## 1 Introduction  
Dyes are heavily used in industry to color fibers, textiles, leather, paper, and other products. Reactive dyes are the most popular choice due to their long shelf-life and considerable versatility [1]. However, up to 50% of the dyes can be left in the effluent due to processing limitations [2]. Colored wastewater can exert a number of adverse environmental effects if discharged untreated into natural water bodies [3]. Dyes can significantly reduce the transparency of water, even at concentrations as low as a few mg/L. The resultant blockage of sunlight affects aquatic plants and can inhibit the primary production process [4]. Colorants also limit the diffusion of atmospheric oxygen in water, which, combined with the inhibition of photosynthesis, may lead to the deoxygenation of water bodies. Moreover, dyes tend to be toxic to aquatic organisms [5]. Further exacerbating the problem, colorants are hard to biodgrade because of their often complicated chemical structure, which means that water contamination with colorants can persist for extended periods of time [6]. These potential environmental effects mean that the decolorization of wastewater requires the most effective methods available. The sorption process is deemed to be one of the most attractive options for treating colored effluent [7]. During sorption, pollutants are adsorbed onto the surface of a sorbent. The exact cost and efficiency of the process depend mainly on the type of sorption materials used [8]. Activated carbon is currently the most popular choice of sorbent for removing dyes [9]. Its large surface area, which can exceed 3000 m\({}^{2}\)/g, bestows activated carbon with a very high sorption capacity [10; 11]. The drawback is that the substance is expensive to produce and regenerate, which is why cheaper and/or more efficient alternatives are being sought. Chitin has been gaining popularity as a sorption material in recent years. This polysaccharide is the main building block of arthropod exoskeletons, as well as a major component of the cell walls of fungi, some algae, and bacteria [12]. Industrial volumes can be harvested from shells of shrimps and crabs, i.e., waste products of seafood processing [13]. Chitin-based sorption materials can prove very useful in the treatment of colored wastewater [14]. Compared with commercial activated carbons, chitin can boast higher sorption capacity towards anionic reactive dyes, which are the major component of colored wastewater [15]. These considerable sorptive properties of chitin are due to the high concentrations of acetamide and amine functional groups, which act as key sorption centers [16]. Unfortunately, raw materials for chitin production are scarce in countries where marine crustaceans are not fished. Furthermore, chitin availability is limited by pharmaceutical companies, which purchase high volumes of biopolymer to produce drugs and dietary supplements. As an alternative, chitin may be harvested from exoskeletons and molts of insect larvae farmed for food and feed [17]. The mealworm (_Tenebrio molitor_) is one example of an insect farmed on a large scale for human consumption in many countries [18] and classified by the European Food Safety Authority as a \"novel food\" in June 2021. The chitin from mealworm molts--a waste product of mealworm farming--has very similar sorptive properties to commercial chitin from snow crab shells [15]. However, just as with crab and shrimp shells, the production of chitin from mealworm exoskeletons and molts is time-consuming and expensive. Other constituents of the exoskeletons/molts, such as protein and minerals (up to 90% of the raw material by weight), are irrecoverably wasted in the process [17; 19; 20]. Theoretically, these components could be capable of adsorbing dyes. It can therefore be hypothesized that \"the total sorption capacity of mealworm exoskeletons and molts against dyes is greater than the sorption capacity of pure chitin extracted from the same quantity of raw material\".