Preparation of Carbon–Iron Composites Materials and Studies of Its Adsorption Properties for the Methylene Blue

Multifunctional self-assembled adsorption microspheres based on waste bamboo shoot shells for multi-pollutant water purification

In this study, multilayer self-assembled multifunctional bamboo shoot shell biochar microspheres (BSSBM) were prepared, in which bamboo shoot shell biochar was used as the carrier, titanium dioxide as the intermediate medium, and chitosan as the adhesion layer. The adsorption behavior of BSSBM on heavy metals Ag(I) and Pd(II), antibiotics, and dye wastewater was systematically analyzed. BSSBM shows a wide range of adsorption capacity. BSSBM is a promising candidate for the purification of real polluted water, not only for metal ions, but also for Tetracycline (TC) and Methylene Blue (MB). The maximum adsorption amounts of BSSBM on Pd(II), Ag(I), TC and MB were 417.3 mg/g, 222.5 mg/g, 97.2 mg/g and 42.9 mg/g, respectively.The adsorption of BSSBM on Pd(II), MB and TC conformed to the quasi-first kinetic model, and the adsorption on Ag(I) conformed to the quasi-second kinetic model. BSSBM showed remarkable selective adsorption capacity for Ag(I) and Pd(II) in a multi-ion coexistence system. BSSBM not only realized the high value-added utilization of waste, but also had the advantages of low cost, renewable and selective adsorption. BSSBM demonstrated its potential as a new generation of multifunctional adsorbent, contributing to the recovery of rare/precious metals and the treatment of multi-polluted water.

A study on the uptake of methylene blue by biodegradable and eco-friendly carboxylated starch grafted polyvinyl pyrrolidone

This study is based on the removal of methylene blue (MB) from aqueous solution by cost effective and biodegradable adsorbent carboxymethyl starch grafted polyvinyl pyrolidone (Car-St-g-PVP). The Car-St-g-PVP was synthesized by grafting vinyl pyrolidone onto carboxymethyl starch by free radical polymerization reaction. The structure and different properties of Car-St-g-PVP were determined by ¹H NMR, FT-IR, XRD, TGA and SEM. A series of batch experiments were conducted for the removal of MB, The adsorption affecting factors such as temperature, contact time, initial concentration of MB dye, dose of Car-St-g-PVP and pH were studied in detail. The other parameters like the thermodynamic study, kinetics and isothermal models were fitted to the experimental data. The results showed that pseudo 2^nd order kinetics and Langmuir's adsorption isotherms were best fitted to experimental data with regression coefficient R² viz. 0.99 and 0.97. The kinetic study showed that the adsorption mechanism favored chemisorption. The Gibbs free energy (ΔG°) for the adsorption process was found to be -7.31 kJ/mol, -8.23 kJ/mol, -9.00 kJ/mol and -10.10 kJ/mol at 25 °C, 35 °C, 45 °C and 55 °C respectively. The negative values of ΔG° suggested the spontaneous nature of the adsorption process. Similarly, the positive values of entropy (ΔS°) and enthalpy (ΔH°) 91.27 J/k.mol and 19.90 kJ/mol showed the increasing randomness and endothermic nature of the adsorption process. The value of separation factor (R_L) was found to be less than one (RL < 1), which supported the feasibility of the adsorption process. The maximum MB removal percentage (% R) was found to be 98.6%. So, these findings show that Car-St-g-PVP can be meritoriously used for the treatment of MB from wastewater.

Effects of composite environmental materials on the passivation and biochemical effectiveness of Pb and Cd in soil: Analyses at the ex-planta of the Pak-choi root and leave

Passivation of soil heavy metals using environmental materials is an important method or important in situ remediation measure. There are more studies on inorganic environmental materials for heavy metal passivation, but not enough studies on organic and their composite environmental materials with inorganic ones. In order to reveal the passivation effect of coal-based ammoniated humic acid (CAHA), biochemical humic acid (BHA), biochar (BC) and other organic types and inorganic environmental materials such as zeolites (ZL) on soil heavy metals and their biological effectiveness. The microstructures of these materials were analyzed by Scanning electron microscope (SEM). The main components of the environmental materials were analyzed by Energy dispersive spectrometer (EDS), Fourier transforms infrared spectroscopy (FT-IR) and X-ray diffraction spectrum (XRD) to elucidate the mechanism of passivation of heavy metals in soil by these environmental materials. The study was conducted to investigate the effects of different types of environmental materials and their combinations on the passivation effect and biological effectiveness of Pb and Cd complex contamination in soil by means of soil incubation and pot experiments using single-factor and multifactor multilevel orthogonal experimental designs. Soil incubation experiments proved that the effective state of soil Pb and Cd in T₇ was reduced by 13.40% and 11.07%, respectively. The extreme difference analysis determined the optimized formulation of soil lead and cadmium passivation as BHA: CAHA: BC: ZL = 3.5:5:20:10. The pot experiment proved that the application of composite environmental materials led to the reduction of lead and cadmium content and increase of biomass of Pak-choi, and the optimal dosage of optimized composite environmental materials was 23.1 g/kg.

Adsorption behavior of Congo red on a carbon material based on humic acid

Humic acid is used as an inexpensive starting material to prepare a strong adsorbent for the removal of Congo red from water.