Adsorption of Ni2+ and Cd2+ from Water by Calcium Alginate/Spent Coffee Grounds Composite Beads

Abstract

The use of heavy metals in technological applications has led to detrimental effects on human health and the environment. Activated carbon and ion-exchange resins are commonly used to remove pollutants but they are expensive. Therefore, the research of low-cost alternatives derived from natural resources and organic wastes is being considered. The aim of this study considers the use of Calcium Alginate/Spent Coffee Grounds (CA-SCGs) composite beads to adsorb heavy metals from aqueous solutions, particularly, the removal of Ni 2+ or Cd 2+ at concentrations from 10 ppm to 100 ppm. CA-SCGs beads were made of equal proportions of alginate and spent coffee grounds and compared with calcium alginate beads (CA beads) and spent coffee grounds (SCGs) in terms of capacity and rate of adsorption. Three cycles of adsorption/desorption were done. The beads were characterized by Scanning Electron Microscopy coupled with an energy-dispersive X-ray spectroscopy (SEM-EDX), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, and point of zero charge. Langmuir, Freundlich, and Sips models, and a pseudo-second-order kinetic equation were used. Sips model showed the best correlation with the adsorption of CA-SCGs beads with capacities of adsorption of 91.18 mg/g for cadmium and 20.96 mg/g for nickel. CA-SCGs beads had a greater adsorption than the CA beads, achieving adsorption percentages close to 100% than alginate alone, showing their effectiveness in heavy metal removal.

A Comparative Study on Cu2+, Zn2+, Ni2+, Fe3+, and Cr3+ Metal Ions Removal from Industrial Wastewaters by Chitosan-Based Composite Cryogels

“…This behavior is associated with many sites/functional groups able to remove efficiently a high quantity of HMIs, while the number of HMIs distributed per sorbent mass unit decreased, accordingly, with the increase of the sorbent dose [14,23,36]. For instance, the saturated sorption capacity of CPLH + , CGCS, and CGCS_CPLH + sorbents decreased from 15 (Figure 2B) when the sorbent dosage increased from 0.01 to 0.04 g. The RE values were around 12%, 40%, and 80% for CPLH + , CGCS, and respectively, CGCS_CPLH + sorbents at a sorbent dose higher than 0.03 g. A RE value higher than 80% was achieved when the Cu 2+ ions removal was studied using single-component aqueous systems [14,20,35,36]. Considering the RE values, the optimal sorbent dose of 0.035 g was chosen for all upcoming sorption experiments.…”

“…Various sorbents including activated carbon [3], carbon nanotubes [4], organic ion exchangers [5], zeolites [6][7][8][9], and polysaccharide-based hydrogels [10][11][12][13][14][15][16] have been tested for the treatment of HMIs-containing wastewaters. Among them, polysaccharides, such as chitosan (CS) [10][11][12], salecan [13], pullulan [14], alginate [15], and pectin [16], as biosorbents, are preferred because they possess several advantages such as high abundance, biodegradability, and nontoxicity, particularly suited for the removal of HMIs from polluted tap or groundwater. Among the available biopolymers, CS has the highest sorption performance toward HMIs [10][11][12] due to its abundant -NH 2 and -OH groups.…”

Choice of Suitable Economic Adsorbents for the Reduction of Heavy Metal Pollution Load

“…The adsorbents of natural origin e.g., chitin, peat moss, clay and zeolites show an efficient removal of toxic heavy metals including Cd, Cr, Hg, Ni, Zn, Cu, Pb [9]. Recently attempts are being made to develop more effective and cheaper adsorbents containing natural polymers for example cyclodextrin [24], chitosan [25], starch and its derivatives [26], alginates [27] etc. The natural polymers like polysaccharides are biodegradable, renewable and abundantly available and have natural ability to associate physically or chemically with a large variety of molecules.…”

Study on the Adsorption of Heavy Metals in Sludge by Calcium Alginate Cross-Linked Zeolite Microspheres

“…They are widely used because of their environmental friendliness, non-toxicity, and low cost. As a kind of biosorbent, sodium alginate is a marine natural polymer polysaccharide extracted from the cell wall of brown algae [13]. Sodium alginate is rich in functional groups, such as hydroxyl and carboxyl groups, and can adsorb metal ions well.…”