No abstract

The work shown in this article demonstrate a novel example of converting olive industry solid waste (OISW) into a magnetic cellulose nanocrystalline (MNCs) to serve as selective magnetic sorbents for methylene blue. Olive industry solid waste contains about 40% cellulose. The cellulose was extracted in a powder form from olive industry solid waste by subjecting it to a multistep pulping and bleaching process. The extracted powder cellulose was then converted to nanocrystalline cellulose (NCs) by acid hydrolysis. The NCs were then treated with a solution of FeCl.6HO, FeSO, and HO by a colloidal suspension method which produced free-flowing porous MNCs. The produced MNCs are characterized by several spectroscopic and analytical techniques such as SEM, TEM, XRD, FTIR VSM, and TGA. The efficiency of the three polymers cellulose powder, NCs, and MNCs toward extracting methylene blue (MB) from water was evaluated. Cellulose powder and NCs showed acceptable tendency for methylene blue. However, MNCs showed excellent extraction efficiency toward MB. The thermodynamic studies revealed a spontaneous adsorption of MB by MNCs at various temperatures. The spontaneous adsorption could be attributed to the electrostatic interaction and H-bonding between MNCs and MB. However, the interaction between cellulose, NCs, and MB is limited to the H-bonding.

No abstract

No abstract

No abstract

Natural based composites of hydroxyapatite/Gum Arabic designed for removal of toxic metal arsenic (III) from waste water were synthesized and evaluated. Several composites with various compositions were prepared by the wet chemical method and analyzed using various spectroscopic and analytical methods such as: Fourier transform infrared spectroscopy, total organic carbon production, XRD analysis and scanning electron microscope. The rates of weight loss and water absorption of the HAp/GA composites as a function of time were evaluated in phosphate-buffered saline solution at 37 °C and a pH of 7.4. The effects of several variables on adsorption of arsenic (III) by HAp/GA composites were evaluated. The variables include arsenic (III) concentration, contact time (t) and complex surface nature of HAp/GA composite. Three surface complexation models were used to study the mechanisms controlled the adsorption. The models were Langmuir, Freundlich and Dubinin Radushkevich. The adsorption kinetic of arsenic (III) on the composite surface was described by three modes: pseudo first order, pseudo second order and the intra particle diffusion. The results revealed that, the rate of adsorption of arsenic (III) by HAp/GA composites was controlled by two main factors: the initial concentration of arsenic (III) and the contact time. The kinetic studies also showed that, the rate of adsorption is a second order. The results indicate that, composite offered in this study could be a valuable tool for removing toxic metals for contaminated water by adsorption.Graphical abstract.

Abstract:The adsorption of chromate on octacalcium phosphate (OCP) was investigated as a function of contact time, surface coverage, and solution pH. The ion exchange method was adapted to establish the interaction mechanism. Stoichiometry exchange of H + /OH − was evaluated at a pH range of 3-10, and obtained values ranged between 0.0 and 1.0. The surface complexes formed between chromate and OCP were found to be > S(HCrO 4 ) and > S(CrO 4 ). The logarithmic stability constant logK 1-1 , and the logK 10 values of the complexes, were 6.0 in acidic medium and 0.1 in alkaline medium, respectively. At low pH and low surface coverage, the bidentate species > S(HCrO 4 ) 2 with logK 10.5 of about 2.9, was favored at a hydration time of less than 150 min. The contribution of an electrostatic effect to the chromium uptake by the OCP sorbent, was also evaluated. The results indicate that the adsorption of chromate on OCP is of an electrostatic nature at a pH ≤ 5.6, and of a chemical nature at a pH > 5.6.

No abstract