Triazine-Based Functionalized Activated Carbon Prepared from Water Hyacinth for the Removal of Hg²⁺, Pb²⁺, and Cd²⁺ Ions from Water

Abstract

A novel chelating adsorbent, based on the functionalization of activated carbon (AC) derived from water hyacinth (WH) with melamine thiourea (MT) to form melamine thiourea-modified activated carbon (MT-MAC), is used for the effective removal of Hg2+, Pb2+, and Cd2+ from aqueous solution. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) theory confirm the successful functionalization of AC with the melamine thiourea chelating ligand through the amidation reaction between the carboxyl groups of oxidized activated carbon (OAC) and the amino groups of melamine thiourea (MT) in the presence of dicyclohexylcarbodiimide (DCC) as a coupling agent. The prepared MT-MAC exhibited extensive potential for the adsorption of the toxic metal ions Hg2+, Pb2+, and Cd2+ from wastewater. The MT-MAC showed high capacities for the adsorption of Hg2+ (292.6 mg·g–1), Pb2+ (237.4 mg·g–1), and Cd2+ (97.9 mg·g–1) from aqueous solution. Additionally, 100% removal efficiency of Hg2+ at pH 5.5 was observed at very low initial concentrations (25–1000 ppb).The experimental sorption data could be fitted well with the Langmuir isotherm model, suggesting a monolayer adsorption behavior. The kinetic data of the chemisorption mechanism realized by the melamine thiourea groups grafted onto the activated carbon surface have a perfect match with the pseudo-second-order (PSO) kinetic model. In a mixed solution of metal ions containing 50 ppm of each ion, MT-MAC showed a removal of 97.0% Hg2+, 68% Pb2+, 45.0% Cd2+, 17.0% Cu2+, 7.0% Ni2+, and 5.0% Zn2+. Consequently, MT-MAC has exceptional selectivity for Hg2+ ions from the mixed metal ion solutions. The MT-MAC adsorbent showed high stability even after three adsorption–desorption cycles. According to the results obtained, the use of the MT-MAC adsorbent for the adsorption of Pb2+, Hg2+, and Cd2+ metal ions from polluted water is promising.

Isotherm and kinetic studies of acid yellow 11 dye adsorption from wastewater using Pisum Sativum peels microporous activated carbon

“…This study's outcomes show that PPAC successfully removes the AY11 dye from the aqueous solution; as a result, PPAC can be used repeatedly without experiencing considerable loss in effectiveness.Anxieties about water shortage continue to grow in some parts of the world with ongoing pollution of present rivers in diverse locations. Chemical materials that place a heavy load on the aquatic environment can be listed as pesticides 1-3 , drugs 4,5 , dyes 6-10 , hydrocarbons 11,12 , and heavy metals [13][14][15][16][17] . These chemicals are introduced into the environment through home sewage or sewage from industrial and hospital facilities 18,19 .…”

Enhanced performance of hydroxyl and cyano group functionalized graphitic carbon nitride for efficient removal of crystal violet and methylene blue from wastewater

“…Due to particle aggregation, which reduces the overall surface area of the adsorbent, the adsorption capacity decreases as the adsorbent amount increases. 43 …”

“…Moreover, the pseudo-first-order (PFO) and the pseudo-second order (PSO) kinetic models have both been extensively used to provide relevant data on the adsorption kinetics, and mechanism of MB and CV adsorption onto f/g-CN. 43 For more details on the two models and the corresponding mathematical equations, see ESI (S3). † The PFO and PSO kinetic models for the MB and CV adsorption onto f/g-CN are shown in Fig.…”

“…These peaks can be attributed to the bonds -NH, N-(C) 3 , and C-N]C, respectively. 3,41,43 In addition, the surface elemental analysis including C, N and O are detected (Table S1 †). The C content of f/ g-CN (58.23%) is higher than g-CN (45.98%) and the O content of g-CN (2.62%) is lower than f/g-CN (11.55%).…”

“…Furthermore, using the PSO model, the correlation coefficient (R 2 ) was 0.999 (Table 1), which was much higher than that (R 2 = 0.748) obtained using the PFO model, indicating that the adsorption of MB or CV onto f/g-CN obeys the PSO kinetics. 43 Additionally, these results suggest that the removal process was controlled by electron transfer between the dye molecules (adsorbate) and the NH x , OH, CN groups on the f/g-CN surface (adsorbent). 14 3.2.5.…”