Research on Separation of Heavy Metals by Utilizing Biomass for Environmental Remediation and 3R

The establishment of a recycling-oriented society practicing the 3Rs (Reduce, Reuse, and Recycle) has become a global necessity. To achieve the 3Rs, contamination must be reduced; specifically, material reuse is unsafe unless it has a low degree of contamination. For example, soil mixed with heavy metals cannot be applied as a base material for plant growth because the contamination degree is greater than the standard value. In the past, heavy metal-injected wood was used in buildings due to its effectiveness against termite attack. In this era, it has become a construction waste. The disposal of this wood, unless treated, may pose an environmental risk. In this study, we first reduced the mercury content in soil derived from a mine using rice husk charcoal and confirmed its impact on plants. Then, chromium was adsorbed and separated using carbonized grape peel as an adsorbent from an elution model solution of wood containing chromium-copper-arsenic food. Next, copper was separated using a biopolymer synthesized by saponifying the peel of a mandarin orange, and finally, arsenic was adsorbed by a biopolymer obtained by chemically modifying zirconia. This study revealed that the amount of mercury in the soil is fixed by using biomass charcoal (rice husks) and has little effect on plants. In addition, the use of biomass charcoal (sulfuric acid heat treatment of grape peels), saponified biomass polymers (orange skins), and their chemical modifications (zirconium) helped separate chromium, copper, and arsenic in the chromate copper arsenate-treated wood leachate.