Abstract
Removing toxic heavy metal species from aqueous solutions is a point of concern in our society. In this paper, a promising biomass adsorbent, the modified waste shrimp shell (MS), for Cu (II) removal was successfully prepared using a facile and simple one-step modification, making it possible to achieve high-efficiency recycling of the waste NaOH solution as the modification agent. The outcome shows that with the continuous increase in pH, temperature and ion concentration, the adsorption effect of MS on Cu (II) can also be continuously improved. Adsorption isotherm and adsorption kinetics were fitted with the Langmuir isotherm model and the pseudo-second-order model, respectively, and the maximum adsorption capacity of Cu (II) as obtained from the Langmuir isotherm model fitting reached 1.04 mmol/g. The systematic desorption results indicated that the desorption rate of Cu (II) in the MS could reach 100% within 6 min, where HNO3 is used as the desorption agent. Moreover, experiments have proven that after five successive recycles of NaOH as a modifier, the adsorption capacity of MS on Cu (II) was efficient and stable, maintaining tendency in 0.83–0.85 mmol/g, which shows that waste NaOH solution can be used as a modification agent in the preparation of waste shrimp shell adsorbent, such as waste NaOH solution produced in industrial production, thereby making it possible to turn waste into renewable resources and providing a new way to recycle resources.
Highlights
The large-scale use of copper as a heavy metal material in production activities such as copper mining, smelting and processing is a key factor that has led to increasingly serious pollution of Cu (II) in water circulation
Le et al extracted substances in green tea as cross-linking agents to prepare magnetic chitosan particles (MCPs) from waste iron residue and waste shrimp shells, and the results showed that the maximum adsorption capacity of Cu (II) reached 2 mmol/g [6]
It was determined that the best preparation conditions of the modified waste shrimp shell (MS) were that: the ratio of waste shrimp shell to NaOH material was 60:1, the concentration of NaOH was 1% and the reaction time was 8 h
Summary
The large-scale use of copper as a heavy metal material in production activities such as copper mining, smelting and processing is a key factor that has led to increasingly serious pollution of Cu (II) in water circulation. The main methods used in removing heavy metal pollution include adsorption [1,6], ion exchange [7], precipitation [8] and membrane process [9]. These technologies have not been applied on a large scale owing to the economic cost limitations and complex processing technology. Studies on the adsorption of Cu (II) using existing biological materials with high adsorption efficiency, abundant resources, environmental friendliness and low price have attracted great interest, such as various types of cellulose [12], crustaceans [13] and lignin [14]
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