Removal of Methylene Blue from Aqueous Solutions by Surface Modified Talc

In this study, raw talc powder surface modification was conducted, and the powder was modified in two different methods using acid washing and ball milling. Modified talc was characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). In order to investigate the adsorption capacity of modified talc on dyes, adsorption experiments were carried out with methylene blue (MB) in aqueous solutions as the target contaminant. The findings of the characterization revealed that both modifications increased the adsorption capacity of talc, which was attributed to changes in specific surface area and active groups. The influence of process parameters such as contact time, pH, dye concentration, and adsorbent dosage on the adsorption performance was systematically investigated. Modified talc was able to adsorb MB rapidly, reaching equilibrium within 60 min. Additionally, the adsorption performance was improved as the pH of the dye solution increased. The isotherms for MB adsorption by modified talc fitted well with the Langmuir model. The pseudo-second-order model in the adsorption kinetic model properly described the adsorption behavior. The results show that the modified talc can be used as an inexpensive and abundant candidate material for the adsorption of dyes in industrial wastewater.

A Novel Adsorbent of Attapulgite & Carbon Composites Derived from Spent Bleaching Earth for Synergistic Removal of Copper and Tetracycline in Water

Simultaneously eliminating tetracycline (TC) and copper (Cu-II) from wastewater was investigated by applying a novel adsorbent fabricated by transforming spent bleaching earth (SBE) into attapulgite & carbon composites (A&Cs). Pyrolysis temperature for A&Cs preparation exhibited a positive effect on Cu(II) adsorption, while the AC500 possessed the greatest performance for TC remediation. Interestingly, a synergistic effect instead of competitive adsorption occurred between Cu(II) and TC under the combined binary system, as both TC and Cu(II) adsorption amount on A&C500 increased more than that in the single system, which could be mainly attributed to the bridge actions between the TC and Cu(II). In addition, hydrogen bonding, ᴨ-ᴨ EDA interaction, pore-filling and complexation exerted significant roles in the adsorption process of TC and Cu(II). In general, this study offered a new perspective on the regeneration of livestock and poultry industry wastewater polluted with antibiotics and heavy metals.

Novel composites with a cross-linked polyaniline shell and oriented palygorskite as ideal microwave absorbers

The obtained composites exhibit a cross-linked shell structure, which has a positive effect on the microwave absorption performance of the materials.

Clay-activated carbon adsorbent obtained by activation of spent bleaching earth and its application for removing Pb(II) ion

BE/C-A750-1/1 is prepared by carbonizing SBE and then activating with KOH. BE/C-A750-1/1 has good adsorption capacity for Pb(II), and the adsorption capacity for Pb(II) is 206.65 mg/g. The harmful effects of coexisting cations are listed in ascending order: K⁺ < Na⁺ < Mg²⁺. Adsorption and desorption studies show that the adsorption capacity of BE/C-A750-1/1 for Pb(II) after adsorption and desorption 3 times is 183.62 mg/g. The adsorption mechanism mainly includes electrostatic attraction, ion exchange, physical adsorption, and chemical complexation. This suggests that activated BE/C may be a promising candidate for removing Pb(II) from industrial wastewater. Clay/carbon nanocomposites were prepared by carbonizing and activating the spent bleaching earth served as adsorbents for the efficient removal of Pb(II) from wastewater.

Bio-mass derived functionalized graphene aerogel: a sustainable approach for the removal of multiple organic dyes and their mixtures

Herein, fabrication of a functionalized graphene aerogel (f-GA) from a biomass (pear fruit)-derived graphene aerogel (GA) is described. f-GA is showing better adsorption capacity towards CV, MB and RhB dyes than GA and activated charcoal.

Enhanced photocatalytic removal of amoxicillin with Ag/TiO2/mesoporous g-C3N4 under visible light: property and mechanistic studies

In present study, an efficient ternary Ag/TiO₂/mesoporous g-C₃N₄ (M-g-C₃N₄) photocatalyst was successfully synthesized through depositing Ag nanoparticles (NPs) on the surface of TiO₂/M-g-C₃N₄ heterojunction. Ag/TiO₂/M-g-C₃N₄ nanocomposite displayed the highest degradation efficiency for amoxicillin (AMX) compared to TiO₂/M-g-C₃N₄ heterojunction, M-g-C₃N₄, and bulk-g-C₃N₄ (B-g-C₃N₄). The removal efficiency of AMX in real situation, surface water (SW), hospital wastewater (HW), and waste water treatment plant (WWTP) also were studied to illustrate the effectiveness of Ag/TiO₂/M-g-C₃N₄ photocatalysts. The vulnerable atoms in AMX structure were revealed through DFT calculation. Additionally, the dominating active groups produced in time of the photocatalytic procedure were determined on account of free radical trapping experiments and ESR spectra. The mechanism of photocatalytic degradation was proposed and verified. The transfer of the electrons and the inhibition of the recombination of photogenerated electron-holes were enhanced effectively under the synergistic effect of the Ag NPs and TiO₂. As a consequence, the catalytic activity of the composite was improved under visible light.

Mesoporous silicate/carbon composites derived from dye-loaded palygorskite clay waste for efficient removal of organic contaminants

Palygorskite (Pal) is a natural abundant environment-friendly adsorbent that has shown high efficiency to decontaminate dye in water. However, the dye removal results in transformation of Pal to a very stable Maya Blue-like structure or waste Pal clay (WPal), which could not be easily regenerated by a commonly used desorption process. This paper presents a use of WPal as the precursor material to synthesize a highly-efficient mesoporous silicate/carbon composite adsorbent. The composite adsorbent has a large specific surface area (427.9 m²·g^-1), a high negative potential (-40.6 mV) and a mesoporous size (3.48 nm). This adsorbent shows almost complete removal of tetracycline (TC), crystal violet (CV) and methylene blue (MB) (initial concentration, 200 mg·L^-1) with the optimal adsorption capacities of 319.8 mg·g^-1, 244.4 mg·g^-1 and 281.7 mg·g^-1, respectively. The active -Si-O^- adsorption sites produced by the breaking of inert Si-O-Si (or M) bonds and the electrostatic interactions of negatively charged adsorbents to adsorbates play a major role in the adsorption process. Adsorption capacities of the developed composite are significantly higher than that of Pal, WPal and hydrothermally treated WPal (HWPal). Results demonstrate that the composite adsorbents have high potential in decontamination of organics in water efficiently.

Enhanced Adsorption of Aqueous Tetracycline Hydrochloride on Renewable Porous Clay-Carbon Adsorbent Derived from Spent Bleaching Earth via Pyrolysis

In this study, spent bleaching earth (SBE) and pyrolyzed SBE (SBE@C) were tested for their capacity to remove tetracycline hydrochloride (TCH) from aqueous solution. The maximum adsorption capacity obtained by the Langmuir model is 0.114 mmol/g for SBE@C and 0.087 mmol/g for SBE. The deleterious effects of coexisting cations were ranked in a decline: Al³⁺ > Mg²⁺ > Na⁺. The results of various characterization methods show that the adsorption mechanisms mainly included π-π interactions, hydrogen bonding, electrostatic interactions, and changes in physical and chemical properties. After 3 repeated cycles of pyrolysis, the adsorption capacity of SBE@C remained at 85.4%, with SBE@C potentially recycled 21 times before complete loss of adsorption capacity. Furthermore, the problem of secondary pollution caused by SBE and residual oil is resolved by the use of SBE@C. All results indicate that SBE@C is a likely candidate for the treatment of TCH wastewater in the coming practical applications.

A γ-Fe2O3-modified nanoflower-MnO2/attapulgite catalyst for low temperature SCR of NOx with NH3

A novel mesoporous γ-Fe₂O₃-modified nanoflower-MnO₂/attapulgite catalyst has been fabricated through a facile hydrothermal method and used for low temperature SCR of NO_x with NH₃.

Fabrication of manganese dioxide/carbon/attapulgite composites derived from spent bleaching earth for adsorption of Pb(ii) and Brilliant green

Manganese dioxide/carbon/attapulgite ternary composites were fabricated via hydrothermal method of the SBE served as adsorbents for the efficient removal of Pb(ii) and BG.