Sludge‐based mesoporous activated carbon: the effect of hydrothermal pretreatment on material preparation and adsorption of bisphenol A

Abstract

Background: The excess sludge produced by sewage treatment plants contains a large number of pollutants, which is of huge environmental risk. Transforming this kind of solid waste into adsorption materials is an effective approach to realize the resource utilization of sludge. Combined with hydrothermal pretreatment and chemical activation, the synthesis of sludgebased mesoporous carbon is used to remove bisphenol A (BPA) in wastewater.Results: A resource recycling measure to prepare mesoporous activated carbons (MACs) from sewage sludge was developed via the combination of hydrothermal pretreatment and chemical activation using sewage sludge and sulfuric acid as carbon precursor and activating agent, respectively. The combination of hydrothermal pretreatment and chemical activation not only can make efficient use of the activating agents but also facilitate the deep pyrolysis of the sludge. The resultant MAC obtained using the hydrothermal pretreatment possessed a larger total surface area, less crystalline phase and a narrower pore size distribution compared to other samples. Meanwhile, the MAC obtained from hydrothermal pretreatment presented the highest amount of adsorption of BPA and achieved a better capture than the reference commercial activated carbons. In addition, a possible adsorption mechanism has been proposed to further analyze the enhanced adsorption performance.Conclusions: The yield and mesoporous content of the obtained MAC is 59.19% and 31.51%, respectively. The maximum adsorption capacity for BPA is 137.87 mg g −1 . Microporosity, hydrogen bonding and π-π effect introduced by the hydrothermal pretreatment play an important role in BPA adsorption.

Mesoporous Carbons of Well-Organized Structure in the Removal of Dyes from Aqueous Solutions

“…Long-term and large-scale production entails an increase of the costs, a corrosion of the equipment and most importantly the environmental burden. A method based on combining the hydrothermal pre-treatment and chemical activation [ 41 ], effectively transforming a carbon precursor seems to be a better solution. In the presented methods the following materials were used as carbon precursors: mustard straw, industrial sludge, walnut and pistachio shell, wood.…”

Thermal and bisphenol-A adsorption properties of a zinc ferrite/β-cyclodextrin polymer nanocomposite

“…The adsorption performance of β-CD-E-T/ZnFe 2 O 4 nanocomposite was compared with previously reported adsorbents for the removal of BPA (Table 4). 13,19,26–30,39,40,50–53,55–58 As reported in Table 4, β-CD based adsorbents like carboxymethyl-β-CD polymer/Fe 3 O 4 composite, β-CD/graphene-magnetite nanocomposite, and polyethylenimine-polyethylene glycol-β-CD polymer were not very effective for the BPA elimination from the aqueous solution. 27,29,30 The β-CD based polymer and composites were having a maximum uptake of 65–139 mg BPA per ‘g’ of adsorbent used.…”

“…53 A decrease in BPA removal efficiency with rising temperatures was noted in prior investigations examining the efficacy of covalent organic frameworks and mesoporous-activated carbon for BPA removal. 19,53 This behavior is typically observed in physical adsorption processes, where the desorption rate increases with temperature. It can be inferred that the adsorption of BPA onto b-CD-E-T/ZnFe 2 O 4 nanocomposite was primarily governed by physical interactions.…”

“…The adsorption performance of b-CD-E-T/ZnFe 2 O 4 nanocomposite was compared with previously reported adsorbents for the removal of BPA (Table 4). 13,19,[26][27][28][29][30]39,40,[50][51][52][53][55][56][57][58] As reported in Table 4, 4). 27,29,30 The reported b-CD based adsorbents exhibited very slow adsorption compared to b-CD-E-T/ZnFe 2 O 4 nanocomposite, except b-CD-4,4 ′ -bis(chloromethyl) biphenyl and TFTPN-ECH-b-CD polymer.…”

A New Approach for Controlling Mesoporosity in Activated Carbon by the Consecutive Process of Air Oxidation, Thermal Destruction of Surface Functional Groups, and Carbon Activation (the OTA Method)

“…To be able to use activated carbon in the separation processes more widely and more efficiently, it is necessary to develop a process of activated carbon synthesis that can control proportionally the amounts of micropores and mesopores. The control of mesopores in activated carbon is mostly achieved through chemical activation, which consists of several methods such as a one-step chemical activation [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ], a two-step chemical activation [ 13 , 14 , 15 , 16 ], a hydrothermal pretreatment followed by a simple chemical activation [ 17 , 18 ], and chemical activation with dual activation agents [ 19 ]. Furthermore, the combined chemical and physical activation has also been used to control the amount of mesopores in activated carbon [ 20 , 21 , 22 , 23 , 24 ].…”