Abstract
Sodium lignosulfonate is a polymer with extensive sources and abundant functional groups. Therefore, it has potential value for research and wide utilization. In this study, the adsorption material was prepared by blending sodium lignosulfonate and chitosan, which could adsorb anionic and cationic dyes and metal ions. The composite was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetry (TG). The results showed that the composite was cross-linked mainly by the strong electrostatic interaction between the protonated amino group in chitosan and the sulfonate group in sodium lignosulfonate. Moreover, the effects of initial concentration, adsorption time, initial pH, and mass ratio of chitosan to sodium lignosulfonate on the adsorption performance of the composite were investigated. Meanwhile, the adsorption processes were agreed well with the pseudo-second-order kinetic model and Langmuir isotherm model. The adsorption mechanism was that the electrostatic interaction between the protonated amino and hydroxyl groups of the composite with anionic (SO3–) and HCrO4– groups of Congo red and Cr(VI), respectively. In addition, the electrostatic interaction between SO3– of the composite and positively charged group of Rhodamine B played an important role in the adsorption of Rhodamine B.
Highlights
Rhodamine B and Congo red as typical dyes are widely used in many industries, which have to be removed from wastewater due to their carcinogenic and mutagenic effects.[5,6]
The results suggested that the hydrogen bonding existed between the hydroxyl group in sodium lignosulfonate and the glucosidic bond in chitosan, and there was the interaction between the hydroxyl group in chitosan and the ether bond in sodium lignosulfonate.[29]
It was found that the composite was cross-linked by weak hydrogen bond and electrostatic interaction
Summary
The wastewater from dyestuff, electroplating, textile and other industries contain dyes, heavy-metal ions, and other harmful chemicals, causing water contamination.[1,2] The dyes in wastewater are harmful to aquatic organisms and affect the aesthetics because of their high toxicity and high visibility.[3,4] Rhodamine B and Congo red as typical dyes are widely used in many industries, which have to be removed from wastewater due to their carcinogenic and mutagenic effects.[5,6] Cr(VI), derived from various industries such as electroplating, textile, storage batteries, and leather tanning, is nonbiodegradable and highly toxic, posing a serious threat to human health.[7,8] To remove these contaminants, various techniques have been developed, including adsorption,[9,10] membrane filtration,[11] catalytic degradation,[12,13] electrochemical process,[14] advanced oxidation process,[11] etc. Adsorption has potential application prospect due to its high efficiency, economic feasibility, and convenient operation. Various adsorption materials have been reported for the removal of pollutants such as polymers,[15] inorganic materials,[16] biomaterials,[17−19] and macromolecular materials.[20] In recent years, biomaterials have become the concern of materials, owing to environmental protection, renewability, and high removal efficiency for pollutants
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