Adsorption of dyes by nanomaterials: Recent developments and adsorption mechanisms

Adsorptive removal of cationic methylene blue dye using carboxymethyl cellulose/k-carrageenan/activated montmorillonite composite beads: Isotherm and kinetic studies.

Productionofactivatedcarbon(AC)fromagriculturalbyproductsis a researchfieldthathas gainedincreased interestin recent years because of its potential for the disposal of agro-residues. At the same time, a beneficial byproduct that can be used in a number of environmental applications is produced. This paper surveys the developments in the production processes of AC fromagriculturalbyproductsinthepast7yearsfrom2005to2012viaconventionalandmicrowaveheating.Emphasisisplaced on the applied methodology and the influences of activating conditions, such as carbonization temperature, retention time, and impregnation ratio. From the review of AC production processes, agricultural wastes produced by a chemical method with microwave heating can be a source of AC with relatively higher surface area than that produced via conventional heating. c � 2013 Society of Chemical Industry Supportinginformationmaybefoundintheonlineversionofthisarticle.

A review: production of activated carbon from agricultural byproducts via conventional and microwave heating

Adsorption can be efficiently employed for the removal of various toxic dyes from water and wastewater. In this article, the authors reviewed variety of adsorbents used by various researchers for the removal of malachite green (MG) dye from an aqueous environment. The main motto of this review article was to assemble the scattered available information of adsorbents used for the removal of MG to enlighten their wide potential. In addition to this, various optimal experimental conditions (solution pH, equilibrium contact time, amount of adsorbent and temperature) as well as adsorption isotherms, kinetics and thermodynamics data of different adsorbents towards MG were also analyzed and tabulated. Finally, it was concluded that the agricultural solid wastes and biosorbents such as biopolymers and biomass adsorbents have demonstrated outstanding adsorption capabilities for removal of MG dye.

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Malachite green “a cationic dye” and its removal from aqueous solution by adsorption

Contamination of natural aquatic ecosystems by wastewater containing heavy metals is a major environmental and human health issue. The removal of heavy metals using adsorption techniques with microwave-irradiated low-cost adsorbents has a few numbers of studies. In this study, the removal efficiency for cadmium (Cd2+) from aqueous solution using olive stone activated carbon (OSAC) prepared by microwave was investigated. Central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the interaction and relationship between operating variables (i.e., radiation power, radiation time, and impregnation ratio), and to develop the optimum operating condition. Equilibrium isotherms in this study were analyzed using the Langmuir and Freundlich. Kinetic data were obtained and analyzed using pseudo-first-order and pseudo-second-order equations. Based on statistical analysis, Cd2+ removal model proved to be significant with very low probability values (

Cadmium removal from aqueous solution using microwaved olive stone activated carbon

Removal of noxious dyes is gaining public and technological attention. Herein grafting polymerization was employed to produce a novel adsorbent using acrylic acid and carboxymethyl cellulose for dye removal. Scanning electron microscopy and Fourier-transform infrared spectroscopy verified the adsorbent formed under optimized reaction conditions. The removal ratio of adsorbent to Methyl Orange, Disperse Blue 2BLN and malachite green chloride reached to 84.2%, 79.6% and 99.9%, respectively. The greater agreement between the calculated and experimental results suggested that pseudo second-order kinetic model better represents the kinetic adsorption data. Equilibrium adsorptions of dyes were better explained by the Temkin isotherm. The results implied that this new cellulose-based absorbent had the universality for removal of dyes through the chemical adsorption mechanism.

Dyes adsorption using a synthetic carboxymethyl cellulose-acrylic acid adsorbent.

BACKGROUND: This paper describes the use of cotton stalk, an agricultural waste, for the preparation of sodium carboxymethyl cellulose (CMC) using microwave heating. The study includes the optimization of pre-treatment and preparation processes, and the characterization of product. RESULTS: The optimal cotton stalk pre-treatment condition involved the addition of 12% alkali to extract cellulose for 6 min at a microwave power of 200 W using the ratio of cotton stalk to solvent 1:9, giving 87.52% cellulose. Response surface methodology was applied to optimize the preparation of CMC, with the best conditions for preparation predicted by the model: $m_{\rm {cotton stalk cellulose}}:m_{\rm {sodium hydroxide}}:m_{\rm {sodium chloroacetate}} = {1.0:1.1:1.2}$ with etherification at 195.5 W of microwave power for 1.97 min. Under these conditions, CMC with degree of substitution (DS) 0.77, viscosity 498.0 cps and purity 92% was produced. The results of Fourier transform infrared (FT-IR) spectroscopy indicated that the product had the characteristics of a high DS. Scanning electron microscopy showed that the particles were nearly clava in shape with length ranging from about 12-100 µm. The product met the quality standards of GB/T1904-2005. CONCLUSION: Preparation of CMC from cotton stalk using microwave heating can shorten the processing time and may be considered a feasible alternative, contributing to solving environmental problems resulting from cotton stalk.

Ping Sun

Papers

Dyes adsorption using a synthetic carboxymethyl cellulose-acrylic acid adsorbent.

Preparation and characterization of sodium carboxymethyl cellulose from cotton stalk using microwave heating