Effect of Solution pH on the Removal of Paracetamol by Activated Carbon of Dende Coconut Mesocarp

Abstract

Activated carbon of dende coconut mesocarp was used to investigate the removal of paracetamol from water by adsorption. The results indicated that the retention of paracetamol was favored in activated carbon with neutral surface properties. The textural features and presence of a transport pores network contri buted to ensuring the accessibility to the inner porosity, and the microporosity must be large enough to accommodate the paracetamol molecule. Chemisorption and mainly physisorption are important in the paracetamol removal. Pseudo-second order equation and Langmuir model were chosen to best present the experimental data. The adsorption process was non-spontaneous and endothermic with increase in system dis order.

Acetaminophen adsorption using a low‐cost adsorbent prepared from modified residues of Moringa oleifera Lam. seed husks

“…The adsorption of APAP onto mod‐MO resulted in a Δ H ° value of 23.11 KJ mol −1 , confirming the endothermic nature of the process. Other studies also have indicated positive values of enthalpy . According to Hayward and Trapnell, the change of enthalpy can infer a physical or a chemical process; those authors explained that the heat involved in physisorption is in the same order of magnitude as the heat of condensation, around 2 to 20 KJ mol −1 .…”

“…Other studies also have indicated positive values of enthalpy. 4,65,66 According to Hayward and Trapnell, 67 the change of enthalpy can infer a physical or a chemical process; those authors explained that the heat involved in physisorption is in the same order of magnitude as the heat of condensation, around 2 to 20 KJ mol −1 . The value of ΔH ∘ is close to this range, so it can be stated that APAP adsorption onto mod-MO involves physical adsorption mechanisms.…”

Effect of Solution pH on the Adsorption of Paracetamol on Chemically Modified Activated Carbons

“…In acidic medium, the paracetamol molecule presents a nitrogen resonance electron pair, as shown in Figure 2 . The carbocation generation in the sp 2 carbon of the amide group facilitates the interaction with the proton acceptor groups of activated carbon, as well as nucleophilic addition with surface groups, such as hydrogen sulfides, trisubstituted amines and hydroxyls ( Figure 3 ) [ 8 , 18 ].…”

Utilização de carvão ativado de dendê in natura e funcionalizado em meio ácido na adsorção de paracetamol

“…As cinéticas de adsorção foram estudadas por meio do contato de 10 mg dos carvões com 20 mL da solução de paracetamol sob agitação de 150 rpm a temperatura controlada de 25 ºC em banho termostatizado Dubnoff da Nova Ética, com coleta de amostras no intervalo de tempo de 5 a 480 minutos no pH de 2,0, pH PCZ e 11,0. Após atingido o tempo previamente especificado, as amostras foram filtradas em papel filtro qualitativo (Unifil, faixa azul, diâmetro de 125 mm), e efetuadas as leituras da concentração do fármaco em espectrofotômetro uv-vis Hach no comprimento de onda de 245 nm [10]. Os ensaios foram realizados em triplicata.…”

“…Verifica-se que o valor de k 2 é menor para o DAC comparado ao valor para DD, provavelmente pela interferência da repulsão eletrostática, uma vez que o DAC possui maior quantidade de grupos ácidos (Tabela 2). De acordo com [10], a molécula do paracetamol, sendo fracamente ácida (pKa = 9,9), interage principalmente com grupos básicos da superfície do carvão.…”