Pitahaya Fruit (Hylocereus spp.) Peels Evaluation for Removal of Pb(II), Cd(II), Co(II), and Ni(II) from the Waters

Manganese dioxide decorated kiwi peel powder for efficient removal of lead from aqueous solutions, blood and Traditional Chinese Medicine extracts

For human health and environment safety, it is of great significance to develop novel materials with high effectiveness for removal of lead from not only aqueous solutions but also human body and traditional Chinese medicines. Here, functional kiwi peel composite, manganese dioxide decorated kiwi peel powder (MKPP), is proposed for the removal of Pb2+ effectively. The adsorption of Pb2+ in aqueous solution is a highly selective and endothermic process and kinetically follows a pseudo-second-order model, which can reach equilibrium with the capacity of 192.7 mg/g within 10 min. Comprehensive factors of hydration energy, charge-to-radius ratio and softness of Pb2+ make a stronger affinity between MKPP and Pb2+. The possible adsorption mechanism involves covalent bond, electrostatic force and chelation, etc. MKPP can be efficiently regenerated and reused with high adsorption efficiency after five cycles. Besides, MKPP can remove over 97% of Pb2+ from real water samples. MKPP can also alleviate lead poisoning to a certain extent and make the Pb level of TCM extract meet the safety standard. This work highlights that MKPP is a promising adsorbent for the removal of Pb2+ and provides an efficient strategy for reusing kiwi peel as well as dealing with the problem of Pb pollution.

Remediation of Methyl Red Dye from Aqueous Solutions by Using Biosorbents Developed from Floral Waste

The disposal of biological waste into water bodies is a major global concern as it leads to water pollution resulting in the loss of plenty of revenue in the cleaning of water bodies. Here, in the present research work, sacred flowers were collected, segregated, sun-dried, and powdered. The dried floral powders (marigold and rose) were characterized by field emission scanning electron microscopy (FESEM), electron diffraction spectroscopy (EDS), Fourier transforms infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The microscopy revealed the irregular spherical shape of the sheet-like structure whose size varies in microns. The EDS revealed the elemental composition which was dominated by mainly carbon and oxygen. The XRD shows the presence of carbon (10-25ɵ) in the amorphous form and the absence of any crystalline phase in the biosorbents. The FT-IR showed peaks that conformed to the presence of functional groups like -OH and a carbonyl group. The dried powders were used as an economical and eco-friendly biosorbent for the removal of methyl red (MR) dye from the aqueous solutions by batch adsorption study. After 60 minutes of contact time, the marigold powder (MGP) and rose petal powder (RPP) showed decolorization of 61.16% and 56.08% for 2 ppm of MR dye. The kinetic revealed that the dye removal reaction does not follow the pseudo-first-order as well as the pseudo-second-order. The utilization of such waste-based biosorbents will minimize solid waste and also will provide an economical biosorbent for the removal of environmental pollutants.

Green Nanoparticle-Aided Biosorption of Nickel Ions Using Four Dry Residual Biomasses: A Comparative Study

The green synthesis of titanium dioxide nanoparticles was performed using the sol-gel method for their use in the modification of several agricultural biomasses (orange, lemon, cassava and yam peels) to evaluate the enhancement of adsorption capacity. To this end, different particle sizes (0.355, 0.5 and 1.0 mm) and initial solution pHs (2, 4 and 6) were assessed to identify the optimum conditions for further experimentation with the selected lignocellulosic materials. The defined conditions reporting the highest removal yields were used to perform adsorption experiments for chemically modified biosorbents. The biomaterials were characterized via elemental and bromatological analysis in order to quantify their composition. After the incorporation of TiO2 nanoparticles, the resulting biosorbents were characterized via FT-IR and SEM techniques. The results revealed that the pH solution significantly affects the nickel ion uptake, reaching the best performance at pH = 6 for all biomasses. Unmodified biomasses shown adsorption capacities between 18–20 mg/g. For chemically modified with TiO2 orange peels and yam peels biomass, the increase in adsorption capacities was 21.3 and 18.01 mg/g, respectively. For cassava and lemon peels chemically modified, it was found the increasing in adsorption capacities with values of 21.3 and 18.01 mg/g, respectively, which suggested that the incorporation of nanoparticles enhances adsorption capacities.