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This study discusses kapok husk (KH) activated by HNO3 as a biosorbent for methylene blue dye and analyses its adsorption ability. The adsorption capacity of KH is 330.161 mg g-1 with optimum conditions at pH 9, concentration 5500 mg L-1, contact time 15 min, and biosorbent temperature 25ºC. The isotherm study followed the Langmuir isotherm model, as seen from the R2 value of 0.9993 and maximum adsorption capacity of 312.5 mg g-1, which indicated a monolayer in the adsorption process. The kinetic data show that KH followed the pseudo-second-order model. The results of the TGA analysis show that thermal stability affects the performance of biosorbents in the adsorption process. FTIR and SEM-EDS characterisation results showed that electrostatic interactions, cation exchange, and pore filling regulate the methylene blue dye adsorption mechanism on the surface of the KH. The reusability of KH through adsorption–desorption cycle analysis was achieved five times. This indicates that the biosorbent can be economically feasible for real wastewater treatment based on its good reusability and simple preparation and activation.

AbstractThe present study investigated the capability of cassava peel (Manihot Esculenta Crantz) in Pb(II) and Cr(VI) removal. The comparative study was conducted using batch method observing some parameters. The results indicated that the optimum adsorption of Pb(II) occurred at pH 5, initial concentration of 1000 mg/L, and contact time of 50 min. On the other hand, the optimal adsorption of Cr(VI) was achieved at pH 2, initial concentration of 1200 mg/L, and contact time of 70 min. The adsorption isotherms of both metals tended to follow the Langmuir model, while the adsorption kinetics suited to pseudo-second-order model. Thermodynamic parameters indicated that the adsorption process was spontaneous (ΔG° negative), endothermic (ΔH° positive), and exhibited surface dispersion on the biosorbent (ΔS° positive). Characterization using Fourier Transform Infrared (FTIR), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), and Thermogravimetry (TGA) provided evidence of both physical and chemical adsorption. The adsorption capacity of cassava peel was also tested on samples collected approximately 30 m from the bay shoreline, resulting in a removal percentage of 94.67% for Pb(II) and 82.28% for Cr(VI) under optimal pH and contact time conditions. [ABSTRACT FROM AUTHOR]

Industrial processes are the main source of Pb(II) contamination of natural water bodies. Pb(II) is a non-biodegradable heavy metal and carcinogen. The recent study explored the ability of citric acid-modified-kepok banana peel (CA-BP) to remove Pb(II) from an aqueous solution using the batch method. The adsorption capacity of kepok banana peel (BP) was also investigated for comparison. The optimum conditions for Pb(II) removal using kepok banana peel were achieved at pH 5, initial concentration of 600 mg l-1, contact time of 75 min, and agitation speed of 100 rpm, with an adsorption capacity of 36.478 mg g-1. Meanwhile, the adsorption capacity of citric acid modified-kepok banana peel was 64.088 mg g-1, which was reached at pH 5, initial concentration of 850 mg l-1, contact time of 75 min, and agitation speed of 150 rpm. The adsorption of Pb(II) onto both sorbents followed the Langmuir isotherm model and pseudo-second-order model, indicating monolayer adsorption with chemical interaction as a rate-limiting step. A Fourier Transform Infra-Red (FTIR) analysis was conducted to identify the functional groups present in the biosorbent and demonstrate a change in the wave number. The surface morphology of the biosorbent was examined using Scanning Electron Microscopy (SEM) before and after the absorption of Pb2+ metal ions. The objective of Energy Dispersive X-ray (EDX) is to quantify the elemental composition of the biosorbent derived from the surface of the kepok banana peel. An X-ray fluorescence (XRF) analysis was conducted to determine the chemical composition of the surface of the kepok banana peel biosorbent. Thermogravimetric Analysis (TGA) was conducted to observe the decrease in mass of the biosorbent as the temperature increased. [ABSTRACT FROM AUTHOR]

Dye water contamination was the main challenge that pressured textile industries tremendously. The present investigation aims to employ solid waste from fisheries industries to remove toxic dye contaminants in an aqueous solution. Shrimp shell waste (SSW) was fishery waste with good potential for adsorbing dyes, one of which is methylene blue. This research studied methylene blue's adsorption capacity using shrimp shell waste as a biosorbent. By studying several parameters, it was found that the adsorption capacity was 48.834 mg g−1 at pH = 10, with an optimum concentration of 550 mg L−1, a contact time of 105 min, and a heating temperature of the biosorbent 120 °C - the results of XRF characterisation shown the differences in the chemical composition percentage before and after adsorption process. The results suggested that SSW can be employed as and low-cost adsorbent for the removal of methylene blue dye from water effectively. [ABSTRACT FROM AUTHOR]

The performance of sago bark for Cd(II) ions removal in the aqueous solution has been investigated using the batch method. The sago bark was facile-treated using HNO3 0.01 M and its ability on Cd(II) removal was evaluated under specific parameters such as pH, contact time, agitation speed, temperature, initial concentration, and adsorbent mass. The adsorption capacity of sago bark was found to be 2.473 mg/g. The Langmuir isotherm model corresponding to the monolayer adsorption process described the adsorption data well. The kinetic and thermodynamic evaluation confirmed that the Cd(II) ion sorption followed a pseudo-second-order model and endothermic. The adsorption capacity decreased after three times adsorption-desorption cycles. This result showed that the treated sago bark could be a good candidate as an adsorbent for Cd(II) removal. [ABSTRACT FROM AUTHOR]

Salt produced from seawater evaporation contains harmful microplastics (MP). For this reason, a technology that can remove MP from seawater using coagulation and filtration techniques is needed. The purpose of this study is to utilize alum as a coagulant and sand as a filtration media to reduce MP pollution in seawater as a source of raw material for salt making. Seawater from Buo Bay, Padang City, Indonesia was taken as raw material for salt production. The MP abundance of salt made from seawater without alum and sand treatment was found to be 400 particles/kg. To reduce the abundance of MP in the salt, we varied the alum concentration (0.1; 0.3; and 0.5 g/L) and sand particle size (=2, =1-<2, and <1 mm). From the results obtained, the optimal condition is an alum concentration of 0.5 g/L and sand particle size is <1 mm. The optimal condition of salt made from seawater in treatment H obtained MP abundance from 400 particles/kg to 30 particles/kg with an MP reduction efficiency of 92.5%. Visual analysis using optical trinocular microscopy found 4 forms of MP, namely: fragments (51.13%), fibers (28.95%), films (15.41%), and pellets (4.05%). Rewith the most dominant MP size found was >100-300 µm. The results of ATR-FTIR analysis identified the types of MP as Polyethylene (14.28%), Polyethylene Terephthalate (42.85%), Polypropylene (14.28%), and Polyamide (28.57%). [ABSTRACT FROM AUTHOR]

Acid-activated corn husk waste (CHW) was used to investigate the adsorption mechanism of Indigo Carmine (IC) dye from an aqueous solution. The effect of different operating parameters such as pH (1-7), initial IC dye concentration (40-400 mg/L), contact time (5-75 min), and heating temperature (25–200 °C) was measured on the removal of IC dye by the CHW. The maximum uptake of IC dye was observed at an initial pH of 2. The maximum capacity of 13.57 mg/g and the maximum dye removal of 89.01 % in wastewater. The adsorbents were characterized using Fourier Transforms Infrared Spectrophotometry (FTIR), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray Fluorescence (XRF), and Thermogravimetry Analysis. The characterization process reveals the differences in adsorbent characteristics before and after the adsorption processes. The Langmuir showed the best fitting (R2 = 0.977) and described multilayer adsorption on diverse surfaces. The pseudo-second-order kinetic model best correlated with the experimental data (R2 = 0.981). Thermodynamics revealed that adsorption was favorable spontaneous and exotherm. The study's results indicated that using CHW as a low-cost adsorbent to treat IC dye was efficient and beneficial to the environment. [ABSTRACT FROM AUTHOR]