Removal of Heavy Metal Ions from Wastewater with Poly-ε-Caprolactone-Reinforced Chitosan Composite

Currently, the requirements for adsorbent materials are based on their environmentally friendly production and biodegradability. However, they are also related to the design of materials to sustain many cycles in pursuit of low cost and profitable devices for water treatments. In this regard, a chitosan reinforced with poly-ε-caprolactone thermoplastic composite was prepared and characterized by scanning electron microscopy; Fourier transforms infrared spectroscopy, X-ray diffraction analysis, mechanical properties, as well as erosion and swelling assays. The isotherm and kinetic data were fitted with Freundlich and pseudo-second-order models, respectively. The adsorption equilibrium capacities at pH 6 of Zn(II), Cu(II), Fe(II), and Al(III) were 165.59 ± 3.41 mg/g, 3.91 ± 0.02 mg/g, 10.72 ± 0.11 mg/g, and 1.99 ± 0.22 mg/g, respectively. The adsorbent material lost approximately 6% of the initial mass in the adsorption-desorption processes.

Facile synthesis and application of cellulosic coagulant from banana peels in cadmium-spiked water

Cellulosic coagulant with low crystallinity and surface charge of -19.2 mV were extracted from wet banana peels (WBE) using kitchen-blending method. Functionalization with ferric chloride and aluminium chloride yielded higher surface charge of -23.8 mV (mWBE). Both WBE and mWBE coagulants were used to target cadmium ions from aqueous solution. Coagulants and the floccules (WBEA and mWBEA) were characterized by XRD, FT-IR, zeta sizer nano series, and SEM/EDs. The amount of cadmium ion coagulated was determined using ICP-OES. The FTIR analysis revealed the functional groups involved in the coordination and subsequent removal of the metals ions around 1634 cm-1, ascribed to the C = O vibrational band of carbonyl group. Microscopic analysis revealed that the mWBE is porous and exhibited microfibers with rod-like morphology. The effects of parameters such as the initial concentration, coagulant dosage and solution pH were investigated. Coagulation results showed that 10 mg of WBE and mWBE could remove about 80% and 90% of the Cd2+ ions respectively. However; the difference in the performance of both materials does not justify the essence of surface modification. Therefore, WBE is considered more efficient and environmentally friendly. Notwithstanding, the performance of these coagulants in real environmental samples will confirm their robustness.

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

Materials coming from renewable resources have drawn recently an increased attention in various applications as an eco-friendly alternative in the synthesis of novel functional materials. Polysaccharides, with their prominent representative - chitosan (CS), are well-known for their sorption properties, being able to remove metal ions from dilute solutions either by electrostatic interactions or chelation. In this context, we proposed here a comparative study on Cu2+, Zn2+, Ni2+, Fe3+, and Cr3+ metal ions removal from industrial wastewaters by CS-based composite cryogels using batch technique. The composite cryogels consisting of CS embedding a natural zeolite, namely clinoptilolite, were synthesized by cryogelation, and their sorption performance were compared to those of CS cryogels and of acid-activated zeolite. A deeper analysis of thermodynamics and kinetics sorption data was performed to get insights into the sorption mechanism of all metal ions onto sorbents. Based on the optimized sorption conditions, the removal of the above-mentioned ions from aqueous solutions by the composite sorbent using dynamic technique was also evaluated.

Unmodified starch as water-soluble binding polymer for chromium ions removal via polymer enhanced ultrafiltration system

BACKGROUND

In this study the removal of Chromium (III) and Chromium (VI) ions are investigated via polymer enhanced ultrafiltration under important process parameters. This study proposes the use of unmodified starch as a novel polymer in the ultrafiltration process and its performance on the removal of chromium ions was compared with a commonly used polymer, polyethylene glycol.

METHODS

The experiments were carried out at 1.5 bar and different pH values by using 10 kDa hollow fiber membrane operating in a cross-flow mode.

RESULTS

The best chromium ions removal obtained approached 99% for Chromium (III) ion by unmodified starch at alkaline pH region and at pH 7 for Chromium (VI) ions retention by polyethylene glycol. Permeate flux behavior are fluctuated for both chromium ions tested at high metal ion concentrations. Low concentration of unmodified starch is applied to reduce gelatinization behavior.

CONCLUSIONS

The findings suggest that binding of chromium ions by unmodified starch is related to granule structure which is probably a principal indicator of the non-ionic behavior of unmodified starch.