Application of Sargassum biomass to remove heavy metal ions from synthetic multi-metal solutions and urban storm water runoff

The ability of Sargassum sp. to biosorb four metal ions, namely lead, copper, zinc, and manganese from a synthetic multi-solute system and real storm water runoff has been investigated for the first time. Experiments on synthetic multi-solute systems revealed that Sargassum performed well in the biosorption of all four metal ions, with preference towards Pb, followed by Cu, Zn, and Mn. The solution pH strongly affected the metal biosorption, with pH 6 being identified as the optimal condition for achieving maximum biosorption. Experiments at different biosorbent dosages revealed that good biosorption capacity as well as high metal removal efficiency was observed at 3g/L. The biosorption kinetics was found to be fast with equilibrium being attained within 50 min. According to the Langmuir isotherm model, Sargassum exhibited maximum uptakes of 214, 67.5, 24.2 and 20.2mg/g for lead, copper, zinc, and manganese, respectively in single-solute systems. In multi-metal systems, strong competition between four metal ions in terms of occupancy binding sites was observed, and Sargassum showed preference in the order of Pb>Cu>Zn>Mn. The application of Sargassum to remove four heavy metal ions in real storm water runoff revealed that the biomass was capable of removing the heavy metal ions. However, the biosorption performance was slightly lower compared to that of synthetic metal solutions. Several factors were responsible for this difference, and the most important factor is the presence of other contaminants such as anions, organics, and other trace metals in the runoff.     

Preparation of a novel zwitterionic graphene oxide-based adsorbent to remove of heavy metal ions from water: Modeling and comparative studies

A novel zwitterionic graphene oxide-based adsorbent was first synthesized in a multistep procedure including the successive grafting of bis(2-pyridylmethyl)amino groups (BPED) and 1,3-propanesultone (PS) onto graphene oxide (GO) sheets. Then, the as-prepared materials were used as adsorbent for the removal of metal ions from aqueous solutions. The influence of solution pH, contact time, metal ion concentration, and temperature onto the adsorption capacity of the zwitterionic GO-BPED-PS adsorbent was investigated and compared with the GO-BPED adsorbent. In particular, it was shown that the maximum adsorption capacities of the GO-BPED-PS adsorbent were as high as 4.174 ± 0.098 mmol.g^?1 for the Ni(II) ions and 3.902 ± 0.092 mmol.g^?1 for the Co(II) ions under optimal experimental conditions (metal ion concentration = 250 mg.L^?1, pH = 7 and T = 293 K). In addition, the adsorption behaviors of Ni(II) and Co(II) ions onto both the GO-BPED and GO-BPED-PS adsorbents fitted well with a pseudo-second-order kinetic model and a Jossens isotherm model. Moreover, adsorption thermodynamics of Ni(II) and Co(II) ions have been studied at various temperatures and confirmed the exothermic adsorption nature of the adsorption process onto the GO-BPED-PS adsorbent. Furthermore, the zwitterionic GO-BPED-PS adsorbent retained good adsorption properties after recycling 18 times which is much better than the conventional adsorbents.     

磁性炭包铁纳米粒子对重金属离子的吸附性能

采用氩电弧等离子体法制备炭包铁纳米粒子,并用体积分数30%的H2O2氧化其外层非晶态类石墨碳层,研究炭包铁纳米粒子对水溶液中Cr、Ni、Cd、Pb、Co和Mn等金属离子的吸附和分离特性。结果表明,炭包铁非晶炭层的特殊结构可通过双氧水氧化处理使其表面产生羧基和羟基。在强碱性介质下,羟基和羧基强化了纳米颗粒表面的静电作用,提高了炭包铁对金属离子的吸附性能。当pH值为8.0～10.0时,炭包铁纳米粒子对Cr、Ni、Cd、Pb、Co和Mn的吸附率均超过90%,对重金属离子的吸附能力明显高于活性炭。     

On-site low-power sensing nodes for distributed monitoring of heavy metal ions in water

Heavy metal pollution in water environments poses a great threat to public health and to the ecological environment due to its high toxicity and non-degradability.However,many existing detection methods require laboratory-based bulky instruments and time-consuming manual operations.Although some on-site systems exist,they are difficult to deploy on a large scale owing to their large size and high cost.Here,we report a sensing node featuring low power consumption and low cost,achieved by integrating microsensor,microfluidic,and electronic modules into a compact size for automatic and scalable heavy metal pollution monitoring.Digital microfluidic and electrochemical sensing modules are integrated on a chip,thereby combining the procedures of sample pretreatment,electrochemical sensing,and waste removal for automatic and continuous monitoring.The feasibility of the platform is demonstrated by Pb2+detection in tap water.With a 3500 mA??h battery,the compact sensing node could work for several years in principle.There is scope for further improvements to the system in terms of wider functionality and reductions in size,power consumption,and cost.The sensing node presented here is a strong candidate for distributed monitoring of water quality as an Internet-of-Things application.     

Modified softwood sawdust as adsorbent of heavy metal ions from water

The sawdust of deciduous softwood-poplar, and coniferous softwood-fir, have been found to possess some adsorption capacities for heavy metal ions. Their adsorption capacities can be increased by previous treatment with a sodium hydroxide solution. Adsorption capacities of alkali modified adsorbents were higher than for unmodified ones from 2.5 to 5 times for copper ions, and about 15 times for zinc ions. Also, for modification can be used solution of sodium carbonate, but that alkaline solution is less efficient than sodium hydroxide solution. The 1% sodium hydroxide solution is suggested for modification of softwood sawdust. It was established that the ion exchange is not only adsorption mechanism, than microprecipitation of metal-hydroxide in the pore liquid was happened, too. At the same time, the leaching of organic matters from modified softwood sawdust were less than from unmodified ones for about 7% for poplar and 23% for fir.     

胶束强化超滤技术在重金属废水处理中的研究进展

胶束强化超滤技术(MEUF)作为一种新兴的水处理技术,在重金属废水净化方面有着较好的应用前景。本文通过总结前人的研究结果,综合讨论了影响金属离子截留效果的各个因素,为优化MEUF提出了一些建议。并就当前采用胶束强化超滤法处理金属离子技术的最新发展与表面活性剂的循环再利用作了简要的介绍。     

Use of spherical targets to minimize effects of neutron scattering by hydrogen in neutron capture prompt gamma-ray activation analysis.

For hydrogenous targets that are thinner than they are wide, element sensitivities (counts.s-1.mg-1) for determining concentrations of elements by neutron capture prompt gamma-ray activation analysis (PGAA) are enhanced relative to sensitivities obtained from measurements on nonhydrogenous materials. These enhancements are caused mainly by elastic neutron scattering by H, which changes the average neutron fluence rate within the matrix. The magnitude of the effect depends on the macroscopic scattering and absorption cross sections and on the size, shape, and orientation of the target with respect to the neutron beam. Sensitivities increase linearly with H density for thin targets of constant size and shape and also vary with target shape. Theoretical work was shown that element sensitivities for hydrogenous targets in the form of spheres are least affected by neutron scattering. Methods were devised for creating solid spheres and for containing liquids in spherical shapes. Element sensitivities were determined for spheres and disks of several hydrogenous materials. For H, B, Cl, K, Br, and Cd, sensitivities for spheres were found to be less affected by neutron scattering. Exceptions were Sm and Gd sensitivities measured in liquids contained in quartz globes.     

Removal of heavy metal ions from water by using calcined phosphate as a new adsorbent

Calcined phosphate (CP) has been employed in our laboratories as a heterogeneous catalyst in a variety of reactions. In this study, CP was evaluated as a new product for removal of heavy metals from aqueous solution. Removal of Pb2+, Cu2+, and Zn2+ on the CP was investigated in batch experiments. The kinetic of lead on CP adsorption efficiency and adsorption process were evaluated and analysed using the theories of Langmuir and Freundlich. The influence of pH was studied. The adsorption capacity obtained at pH 5 were 85.6, 29.8, and 20.6 mg g(-1) for Pb2+, Cu2+ and Zn2+, respectively. We hypothesize at pH 2 and 3, the dissolution of CP and precipitation of a fluoropyromorphite for lead and the formation of solid-solution type fluorapatite for copper. The results obtained show that CP is a good adsorbent for these toxic heavy metals. The abundance of natural phosphate, its low price and non-aggressive nature towards the environment are advantage for its utilisation in point of view of wastewater and wastes clean up.     

Adsorption of divalent heavy metal ions from water using carbon nanotube sheets

Removal of some divalent heavy metal ions (Cu(2+), Zn(2+), Pb(2+), Cd(2+), Co(2+)) from aqueous solutions using carbon nanotube (CNT) sheets was performed. CNT sheets were synthesized by chemical vapor deposition of cyclohexanol and ferrocene in nitrogen atmosphere at 750°C, and oxidized with concentrated nitric acid at room temperature and then employed as adsorbent for water treatment. Langmuir and Freundlich isotherms were used to describe the adsorption behavior of heavy metal ions by oxidized CNT sheets. The obtained results demonstrated that the oxidized CNT sheets can be used as an effective adsorbent for heavy metal ions removal from water. It was found out that kinetics of adsorption varies with initial concentration of heavy metal ions. Preference of adsorption onto the oxidized CNT sheets can be ordered as Pb(2+)>Cd(2+)>Co(2+)>Zn(2+)>Cu(2+). Using the oxidized CNT sheets, waste water treatment without CNT leakage into water is economically feasible. Therefore, CNT sheets have good potential application in environmental protection.     

The efficiency of various thermoluminescence dosemeter types to heavy ions

Dose verification in heavy-ion beams using passive dosemeter systems, e.g. thermoluminescence dosemeters (TLDs), is crucial due to the changing efficiency of the dosemeters for different ion species and linear energy transfer (LET) values. This behaviour leads to a falsification of absorbed dose that can be significant for many applications, e.g. in space or radiotherapeutic dosimetry. TLDs can only be established as a 'reference' system in heavy-ion beams or other radiation fields if the efficiency functions for all contributing ion species and LET values are provided. In the framework of a research project of the Atominstitute of the Austrian Universities irradiations with various ions were performed in the years 2001-2003 at the Heavy Ion Medical Accelerator (HIMAC) of the National Institute for Radiological Sciences (NIRS) in Chiba, Japan. Efficiency values were recorded in dependence on ion species and LET in a range from 2 to 400 keV microm(-1). The efficiencies of five different commercially available TLD materials namely TLD 600, TLD 700, TLD 700H, TLD 300 and TLD 200 were investigated.     

Anchoring DTPA grafted PEI onto carboxylated graphene oxide to effectively remove both heavy metal ions and dyes from wastewater with robust stability

Highly efficient adsorbents, which can effectively remove both metal ions and dyes from wastewater with robust stability, are strongly required for the remediation of current polluted aqueous system, but still a challenge to be realized. Herein, a new adsorbent has been designed to solve this problem by anchoring diethylene triamine pentaacetic acid (DTPA) grafted polyethyleneimine (PEI) onto carboxylated GO (GOC-g-PD). Given the amino and carboxyl active groups from PEI and GOC/DTPA, our GOC-g-PD displays good adsorption capacity against not only inorganic metal ions (Cu²⁺ and Pb²⁺) but also organic dye (methylene blue: MB). The maximum adsorption capacity of GOC-g-PD for Cu²⁺, Pb²⁺ and MB reached 309.60 mg·g^?1, 316.17 mg·g^?1 and 262.10 mg·g^?1, respectively. Furthermore, our GOC-g-PD also exhibits good cycling stability and chemical stability against wide pH values. These outstanding properties revealed our GOC-g-PD held great potential in purifying the sewage discharged from industries.

Graphical abstract

     

Evaluation of iron-based hybrid materials for heavy metal ions removal

The article presents in detail the results of the sorption of heavy metal ions such as Cu(II), Zn(II), Cd(II), and Zn(II) in the presence of ethylenediamine-N,N′-disuccinic acid as well as chromium(VI) on Purolite Arsen X^np and Lewatit FO36. Factors affecting the sorption equilibrium (sorbent dose, contact time, temperature, pH, and the presence of interfering ions) were studied. To compare the surface morphologies of the studied ion exchangers, scans using atomic force microscope were also recorded, and attenuated total reflectance infrared spectroscopy was applied to establish the adsorption mechanism. The main parameters affecting sorption are initial concentration of the solution, pH, and phase contact time. Temperature has only a slight influence. The kinetic data were fitted using the pseudo-first-order and pseudo-second-order models. In the case of Cr(VI) adsorption, the equilibriums on Purolite Arsen X^np and Lewatit FO36 were established within 60 min, in the case of Cu(II) and Zn(II) within 30–40 min and for Cd(II) and Pb(II) even less than 30 min. Moreover, it was found that the effectiveness of adsorption in the case of Cr(VI), Cu(II), Zn(II), Cd(II), and Pb(II) on Purolite ArsenX^np was higher than that on Lewatit FO36.     

Removal of heavy metal ions by iron oxide coated sewage sludge

The municipal sewage sludge was modified with iron oxide employed in metal ions removal. The surface modification method was proposed and the effect of parameters in the preparation was studied. The iron oxide coated sludge had higher surface area, pore volume and iron content, compared to uncoated sludge. The suitable conditions for removal of Cu(II), Cd(II), Ni(II) and Pb(II) ions from solutions were investigated using batch method. The suitable pH value in the extraction was 7 for adsorption of Cd(II) and Ni(II), 6 for Cu(II) and 5 for Pb(II) ions. The presence of NaNO(3), Ca(NO(3))(2) and Na(2)SO(4) in metal solution in the concentration of 0.01 M and 0.50 M could reduce the removal efficiency. The adsorption isotherms for the adsorption of the metal ions were defined by Langmuir relation. The maximum adsorption capacity of the iron oxide coated sludge for Cu(II), Cd(II), Ni(II) and Pb(II) was 17.3, 14.7, 7.8 and 42.4 mg g(-1), respectively. The adsorption kinetics for every metal ions followed pseudo-second order model. The metal removal from wastewater by iron oxide coated sludge was also demonstrated.     

Biosorption of heavy metal ions from aqueous solution by red macroalgae

Biosorption is an effective process for the removal and recovery of heavy metal ions from aqueous solutions. The biomass of marine algae has been reported to have high biosorption capacities for a number of heavy metal ions. In this study, four species of red seaweeds Corallina mediterranea, Galaxaura oblongata, Jania rubens and Pterocladia capillacea were examined to remove Co(II), Cd(II), Cr(III) and Pb(II) ions from aqueous solution. The experimental parameters that affect the biosorption process such as pH, contact time and biomass dosage were studied. The maximum biosorption capacity of metal ions was 105.2mg/g at biomass dosage 10 g/L, pH 5 and contact time 60 min. The biosorption efficiency of algal biomass for the removal of heavy metal ions from industrial wastewater was evaluated for two successive cycles. Galaxaura oblongata biomass was relatively more efficient to remove metal ions with mean biosorption efficiency of 84%. This study demonstrated that these seaweeds constitute a promising, efficient, cheap and biodegradable sorbent biomaterial for lowering the heavy metal pollution in the environment.     

Systematic analysis of neutron yields from thick targets bombarded by heavy ions and protons with moving source model

A simple phenomenological analysis using the moving source model has been performed on the neutron energy spectra produced by bombarding thick targets with high energy heavy ions which have been systematically measured at the Heavy-Ion Medical Accelerator (HIMAC) facility (located in Chiba, Japan) of the National Institute of Radiological Sciences (NIRS). For the bombardment of both heavy ions and protons in the energy region of 100–500 MeV per nucleon, the moving source model incorporating the knock-on process could be generally successful in reproducing the measured neutron spectra within a factor of two margin of accuracy. This phenomenological analytical equation is expressed having several parameters as functions of atomic number Z_p, mass number A_p, energy per nucleon E_p for projectile, and atomic number Z_T, mass number A_T for target. By inputting these basic data for projectile and target into this equation we can easily estimate the secondary neutron energy spectra at an emission angle of 0–90° for bombardment with heavy ions and protons in the aforementioned energy region. This method will be quite useful to estimate the neutron source term in the neutron shielding design of high energy proton and heavy ion accelerators.     

A multi-criteria decision analysis framework for evaluating point-of-use water treatment alternatives

Despite significant progress on meeting global water targets, the lack of access to safe drinking water remains a significant problem in today’s world. Statistics from health agencies indicate that waterborne diseases are among the leading causes of health-related mortalities, particularly in developing nations. This paper examines the performance and applicability of various point-of-use (POU) water treatment alternatives, namely (i) solar disinfection; (ii) boiling of water; (iii) chlorination; (iv) disinfection–flocculation with a natural coagulant (powdered Moringa seeds); (v) filtration with ceramic pots; and (vi) biosand filtration. We evaluated the efficacy of each alternative using a set of criteria based on environmental sustainability, technological performance, financial viability, and social acceptability. We also integrated several multi-criteria decision analysis (MCDA) approaches to determine the most suitable water treatment method for a given community. The analytic hierarchy process (AHP) was implemented to elicit various preference structures and to generate the weights for the criteria. Subsequent ranking of the POU alternatives was then performed using the technique for order preference by similarity to ideal solutions (TOPSIS) method. Sensitivity analysis and visualization charts were developed to evaluate the impact of changes in preference ratings of each alternative with respect to the criteria. A case study was implemented in a rural area in the Philippines to determine the optimal POU alternatives given variations in AHP and TOPSIS input data. The resulting MCDA framework is flexible and can accommodate the inclusion of other alternatives and criteria, and it can also be generalized for other regions and applications.     

Use of membranes for heavy metal cationic wastewater treatment: flotation and membrane filtration

A new water treatment process—membrane flotation—is presented. The hydrodynamics of air sparging with the use of microporous membranes was studied as well as the membrane flotation efficacy for cationic wastewater treatment. The performance of membrane filtration processes was evaluated. Ways of integration of flotation and membrane filtration in cationic wastewater treatment practice are discussed.     

Detection of heavy metal ions in water by high-resolution surface plasmon resonance spectroscopy combined with anodic stripping voltammetry

High-resolution differential surface plasmon resonance (SPR) with anodic stripping voltammetry (ASV) capability has been demonstrated for detecting heavy metal ions in water. Metal ions are electroplated onto the gold SPR sensing surface and are quantitatively detected by stripping voltammetry. Both the SPR angular shift and electrochemical current signal are recorded to identify the type and amount of the metal ions in water. The performance of the combined approach is further enhanced by a differential detection approach. The gold sensor surface is divided into a reference and a sensing area, and the difference in the SPR angles from the two areas is detected with a quadrant cell photodetector as a differential signal. Our system demonstrated quantitative detection of copper, lead, and mercury ions in water from part-per-million to sub-part-per-billion levels with good linearity.