Adsorption Characteristics of Allura Red AC onto Sawdust and Hexadecylpyridinium Bromide-Treated Sawdust in Aqueous Solution

Abstract

The Allura red AC (ARAC) dye adsorption onto natural sawdust (NSD) and hexadecylpyridinium bromide-treated sawdust (MSD) was investigated in aqueous solution as a function of contact time, solution pH, particle size, adsorbent dosage, dye concentration, temperature, and ionic strength. The adsorbents were characterized by Fourier transform infrared spectroscopy and X-ray diffraction crystallography. The dye adsorption onto both adsorbents was confirmed by field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The maximum dye adsorption was found within 120 min at pH 2.0 for NSD and pH 3.0 for MSD, respectively, with a particle size of 0–75 μm and an adsorbent dosage of 0.07 g/50 mL ARAC dye solution (50 μmol/L). The batch adsorption kinetic data were followed by the pseudo-second-order kinetic model rather than the pseudo-first-order and Elovich kinetic models. Equilibrium adsorption isotherms were explained by the Langmuir isotherm model, and the maximum extent of adsorption was found to be 52.14 μmol/g for NSD and 151.88 μmol/g for MSD at 55 °C. The values of activation energy (E a) and thermodynamic parameters (ΔG ⧧, ΔH ⧧, ΔS ⧧, ΔG°, ΔH° and ΔS°) proved that the ARAC dye adsorption onto both adsorbents NSD and MSD is a spontaneous-endothermic physisorption process. ARAC (98–99%) was released from dye-loaded adsorbents in aqueous solution (pH ≥ 12) within 120 min. The adsorbents NSD and MSD were reused for a second time without significant loss of their adsorption efficiency.

Bamboo-Based Biofoam Adsorbents for the Adsorption of Cationic Pollutants in Wastewater: Methylene Blue and Cu(II)

“… 52 Cu(II) removal reached 95.16% for PUα 1 within 24 h and then decreased with increasing time, which was probably ascribed to all of the active sites on α-cellulose being saturated with Cu(II). 54 About 100% Cu(II) removal was obtained by PUN 1 within 48 h, which was probably ascribed to the huge specific surface of PUN 1 with a negative charge to attract Cu(II). 3 The 100% Cu(II) removal by PUB 1 within 24 h suggested that low-cost PUB 1 could be used for the adsorption and recovery of Cu(II) from wastewater.…”

From Waste to Biosorbent: Removal of Congo Red from Water by Waste Wood Biomass

“…Pine bark 1.6 100 [9] Lemon-scented gum sawdust 0.523 >80 [10] Fir (Abies nordmanniana) sawdust 28.1 86 [11] Chir pine (Pinus roxburghii) sawdust 5.8 72 [12] Eucalyptus (Eucalyptus globulus) sawdust ->80 [13] Methylene Blue White cedar sawdust 55.15 - [14] Poplar waste biomass 21.9 98.50 [15] Pine sawdust (Pinus strobus) 10.3 99.94 [16] Cedar tree sawdust 142.36 - [17] Basic Violet 1 Chir pine (Pinus roxburghii) sawdust 11.3 96 [12] Disperse Orange 30 Poplar sawdust 0.089 83.4 [18] Eriochrome Black T Sawdust unspecified 40.96 80 [19] Allura Red AS Sawdust unspecified 50.98 - [20] Safranine O Sawdust unspecified -98 [21] Compared to activated carbon and biochar, native lignocellulosic materials as biosorbents are mostly inferior, i.e., adsorption capacities of native materials are lower. Therefore, attempts have been made to improve the adsorption capacities of such materials by phys-ical and/or chemical methods, including the production of biochar.…”

Chitosan Beads Incorporated with Graphene Oxide/Titanium Dioxide Nanoparticles for Removing an Anionic Dye

“…The variation in the initial concentration of FD&C Red 40 dye is of great importance as it allows for evaluating the performance of the CS-TiO 2 -GLA beads in their role as adsorbents [31]. The dye molecules diffuse through the solution to the surface of the beads, where they adsorb and gradually penetrate the boundary layer [32].…”

“…At low initial dye concentrations, the ratio between the number of available adsorption active sites on the beads is higher than the number of molecules in solution so that the material can rapidly adsorb FD&C Red 40 dye (with a high percentage of removal). However, as the initial concentration increases, the number of adsorption active sites decreases concerning the amount of adsorbate in solution, reducing the removal percentage [32]. In turn, the higher the FD&C Red 40 dye concentration, the greater the electrostatic repulsion between the molecules (due to the dissociated sulfonate groups) when they enter the surface of the beads.…”