A review on conventional and novel materials towards heavy metal adsorption in wastewater treatment application

Current technologies for removing heavy metal ions are typically metal ion specific. Herein we report the development of a broad-spectrum heavy metal ion trap by incorporation of ethylenediaminetetraacetic acid into a robust metal-organic framework. The capture experiments for a total of 22 heavy metal ions, covering hard, soft, and borderline Lewis metal ions, show that the trap is very effective, with removal efficiencies of >99% for single-component adsorption, multi-component adsorption, or in breakthrough processes. The material can also serve as a host for metal ion loading with arbitrary selections of metal ion amounts/types with a controllable uptake ratio to prepare well-dispersed single or multiple metal catalysts. This is supported by the excellent performance of the prepared Pd2+-loaded composite toward the Suzuki coupling reaction. This work proposes a versatile heavy metal ion trap that may find applications in the fields of separation and catalysis.

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A versatile MOF-based trap for heavy metal ion capture and dispersion.

A green, porous and eco-friendly magnetic geopolymer adsorbent for heavy metals removal from aqueous solutions

As a class of famous carbon materials, biochars (BCs) and their derivative materials with excellent physicochemical properties and diversified functionalities present great potential in wastewater treatment fields. This review focuses on the latest development in reported biochar-based materials as superior adsorbents or catalysts for removing harmful organic contaminants from wastewater. The construction and properties of biochar-based materials are briefly introduced at the beginning. As one of the major factors affecting the properties of BCs, the wide diversity of feedstocks, such as agricultural and forest residues, industrial by-products as well as municipal wastes, endows BCs different chemical compositions and structures. Woody and herbaceous BCs usually have higher carbon contents, larger surface areas and strong aromaticity, which is in favor of the organic contaminant removal. Driven by the desire of more cost-effective materials, several types of biochar-based hybrid materials, such as magnetic BC composites (MBC), nanometal/nanometallic oxides/hydroxide BC composites and layered nanomaterial-coated BCs, as well as physically/chemically activated BCs, have also been developed. With the help of foreign materials, these types of hybrid BCs have excellent capacities to remove a wide range of organic contaminants, including organic dyestuff, phenols and chemical intermediates, as well as pharmaceutically active compounds, from aquatic solutions. Depending on the different types of biochar-based materials, organic contaminants can be removed by different mechanisms, such as physical adsorption, electrostatic interaction, π–π interaction and Fenton process, as well as photocatalytic degradation. In summary, the low cost, tunable surface chemistry and excellent physical–chemical properties of BCs allow it to be a potential material in organic contaminant removal. The combination of BCs with foreign materials endows BCs more functionalities and broader development opportunities. Considering the urgent demand of practical wastewater treatment, we hope more researches will focus on the applications and commercialization of biochar-based materials.

Biochar-based materials and their applications in removal of organic contaminants from wastewater: state-of-the-art review

Activated biochar derived from Opuntia ficus-indica for the efficient adsorption of malachite green dye, Cu+2 and Ni+2 from water.

Comparison of sorption and desorption studies of heavy metal ions from biochar and commercial active carbon

This article seeks to provide a conceptual framework and a methodological apparatus for investigating conflicts between central and local governments. Our work is inspired by contemporary recentralization processes seen in Europe, which are motivated both pragmatically (to counteract the financial crisis) and ideologically (the “illiberal turn”). These phenomena refer to the broader concept of conflict of interest, which is at the core of democratic systems. We see the limiting the autonomy of substatal actors as a sign of democratic crisis. Although our study draws upon empirical phenomena observed in Poland, its ambition is to provide a universal framework to analyze central-local relations. By combining the theoretical distinction between different dimensions of the political universum, with the easy-to-operationalize variables that make up the Local Autonomy Index our paper proposes two typologies to capture, respectively, centralistic actions, and local governments’ reactions. These typologies can be used to map the patterns of central-local relations in particular countries, and facilitate comparative studies. 

J. Krukowska

Papers

Comparison of sorption and desorption studies of heavy metal ions from biochar and commercial active carbon

The multiple faces of recentralization: A typology of central-local interactions