Abstract
Raw bentonite (RB) was chemically modified by citric acid (CA) to obtain a low-cost and environment-friendly citric acid incorporated bentonite (CAB) adsorbent, which was applied for the adsorptive removal of Congo Red (CR). The effect of adsorbent dosage, contact time, ionic strength, surfactant and pH on adsorption was investigated. Adsorption equilibrium data fitted well with Langmuir model while the Langmuir adsorption capacity of CR on CAB reached up to 384 mg·g‒1. Furthermore, CR adsorption on CAB followed pseudo-second kinetic model while intra-particle diffusion was not the only rate-limiting step as determined from intra-particle diffusion model investigation. RB and CAB were characterized by XRD, FT-IR and BET techniques. A proposed mechanism for the adsorption of CR over CAB suggested chemical adsorption phenomenon mainly controlled by chelation, hydrogen bonding and fixing.
Highlights
Dyes are widely used in textile, printing, feather, cosmetics, and plastics industries due to their bright colored and washable nature and sunfast feature (Rosa et al, 2018)
The active adsorption sites increased with increasing adsorbent dosage, which led to grater Congo Red (CR) adsorption
CR adsorption capacity decreased with increasing adsorbent dosage, which could be attributed to aggregation of adsorption sites with each other resulting in decreasing total surface area available to CR and increase in diffusion path length (Bernstein et al, 2018)
Summary
Dyes are widely used in textile, printing, feather, cosmetics, and plastics industries due to their bright colored and washable nature and sunfast feature (Rosa et al, 2018). The effluents discharged by these industries contain untreated dyes which can be toxic to human beings and aquatic life and their removal from contaminated wastewater is essential. Various methods such as adsorption over activated carbon (Wen et al, 2016), thermolysis, and coagulation (Yen et al, 2017), membrane separation (Cazzorla et al, 2018; Ye et al, 2018), electrochemical decolorization (Xu L. et al, 2018), photocatalytic degradation (Liu et al, 2019), and biological treatment (Banihani et al, 2018) have been widely reported for the removal of organic pollutants. Low-cost adsorbents including acid treated red mud (Toor et al, 2015), sand (Li P. et al, 2018), raw pine and acid treated pine (Schorr et al, 2018), Ashoka leaf (Shivaprakash et al, 2018), sulphuric acid treated Palm flower (Magdalena et al, 2018), hen feathers (Tesfaye et al, 2018), and clay minerals (Shaban et al, 2018) have been investigated for the treatment of dyes containing wastewater
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
