Granulation of Fe–Al–Ce hydroxide nano-adsorbent by immobilization in porous polyvinyl alcohol for fluoride removal in drinking water

A Viable and sustainable flat- membrane plate-and-frame module for spent acid regeneration and metal ion recovery

This study provides techno-economical insights for acid regeneration and metal recovery from spent acidic wastewater by a diffusion dialysis plate-and-frame module using Quaternized Polyepichlorohydrin - Polyacrylonitrile (QPECH-PAN) membranes. Quaternized Polyepichlorohydrin (QPECH) membranes were synthesized using 1,4-diazobicyclo[2.2.2]octane (DABCO) and blended with polyacrylonitrile (PAN). Said membranes were analyzed in terms of their mechanical, physicochemical, and electrochemical characteristics, providing significant results comparable to the commercial membranes (IEC: 1.76 mmol/g, SD: 60.91%, Permselectivity: 79.5 ± 0.31%, and transport no. t_(-): 0.5). Mechanical characterization reveals that the QPECH-PAN membranes possess comparable mechanical strengths (tensile strength: 329.56 MPa). Further, sheet resistivity (6.11 Ω cm²) and conductivity (0.16 S/cm²) reveal the relative conductive nature of these membranes. Percent acid recovery and metal ion recovery ratios were found to be 72% and 48% respectively, and separation factors were 126.8 and 84.57 respectively. The QPECH-PAN membrane's techno-economic feasibility was also analyzed within the context of a textile industry processing up to 5500 kg/d of acidic wastewater. It indicates a potential cost saving of US $0.53 million on H₂SO₄ and NaOH, as well as an OPEX saving of 40.91% against a semi-continuous acid neutralizer.

A novel tri-metal adsorbent used for defluoridation technique from groundwater: performance and mechanism

In this research article, a novel adsorbent (Zn-Fe-Al) was synthesized successfully by a simple chemical route where three oxides combined to enhance affinity towards fluoride. The physicochemical properties of the adsorbent were used to characterize and assess its effectiveness in defluoridation with both synthetic and groundwater. The TEM results demonstrated the overlapping of metals, and EDX shows the metals present in the adsorbent. The maximum defluoridation efficiency (97%) of Zn-Fe-Al was obtained at an optimized initial pH 7 and adsorbent dose 0.08 g L-1. The fluoride adsorption on Zn-Fe-Al followed the D-R isotherm and intraparticle diffusion. The maximum adsorption capacity of Zn-Fe-Al was found to be 187 mg g-1. The adsorption of fluoride on Zn-Fe-Al was found to be endothermic and spontaneous. The Zn-Fe-Al adsorbent exhibited satisfactory defluoridation performance on real groundwater. The co-existing ions were also investigated. The adsorption mechanisms for fluoride were electrostatic interaction and ion exchange. These results demonstrated that Zn-Fe-Al adsorbent was considered high potential for effective defluoridation of groundwater.

Management of Solid Waste Containing Fluoride-A Review

Technological and economic development have influenced the amount of post-production waste. Post-industrial waste, generated in the most considerable amount, includes, among others, waste related to the mining, metallurgical, and energy industries. Various non-hazardous or hazardous wastes can be used to produce new construction materials after the “solidification/stabilization” processes. They can be used as admixtures or raw materials. However, the production of construction materials from various non-hazardous or hazardous waste materials is still very limited. In our opinion, special attention should be paid to waste containing fluoride, and the reuse of solid waste containing fluoride is a high priority today. Fluoride is one of the few trace elements that has received much attention due to its harmful effects on the environment and human and animal health. In addition to natural sources, industry, which discharges wastewater containing F− ions into surface waters, also increases fluoride concentration in waters and pollutes the environment. Therefore, developing effective and robust technologies to remove fluoride excess from the aquatic environment is becoming extremely important. This review aims to cover a wide variety of procedures that have been used to remove fluoride from drinking water and industrial wastewater. In addition, the ability to absorb fluoride, among others, by industrial by-products, agricultural waste, and biomass materials were reviewed.

Bead-Shaped Mesoporous Alumina Adsorbents for Adsorption of Ammonia

It is of great importance to remove toxic gases by efficient methods for recovering the atmosphere to safe levels. The adsorption of the toxic gas molecules on solid adsorbents is one of the most useful techniques because of its simple operation and economic feasibility. Here, we report the uniform Bead-Shaped Mesoporous Alumina (BSMA) with tunable particle size for use as an adsorbent for removal of toxic ammonia. The BSMA particles with tunable diameters were synthesized by means of a sol–gel reaction of Al(NO₃)₃∙9H₂O as an alumina precursor in the presence of chitosan as a template. When the ammonia solution is added dropwise to the prepared viscose mixture containing chitosan, acetic acid, and the alumina precursor solution, the sol–gel condensation reaction of the alumina precursor occurs in the chitosan polymer metrics, resulting in bead-shaped chitosan-aluminum hydroxide particles. Then, final Bead-Shaped Mesoporous Alumina (BSMA) particles are obtained by calcination at a high temperature. During the synthesis, changing the mole ratio of the chitosan template to the alumina precursor allowed the particle diameter of the final bead sample to be finely controlled. In addition, the prepared BSMA particles have well-developed mesoporous characteristics with relatively large surface areas, which are beneficial for adsorption of gas molecules. In an ammonia adsorption experiment, the BSMA-1.5 sample, which has the smallest particle diameter among the bead samples, was the best in terms of adsorption capacity. In this manuscript, we systemically discuss the relationship between the characteristics of BSMA samples and their adsorption of ammonia.

Synthesis and fabrication of antibacterial hydrogel beads based on modified-gum tragacanth/poly(vinyl alcohol)/Ag0 highly efficient sorbent for hard water softening

In the current study, hard water softening for the removal of Ca²⁺ and Mg²⁺ ions was performed using hydrogel beads based on Gum Tragacance (GT) modified by using 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and poly(vinyl alcohol). The antibacterial spherical hydrogel beads were fabricated by instantaneous gelation of well dispersed mixture of poly(AMPS)-g-GT (1 g), poly(vinyl alcohol) (PVA, 1 g) flocculent, green-synthesized silver metal nanoparticles (AgNPs, 10 mg), and graphene oxide (GO, 10 mg) in the acetone solution of boric acid and then transferring into the different amounts (0.5-2.5 mL) of acidic solution of glutaraldehyde (GA) as cross-linker. The beads were fully characterized and their adsorption behavior matched well with the pseudo-second-order kinetic and the Langmuir isotherm models with the maximum adsorption of Ca²⁺(114.18 mg g^-1) and Mg²⁺(162.46 mg g^-1). The removal ability of the beads decreased by 6% after four adsorption/desorption cycles. The antibacterial performance of the hydrogel beads was also investigated against Gram-positive and Gram-negative bacteria.

Facile synthesis of magnetic La–Zr composite as high effective adsorbent for fluoride removal

A novel magnetic composite of La–Zr was prepared by co-precipitation method, and its fluoride removal ability was investigated in batch studies.

Novel magnetic core–shell Ce–Ti@Fe3O4 nanoparticles as an adsorbent for water contaminants removal

Magnetic core–shell Ce–Ti@Fe₃O₄ nanoparticles were synthesized by coating cerium titanate on magnetite under mild experimental conditions.

Removal of dyes and heavy metal ions from water by magnetic hydrogel beads based on poly(vinyl alcohol)/carboxymethyl starch-g-poly(vinyl imidazole)

Highly porous magnetic nanocomposite hydrogel (m-CVP) beads were prepared and used for the removal of dyes and heavy metal ions.

Porous zirconium alginate beads adsorbent for fluoride adsorption from aqueous solutions

The porous adsorbent was prepared by loading with zirconium ions. A batch of adsorption experiments were carried under various conditions. The result suggested that the adsorbent showed well potential for defluorination.

A Review on Adsorption of Fluoride from Aqueous Solution

Fluoride is one of the anionic contaminants which is found in excess in surface or groundwater because of geochemical reactions or anthropogenic activities such as the disposal of industrial wastewaters. Among various methods used for defluoridation of water such as coagulation, precipitation, membrane processes, electrolytic treatment, ion-exchange, the adsorption process is widely used. It offers satisfactory results and seems to be a more attractive method for the removal of fluoride in terms of cost, simplicity of design and operation. Various conventional and non-conventional adsorbents have been assessed for the removal of fluoride from water. In this review, a list of various adsorbents (oxides and hydroxides, biosorbents, geomaterials, carbonaceous materials and industrial products and by-products) and its modifications from literature are surveyed and their adsorption capacities under various conditions are compared. The effect of other impurities on fluoride removal has also been discussed. This survey showed that various adsorbents, especially binary and trimetal oxides and hydroxides, have good potential for the fluoride removal from aquatic environments.