ABSTRACT
Composite functional materials offer promising opportunities for the development of tailored adsorbents with enhanced bioremediation potential towards toxic, carcinogenic endocrine disrupters such as Bisphenol A (BPA). Copyrolysis of microalga Chlorella sp. (CH) alkali lignin (L) with K2CO3 impregnation yielded a carbon-based composite (CHL-AC) with a micro-mesoporous structure of 0.643 cm3/g, surface area of 1414 m2/g, and BPA adsorption capacity of Qmax 316.858 mg/g. Enhanced BPA removal efficiency indicated a positive synergistic effect upon a combination of L and CH, resulting in a 73.24 % removal efficiency compared with the individual carbon components of 52.33 % for L-AC and 67.35 % for CH-AC. The kinetics and equilibrium results were described well by the pseudo second-order kinetic model and Freundlich isotherm, respectively. This paper elucidates the blending of microalgae and lignin into high-value carbon composite material, CHL-AC, with immense potential for the treatment of BPA-contaminated waters to contribute to Goal 6 (clean water and sanitation).
Subject(s)
Chlorella , Microalgae , Water Pollutants, Chemical , Water Purification , Alkalies , Lignin , Plasticizers , Adsorption , Water Pollutants, Chemical/analysis , Water Purification/methods , Carbon/chemistry , Kinetics , Hydrogen-Ion ConcentrationABSTRACT
A FeCl3-activated seaweed carbon/MCM-41/alginate hydrogel composite (ECAC/MCM-41/ ALG) cross-linked with calcium chloride (2% CaCl2) was synthesized for the biosorption of bisphenol A (BPA) plasticizer and basic blue (BB) dye. Biosorption uptakes of BPA and BB were performed in a batch mode with varying solution pH from 3 to 11, initial sorbate concentration from 25 to 300 mg/L, reaction time from 0 to 10 h, and biosorption temperature from 30 to 50 °C. The maximum BPA and BB uptake mechanisms were fast, which occurred within contact times of 1 and 2 h with monolayer coverage capacities of 222.32 and 190.11 mg/g at 50 °C, respectively. Cyclic biosorption/desorption behavior was evaluated via an ethanol elution to evaluate the feasibility of the ECAC/MCM-41/ALG for long-term application. Results revealed the biosorption renewability for five cycles up to 80% of the newly synthesized hydrogel composite for the purification of industrial wastewater laden with emerging contaminants.
Subject(s)
Seaweed , Water Pollutants, Chemical , Adsorption , Alginates , Benzhydryl Compounds , Hydrogels , Hydrogen-Ion Concentration , Kinetics , Phenols , Plasticizers , Silicon Dioxide , ThermodynamicsABSTRACT
Epichlorohydrin crosslinked chitosan/carbon-clay (CSCC) biohybrid adsorbent was prepared for the adsorption of cationic methylene blue (MB) and anionic azo acid blue 29 (AB 29). The 40:60 wt% of chitosan (CS) and carbon-clay (CC) was selected as the best biohybrid adsorbent (CS40CC60) for the adsorption of both dyes. The adsorption of MB and AB 29 on CS40CC60 was carried out in a batch process to investigate the effects of initial dye concentration (25-400 mg/L), initial pH (3-11), contact time and adsorption temperature (30, 40 and 50 °C). The kinetics results of dyes adsorption onto CS40CC60 fit well to the pseudo-second-order model. The isotherms analysis demonstrated that the Freundlich isotherm described the adsorption data, and the qmax (mg/g) were 95.31 for MB and 167.35 for AB29 at 50 °C. These findings reveal the potential and effectiveness of the newly prepared biohybrid adsorbent for the adsorption of both dyes.
Subject(s)
Anions/chemistry , Carbon/chemistry , Cations/chemistry , Chitosan/chemistry , Clay/chemistry , Coloring Agents/chemistry , Epichlorohydrin/chemistry , Adsorption , Cross-Linking Reagents/chemistry , Hydrogen-Ion Concentration , Kinetics , Methylene Blue , Spectroscopy, Fourier Transform Infrared , Water Pollutants, ChemicalABSTRACT
In this work, mesoporous-activated carbon (CSAC) was prepared from chitosan flakes (CS) via single-step sodium hydroxide activation for the adsorption of methylene blue (MB). CSAC was prepared using different impregnation ratios of NaOH:CS (1:1, 2:1, 3:1, and 4:1) at 800°C for 90min. The adsorption performance of CSAC was evaluated for MB at different adsorption variables, such MB initial concentrations (25-400mg/L), solution pH (3-11), and temperature (30-50°C). The adsorption isotherm data of CSAC-MB were well fitted to Langmuir model with a maximum adsorption capacity 143.53mg/g at 50°C. Best representation of kinetic data was obtained by the pseudo-second order model. CSAC exhibited excellent adsorption uptake for MB and can potentially be used for other cationic dyes.
Subject(s)
Charcoal/chemistry , Chitosan/chemistry , Methylene Blue/chemistry , Methylene Blue/isolation & purification , Sodium Hydroxide/chemistry , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/isolation & purification , Adsorption , Hydrogen-Ion Concentration , Kinetics , Porosity , TemperatureABSTRACT
Cross-linked chitosan/sepiolite composite was prepared from sepiolite clay and chitosan, and was cross-linked using epichlorohydrin. Among the various weight ratio percentage of chitosan and sepiolite clay composites, CS50SP50 was selected as the best adsorbent for both methylene blue (MB) and reactive orange 16 (RO 16). At an optimum adsorbent dosage of 0.2g/100mL, the effects of initial dye concentration (25-400mg/L) and pH (3-11) on MB and RO 16 adsorption onto CS50SP50 composite were studied. Monolayer adsorption capacities of CS50SP50 composite for MB and RO 16 were 40.986mg/g and 190.965mg/g, respectively at 30°C. Freundlich, Langmuir and Temkin isotherms applied on the adsorption data for both the dyes reveal that data fitted best for Freundlich model. For both the dyes pseudo-second-order kinetics were found to describe the adsorption process better than pseudo-first-order kinetics. The adsorption capacity of CS50SP50 composite for both the dyes was found better compared to previous studies thus making it potentially low-cost adsorbent for removal of both cationic and reactive dyes.
