Idris et al. 2023 — Adsorption techniques for heavy-metals remediation (Elsevier book-chapter review)

Single-chapter narrative review surveying the families of adsorbent materials studied for removing Co, Cr, Pb, Ni, Hg, As, U, Cd, and Cu from industrial wastewater: microbial biomass (fungi, bacteria, algae), lignocellulosic biomass, industrial wastes (fly ash, sewage-sludge activated carbon), natural waste adsorbents (clay, zeolite, chitosan, peat, siliceous materials), derived and hybrid composites, and nanomaterial adsorbents (MOFs, graphene-oxide composites). The chapter is descriptive — it walks through each adsorbent family with examples drawn from 109 cited references, names representative capacity figures from the primary literature, and frames adsorption as cheaper and more flexible than chemical or biological alternatives. There is no primary sampling, no PRISMA, no quality assessment, and no quantitative synthesis. The scope is wastewater-treatment engineering, not food or supply-chain contamination; relevance to the Heavy Metal Index is limited to (a) the broad inventory of materials that have been tested against heavy-metal-bearing aqueous matrices, and (b) the list of food-derived feedstocks (rice husk, sugarcane bagasse, palm-oil-mill biomass, fruit and vegetable peels, corncobs, sewage sludge) that appear elsewhere in the HMI corpus as commodity inputs. Evidence tier C; cite as a leads document only.

Key numbers

The chapter restates a handful of figures from its 109 cited primary references rather than reporting any author-derived measurements. Each value below is the chapter’s restatement, not a verified primary number; cross-check against the underlying paper before any quantitative use.

Adsorbate-percentage and adsorption-capacity equations the chapter cites (§1.3, p. 3)

• Adsorbate percentage: R = [(Ci − Cf) × 100] / Ci, where R is the percent adsorbate adhered, Ci is the initial metal-ion concentration (mg/L), and Cf is the final concentration (mg/L). Attributed to ref [16].
• Adsorption capacity: Q = [(Ci − Cf) × V] / m, where V is solution volume (mL), Ci and Cf are initial and final concentrations (mg/L), and m is the mass of biomass. Attributed to ref [16].

Representative biosorbent and adsorbent figures restated by the chapter

• Bacillus subtilis preconditioning, biosorption-capacity ordering (§1.3.2, p. 4): “supercritical CO2 pretreatment (98.54) > steam autoclave pretreatment (99.2) > living biomass (96.3)” attributed to refs [38–40]. The ordering and values as printed are internally inconsistent (99.2 > 98.54 yet stated in the opposite order); treat as a transcription defect and consult refs 38–40 before citing.
• Modified peat (Sphagnum and Carex peat, basic-modified), removal efficiencies (§1.6.4, p. 9): Pb(II) 23.07 %, Co(II) 23.53 %, Ni(II) 26.19 %. Attributed to ref [92].
• Mesoporous silica, maximum adsorption capacities (§1.6.5, p. 9): Pb(II) 58.5 mg/g; Cu(II) 36.3 mg/g; Cd(II) 32.3 mg/g. Attributed to ref [95].
• Activated carbon from sewage sludge, maximum adsorption capacity (§1.5, p. 8): 1358.5 mg/g for iodine and 139.4 mg/g for dye, prepared at a 1:1 sludge-to-reagent ratio. Attributed to refs [78, 79].
• Uranium and thorium ion reduction (§1.3.1, p. 4): Rhizopus arrhizus biomass reduces uranium and thorium ions “approximately 2.3 and 20 times faster than the ion exchange resin approach, respectively.” Attributed to ref [32].
• Clay adsorption scope (§1.6.1, p. 8): natural clay reported to adsorb Cu(II), As(V), Cd(II), Pb(II), and Cr(VI); modified clay reported to adsorb Cr(VI), Fe(III), Hg, and Mn(II). Attributed to ref [81].

Pretreatment-effect figure mentioned in passing (§1.5, p. 7)

• Food-, beverage-, drug-, pharmaceutical-, fermentation-, sugar-refining-, and power-industry ashes: “around 30 % is used as a component by refineries, but the remaining 70 % is discharged into the environment along with other effluents, causing contamination.” Attributed to ref [70]. Restated without specifying jurisdiction or measurement basis.

Methods (brief)

Narrative review of secondary literature on adsorbent materials for heavy-metal removal from aqueous matrices. No PRISMA, no inclusion criteria, no quality assessment, no formal extraction, no quantitative synthesis. 109 references cited (book-chapter format; the author network around Yaqoob AA and Ibrahim MNM is heavily self-cited, with ~25 of the 109 references drawn from prior chapters and papers by the same authors). Structure: §1.1 introduction; §1.2 adsorption as a physicochemical method; §1.3 microbes (fungi, bacteria, algae) as adsorbents; §1.4 lignocellulosic material as adsorbent; §1.5 industrial wastes as adsorbents; §1.6 natural waste adsorbents (clay, zeolite, chitosan, peat, siliceous material); §1.7 derived and hybrid adsorbents; §1.8 nanomaterial adsorbents; §1.9 conclusion. Five authors across three institutions. The chapter is part of an Elsevier-published edited volume; peer-review depth on individual chapters of such volumes is typically lighter than a primary-journal article.

Limitations

C-tier review with no primary data and material structural defects. The text contains several internally inconsistent restatements of cited values — for example, the Bacillus subtilis pretreatment ordering inverts its own numerical ranking (98.54 stated as greater than 99.2). English-language editing is uneven (e.g., “exposure to which causes a variety of health risks,” “this microbial population has the capability to reduce uranium and thorium ions at faster rate, approximately 2.3 and 20 times faster than the ion exchange resin approach, respectively,” paragraph-level subject-verb agreement drift). The references list mixes primary research papers with review chapters and conference proceedings without distinguishing tier. The discussion frames adsorption-capacity figures as comparable across substrates even though pH, ionic strength, contact time, particle size, and isotherm-model fit differ substantially across the cited primary studies — the comparability claim is not defensible without restating the underlying experimental conditions. The chapter does not address regulatory drinking-water or wastewater-discharge limits anywhere in its 18 pages, despite framing the work as wastewater remediation.

Implications

This source has minimal direct value for the Heavy Metal Index. The wiki’s scope is heavy-metals occurrence in food and personal-care supply chains; this paper is a wastewater-treatment engineering review. It is retained as a leads document for two narrow purposes:

Material-science leads: the chapter inventories food-derived feedstocks studied as heavy-metal adsorbents — rice husk, sugarcane bagasse, palm-oil-mill biomass, fruit and vegetable peels, corncobs, soybean hulls, Spirulina and Chlorella vulgaris, Saccharomyces cerevisiae spent brewer’s yeast, sewage sludge–derived activated carbon. Several of these are themselves commodities that appear in the HMI corpus as contamination subjects. The adsorption studies cited here are not direct evidence about contamination in those ingredients, but they document baseline metal-binding affinities between those plant matrices and Pb, Cd, Cu, Ni, Cr, Hg, As, U, Zn, and Co — useful background for understanding metal uptake during cultivation, processing, and packaging.

Industrial-source context: the framing that “around 30 % [of industrial ash] is used as a component by refineries, but the remaining 70 % is discharged into the environment along with other effluents” (§1.5) is restated without source jurisdiction or measurement basis but corroborates the broader literature on industrial-effluent contribution to soil and aquatic heavy-metal loads. Cite the primary reference [70] (Wake H., Estuarine Coastal Shelf Sci. 2005;62:131-40), not this chapter, when referencing the figure.

Wiki pages this source may touch

• lead
• cadmium
• chromium
• nickel
• copper
• mercury
• arsenic
• zinc
• cobalt
• uranium

Page history

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