Preparation of Activated Carbon from Herbal Residues and Kinetics of Cephalosporin Antibiotic Adsorption in Wastewater

Abstract

In order to utilize the leftover materials from traditional Chinese medicine production and to remove antibiotics from wastewater, extracted herbal residues were used as raw materials to produce activated carbon. To keep a constant quality and adsorption ability across cephalosporin antibiotic samples, all samples were divided into rhizomes, fruits, and leaves to make activated carbon by step-wise carbonization and overheated steam activation. The three kinds of carbon were mixed in the optimal ratio of 5:4:2, which had homogeneity in quality with a high adsorption capacity. Maximum adsorption of the mixture to cefalexin and cefradine were 7.1 mg/g, and the mixture removed 84% of the antibiotics from treated wastewater. Approximately 90% of the antibiotics was desorbed after ultrasonic treatment of the distilled water-carbon mixture for 10 min, and a re-adsorption capacity of 80% was maintained for next use. The adsorption process is dominated by a pseudo-second order kinetic reaction, with two active sites binding to one antibiotic molecule. The rate-limiting step is an intra-particle diffusion process. The isothermal adsorption process conforms to Langmuir and Tempkin isotherm models, showing multilayer and physical adsorption. The activated carbon from herbal residues can adsorb a low concentration of antibiotics in wastewater and be recycled after ultrasonic treatment.

Recent Advances in Solid Residues Resource Utilization in Traditional Chinese Medicine

“…As mentioned in other research, biochar has a high carbon content, a densely packed pore structure, a large specific surface area, and stable physicochemical characteristics [58–60] . Therefore, it can be applied to sequester carbon, adsorb heavy metals, adsorb organic matter, and protect the environment [61–63] …”

“…Biochar is a prominent adsorbent for metals, drug residues, and pollutants [59–66] . However, the adsorption performance of biochar is influenced by the raw materials, pyrolysis temperature, and pyrolysis rate [61–63] .…”

“…At the same time, TCMR contains a high percentage of lignocellulose, which has the potential to be utilized as a raw material for biochar. Currently, numerous studies have focused on the preparation of highly adsorbent active biochar materials from TCMR [61–63] . For instance, Danshen residue was slowly pyrolyzed at 250–800 °C to prepare biochar, which was then employed as a sulfamethoxazole adsorbent.…”

“…[58][59][60] Therefore, it can be applied to sequester carbon, adsorb heavy metals, adsorb organic matter, and protect the environment. [61][62][63]…”

Membranes for the life sciences and their future roles in medicine

“…If untreated, they will pollute the urban water system and cause accumulation in organisms. There are many methods to treat medical wastewater, including adsorption [186] , [187] , advanced oxidation processes (AOP) [188] , [189] , [190] , [191] , [192] and membrane filtration [193] , [194] , [195] . Traditionally, activated carbon and sludge are the adsorption materials most commonly applied to remove drug molecules, and they rely on porous structures and biodegradation, respectively.…”