Search

Present study is a novel attempt to experimentally verify that electrochemical treatment of organic pollutants on stainless steel (SS) anode is a combination of electro‐oxidation (EO) and electro‐coagulation (EC) with quantitative estimation of individual contributions of the two mechanisms. Target organic pollutants, metformin HCl (MET‐HCl) and lamotrigine (LAM), were electrochemically treated with SS anode for this purpose. Experiments were designed using central composite rotatable design (CCRD) to assess the effect of current density (CD) and supporting electrolyte concentration (SEC) as independent process parameters. Under all conditions, the process was experimentally verified to be a combination of EO and EC. For MET‐HCl, true mineralization (TM) as a result of EO contribution varied between 50.13% and 66.64%. EO contribution and resulting TM for LAM ranged from 37.5% to 61.83%. EC contributed 30.6%–31.84% towards MET‐HCl remediation causing the TOC to be transferred from the liquid to the sludge produced (SP). EC contribution was 23.68%–35.89% for LAM remediation. Thus, apparent mineralization (AM), the sum of EO and EC contributions, ranged from 80.63% to 97.79% for MET‐HCl and 61.18% to 96.82% for LAM. Process parameters were statistically optimized using response surface methodology (RSM) to simultaneously maximize TM and AM with minimal energy consumption and maximal current efficiency. The optimized conditions were 0.83 mA/cm2 CD and 86.66 ppm SEC for MET‐HCl. The corresponding values were 1.31 mA/cm2 CD and 79.51 ppm SEC for LAM. [ABSTRACT FROM AUTHOR]

Effective use of waste lignin is always a challenging task, technologies have been applied in the past to get value-added compounds from waste lignin. However, the existing technologies are not economical and efficient to produce the value-added chemicals. Alkali soluble lignin from rice straw hydrolysis residue (RSHR) is subjected to photocatalytic conversion into value-added compounds. Photocatalysis is one of the multifarious advanced oxidation processes (AOPs), carried out with TiO2 nanoparticles under a 125 W UV bulb. Gas chromatography mass spectroscopy (GCMS) confirmed the formation of vanillin and 4-hydroxybenzaldehyde. RSM and ANN techniques are adopted to optimize the process conditions for the maximization of the products. The response one (Y1) vanillin (24.61 mg) and second response (Y2) 4-hydroxybenzaldehyde (19.51 mg) is obtained at the optimal conditions as 7.0 h irradiation time, 2.763 g/L catalyst dose, 15 g/L lignin concentration, and 14.26 g/L NaOH dose for alkali treatment, suggested by face-centered central composite design (CCD). RSM and ANN models are statistically analyzed in terms of RMSE, R2 and AAD. For RSM the R2 0.9864 and 0.9787 while for ANN 0.9875 and 0.9847, closer to one warrant the good fitting of the models. Therefore, in terms of higher precision and predictive ability of both models the ANN model showed excellence for both responses as compared to the RSM model. [ABSTRACT FROM AUTHOR]

Low-temperature thermal decomposition (LTTD) of Rice straw hydrolysis residue (RSHR) was studied using thermogravimetric analysis and Fourier Transform Infrared spectroscopy (TGA-FTIR) at different heating rates. During thermogravimetry, the maximum rate of mass loss of 135% per min was observed at 339 °C (Tmax) for heating rate of 50 °C per min. Tmax decreased to 323, 315, and 299 °C with decrease in heating rate to 40, 30, and 20 °C min-1, respectively. LTTD of RSHR yields volatile oxygenated organics - acids, esters, aldehydes, ketones, alcohols and phenols - as revealed by the FTIR spectra of evolved gases. At increased decomposition temperature, carbonyl moieties were less conjugated. The main gaseous products of LTTD were carbon dioxide, carbon monoxide, and methane. Kinetics of LTTD of RSHR was analysed using thermogravimetry results. Activation energy of LTTD followed a Lorentzian distribution with respect to residual mass fraction (RMF). Dependence of LTTD rate on RMF was found to adhere to the truncated Sestak and Berggren model. [ABSTRACT FROM AUTHOR]

The article discusses the economic potential of black liquor electrolysis in treating small agro-based paper mills. It notes that economic simulation was used to calculate the potential costs and earnings associated with black liquor electrolysis for agro-based mills, which shows that black liquor would give a payback of 0.6-4.2 years. It mentions that economic indices affecting payback for low and high potential electrolysis are the capital costs of electrolyzer and the hydrogen selling price.

The article discusses a study on the aid of batch electrolysis experiments to reduce organic pollutants on value-added products of small agro-residue-based paper mills from soda black liquor of agricultural residues. It states that complete removal of COD is possible through prolonged electrolysis with a sodium carbonate remaining. It mentions that the process is energy-efficient even though it is slow.