Selective Adsorption of Pb(II) from Aqueous Medium by Cross-Linked Chitosan-Functionalized Graphene Oxide Adsorbent

Abstract

Functionalization of graphene oxide (GO) was achieved by synthesizing aminopropylsilane graphene oxide (APSGO) by a condensation reaction. Cross-linked chitosan (CHI) adsorbent grafted with aminopropylsilane graphene oxide was synthesized in acidic medium by sol–gel in the presence of glutaraldehyde. Reported adsorbent, with a high surface concentration of active sites (−NH2/NH) and low swelling properties (due to incorporation of silica and formal cross-linking), was assessed for Pb­(II) adsorption in aqueous medium. The spherical and rough surface of the pristine beads was altered after Pb2+ adsorption. The selective removal of Pb2+ using cross-linked CHI-APSGO adsorbent was attributed to its larger hydrated radius than other metal ions (Cu2+, Ni2+, and Cr3+). In a batch process and under different operating conditions, the effect of time, temperature, pH, adsorbent dose, and adsorbate concentration were also analyzed. Thermodynamic parameters (ΔG °, ΔH °, and ΔS°) confirmed an endothermic and spontaneous process, while the equilibrium adsorption obeyed Langmuir and Freundlich isotherms. The adsorption capacity of CHI-APSGO adsorbent (566.2 mg/g at pH 5.0) was comparatively higher than other adsorbents cited earlier. Desorption studies also revealed effective utilization of cross-linked CHI-APSGO material for selective removal of Pb2+ from wastewater.

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

“…When the temperature increases to 40 • C, the removal efficiency reaches 99.3%. These experimental results are similar to the reported literature and indicate that the process by which Alg-PAM binds to Pb 2+ is endothermic [26,27].…”

Melamine-based functionalized graphene oxide and zirconium phosphate for high performance removal of mercury and lead ions from water

“…12 Finally, it should be noted that the developed M-ZrP adsorbent exhibits one of the highest maximum adsorption capacity (q max ) of Pb(II) ions reported in literature for a variety of organic, inorganic, hybrid, and MOF adsorbents. [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] The removal capacity for lead ions by M-ZrP is 680.4 mg g À1 and 1000 mg g À1 using an adsorbent dose of 1 g L À1 and 2 g L À1 , respectively. This removal capacity is higher than most of the reported values for Pb(II) removal by other ZrP-modied adsorbents such as ZrPchloromethylated polystyrene (556.0 mg g À1 ), 51 polymer based-ZrP (398.0 mg g À1 ), 19 Go-ZrP (363.4 mg g À1 ), 21 ZrP-polysulfone (302.1 mg g À1 ), 52 and ZrP-polyvinyl alcohol (121.1 mg g À1 ).…”

“…Therefore, the M-ZrP adsorbent is clearly among the very top performing adsorbents reported in literature for the lead removal from contaminated industrial and wastewater. [19][20][21][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64]…”

Green Graphene–Chitosan Sorbent Materials for Mercury Water Remediation

“…A widely accessible natural biopolymer obtained from the alkaline deacetylation of chitin, chitosan (CH), is hydrophilic, environmentally friendly, and nontoxic and has been used as an agent for the removal of dyes and heavy metals from contaminated waters [ 24 ]. For the specific case of heavy metal(loid)s, the adsorption onto GO–CH-based materials has been studied for the removal of Cr [ 25 , 26 , 27 , 28 , 29 , 30 ], Cu [ 25 , 31 , 32 , 33 , 34 ], Pb [ 25 , 31 , 32 , 35 , 36 , 37 ], As [ 32 , 38 ], Au, and Pd [ 39 ] or U [ 28 ]. GO–CH was also applied to remove Hg [ 40 ], although only in deionized water and for relatively high concentrations of material (1 g L –1 ) and Hg (up to 500 mg L –1 ), which in addition to not being environmentally friendly, are not representative of real cases.…”