Functionalized Attapulgite for the Adsorption of Methylene Blue: Synthesis, Characterization, and Adsorption Mechanism

Abstract

Attapulgite (denoted as APT, also called palygorskite) has been regarded as the green material in the "21st century world" and has attracted widespread attention due to its advantages of low cost, natural abundance, nontoxic nature, and environmental friendliness. However, the limited adsorption sites and surface charges of natural APT greatly hinder its application as an adsorbent in industrial fields. In this work, natural APT was modified with sodium humate (SA) via a facile one-step hydrothermal process to improve its adsorption capacity and systematically studied its ability to remove methylene blue (MB) from aqueous solutions. The effect of hydrothermal modification in the presence of SA on the microscopic structure, morphology, and physicochemical properties of APT was studied by field-emission scanning electron microscopy, Fourier transform infrared spectrometry, X-ray diffraction, and Brunauer−Emmett−Teller analyses. The adsorption properties of the modified APT toward MB were evaluated systematically. The results demonstrated that the modified APT has a high adsorption capacity of 227.27 mg/g and also shows a high removal rate up to 99.7% toward MB in a dye solution with an initial concentration of 150 mg/L, which was a 64.7% increase as compared to that of raw APT. The adsorption kinetics could be fitted to the pseudo-second-order model, while the adsorption isotherm could be welldescribed with the Langmuir model. It was concluded that electrostatic attraction, hydrogen-bonding interaction, and chemical association are the main driving force during the adsorption process.

Study on the Adsorption Properties of Oxalic Acid-Modified Cordierite Honeycomb Ceramics for Neutral Red Dyes

“…The Langmuir isotherm model was typically used when the guest was evenly distributed over the adsorbents in monolayer coverage, 50 which is expressed as (5) where q e is the maximum adsorption capacity (mg•g −1 ), q m is the equilibrium adsorption capacity of NR on CORA (mg• g −1 ), K L is a constant associated with the affinity of the binding sites and energy of adsorption (L•mg −1 ), and C e is the equilibrium concentration of NR in the suspension (mg•L −1 ).…”

“…A significant amount of waste is produced as a result of the population’s rapid growth, human society’s rapid development, and extensive agricultural practice . Human life and health are in danger due to water pollution. − Since dyes are used in the printing and dyeing industries to color products, these industries have become the focus of wastewater treatment. − The dark organic dye wastewater pollutants will reduce sunlight’s ability to pass through water and impact aquatic plants. , Additionally, toxic substances are highly concentrated and difficult to degrade, and dyes may be mutagenic and carcinogenic to aquatic organisms, which could seriously harm human health , and cause serious environmental pollution …”

Study on anti-seepage mechanism of attapulgite-modified loess in Northwest China

“…Attapulgite is a dense soil abundant in Zhangye City, Gansu province. It is composed of montmorillonite and attapulgite [8] . Because it contains a large amount of active silica and alumina after calcination, it is widely used in light industry, textile, decolorization, water treatment, and other fields.…”

Remarkable synergy between sawdust biochar and attapulgite/diatomite after co-ball milling to adsorb methylene blue

“… 17 Besides, they are abundant, highly stabile, and environmentally friendly. 18 Studies have shown that the surface properties of biochar materials were enhanced by doping minerals and have obvious effects, which is owing to the synergistic effect between oxygen-containing surface functional groups and layered mesoporous structure, therefore, it was helpful for the biochar-based clay composites to be chemisorbed by MB through cation exchange. 19 Given that co-ball milling of biochar with minerals/metal oxides has produced many excellent composite adsorbents, it was likely that this technique may be useful to combine the strong sorption ability of ATP and DE with that of biochar, creating synergy to adsorb MB in aqueous solution.…”