Application of Rice Pad (Oryza Sativa) as a Sorption Material to Remove Pollutants From Aquatic Environment

Abstract

The use of rice husk (the waste in the production of seeded rice (Oryza sativa) as a sorption material for the removal of pollutants of various classes – inorganic (Cr, Ni, Co, Pb, Hg, As, Cd, Cu, Zn) and organic substances (synthetic and natural dyes, phenols, antibiotics, polycyclic aromatic compounds, humic acids, pesticides, chitosan) from aqueous media is generalized. The literature data on the structure of seeded rice, the volume of its cultivation, the chemical composition, and some components of rice husk are given.
 The methods of physical and chemical (the use of inorganic acids, salts, and alkalis) are described activation, as well as modification of rice husks using surfactants, Fe3O4 nanoparticles, functional agents, and monomers (polymerization reactions). Quantitative characteristics of the absorption of various pollutants (recoveries, equilibrium limit sorption) are given. The influence of pH, temperature, the concentration of pollutants, phase contact time, volume, and mass of rice husk on sorption and removal of pollutants from aqueous media is shown. Possible sorption mechanisms, kinetic and sorption models are described. It is revealed that the isotherms of the sorption of pollutants in most cases are most adequately described by Langmuir and Freundlich models, and the kinetics of the process is a pseudo-second-order model.

Heavy metal sorption by native shells of pea grain

“…By adjusting its parameters, it is possible to obtain materials with different sorption capacity and selectivity. Activation of grain wastes with inorganic acids followed by treatment with organic salts also considerably increases the degree of pollutants extraction [3].…”

“…By polymerisation of grain waste, highly effective grafted copolymers with high sorption capacity and easy separability after wastewater treatment can be obtained [3]. Sorbents obtained from husks by pyrolysis are characterised by large volumes of micropores and mesopores, because they actively sorb heavy metal ions [11,12].…”

“…The advantages of using grain wastes as sorption materials are their availability, low cost, comparative efficiency, and ease of processing technology, as well as the possibility of regeneration [2]. Factors that significantly affect the sorption capacity of materials from waste grain processing are the concentration of sorbate and time of interaction with it, particle size, dosage, initial humidity of raw materials [3,4].…”