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.
En vi ron men tal pro tec tion must re quire the use of nat u ral prod ucts in stead of chem i cals to min i mize pollu tion. Thus, this in ves ti ga tion stud ies the use of some plant flow ers as nat u rally oc cur ring acid-base in di cators. We uti lized plant flow ers of Celosia cris tate Linn, Bombax ceiba L., Poin ci ana regia and Hi bis cus subdariffa. These flow ers con tain anthocyanine pig ments whose col our de pends on pH; there fore they are used as pH in di ca tors. The acid-base equi lib ria of these pig ments were in ves ti gated us ing spec tro pho to met ric and potentiometric meth ods. The pk val ues are 9.6 for Celosia cris tate Linn, 5.7 for Bombax ceiba L., 8.6 for Poin ci ana regia and 2.8 & 7.3 for Hi bis cus subdariffa. Ex per i men ta tion of these in di ca tors on dif fer ent concen tra tions of acid-base ti tra tions in the pres ence of vari able con cen tra tions ex hib ited sim i lar re sults as for syn thetic in di ca tors.
IN TRO DUC TIONUse ful ness of plants re fers to whether they can be used as food and me dic i nal drugs for man, for age for an i mals, timber for build ing and fire wood for heat ing and cook ing. In addi tion to these ad van tages, plants can be used for other purposes. The aim of this study is to use some plant flow ers as nat u rally oc cur ring acid-base in di ca tors. These plants are Celosia cris tate Linn (AMARANTHACEAE), Bombacace sep. (BOMBACACEAE), Poin ci ana regia (LEGUMINOSAE), and Hi bis cus subdriva (MALVACEAE). The eco nomic uses of these plants are as gar den ornamentals and potherbs, used lo cally in Af rica, sources of dyes and tim ber, 1 and as me dic inal plants and drink. In Egypt, the wa ter ex tract of Hi bis cus subdriva is used as a hot or cold drink. The plant flow ers contain anthocyanine, 1,2 i.e., a pig ment usu ally re spon si ble for pink, red, pur ple, vi o let and blue colours in flow er ing plants. The dyes ex tracted from the flower of these plants change their colours ac cord ing to the hy dro gen ion con cen tra tion of the so lu tion. There fore, they may be uti lized as acid-base indi ca tors. The chief char ac ter is tic of the pH in di ca tors is that the col our change from a pre dom i nantly al ka line col our is not sud den but takes place within in ter vals of pH termed the colour-change in ter vals of in di ca tor. 3 The po si tion of the colour-change in ter vals in the pH scale var ies widely with differ ent in di ca tors. The in di ca tor is weak acid (or base) and their equi lib ria in aque ous so lu tion may writ ten as fol lows: 3
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