A comprehensive review on recent developments in bentonite-based materials used as adsorbents for wastewater treatment

The process of adsorption is considered to be one of the best water treatment technologies around the world. Different heavy metals, due to their toxic and hazardous nature, are possibly the most widespread groundwater contaminants imposing a serious threat to human health. In this review, an attempt has been made to discuss the use of two common clay materials, namely kaolinite and montmorillonite, along with their modified forms for heavy metal removal on the basis of published reports (2008 onwards). The modifications of clays have been attempted by the process of pillaring, intercalation, acid/base activation, functionalization, etc. The adsorption of toxic metals, viz., As, Cd, Cr, Co, Cu, Fe, Pb, Mn, Ni, Zn, etc., has been studied predominantly. Montmorillonite and its modified forms have much higher metal adsorption capacity compared to that of kaolinite as well as modified-kaolinite. The modification often boosted the adsorption capacities of the clays, however, reverse trends are also reported in some cases.

Adsorption of heavy metals on kaolinite and montmorillonite: a review.

Clay–polymer nanocomposites: Progress and challenges for use in sustainable water treatment

THE half-century which has elapsed since the first issue of NATURE has witnessed an extraordinary development of science in general, but in no department has it been more marked, or the changes more profound, than in chemistry. Before dealing with the period over which the existence of this journal extends, it may not be uninteresting to indicate, in the broadest possible outline, the main features of progress in chemical science to which the growth we have witnessed during the last fifty years is in reality due.

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Progress of Chemistry

Adsorption of Acid Yellow 99 by polyacrylonitrile/activated carbon composite: Kinetics, thermodynamics and isotherm studies

Poly(acrylic acid) modifying bentonite with in-situ polymerization for removing lead ions.

Preparation of xanthated bentonite and its removal behavior for Pb(II) ions

A new kind of self-cross-linked potato starch graft copolymer (PoSt-g-P) was prepared successfully by emulsifier-free emulsion polymerization, in which methyl methacrylate (MMA), acrylic acid (AA) and butyl acrylate (BA) were used as main monomers, and diacetone acrylamide (DAAM) as functionality monomers. The keto-carbonyl group in the potato starch graft copolymer /DAAM could react with adipic dihydrazide (ADH) at ambient temperature to form cross-linked thin film. The film properties of emulsion were measured, which showed excellent properties in hardness, gloss and water resistance. The humidity-sensitive coatings (PoSt-g-P-C) were prepared by the self-cross-linked PoSt-g-P, pigments and fillers. Adipic dihydrazide was used as a cross linking agent and assistant. Its humidity controlling properties were also measured and shown high activity in increasing humidity and dehumidify.

Preparation of Potato Starch Graft Copolymer and its Application in Functional Coatings

Loess based copolymer (L/CoPolym), a typical silicate minerals / copolymer composite, was used as polymer adsorbent for removing basic fuchsin (BF) in wastewater. Under the optimal condition of adsorption, the removal rate of BF reached to 98.2%, and the adsorption capacity got to 565.0 mg/g. Adsorption dynamics were consistent with pseudo-second-order kinetic model and isotherm model can meet the Freundlich isotherm.

Loess Based Copolymer Composite for Removing Basic Fuchsin

Basic Fuchsin (BF) is a toxic triphenylmethane dye with molecular formula C20H20ClN3, which is easy to caused serious public health problems. There is a need to develop a cost effective method for its removal from the wastewater containing BF. Here, a novel composite polymer adsorbent, poly (maleic anhydride - acrylic acid - vinyl acetate)/Na-bentonite composite cross-linked with N,N'-methylenebisacrylamide was prepared by in situ copolymerization. The polymer adsorbent (NaB-PMAVM) was characterized and applied to remove BF. It was found that the removal of BF reached to 95.96%. The adsorption isotherms and kinetics were best-fit with the Freundlich isotherm model and the pseudo-second-order kinetic, respectively.

Rong Min Wang

Papers

Poly(acrylic acid) modifying bentonite with in-situ polymerization for removing lead ions.

Preparation of xanthated bentonite and its removal behavior for Pb(II) ions

Preparation of Potato Starch Graft Copolymer and its Application in Functional Coatings

Loess Based Copolymer Composite for Removing Basic Fuchsin

Bentonite-Copolymer Composite for Removing Basic Fuchsin