This review compiles different analytical methods reported by the researchers studying heavy metal contents in seaweed samples from a variety of natural and commercial sources. Heavy metals in seaweed affect environmental health and human health due to seaweed’s role in the aquatic food chain and human consumption. The potential for heavy metal presence in seaweed is due to industrial pollution and other human activities. There is an ongoing demand for evaluation of the presence of nutritional as well as hazardous metals in raw and processed seaweeds. This review article will look at the importance and usage of seaweed, the importance of measuring heavy metals in seaweed, seaweed’s ability to absorb heavy metals, the health risks of consuming seaweed, and reported atomic spectroscopy-based heavy metal analysis methods in research on seaweed.

As a cost-effective sorbent, modified biochar has received increasing attention for the removal of heavy metal contaminants. Among several chemical modification methods, introducing thiol functional groups onto the surface of biochar has been identified as an effective enhancement approach for the heavy metal sorption and removal capacity of this porous adsorbent material. In general, chemical impregnation is a widely used method to graft thiol groups onto the surface of carbon-based materials. However, limited comparative data are available on the efficacy of the present biochar thiolation methods. In this study, the biochar of nine different organic sources was modified by two frequently used agents with distinct thiolation mechanisms: 3-Mercaptopropyltrimethoxysilane (3-MPTS) and β-mercaptoethanol. In addition to chemical impregnation, the ball milling method, a simple and environmentally friendly alternative thiolation method, was also evaluated. A comprehensive structural characterization of the biochar samples was completed before and after thiolation. A higher concentration of sulfur on the surface of the biochar was achieved through thiolation with β-mercaptoethanol, in which the thiolation mechanism is performed through an esterification reaction with the carboxylic acid functional groups of the activated biochar. Chemical impregnation was found to be a more effective thiolating method than ball milling using the same thiolating agent.