Rapidly regenerated CNC/TiO2/MnO2 porous microspheres for high-efficient dye removal

Utilization of battery waste derived ZnO in the removal of dye from aqueous solution: A waste to wealth approach

Every year a huge amount of zinc carbon batteries is discarded as waste and the management of such waste has become a growing concern all over the world. However, from these waste carbon batteries different kinds of valuable materials could be recovered. On the other hand, different industries discharged large volumes of dye wastewater into the environment which has a profound impact on environment and as well as human health. In this study, ZnO was recovered from the waste carbon batteries through pyrometallurgy process and utilized it for the treatment of methylene blue and methyl orange dye water. The batch adsorption process was carried out to observe the effect of adsorbent dosage, pH, contact time, stirring speed and temperature. Under the obtained optimal conditions adsorption kinetics (Pseudo-first order and pseudo-second order) and adsorption isotherms (Langmuir, Freundlich and Temkin) were analyzed. The results disclosed that 0.5 g and 0.6 g of ZnO showed maximum removal efficiency for MB and MO dye solution (50 ppm) whereas pH 13 and 6 were the optimal for MB and MO respectively. Kinetic studies indicate that both the adsorption processes were pseudo-second order. It was also revealed that based on regression coefficient R2 value the adsorption of MB and MO on ZnO is followed Langmuir model. Furthermore, the findings revealed that the MO adsorption on ZnO is a chemical adsorption process and MB adsorption is a physical adsorption process.

Multi-functional nanocellulose based nanocomposites for biodegradable food packaging: Hybridization, fabrication, key properties and application

Nowadays, non-degradable plastic packaging materials have caused serious environmental pollution, posing a threat to human health and development. Renewable eco-friendly nanocellulose hybrid (NCs-hybrid) composites as an ideal alternative to petroleum-based plastic food packaging have been extensively reported in recent years. NCs-hybrids include metal, metal oxides, organic frameworks (MOFs), plants, and active compounds. However, no review systematically summarizes the preparation, processing, and multi-functional applications of NCs-hybrid composites. In this review, the design and hybridization of various NCs-hybrids, the processing of multi-scale nanocomposites, and their key properties in food packaging applications were systematically explored for the first time. Moreover, the synergistic effects of various NCs-hybrids on several properties of composites, including mechanical, thermal, UV shielding, waterproofing, barrier, antimicrobial, antioxidant, biodegradation and sensing were reviewed in detailed. Then, the problems and advances in research on renewable NCs-hybrid composites are suggested for biodegradable food packaging applications. Finally, a future packaging material is proposed by using NCs-hybrids as nanofillers and endowing them with various properties, which are denoted as "PACKAGE" and characterized by "Property, Application, Cellulose, Keen, Antipollution, Green, Easy."

Modified alginate materials for wastewater treatment: Application prospects

Sodium alginate is a natural macromolecule widely used because of its abundance, low cost of acquisition, and rich hydroxyl and carboxyl groups in the matrix. The physical modification of sodium alginate can be made by blending it with polymer materials. The so-yielded alginate complex is commonly unstable in an aqueous environment due to alginate backbones' high hydrophilicity. The chemical modification can remove its hydrophilic groups and introduce special functional groups or polymers onto the alginate backbones to provide excess reaction sites for specific reactions and effective complexation sites for accommodating antibiotics, dyes, heavy metal ions, and radioactive elements. Sodium alginate has been used in water treatment engineering under revised modification protocols. This article also reviews the latest modification protocols for sodium alginate and outlines the novel application of the modified materials. The limitations of modified sodium alginate materials are described, and research prospects are put forward.

Recent advances in biopolymer-based advanced oxidation processes for dye removal applications: A review

Over the past few years, synthetic dye-contaminated wastewater has attracted considerable global attention due to the low biodegradability and the ability of organic dyes to persist and remain toxic, causing numerous health and environmental concerns. As a result of the recalcitrant nature of those complex organic dyes, the remediation of wastewater using conventional wastewater treatment techniques is becoming increasingly challenging. In recent years, advanced oxidation processes (AOPs) have emerged as a potential alternative to treat organic dyestuffs discharged from industries. The most widely employed AOPs include photocatalysis, ozonation, Fenton oxidation, electrochemical oxidation, catalytic heterogeneous oxidation, and ultrasound irradiation. These processes involve the generation of highly reactive radicals to oxidize organic dyes into innocuous minerals. However, many conventional AOPs suffer from several setbacks, including the high cost, high consumption of reagents and substrates, self-agglomeration of catalysts, limited reusability, and the requirement of light, ultrasound, or electricity. Therefore, there has been significant interest in improving the performance of conventional AOPs using biopolymers and heterogeneous catalysts such as metal oxide nanoparticles (MONPs). Biopolymers have been widely considered in developing green, sustainable, eco-friendly, and low-cost AOP-based dye removal technologies. They inherit intriguing properties like biodegradability, renewability, nontoxicity, relative abundance, and sorption. In addition, the immobilization of catalysts on biopolymer supports has been proven to possess excellent catalytic activity and turnover numbers. The current review provides comprehensive coverage of different AOPs and how efficiently biopolymers, including cellulose, chitin, chitosan, alginate, gelatin, guar gum, keratin, silk fibroin, zein, albumin, lignin, and starch, have been integrated with heterogeneous AOPs in dye removal applications. This review also discusses the general degradation mechanisms of AOPs, applications of biopolymers in AOPs and the roles of biopolymers in AOPs-based dye removal processes. Furthermore, key challenges and future perspectives of biopolymer-based AOPs have also been highlighted.