The isolation of nanocellulose has been extensively investigated due to the growing demand for sustainable green materials. Cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs), which have the same chemical composition but have different morphology, particle size, crystallinity, and other properties depending on the precursor and the synthesis method used. In comparison, CNC particles have a short rod-like shape and have smaller particle dimensions when compared to CNF particles in the form of fibers. CNC synthesis was carried out chemically (hydrolysis method), and CNF synthesis was carried out mechanically (homogenization, ball milling, and grinding), and both can be modified because they have a large surface area and are rich in hydroxyl groups. Modifications were made to increase the adsorption ability of heavy metal ions. The Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric (TG), and dynamic light scattering (DLS) can reveal the characteristics and morphology of CNCs and CNFs. The success and effectiveness of the heavy metal adsorption process are influenced by a few factors. These factors include adsorbent chemical structure changes, adsorbent surface area, the availability of active sites on the adsorbent’s surface, adsorption constants, heavy metal ionic size differences, pH, temperature, adsorbent dosage, and contact time during the adsorption process. In this review, we will discuss the characteristics of CNCs and CNFs synthesized from various precursors and methods, the modification methods, and the application of CNCs and CNFs as heavy metal ion adsorbents, which includes suitable isotherm and kinetics models and the effect of pH on the selectivity of various types of heavy metal ions.

The purpose of this study was to determine the effect of adding agar powder as a thickener to the physical, chemical, and sensory characteristics of papaya dodol and to determine the water content, vitamin C, and organoleptic content of papaya dodol by adding agar powder as a thickener to the physical, chemical characteristics, and sensory lunkhead papaya. The research method used was a completely randomized design (CRD) with three replications with the addition of agar powder, namely control without the addition of 0% P1 agar powder, 3% P2 agar powder, 5% P3 agar powder and 7% P4 agar powder. In this study the parameters observed were water content, vitamin C, and organoleptic properties of papaya dodol with the addition of agar powder as a thickener to the physical, chemical, and sensory characteristics of papaya dodol. The addition of agar powder in the manufacture of papaya dodol increases the water content in the product. In addition, agar powder can also protect vitamin C during the processing, although it still suffers damage when heated. The use of agar powder also gives a significantly different chewy texture to papaya dodol. However, the agar powder did not have a significant effect on the color, aroma, and taste of the papaya dodol, because the papaya dodol aroma was stronger and more dominant, while the agar powder had no taste and its gelatinous nature did not affect the change in the taste of the papaya dodol.