Kinetic, isotherm and thermodynamic studies of the adsorption of crystal violet by activated carbon from peanut shells

Solid-Waste-Derived Carbon Dioxide-Capturing Materials

Solid sorbents are considered to be promising materials for carbon dioxide capture. In recent years, many studies have focused on the use of solid waste as carbon dioxide sorbents. The use of waste resources as carbon dioxide sorbents not only leads to the development of relatively low-cost materials, but also eliminates waste simultaneously. Different types of waste materials from biomass, industrial waste, household waste, and so forth were used as carbon dioxide sorbents with sufficient carbon dioxide capture capacities. Herein, progress on the development of carbon dioxide sorbents produced from waste materials is reviewed and covers key factors, such as the type of waste, preparation method, further modification method, carbon dioxide sorption performance, and kinetics studies. In addition, a new research direction for further study is proposed. It is hoped that this critical review will not merely sum up the major research directions in this field, but also provide significant suggestions for future work.

Development of high quality activated carbon from biological sludge and its application for dyes removal from aqueous solutions

A high quality activated carbon was developed from biological sludge of a beverage wastewater treatment plant (BWTP). The material was characterized and its adsorption potential to remove Allura Red AC and Crystal Violet dyes from aqueous media was verified. The ACBS (activated carbon from beverage sludge) revealed mesoporous features, presenting average pore diameter of 6.32 nm, pore volume of 0.5098 cm³ g^-1 and surface area of 631.8 m² g^-1. Adsorption was adequate using 0.25 g L ^-1 of ACBS, and, the process was favored at pH 2.0 for Allura Red AC and pH 8.0 for Crystal Violet. From the kinetic viewpoint, the data were satisfactorily represented by the pseudo-second order model. Freundlich and Sips models were suitable to represent the adsorption equilibrium of the Allura Red and Crystal Violet, respectively. The maximum values for adsorption capacities were 287.1 mg g^-1 for Allura Red and 640.7 mg g^-1 for Crystal Violet. The adsorption of both dyes was thermodynamically spontaneous, favorable and endothermic. In brief, the residual sludge of a wastewater treatment plant may be used as an eco-friendly precursor for ACBS production. ACBS was an efficient adsorbent material able to uptake dyes from aqueous solutions.

Adsorptive removal of antibiotics from water using peanut shells from agricultural waste

The residues of sulfonamides in the environment have received widespread attention because of their potential hazards. In this study, the potential of peanut shells for antibiotic removal from aqueous solutions was investigated for four antibiotics (sulfamerazine, sulfamethazine, sulfathiazole, and sulfamethoxazole). The properties of the peanut shells were characterized using Brunauer–Emmett–Teller method, X-ray photoelectron spectroscopy, scanning electron microscopy and Fourier-transform infrared spectroscopy analyses, and the results of the analyses showed that the significant properties of peanut shells were mainly attributed to the antibiotics' adsorption process. A batch adsorption experiment was conducted to study the effect of dosage, concentration, and water factors (Fe³⁺, Mn²⁺, and Ca²⁺) on antibiotic adsorption. Adsorption kinetics and isotherms were also studied. The kinetic data showed that a pseudo-second order kinetic model fitted the experimental data, the adsorption isotherm experimental data fitted the Henry linear adsorption model well, and methanol was found to be an effective eluent for desorption of the antibiotics. The results indicate that peanut shells are a promising material for the removal of antibiotics from contaminated water, when present at low initial concentrations.

The porous structure of the materials was determined using the surface area and pore size analyzer (JW-BK132F) by N₂ adsorption–desorption isotherms at 77 K.

Removal of cationic and anionic dyes from aqueous solution with magnetite/pectin and magnetite/silica/pectin hybrid nanocomposites: kinetic, isotherm and mechanism analysis

Novel adsorbents, magnetite nanoparticles modified with pectin shell and silica/pectin double shell, were fabricated and tested for single dye and dye mixture adsorption from water samples.

Comparison between Brazilian agro-wastes and activated carbon as adsorbents to remove Ni(II) from aqueous solutions

This research was performed to find an alternative, low-cost, competitive, locally available and efficient adsorbent to treat nickel (Ni) containing effluents. For this purpose, several Brazilian agro-wastes like sugarcane bagasse (SCB), passion fruit wastes (PFW), orange peel (OP) and pineapple peel (PP) were compared with an activated carbon (AC). The adsorbents were characterized. Effects of fundamental factors affecting the adsorption were investigated using batch tests. Kinetic and equilibrium studies were performed using conventional models. It was verified that the adsorption was favored at pH of 6.0 for all agro-wastes, being dependent of the Ni speciation, point of zero charge and surface area of the adsorbents. The Ni removal percentage was in the following order: SCB > OP > AC > PFW > PP. From the kinetic viewpoint, the Elovich model was appropriate to fit the Ni adsorption onto SCB, while for the other adsorbents, the pseudo-first-order model was the most suitable. For all adsorbents, the Langmuir model was the more adequate to represent the equilibrium data, being the maximum adsorption capacities of 64.1 mg g(-1), 60.7 mg g(-1), 63.1 mg g(-1), 48.1 mg g(-1) and 64.3 mg g(-1) for SCB, PFW, OP, PP and AC, respectively. These results indicated that mainly SCB and OP can be used as alternative adsorbents to treat Ni containing effluents.

Adsorption of Arsenite by Six Submerged Plants from Nansi Lake, China

Nansi Lake is the largest and the most important freshwater lake in north China for the South-North Water Transfer Project. Due to long-time and large-scale fish farming of history, the excess fish food and excretion usually release pentavalent arsenic, which is converted into trivalent arsenic (As (III)) in the lake sediment and released into lake water. Adsorption of arsenite using six submerged plants (Mimulicalyx rosulatus,Potamogeton maackianus,Hydrilla,Watermifoil,Pteris vittata, andPotamogeton crispus) as adsorbing materials was investigated. The experimental data obtained have been analyzed using Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models and the pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetics models. According to the results, the As (III) equilibrium data agreed well with the Freundlich isotherm model. The adsorption capacity of the plants was in the following order:Potamogeton crispus>Pteris vittata>Potamogeton maackianus>Mimulicalyx rosulatus>Hydrilla>Watermifoil. The sorption system with the six submerged plants was better described by pseudo-second-order than by first-order kinetics. Moreover, the adsorption withPotamogeton crispuscould follow intraparticle diffusion (IPD) model. The initial adsorption and rate of IPD usingPotamogeton crispusandPteris vittatawere higher than those using other plants studied.