Modified Ziziphus spina-christi stones as green route for the removal of heavy metals

Abstract

Green routes for remediation of heavy metals are worldwide challenges to overcome pollution problems on one hand and control the adverse impact of chemicals on the other hand. Biosorption is one of the most effective methods for removing lower level of heavy metals. The idea to apply natural resources as a green method for removal of heavy metals, this route has no adverse impacts on the environment. This study investigated the ability of chemically modified Ziziphus spina-christi stones (ZSCs) as agriculture by-products to perform the biosorption of Pb(II), Zn(II) and Cd(II) ions from wastewater in a single and ternary metal system. The characteristic functional groups of chemically modified ZSCs were analyzed by Fourier transform infrared. In comparison with acidic ZSCs, alkali-modified ZSCs by KOH was more effective and enhanced the removal efficiency of ZSCs. Using Langmuir isotherm, the maximum adsorption capacity on the modified ZSCs for Pb(II) was 9.06 mg/g, for Zn(II) obtained by using ZSC–citric acid was 4.19 mg/g and 5.38 mg/g for Cd(II) as obtained by using ZSC–H2O2. The molecular electrostatic potential, which was calculated at B3LYP/6-31G(d,p), indicated that each metal is di-hydrated, forming a complex with two units of amino acids. This mechanism demonstrated the uptake process by ZSCs.

Pb(II) Ion Removal Potential in Chemically Modified Ziziphus joazeiro Barks

“…Analyzing the FT-IR spectrum, the peak of 3360.04 cm −1 was shifted to 3401.63 cm −1 , with a significant increase in intensity and width after the alkaline treatment. These peaks are commonly associated with intra- and intermolecular -OH stretching vibration from cellulose, lignin and hemicellulose [ 81 ], in addition to saponins [ 82 ]; such behavior was also observed in the treatment performed by [ 12 , 83 ]. The 2933.33 cm −1 peak referring to the stretching of the C-H bonds of the hydrocarbons became more discreet, while those in the 1200 to 1500 cm −1 range showed a number of peaks and a reduction in width.…”

“…The peak of 1606.20 cm −1 can be associated with the structure of the aromatic compounds probably from the lignin structure [ 50 , 84 ], suggesting the permanence of its structure after alkalinization. Similarly, it occurred at 1730.95 cm −1 in the C=O stretches related to carboxylic groups, such as carboxylic and ester [ 12 , 39 , 85 ].…”

“…The peak of 1036.65 cm −1 refers to the C-O stretches of holocellulose and lignin [ 81 ], which may come from ether and phenol [ 12 ], or the carboxylic and alcohol groups [ 86 ], and can also be attributed to the linkage absorption C-O-C [ 87 ] to oligosaccharide present in the structure of saponin [ 27 , 88 ], assuming that this substance has not been completely removed by contact with 0.5 N NaOH, as the alkaline treatment generally induces extensive modifications in the polysaccharides [ 89 , 90 ]. After contact with Pb(II) ions, the enlargement and increase in intensity of this region can be noticed.…”

“…Among many vegetal options, the genus Ziziphus is still discreetly explored, due to its medicinal and cosmetic benefits, but it still shows promising results. A brief literary survey points out six leading species of adsorptive studies, namely: Ziziphus spina-christi L. [ 11 , 12 , 13 , 14 , 15 ]; Ziziphus mauritiana , Ziziphus jujube or Zizipus jujuba [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]; Ziziphus lotus [ 23 , 24 , 25 , 26 ] and Ziziphus vulgaris [ 27 ].…”

Comparison of the Effect Aqueous Extract and Nano-Sidr Synthetic of Leaves Ziziphus Spina-christi with Silver Nanoparticles the on Biofilm of Local Isolates of Staphylococcus. Spp

“…The same method has been used, and that Sidr plant possesses functional groups similar to curcumin. These functional groups are linked with other compounds through a unique hydrogen bond [27]. Sidr leaves contain secondary anti-bacterial and anti-inflammatory metabolic compounds such as alkaloids, flavonoids, sapogenins, saponins and tannins.…”