Potential of fusion technique in production of mesoporous zeolite A powder from poor kaolin through modification by boehmite: Effect of clay mineralogy on particle morphology

Amendment of Sargassum oligocystum bio-char with MnFe2O4 and lanthanum MOF obtained from PET waste for fluoride removal: A comparative study

The use of biomass and waste to produce adsorbent reduces the cost of water treatment. The bio-char of Sargassum oligocystum (BCSO) was modified with MnFe2O4 magnetic particles and La-metal organic framework (MOF) to generate an efficient adsorbent (BCSO/MnFe2O4@La-MOF) for fluoride ions (F-) removal from aqueous solutions. The performance of BCSO/MnFe2O4@La-MOF was compared with BCSO/MnFe2O4 and BCSO. The characteristics of the adsorbents were investigated using various techniques, which revealed that the magnetic composites were well-synthesized and exhibited superparamagnetic properties. The maximum adsorption efficiencies (BCSO: 97.84%, BCSO/MnFe2O4: 97.85%, and BCSO/MnFe2O4@La-MOF: 99.36%) were achieved under specific conditions of pH 4, F- concentration of 10 mg/L, and adsorbent dosage of 3, 1.5, and 1 g/L for BCSO, BCSO/MnFe2O4, and BCSO/MnFe2O4@La-MOF, respectively. The results demonstrated that the experimental data adheres to a pseudo-second-order kinetic model. The enthalpy, entropy, and Gibbs free energy were determined to be negative; thus, the F- adsorption was exothermic and spontaneous in the range of 25-50 °C. The equilibrium data of the process exhibited conformity with the Langmuir model. The maximum adsorption capacities of F- ions were determined as 10.267 mg/g for BCSO, 14.903 mg/g for the BCSO/MnFe2O4, and 31.948 mg/g for BCSO/MnFe2O4@La-MOF. The KF and AT values for the F- adsorption were obtained at 21.03 mg/g (L/mg)1/n and 100 × 10+9 L/g, indicating the pronounced affinity of the BCSO/MnFe2O4@La-MOF towards F- than other samples. The significant potential of the BCSO/MnFe2O4@La-MOF magnetic composite for F- removal from industrial wastewater, makes it suitable for repeated utilization in the adsorption process.

Polypyrrole-decorated bentonite magnetic nanocomposite: A green approach for adsorption of anionic methyl orange and cationic crystal violet dyes from contaminated water

In the presented study, a novel polypyrrole-decorated bentonite magnetic nanocomposite (MBnPPy) was synthesized for efficient removal of both anionic methyl orange (MO) and cationic crystal violet (CV) dyes from contaminated water. The synthesis of this novel adsorbent involved a two-step process: the magnetization of bentonite followed by its modification through in-situ chemical polymerization. The adsorbent was characterized by SEM/EDX, TEM/SAED, BET, TGA/DTA-DTG, FTIR, VSM, and XRD studies. The investigation of the adsorption properties of MBnPPy was focused on optimizing various parameters, such as dye concentration, medium pH, dosage, contact time, and temperature. The optimal conditions were established as follows: dye concentration of Co (CV/MO) at 100 mg/L, MBnPPy dosage at 2.0 g/L, equilibrium time set at 105 min for MO and 120 min for CV, medium pH adjusted to 5.0 for MO dye and 8.0 for CV dye, and a constant temperature of 303.15 K. The different kinetic and isotherm models were applied to fit the experimental results, and it was observed that the Pseudo-2nd-order kinetics and Langmuir adsorption isotherm were the best-fitted models. The maximal monolayer adsorption capacities of the adsorbent were found to be 78.74 mg/g and 98.04 mg/g (at 303.15 K) for CV and MO, respectively. The adsorption process for both dyes was exothermic and spontaneous. Furthermore, a reasonably good regeneration ability of MBnPPy (>83.45%/82.65% for CV/MO) was noted for up to 5 adsorption-desorption cycles with little degradation. The advantages of facile synthesis, cost-effectiveness, non-toxicity, strong adsorption capabilities for both anionic and cationic dyes, and easy separability with an external magnetic field make MBnPPy novel.

ZnO@ activated carbon derived from wood sawdust as adsorbent for removal of methyl red and methyl orange from aqueous solutions

Activated carbon (AC) and ZnO@AC composite derived from wood sawdust were prepared to be utilized as adsorbents for methyl red (MR) and methyl orange (MO) anionic dyes from the aqueous solutions. The maximum adsorption capacity of the AC and ZnO@AC composite toward both dyes was achieved in the strong acidic medium (pH = 3), and under stirring for 60 min. The kinetic studies revealed that the adsorption of MR and MO dyes onto the AC and ZnO@AC composite fitted well with the pseudo-second-order model. Furthermore, the intraparticle diffusion and Elovich kinetic models confirmed the adsorption is controlled by external surfaces, and the adsorption is chemisorption process. The isotherm results indicated that the MR and MO dye adsorption occurred via monolayer adsorption, and the estimated maximum adsorption capacities of both dyes onto the ZnO@AC composite were higher than those achieved by AC. Thermodynamic analysis suggested that the adsorption is endothermic and spontaneous. The mechanism for MR, and MO dyes adsorption onto the AC and ZnO@AC composite is proposed to be controlled by electrostatic bonding, π-π interactions, and ion exchange, while H-bonding and n-π interactions were minor contributors. This study reveals the potential use of carbon-based adsorbents derived from wood sawdust for the removal of anionic dyes from wastewater.

Nylon fiber waste as a prominent adsorbent for Congo red dye removal

In this research nylon fibers wastes (NF) were fabricated into porous sheet using a phase inversion technique to be utilized as an adsorbent materials for Congo red dye (CR). The fabricated sheet denoted as NS was characterized using FTIR and XRD. The surface studies of the adsorbent materials using SEM and BET analysis reveals a highly pores structure with an average pore volume 0.61 cc/g and BET surface area of 767 m2/g. The adsorption studies of fabricated NS were employed into CR at different parameters as pH, effect of time and dye concentration. The adsorption isotherm and kinetic studies were more fit to Langmuir and pseudo second order models. The maximum adsorption capacity qmax reached 188 mg/g with removal percentage of 95 for CR concentration of 400 mg/L at pH 6 and 0.025 g NS dose for 10 ml CR solution. The regeneration study reveals a prominent adsorption behavior of NS with removal % of 88.6 for CR (300 mg/L) after four adsorption desorption cycles. Effect of incorporation of NaonFil Clay to NS was studied using Response Surface Methodology (RSM) modeling and reveals that 98.4% removal of CR could be achieved by using 19.35% wt. of fiber with 8.2 g/L dose and zero clay, thus at a predetermined parameters studies of NanoFil clay embedded into NS, there are no significant effect for %R for CR.

Adsorption of Heavy Metals in Contaminated Water Using Zeolite Derived from Agro-Wastes and Clays: A Review

Due to climate change and anthropogenic activities such as agriculture, mining, and urbanization, water contamination has become a very real modern problem. Modern solutions such as activated carbon, reverse osmosis, and ultrafiltration, among others, have been employed in the decontamination of water. These methods are, however, expensive to set up and maintain and therefore have proved a challenge to implement in developing countries. Zeolite materials exhibit excellent structural properties, such as high ion exchange capacity, porosity, and relative surface area, which make them attractive to water decontamination processes. However, conventional zeolites are expensive, and recent research has focused on utilizing low-cost materials such as agro-wastes and clays as raw materials for the synthesis of zeolites. This review aims to discuss the role of low-cost zeolites in their removal of heavy metals and the feasibility of agro-wastes and natural clays in the synthesis of zeolites. Recent research studies based on the synthesis of zeolites from clays and agro-wastes and their application in heavy metal removal have been reviewed and discussed. Agro-wastes such as rice husk ash and sugarcane bagasse ash and layered silicate clays such as kaolinite and smectites are particularly of interest to zeolite synthesis due to their high silica to alumina ratio. Zeolites synthesized through various methods such as hydrothermal, molten salt, and microwave irradiation synthesis have been discussed with their effect on the adsorption of various heavy metals.