Treatment of biodiesel wastewater by adsorption with commercial chitosan flakes: parameter optimization and process kinetics

A scientometric analysis and recent advances of emerging chitosan-based biomaterials as potential catalyst for biodiesel production: A review

Chitosan is a widely available polymer with a reasonably high abundance, as well as a sustainable, biodegradable, and biocompatible material with different functional groups that are used in a wide range of operations. Chitosan is frequently employed in widespread applications such as environmental remediation, adsorption, catalysts, and drug formulation. The goal of this review is to discuss the potential applications of chitosan and its chemically modified solids as a catalyst in biodiesel production. The existing manuscripts are integrated based on the nature of materials used as chitosan and its modifications. A short overview of chitosan's structural characteristics, properties, and some ideal methods to be considered in catalysis activities are addressed. This article includes an analysis of a chitosan-based scientometric conducted between 1975 and 2023 using VOS viewer 1.6.19. To identify developments and technological advances in chitosan research, the significant scientometric features of yearly publication results, documents country network, co-authorship network, documents funding sponsor, documents institution network, and documents category in domain analysis were examined. This review covers a variety of organic transformations and their effects, including chitosan reactions against acids, bases, metals, metal oxides, organic compounds, lipases, and Knoevenagel condensation. The catalytic capabilities of chitosan and its modified structures for producing biodiesel through transesterification reactions are explored in depth.

Treatability of biodiesel wastewaters by using KMnO4 and KMnO4/O3 processes and kinetic analysis

This study aims to investigate the treatability of electrocoagulated biodiesel wastewater (ECBD) by KMnO₄ and KMnO₄/O₃ processes. The ECBD removal efficiencies of both KMnO₄/O₃ and KMnO₄ methods were compared, and the COD and MeOH removal efficiencies with the KMnO₄/O₃ process gave better results than the KMnO₄ process. For the ECBD removal efficiencies, the experimental parameters including pH, KMnO₄ dose, O₃ dose and reaction time were optimized by changing one parameter at a time. As a result of 6 h of KMnO₄ oxidation, 91.74% of COD and 95.93% of MeOH removal was achieved under the optimum conditions. However, the COD and MeOH removal efficiencies have been obtained under optimum conditions for KMnO₄/O₃ as 97.79% and 98.30%, respectively. The second-order kinetic model has been found to be the most suitable model for both processes and the R² has been found as 0.999 and 0.999 for KMnO₄ and KMnO₄/O₃, respectively. The reaction k has also been calculated as 6 × 10^-5 L·mg^-1·min^-1 and 1.63 × 10^-4 L·mg^-1·min^-1 for COD and MeOH in KMnO₄ oxidation, respectively. Furthermore, the k has also been calculated as 6 × 10^-5 L·mg^-1·min^-1 and 1.6 × 10^-4 L·mg^-1·min^-1 for COD and MeOH in KMnO₄/O₃ oxidation, respectively.

Efficient removal of nitrogen and phosphorus in aqueous solutions using modified water treatment residuals-sodium alginate beads

A high-performance sorbent, modified water treatment residuals-sodium alginate beads (WTR-SA beads), was prepared through a series of salt and combined thermal roasting composite modification between water treatment residuals and sodium alginate. The properties of modified WTR-SA beads composites were characterized by SEM-EDS, FT-IR, XRD, and BET. The adsorption performance of WTR-SA beads was investigated in removing nitrogen and phosphorus from wastewater. Compared to the unmodified WTR, the removal efficiency of nitrogen and phosphorus onto the modified WTR-SA beads was increased from 22.34 and 77.13% to 95.14 and 98.31%, respectively. The adsorption capacities of nitrogen and phosphorus onto the modified WTR-SA beads were reach a maximum of 2.52 mg/g and 6.45 mg/g, respectively. The adsorption behavior can be well described using a quasi-second-order kinetic model and Langmuir isotherm model. The thermodynamic properties of nitrogen adsorption indicated that the adsorption was spontaneous and exothermic. On the contrary, the adsorption process of phosphorus is an endothermic reaction. The adsorption of nitrogen by modified WTR-SA beads is mainly carried out through ion exchange and hydroxyl complexation, and ion exchange plays a major role in it. While, the adsorption of modified WTR-SA beads on phosphorus is affected by three actions: ligand exchange, chemical precipitation, and ion exchange, which ligand exchange is the main effect. Based on these results, it can be concluded that the modified WTR-SA beads are a high efficiency adsorbent for removing nitrogen and phosphorus from domestic and industrial wastewater.

A comprehensive review on the applications of functionalized chitosan in petroleum industry

The biomaterials have gained the attention for utilization as sustainable alternatives for petroleum-derived products due to the rapid depletion of petroleum resources and environmental issues. Chitosan is an economical, renewable and abundant polysaccharide having unique molecular characteristics. Chitosan is derived by deacetylation of chitin, a natural polysaccharide existing in insects' exoskeleton, outer shells of crustaceans, and some fungi cell walls. Chitosan is widely used in numerous domains like agriculture, food, water treatment, medicine, cosmetics, fisheries, packaging, and chemical industry. This review aims to account for all the efforts made towards chitosan and its derivatives for utilization in the petroleum industry and related processes including exploration, extraction, refining, transporting oil spillages, and wastewater treatment. This review includes a compilation of various chemical modifications of chitosan to enhance the petroleum field's performance and applicability.

Different strategies for the lipase immobilization on the chitosan based supports and their applications

Immobilized enzymes have received incredible interests in industry, pharmaceuticals, chemistry and biochemistry sectors due to their various advantages such as ease of separation, multiple reusability, non-toxicity, biocompatibility, high activity and resistant to environmental changes. This review in between various immobilized enzymes focuses on lipase as one of the most practical enzyme and chitosan as a preferred biosupport for lipase immobilization and provides a broad range of studies of recent decade. We highlight several aspects of lipase immobilization on the surface of chitosan support containing various types of lipase and immobilization techniques from physical adsorption to covalent bonding and cross-linking with their benefits and drawbacks. The recent advances and future perspectives that can improve the present problems with lipase and chitosan such as high-price of lipase and low mechanical resistance of chitosan are also discussed. According to the literature, optimization of immobilization methods, combination of these methods with other techniques, physical and chemical modifications of chitosan, co-immobilization and protein engineering can be useful as a solution to overcome the mentioned limitations.

Pristine and modified chitosan as solid catalysts for catalysis and biodiesel production: A minireview

Chitosan is one of the readily available polymers with relatively high abundance, biodegradable and sustainable materials with divergent functional groups that are employed in broad range of applications. Chitosan is widely used in many fields like adsorption, drug carrier for therapeutic activity, environmental remediation, drug formulation and among others. One of the unique features of chitosan is that it can be transformed to other forms like beads, films, flakes, sponges and fibres depending upon the applications. This review is aimed at showing the potential applications of chitosan and its modified solids in organic transformations. The number of existing articles is organized based on the nature of materials and subsequently with the types of reactions. After a brief description on the structural features of chitosan, properties, characterization methods including various analytical/microscopic techniques and some of the best practices to be followed in catalysis are also discussed. The next section of this review describes the catalytic activity of native chitosan without any modifications while the subsequent sections provide the catalytic activity of chitosan derivatives, chitosan covalently modified with metal complexes/salts through linkers and chitosan as support for metal nanoparticles (NPs). These sections discuss number of organic reactions that include Knoevenagel condensation, oxidation, reduction, heterocycles synthesis, cross-coupling reactions and pollutant degradation among others. A separate section provides the catalytic applications of chitosan and its modified forms for the production of fatty acid methyl esters (FAME) through esterification/transesterification reactions. The final section summarizes our views on the future directions of this field in the coming years.

Sustainable and green approach of chitosan production from Penicillium citrinum biomass using industrial wastewater as a cheap substrate

Marine sources especially crustaceans have been extensively used worldwide for the production of chitosan. However, limited availability as well as variations in the properties of the derived chitosan is a serious drawback of utilizing marine sources for chitosan production. This study investigated sustainable and green approach of fungal chitosan production using paper mill wastewater as a cheap and easily available substrate. The fungus Penicillium citrinum IITG_KP1 used in this study was initially isolated from an infected bamboo shoot. Addition of acetic acid at low levels led to a 150% increase in the yield of chitosan from 95 g/kg to 138 g/kg of dry fungal biomass. This result correlated well with an increase in xylose uptake rate due to acetic acid addition that was confirmed by enhanced activity of xylose reductase (XR) and xylitol dehydrogenase (XDH) enzymes in the presence of acetic acid. Very high COD removal efficiency (75%) along with 70% phenolic reduction and 84% decolourization efficiency of the raw paper mill wastewater without any prior pre-treatment was further achieved by carrying out the fungal fermentation using a bioreactor under batch mode of operation. The fungal chitosan showed properties comparable with those of a commercially available standard.

Optimal Hydrogen Production Coupled with Pollutant Removal from Biodiesel Wastewater Using a Thermally Treated TiO₂ Photocatalyst (P25): Influence of the Operating Conditions

This work aimed to produce hydrogen (H₂) simultaneously with pollutant removal from biodiesel wastewater by photocatalytic oxidation using a thermally-treated commercial titanium dioxide (TiO₂) photocatalyst at room temperature (~30 °C) and ambient pressure. The effects of the operating conditions, including the catalyst loading level (1-6 g/L), UV light intensity (3.52-6.64 mW/cm²), initial pH of the wastewater (2.3-8.0) and reaction time (1-4 h), on the quantity of H₂ production together with the reduction in the chemical oxygen demand (COD), biological oxygen demand (BOD) and oil and grease levels were explored. It was found that all the investigated parameters affected the level of H₂ production and pollutant removal. The optimum operating condition for simultaneous H₂ production and pollutant removal was found at an initial wastewater pH of 6.0, a catalyst dosage of 4.0 g/L, a UV light intensity of 4.79 mW/cm² and a reaction time of 2 h. These conditions led to the production of 228 μmol H₂ with a light conversion efficiency of 6.78% and reduced the COD, BOD and oil and grease levels by 13.2%, 89.6% and 67.7%, respectively. The rate of pollutant removal followed a pseudo-first order chemical reaction with a rate constant of 0.008, 0.085 and 0.044 min^-1 for the COD, BOD and oil and grease removal, respectively.