Methods to prepare biosorbents and magnetic sorbents for water treatment: a review

Abstract

Access to drinkable water is becoming more and more challenging due to worldwide pollution and the cost of water treatments. Water and wastewater treatment by adsorption on solid materials is usually cheap and effective in removing contaminants, yet classical adsorbents are not sustainable because they are derived from fossil fuels, and they can induce secondary pollution. Therefore, biological sorbents made of modern biomass are increasingly studied as promising alternatives. Indeed, such biosorbents utilize biological waste that would otherwise pollute water systems, and they promote the circular economy. Here we review biosorbents, magnetic sorbents, and other cost-effective sorbents with emphasis on preparation methods, adsorbents types, adsorption mechanisms, and regeneration of spent adsorbents. Biosorbents are prepared from a wide range of materials, including wood, bacteria, algae, herbaceous materials, agricultural waste, and animal waste. Commonly removed contaminants comprise dyes, heavy metals, radionuclides, pharmaceuticals, and personal care products. Preparation methods include coprecipitation, thermal decomposition, microwave irradiation, chemical reduction, micro-emulsion, and arc discharge. Adsorbents can be classified into activated carbon, biochar, lignocellulosic waste, clays, zeolites, peat, and humic soils. We detail adsorption isotherms and kinetics. Regeneration methods comprise thermal and chemical regeneration and supercritical fluid desorption. We also discuss exhausted adsorbent management and disposal. We found that agro-waste biosorbents can remove up to 68–100% of dyes, while wooden, herbaceous, bacterial, and marine-based biosorbents can remove up to 55–99% of heavy metals. Animal waste-based biosorbents can remove 1–99% of heavy metals. The average removal efficiency of modified biosorbents is around 90–95%, but some treatments, such as cross-linked beads, may negatively affect their efficiency.

Nanotechnology Approaches for the Remediation of Agricultural Polluted Soils

“…58 These include microbial biomass, agricultural wastes, nano-MgO, Fe 3 O 4 nanoparticles, CaO/Fe 3 O 4 nanoparticles, and activated carbon/Fe 3 O 4 nanocomposites, which is a composite of nanoadsorbents and biosorbents. 59 5.4. Nanobiosurfactants.…”

Fabrication of a Mixed Matrix Membrane Using Nitrogen-Enriched Nanoporous Polytriazine for Removal of Pb2+ from Aqueous Solution

“…Moreover, the adsorption capacity and efficiency are major concerns for the adsorbents. Metal leaching as well as the toxicity of metal-based adsorbents like metal oxides and magnetic adsorbents is a further major cause of concern. − Nowadays, metal-free systems such as heteroatom-enriched adsorbents are gaining more attention. − Recently, various heteroatom-enriched materials for the removal of Pb 2+ from aqueous solutions have been discovered. Owing to the tunable textural features, high specific surface area, and heteroatom enrichment, heavy metal ions are selectively removed from aqueous solution.…”

“…Many adsorbents have been reported to remove Pb 2+ from aqueous solutions such as metals, metal oxides, resins, activated carbon, metal–organic framework, zeolites, and biochar-based adsorbents. − There are several natural adsorbents, such as biological waste material like low-value lignocellulose, used to synthesize activated carbon having a specific surface area of 1368 m 2 g –1 , as well as the carbon nanotube for wastewater treatment for the removal of lead ions from aqueous solution. − Although these types of adsorbents have been synthesized by a green method and natural waste, they lack selectivity. Moreover, the adsorption capacity and efficiency are major concerns for the adsorbents.…”

Enhanced removal of Ce(iii) and Sr(ii) ions from aqueous solution using ultrasonication-assisted sawdust-TiO2 sorbent

“…They found that the best method is the adsorption process, which is due to its unique properties in terms of reducing time and obtaining a high removal rate of metal ions and radioactive isotopes using different adsorbents. [5][6][7][8][9][10] Lately, biomass materials like coconut shell activated carbon, 11,12 sawdust, [13][14][15] activated carbon, [16][17][18][19] natural materials, 20,21 activated carbon derived from pine sawdust, 22 magnetic plastic waste-biomass char composite (MPBC), 23 activated carbon and carbon nanotubes that synthesized from biomass, [24][25][26][27][28][29] .....etc., have been used as adsorbents to isolate heavy metal ions, organics, dyes and radioactive isotopes from contaminated water. Where, these biomass materials include numerous function groups as -COOH, -OH, and CO and these groups are associated with the element through ion-exchange, van der Waals interactions, complexation or co-precipitation.…”

“…For instance, the extraction and separation of cerium(III) using a modified graphite adsorbent, 53 adsorption of Ce(III) onto cellulose/graphene composite, 54,55 capture of cerium(III) using a ligand, 56 adsorption of Ce 3+ ions by a hydrophobic ionic liquid, 57 capture of Sr 2+ ions by a layered potassium neodymium phosphate, 58 removal of Sr 2+ ions by potassium phosphatoantimonate, 59 performance of membranes for the separation of Sr 2+ ions, 60,61 separation of strontium by resin, 62 layered potassium calcium phosphate for Sr(II) removal, 63 selective Sr 2+ uptake by oxalates, 64 adsorption of strontium ions by a metal-organic framework, 65 adsorption of Sr(II) in acid solution by a porous silica, 66 and adsorption of strontium radionuclide onto zeolites. 9 Newly, many researches have focused on the removal of contaminants from polluted water using the adsorption process in the presence of ultrasound waves, which greatly helps the transfer and entry of the adsorbate ions into the pores of the absorbent material. [67][68][69][70][71][72][73] Among them, Sivalingam et al indicated that the adsorption method in the presence of ultrasonication reduces the time for the adsorption process to occur.…”