Comparative study for removal of cationic and anionic dyes using alginate-based hydrogels filled with citric acid-sawdust/UiO-66-NH2 hybrid.

Nowadays, a big challenge is developing a sustainable and effective method for removing contaminants like dyes from aqueous solutions. In this regard, Zr-based metal-organic framework (UiO-66-NH2) and sawdust as the ideal adsorbents were used. Due to their low separation in adsorption processes, embedding into alginate and obtaining composite beads are suggested as a suitable strategy. The achieved Ca-alginate/citric acid (CA)-sawdust/UiO-66-NH2 hydrogel beads were used to compare cationic and anionic dyes removal. This sorbent indicated an excellent selectivity for removing methylene blue versus methyl orange in a binary system. pH = 6, adsorbent amount = 80 mg, methylene blue concentration = 10 mg/L, and contact time = 420 min were achieved as optimal parameters on methylene blue adsorption with an adsorption capacity of about 26 mg/g. The removal process of methylene blue followed linear Freundlich isotherm and nonlinear pseudo-2nd-order kinetic models. The regeneration test demonstrated methylene blue removal efficiency higher than about 89 % after 9 cycles. According to the outcomes, methylene blue could be attached to the adsorbent surface through the electrostatic, hydrogen bonding, and π-π interactions of the aromatic rings. These results confirm the potential of Ca-alginate/CA-sawdust/UiO-66-NH2 hydrogel beads as a selective bio-sorbent for cationic dye removal.

Metal ion chelation of poly(aspartic acid): From scale inhibition to therapeutic potentials.

Poly(aspartic acid) (PASP) is a biodegradable, biocompatible water-soluble synthetic anionic polypeptide. PASP has shown a strong affinity and thus robust complexation with heavy and alkaline earth metal ions, from which several applications are currently benefiting, and several more could also originate. This paper discusses different areas where the ion chelation ability of PASP has thus far been exploited. Due to its calcium chelation ability, PASP prevents precipitation of calcium salts and hence is widely used as an effective scale inhibitor in industry. Due to potassium chelation, PASP prevents precipitation of potassium tartrate and is employed as an efficient and edible stabilizer for wine preservation. Due to iron chelation, PASP inhibits corrosion of steel surfaces in harsh environments. Due to chelation, PASP can also enhance stability of various colloidal systems that contain metal ions. The chelation ability of PASP alleviated the toxicity of heavy metals in Zebrafish, inhibited the formation of kidney stones and dissolved calcium phosphate which is the main mineral of the calcified vasculature. These findings and beyond, along with the biocompatibility and biodegradability of the polymer could direct future investigations towards chelation therapy by PASP and other novel and undiscovered areas where metal ions play a key role.

Bio-sorbent alginate/citric acid-sawdust/Fe3O4 nanocomposite beads for highly efficient removal of malachite green from water.

Sawdust is a by-product of wood-related industries with striking features for pollutant uptake. For the first time in the current study, sustainable magnetic alginate composite beads containing citric acid-modified sawdust (CA-sawdust) as a bio-waste and Fe3O4 nanoparticles were designed. This novel eco-friendly composite (Alginate/CA-sawdust/Fe3O4 beads) was successfully applied to remove cationic malachite green (MG). Easy separation under a magnetic field and reusability could be mentioned as two significant properties of this bio-sorbent. The removal percentage of MG using alginate/CA-sawdust/Fe3O4 beads was calculated to be 90-95 %. This process was well-described with Langmuir isotherm and nonlinear pseudo-first-order kinetic models. Moreover, both film and intraparticle diffusion models were found to be probable removal mechanisms.

Single-Atoms on Covalent or Metal-Organic Frameworks: Current Findings and Perspectives for Pollutants Abatement, Hydrogen Evolution, and Reduction of CO2.

Nowadays, attention to single-atoms and also porous structures like metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) for the preparation of high-performance material is expanding rapidly. These dazzling materials with unprecedented properties have lots of applications, especially as promising catalysts for organic pollutants abatement, hydrogen evolution, reduction of CO2, etc. To provide an in-depth understanding, in this mini-review, we begin with a brief description and a general background about single-atoms, COFs, as well as MOFs. After considering some fundamentals, the synergism effects, advantages, and their applications are discussed.

Sawdust, a versatile, inexpensive, readily available bio-waste: From mother earth to valuable materials for sustainable remediation technologies.

Sawdust or wood shaving is a relatively abundant and inexpensive lignocellulosic compound, which is provided by mother nature. It is a waste of industry and agriculture, that is found in large quantities and has disposal problems. Nowadays, waste management (like sawdust) and research on converting it to different compounds for special applications and goals have been receiving tremendous attention. So, introducing sawdust as a kind of interesting bio-waste and turn it into wealth for diverse utilizations can be mentioned as the main goal of this overview. In this regard, in the first part, sawdust structure and properties are considered. It is then followed by highlighting its wide applications in sustainable water remediation technology, production of activated carbon, oil-water separation, and high-performance composites fabrication. Please come on to start a journey on this motivating topic.

A journey to the world of fascinating ZnO nanocomposites made of chitosan, starch, cellulose, and other biopolymers: Progress in recent achievements in eco-friendly food packaging, biomedical, and water remediation technologies.

Green chemistry or in other words "green world" is referred to a sustainable environment using biocompatible, biodegradable, renewable, economical, and simple materials, and methods. Without any exaggeration, the exceptional chemical and physical properties of ZnO bionanocomposites beside various utilizations, make it vital materials in research and green chemistry field. Biocompatible ZnO nanoparticles with fascinating antimicrobial, physicochemical, as well as photocatalytic performance could be applied as a prominent candidate to reinforce diverse biopolymer matrixes, for instance, chitosan, starch, cellulose, gelatin, alginate, poly(hydroxyalkanoates), carrageenan, and so on. With a combination of advantageous properties of these materials, they could be illustrated specific utilizations in different areas. In this regard, the following context focuses on highlighting the recent achievements of this category of material on three important and widely used scopes: eco-friendly food packaging, biomedical specially wound dressings, and water remediation technologies.