RESUMEN

Addressing industrial wastewater treatment challenges and removing hazardous organic pollutants, such as carcinogenic methyl orange (MO) and azo dyes, is a pressing concern. This study explores the use of the Zea mays envelope, an agricultural waste product, to produce Z. mays activated carbon (ZMAC) through the chemical activation of maize envelopes with phosphoric acid. Various analytical techniques, including FTIR, XRD, TGA, DSC, and SEM, characterize ZMAC. Results show that ZMAC exhibits an impressive monolayer adsorption capacity of 66.2 mg/g for MO. The Langmuir isotherm model fits the experimental data well, indicating monolayer coverage of the MO on the ZMAC surface. The pH-sensitive adsorption process demonstrates an optimal removal efficiency at pH 4. ZMAC follows the pseudo-second-order kinetic model, and diffusion rate constant analysis identifies three consecutive stages in the adsorption process. Moreover, the uptake of MO ions by ZMAC is identified as an exothermic and spontaneous process. Reusability tests demonstrate efficient regeneration of ZMAC up to five times with 1 mL of 2 M HNO3 in each cycle, without sorbent mass loss. Thermodynamic analysis shows an increase in the uptake capacity from 66.2 to 73.2 mg/g with temperature elevation. This study offers practical solutions for industrial wastewater treatment challenges, providing an environmentally sustainable and effective approach to mitigate the risks associated with hazardous organic pollutants.

RESUMEN

The arsenic (As) pollution of water has been eliminated via intensive scientific efforts, with the purpose of giving safe drinking water to millions of people across the world. In this study, the adsorption of As(V) from a synthetic aqueous solution was verified using a Bentonite-Anthracite@Zetag (BT-An@Zetag) composite. The SEM, FT-IR, XRD, DSC, TGA, and SBET techniques were used to characterize the (BT-An@Zetag) composite. The adsorption of As(V) was explored using batch adsorption under varied operating scenarios. Five kinetic modelswere used to investigate kinetic data, whereas three isotherms had been used to fit empirical equilibrium data. According to the findings, the adsorption mechanism of As(V) was best described by the Freundlich isotherm with a maximum monolayer coverage of 38.6 mg/g showing pseudo-second-order mode. The estimated enthalpy (H°) indicates that the adsorption process is both chemical and endothermic.The calculated free energy (G°) indicates that the reaction is nonspontaneous. After four sequential adsorption cycles, the produced BT-An@Zetag composite demonstrated good reusability and a greater adsorption affinity for As(V) ions. Overall, the BT-An@Zetag composite is suited for removing arsenic from wastewater using adsorption as a cost-effective and efficient technique.

Asunto(s)

Arsénico , Quitosano , Contaminantes Químicos del Agua , Humanos , Bentonita/química , Carbón Mineral , Espectroscopía Infrarroja por Transformada de Fourier , Contaminantes Químicos del Agua/química , Quitosano/química , Adsorción , Agua/química , Cinética , Termodinámica , Concentración de Iones de Hidrógeno

RESUMEN

We synthesized a stable, eco-friendly, and low-cost polyaniline@ß-cyclodextrin (PANI@ß-CD) nanocomposite via oxidative polymerization for phenol adsorption from water waste since phenol pollution is a global danger to human and animal health and the environment. The production of the composite and synergistic alteration of PANI with ß-CD resulted in 66% reduction in particle size from 59 nm (PANI) to 20 nm (PANI@ß-CD) as well as better phenol adsorption. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TGA) were used to analyze the produced PANI@ß-CD nanocomposite. Our results show the optimum conditions for phenol adsorption: time (50 min), pH (8.0), nanosorbent dose (0.5 g), and the sorption isotherm fitted with Langmuir model; the monolayer adsorption capacity of the prepared PANI@ß-CD for phenol was determined to be 8.56 mg g-1. The average pore size, total pore volume, and surface area of PANI/ßCD nanocomposite are 15.62 nm, 0.1586 cm3/g, and 90.901 m2/g, respectively, for the pseudo second order model. Finally, modifying PANI nanoparticles with ßCD allowed reusability up to four cycles with superior adsorption performance of ∼95% using (0.01 N) HNO3.

RESUMEN

Raw anthracite was impregnated with a minute amount of multi-walled carbon-nanotubes at a solid/solid ratio of 50 : 1 via calcination at 950 °C for 2 h to produce anthracite/carbon nanotube (An/CNT) composite with superior sorption efficiency. Both An/CNT composite and its precursor anthracite were characterized by XRD, SEM, FT-IR and BET surface area (S BET). The removal efficiency of an azo dye methyl orange (MO) by the An/CNT composite was evaluated under different experimental parameters. The MO sorption isotherm data fitted to the Langmuir model well with an R 2 of 0.999 and a MO sorption capacity (q max) of 416.7 mg g-1. The distribution coefficient K d decreases from 117.9 to 16.1 L g-1 as the initial MO concentrations increased from 40 to 140 mg L-1. The MO sorption kinetic data was well described by the pseudo-second-order equation with an R 2 of 1. The external (film) diffusion followed by intra-particle diffusion was the major driving process during the early stage of MO sorption. The electrostatic interaction between the oxygen- and nitrogen-bearing functional groups on the An/CNT surface and MO ions was the key controlling mechanism for the MO sorption process, particularly at pH < pHPZC of the composite. Meanwhile, valuable contributions from Yoshida and dipole-dipole H bonding mechanisms can explain the MO sorption by the addressed composite, especially at pH > pHPZC.