A highly efficient polyampholyte hydrogel sorbent based fixed-bed process for heavy metal removal in actual industrial effluent

Abstract

a b s t r a c tHigh sorption capacity, high sorption rate, and fast separation and regeneration for qualified sorbents used in removing heavy metals from wastewater are urgently needed. In this study, a polyampholyte hydrogel was well designed and prepared via a simple radical polymerization procedure. Due to the remarkable mechanical strength, the three-dimensional polyampholyte hydrogel could be fast separated, easily regenerated and highly reused. The sorption capacities were as high as 216.1 mg/g for Pb(II) and 153.8 mg/g for Cd(II) owing to the existence of the large number of active groups. The adsorption could be conducted in a wide pH range of 3e6 and the equilibrium fast reached in 30 min due to its excellent water penetration for highly accessible to metal ions. The fixed-bed column sorption results indicated that the polyampholyte hydrogel was particularly effective in removing Pb(II) and Cd(II) from actual industrial effluent to meet the regulatory requirements. The treatment volumes of actual smelting effluent using one fixed bed column were as high as 684 bed volumes (BV) (7736 mL) for Pb(II) and 200 BV (2262 mL) for Cd(II). Furthermore, the treatment volumes of actual smelting effluent using tandem three columns reached 924 BV (31,351 mL) for Pb(II) and 250 BV (8483 mL) for Cd(II), producing only 4 BV (136 mL) eluent. Compared with the traditional high density slurry (HDS) process with large amount of sludge, the proposed process would be expected to produce only a small amount of sludge. When the treatment volume was controlled below 209.3 BV (7103 mL), all metal ions in the actual industrial effluent could be effectively removed (<0.01 mg/L). This wok develops a highly practical process based on polyampholyte hydrogel sorbents for the removal of heavy metal ions from practical wastewater.

Synthesis of Sodium Acrylate and Acrylamide Copolymer/GO Hydrogels and Their Effective Adsorption for Pb2+ and Cd2+

“…However, when the MBA content is higher than 0.8%, the MBA will make the networks of hydrogel extremely dense and smooth The environmental conditions such as pH and ionic strength will have influences on the surface charge of adsorbent as well as the ionization degree and solubility of adsorbates, consequently influencing the removal efficiency of heavy metal ions. 2,[13][14] In order to evaluate the influence of environmental conditions on the adsorption of Pb 2+ and Cd 2+ by the P(AANa-co-AM)/GO hydrogel, a series of adsorption and Mg 2+ ) were carried out. The adsorption results of Pb 2+ and Cd 2+ by the P(AANa-co-AM)/GO hydrogel as a function of pH are present in Figure 4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 This may be due to that the hydrated radius of Mg 2+ and Ca 2+ is smaller than that of Cd 2+ but larger than that of Pb 2+ .…”

“…Recently, various studies have found that hydrogel adsorbents exhibited super adsorption capacity, wide pH independence, easy regeneration and good reusability for removal of toxic metal ions and dyes from wastewater. [13][14][19][20][21][22] As a novel adsorbent, hydrogels are polymers with three dimensional (3-D) networks which can be formed via physical or chemical cross-linking using various water-soluble monomers 19,20,23 . Hydrogel adsorbents have attracted special attention in recent years for removing heavy metal ions due to the abundant functional groups and swollen polymeric networks of the polymer chain.…”

Selective removal of heavy metal ions by disulfide linked polymer networks

“…The demand for new sorbents, which not only have a high surface area but which are also selective, continues to drive research into efficient and functionalized sorbent materials [31]. In a situation of growing environmental problems-global warming and water pollution, the breadth of potential applications is widening for these functionalized sorbents.…”

Facile Fabrication of a Low-Cost Alginate-Polyacrylamide Composite Aerogel for the Highly Efficient Removal of Lead Ions

“…However, when the concentration of Pb 2+ exceeds 50 mM, the adsorption capacity of Alg-PAM remains stable and shows no further increase. Therefore, the maximum adsorption capacity of Alg-PAM for Pb 2+ is 252.2 mg/g, which is higher than that of most of the reported Pb 2+ sorbents (Table 2) [28][29][30][31][32][33][34][35][36][37][38][39][40][41].…”