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http://crossmark.crossref.org/dialog/?doi=10.1007/s11356-016-7572-6&domain=pdf
Web End = Environ Sci Pollut Res (2016) 23:2360623618 DOI 10.1007/s11356-016-7572-6
http://crossmark.crossref.org/dialog/?doi=10.1007/s11356-016-7572-6&domain=pdf
Web End = RESEARCH ARTICLE
Enhanced adsorption of methylene blue by citric acid modification of biochar derived from water hyacinth (Eichornia crassipes)
Yan Xu1,2 & Yunguo Liu1,2 & Shaobo Liu3,4 & Xiaofei Tan1,2 & Guangming Zeng1,2 &
Wei Zeng1,2 & Yang Ding1,2 & Weicheng Cao1,2 & Bohong Zheng4
Received: 12 May 2016 /Accepted: 1 September 2016 /Published online: 10 September 2016 # Springer-Verlag Berlin Heidelberg 2016
Abstract In this work, a novel potential adsorbent, citric acid (CA)-modified biochar, named as CAWB, was obtained from water hyacinth biomass by slow pyrolysis in a N2 environment at 300 C. The CA modification focused on enhancing the contaminants adsorption capacity of biochar pyrolyzed at relatively low temperature. Over 90 % of the total methylene blue (MB) could be removed at the first 60 min by CAWB, and the maximum MB adsorption capacity could reach to 395 mg g1. The physicochemical properties of CAWB was examined by FTIR, XPS, SEM, and BET analysis. The results indicated that the additional carboxyl groups were introduced to the surface of CAWB via the esterification reaction with CA, which played a significant role in the adsorption of MB. Batch adsorption studies showed that the initial MB concentration, solution pH, background ionic strength, and temperature could affect the removal efficiency obviously. The adsorption process could be well described by the pseudo-second-order kinetic model and Langmuir isotherm.
Thermodynamic analysis revealed that the MB adsorption onto CAWB was an endothermic and spontaneous process. The regeneration study revealed that CAWB still exhibited an excellent regeneration and adsorption performance after multiple cycle adsorptions. The adsorption experiments of actual dye wastewater by CAWB suggested that it had a great potential in environmental application.
Keywords Biochar . Water hyacinth . Citric acid . Modification . Adsorption . Dye wastewater
Introduction
Synthetic dyestuffs have been an important class of pollutants, which are extensively utilized in many fields such as textiles, paper, plastic, leather, cosmetics, food processing, wool, and printing (Yagub et al. 2014). The residual dyes in the waste-waters have posed a serious threat to the environment due to their high visibility, recalcitrance, and adverse effects on both the aquatic biota and human health (Mahmoud et al. 2012).