Waste Material Adsorbents for Zinc Removal from Wastewater: A Comprehensive Review

Abstract

This review examines a variety of adsorbents and discusses mechanisms, modification methods, recovery and regeneration, and commercial applications. A summary of available researches has been composed by a wide range of potentially low-cost modified adsorbents including activated carbon, natural source adsorbents (clay, bentonite, zeolite, etc.), biosorbents (black gram husk, sugar-beet pectin gels, citrus peels, banana and orange peels, carrot residues, cassava waste, algae, algal, marine green macroalgae, etc.), and byproduct adsorbents (sawdust, lignin, rice husk, rice husk ash, coal fly ash, etc.). From the literature survey, different adsorbents were compared in terms of Zn2+adsorption capacity; also Zn2+adsorption capacity was compared with other metals adsorption. Thus, some of the highest adsorption capacities reported for Zn2+are 168 mg/g powdered waste sludge, 128.8 mg/g dried marine green macroalgae, 73.2 mg/g lignin, 55.82 mg/g cassava waste, and 52.91 mg/g bentonite. Furthermore, modification of adsorbents can improve adsorption capacity. Regeneration cost is important, but if consumption of virgin adsorbent is reduced, then multiple economic, industrial, and environmental benefits can be gained. Finally, the main drawback of the already published Zn2+adsorption researches is that their use is still in the laboratory stage mostly without scale-up, pilot studies, or commercialization.

Adsorption of methylene blue from aqueous solution using untreated and treated (Metroxylon spp.) waste adsorbent: equilibrium and kinetics studies

“…Only a few biosorbents had higher sorption capacities than SKOH; key considerations in which SKOH may prove more advantageous, however, are the availability and simple processing requirements of the adsorbent. Adsorbents may be considered low cost if they are abundant, require little processing and have low economic value [39]. As mentioned previously, sago hampas waste is readily available in the Asia-Pacific region as an agricultural waste that can be sourced at free cost.…”

Removal of Heavy Metals from Wastewater using Date Palm as a Biosorbent: A Comparative Review

“…These adsorbents are classified into two types: conventional and non-conventional, as shown in Figure 1. Conventional adsorbents have been used on limited scale, including alumina, zeolite, AC, silica gel and bauxite (Baral et al 2007;Gupta et al 2013;Izhar et al 2014;Jacques et al 2007;Kim et al 2013;Sankararamakrishnan et al 2014;Wang & Peng 2010;Zwain et al 2014); among the non-conventional, the most frequently used is agricultural waste (Table 2). …”

Enhancing reactive blue 4 adsorption through chemical modification of chitosan with hexadecylamine and 3-aminopropyl triethoxysilane

“…These drawbacks will lead to serious environmental issues if the effluents enter the environment without proper dye elimination. Among various techniques used for elimination of dyes, adsorption is reported widely as an effective method due to its low cost, effectiveness, convenience as well as producing high-quality discharged effluents [4,5].…”