Cadmium (Cd2+) removal by nano zerovalent iron: surface analysis, effects of solution chemistry and surface complexation modeling

Nano zerovalent iron (nZVI) is an effective remediant for removing various organic and inorganic pollutants from contaminated water sources. Batch experiments were conducted to characterize the nZVI surface and to investigate the effects of various solution properties such as pH, initial cadmium concentration, sorbent dosage, ionic strength, and competitive ions on cadmium removal by nZVI. Energy-dispersive X-ray and X-ray photoelectron spectroscopy results confirmed removal of Cd²⁺ ions by nZVI through adsorption. Cd²⁺ adsorption decreased in the presence of competitive cations in the order: Zn²⁺?>?Co²⁺?>?Mg²⁺?>?Mn²⁺?=?Cu²⁺?>?Ca²⁺?>?Na²⁺?=?K⁺. Higher concentrations of Cl^? significantly decreased the adsorption. Cadmium removal increased with solution pH and reached a maximum at pH 8.0. The effects of various solution properties indicated Cd²⁺ adsorption on nZVI to be a chemisorption (inner-sphere complexation) process. The three surface complexation models (diffuse layer model, constant capacitance model, and triple layer model) fitted well to the adsorption edge experimental data indicating the formation of nZVI–Cd bidentate inner-sphere surface complexes. Our results suggest that nZVI can be effectively used for the removal of cadmium from contaminated water sources with varying chemical conditions.     

Removal of melanoidin present in distillery effluent as a major colorant: a review

Effluent originating from distilleries contain large amount of dark brown coloured wastewater called molasses spent wash (MSW). This MSW is the unwanted residual liquid waste to dispose because of low pH, high temperature, dark brown colour, high ash content, unpleasant odour and high percentage of organic and inorganic matter. Dark brown colour of MSW is due to the presence of melanoidin pigment. It reduces sunlight penetration in rivers and lakes which in turn decrease both photosynthetic activity and dissolved oxygen concentration affecting aquatic life. So the disposal of this effluent is one of the critical environmental issues. A number of treatment processes have been employed for the distillery waste management. This review paper present an overview of the pollution problems caused by melanoidin and the technologies employed globally for its removal.     

A review on microplastic pollution in the mangrove wetlands and microbial strategies for its remediation

Environmental Science and Pollution Research - Mangroves are one of the most productive ecosystems in the world harboring huge biological diversity. The prime ecological roles of mangroves are...     

Degradation studies of novel degradable starch-polyethylene plastics containing oxidized polyethylene and prooxidant

Linear low-density polyethylene films were prepared that contained native corn starch (7, 14, or 28%), low or high molecular weight oxidized polyethylene (15%), and a prooxidant mixture (18% POLYCLEAN II) that contains manganese and vegetable oil. For each mixture all components were first mixed at high temperatures in a twin-screw extruder and pelletized. The pellets were cast into films using a single-screw extruder. Oxidized-polyethylene addition did not impair the transparency and thickness of the films and did not reduce the percentage elongation, whereas significant reductions in film mechanical properties were observed. Thermal and photodegradation properties of each film were evaluated by 70°C forced-air oven treatment (20 days), by high-temperature, high-humidity treatment in a steam chamber (20 days), and by exposure to ultraviolet light (365 nm; 4 weeks). Changes in the mechanical properties of the films were determined by an Instron Universal Test Machine; in the carbonyl index, Fourier transform infrared spectroscopy; and in molecular weight, by high-temperature gel-permeation chromatography (HT-GPC). The addition of oxidized polyethylene, especially high molecular weight oxidized polyethylene, and up to 14% starch to the films significantly increased the rate of thermal and photodegradation.Journal Paper No. J-15363 of the Iowa Agriculture and Home Economics Experiment Station, Ames. Project No. 0178 and 2889.     

Pure-culture and enzymatic assay for starch-polyethylene degradable plastic biodegradation withStreptomyces species

Eleven starch-polyethylene degradable plastic films were prepared from masterbatches from Archer Daniels Midland Inc. (ADM), EcoStar Inc. (SLS), and Fully Compounded Plastic Inc. The biodegradability of initial and 70°C heat-treated materials was determined using a pure-culture assay withStreptomyces badius 252,S. setonii 75Vi2, orS. viridosporus T7A or without bacterial culture (control). Films were treated with 10-foldS. setonii culture concentrates and compared with inactive enzyme controls. Changes in each films mechanical property, molecular weight distribution, and Fourier-transformed infrared spectrum (FT-IR) were determined, and results were evaluated for significant differences by analysis of variance. Cell mass accumulation on each film was quite pronounced. In pure-culture studies, biodegradation was demonstrated for ADM-7 and SLS-2 initial films and for ADM-6 heat-treated films, whereas after 3-week treatment with activeS. setonii culture concentrates (enzyme assay), reductions in mechanical properties and changes in FT-IR spectrum were illustrated by all the films except SLS-2. Thus the absence of biofilm formation on the film surface permitted enzymatic attack of the materials. Furthermore, inhibition of chemical oxidative degradation in the pure-culture assay was demonstrated for ADM-11, SLS-5, and SLS-10 initial materials and for ADM-4, ADM-7, SLS-8, and SLS-10 heat-treated films. These data suggest that biological and chemical degradation were directly affected by the reduction in oxygen tension on the plastic film surface due to cell mass accumulation. This same phenomenon could be the cause for slow degradation rates in nature.Journal Paper No. J-15061 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project Nos. 0178 and 2889.     

Perspectives on social capacity building for natural hazards: outlining an emerging field of research and practice in Europe

Social capacity building for natural hazards is a topic increasingly gaining relevance not only for so-called developing countries but also for European welfare states which are continuously challenged by the social, economic and ecological impacts of natural hazards. Following an outline of recent governance changes with regard to natural hazards, we develop a heuristic model of social capacity building by taking into account a wide range of existing expertise from different fields of research. Particular attention is paid to social vulnerability and its assessment, as well as to risk communication and risk education as specific strategies of social capacity building. We propose to distinguish between interventionist and participatory approaches, thus enabling for a better understanding of existing practices of social capacity building as well as their particular strengths and weaknesses. By way of conclusion, we encourage more research on social capacity building for natural hazards in the European context which at present is highly diverse and, at least in parts, only poorly investigated.     

Biomarker-assisted assessment of aquatic health using the cosmopolitan common carp,Cyprinus carpio (L): a case study of bisphenol-A exposures

Environmental Science and Pollution Research - Monitoring aquatic health from environmental pollutants is critical, none more so than bisphenol-A (BPA), a ubiquitous endocrine-disrupting chemical...