Removal of Lignin from Wastewater Generated by Mechanical Pulping Using Activated Charcoal and Fly Ash: Adsorption Kinetics

Abstract

The possible application of adsorption for the removal of lignin-related material found in wastewater generated by mechanical pulping was investigated. Activated charcoal and fly ash were used as adsorbents in batch experiments. The lignin-related material exhibited properties well-suited for adsorption onto both adsorbents, although the sorption capacity of activated charcoal exceeds that of fly ash. The experimental data were fitted to pseudo-first-and pseudo-second-order rate kinetic expressions, and an attempt was made to find the rate-limiting step involved in the adsorption processes. The results showed that lignin adsorption onto both activated charcoal and fly ash follows pseudo-second-order rate kinetics and that both boundary-layer diffusion and intraparticle diffusion are likely involved in the rate-limiting mechanisms. Adsorption is an interesting option in advanced wastewater treatment, and fly ash appears to be a suitable low-cost adsorbent for recalcitrant organic pollutants.

Removal of Lignin from Wastewater Generated by Mechanical Pulping Using Activated Charcoal and Fly Ash: Adsorption Isotherms and Thermodynamics

“…The adsorbents were added to the lignin solutions in 200 mL sample flasks mounted either on a shaker or in a water bath shaker at 200 rpm to keep the adsorbent suspended. The adsorption time for the equilibrium studies was set to 6 h: kinetic studies showed that there was no significant increase in lignin adsorption onto either of the two adsorbents after this time . All samples were filtered using Whatman GF/A fiberglass filters (Schleicher and Schuell, Maidstone, U.K.) to remove the adsorbent.…”

Catalytic oxidation of organic pollutants in wastewater via a Fenton-like process under the catalysis of HNO3-modified coal fly ash

“…When the H 2 O 2 dosage is excessive, the degradation rate of p-NP would decrease with the increase of the H 2 O 2 dosage. This could be attributed to the reaction of cOH with H 2 O 2 and the reaction of two cOH radicals (see eqn (4) and (5)). Both of the two side reactions inhibit the effective utilization of H 2 O 2 and the rapid oxidation of p-NP.…”

“…(1) (5) cOH + organics / intermediates / inorganics (6) Although the Fenton process can oxidize a wide variety of organics, and is even be able to destroy them to produce carbon dioxide (CO 2 ), water (H 2 O) and inorganic salts (eqn (6)), the recycling of the catalyst (Fe 2+ ) cannot be easily achieved, leading to the generation of sludge containing Fe ions. The treatment of the sludge is expensive in terms of labour, reagents, and time, and is complex in operation.…”

“…Thus, proper treatment of CFA is required. Over the years, many studies [5][6][7][8][9][10][11][12][13][14] have revealed that pre-treated CFA can be used as an effective low-cost adsorbent for the removal of organic and inorganic metallic elements (such as arsenic, nickel, calcium, copper, iron and manganese ions) in wastewater. However, the catalytic property of CFA has not attracted enough attention and just a small number of studies [15][16][17] have been conducted until now.…”

Optical-Switch-Enabled Microfluidics for Sensitive Multichannel Colorimetric Analysis

“…Activated charcoal is commonly used for the color removal in the treatment and purification of water and wastewater, − with the laboratory characterization of the adsorption kinetics of chromophores on activated charcoal being necessary to optimize relevant parameters, e.g., dose, retention time for the pilot, or large-scale operation. , That said, conventional manual batch-sampling is challenging to acquire real-time data and makes this process laborious. Accordingly, we used the OSEMC system to characterize the adsorption kinetics of 100-mesh activated charcoal (Sigma, St. Louis, USA) in a real-time fashion, using tartrazine with a λ max at 428 nm (Sigma, St. Louis, USA) as a model target.…”