals in surface soil was assessed using 66 soil samples collected from Ahvaz oil field. To this end, the contents of heavy metals were measured by the inductively coupled plasma spectroscopy (ICP-OES). Mean levels of As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn were 5.9, 0.4, 7.1, 36.5, 41.2, 39.8, 67.4, 31.5, and 77.6 mg/kg, respectively. Contents of all studied heavy metals, with the exception of Co, Cr, and V, were several times higher than that of baselines. Correlation coefficients and principal component analysis (PCA) identified two main groups as sources of heavy metals in the surface soil of Ahvaz oil-field. Metals such as Co, Cr, and V were observed to originate from natural sources and As, Cd, Cu, Ni, Pb, and Zn originated from anthropogenic sources such as petroleum leakage and the pollution caused by drilling mud from oil wells. Pb and Zn were of significantly high EF mean enrichment value, and Co, Cu, Cd, and As had high enrichment in surface soil. Pb, Cr, V, Zn, Co, Cu, Ni, and As had a low potential ecological risk (PER) whereas Cd had a moderate PER. The risk of carcinogenic and non-carcinogenic diseases was detected to be higher in children than in adults. The carcinogenic risk (Cr) calculation was more than 1 × 10-6 for children and adults. Additionally, the CR of Cr for both children and adults indicated risk under control conditions.

Heavy metal pollution and ecological risk assessment in brownfield soil from Xi'an, China: An integrated analysis of man-land interrelations.

The core of urbanization is land use change, resulting in the urban sprawl and urban population explosion. The problem of land resources shortage and ecological environment destruction has become increasingly prominent. Land use change and human activities can directly lead to urban soil pollution. This study analyzed the concentration of Cd, Cr, Cu, Ni, Pb, Zn, Hg and As in the original site of Xi'an chlor-alkali chemical plant, which was know as a brownfield. The results showed the concentrations of Hg, Pb and Zn in research areas were obviously higher than soil background value. Through pollution index (PI) method and Geo-accumulation Index (Igeo) method, totally 26 sample points in different areas (A, B, C, D) were classified into different pollution degrees. The CPI results indicated 9 sample points were heavily polluted, accounting for 34.6% of the total. Among them, 6 out of 9 were located in area A. 12 samples points were not polluted. The average Igeo values of single heavy metal were arranged in the order of Hg (1.83) > Zn (1.26) > Pb (0.33). The pollution of Hg was relatively serious and extensive, especially in area A. It was mainly because of the historical pollution produced by chemical plant. The pollution of Pb in each point was quite different. Mainly influenced by automobile related activities, Igeo(Pb) in sample point 15 and 16 were all beyond 4.00. The average potential ecological risk (PER) of each area was in the order of A (1428) > B (297) > D (249) > C (163). The ecological risk was mainly determined by previous industrial production and present human activity at the same time. People and land are interdependent and interactive. The understanding on the mechanism of man-land interralations, regarding to urban land use and ecological environment, will promote urban sustainability.

Comparative study on photocatalytic degradation of the antidepressant trazodone using (Co, Fe and Ru) doped titanate nanowires: Kinetics, transformation products and in silico toxicity assessment.

Titanate nanomaterials have been outstanding in the removal of emerging contaminants by the photocatalysis process. These photocatalysts, when modified through techniques such as doping with metals, they have advantages over TiO2, especially in the region of visible light. In this work, the photocatalytic performance of four recent reported catalysts, pristine titanate nanowires, cobalt-doped titanate nanowires, iron-doped titanate nanowires and ruthenium-doped titanate nanowires, for the removal of the antidepressant trazodone under visible light radiation was compared. The iron-doped titanate nanowires presented the best catalytic activity by the catalyst surface area. Additionally, thirteen transformation products (TPs) were identified by high-resolution mass spectrometry and, to the best of our knowledge, nine of them have never been described in the literature. It was shown that for each catalyst different TPs were formed with distinct time profiles. Finally, toxicity assessment by computational methods showed that TPs were not readily biodegradable and they presented toxicity to aquatic organisms with mutagenic potential. These findings reinforce the importance of taking into consideration the TPs formed during the removal of pollutants since many of them may be toxic and can be produced during photocatalysis.

A radiation shielding sensitivity analysis based on metal hydrides multilayers.

In order to shield neutron and gamma rays efficiently, a multilayer model is designed with metal hydrides and heavy metals and is analysed based on Monte Carlo simulations. In terms of shielding performance, the hydrogen in metal hydrides acts as a moderator to slow down the neutron energy and heavy metals are good for absorbing gamma rays. A simulation and calculational analysis are carried out with various parameters such as spectrum change, shield thickness, and number of multilayers. In addition, the rate of DPA (displacement per atom) is analysed to estimate both the lifetime and radiation resistance with the MCNP code. From lots of simulations, ZrH2 and W couples are the best candidate especially for shielding gamma rays, while TiH2 with W is good for neutron shielding. The concept of multilayer metal hydride such as TiH2 and ZrH2 coupled with W could be one of best combinations to shield both neutron and gamma-rays in many nuclear facilities such as nuclear reactor, fusion reactor and other applications.