A review of research trends on the usage of photocatalysis for wastewater treatment: bibliometric analysis.

Photocatalysis is seen as a viable alternative to treating water pollution, due to its flexibility, low cost, and ability to use visible light which is a plentiful and free energy source. Hence, determining the topics of interest and widening collaboration networks will go a long way in improving research in this field. In this study, we aimed to analyze the global research trends on the usage of photocatalysis for wastewater treatment using bibliometric analysis, centered on the outputs of publications, co-authorships, countries of affiliation, and author's keyword co-occurrences. Bibliometric analysis is a review method that is well-known and more conversant to Social Science. Employing it in Physical Science, which is rarely seen, will provide an avenue and yet another method of determining common research topics as well as the potential opportunities and future research in the field. A potential hybrid review paper of great importance to future research in the area will be produced. A total of 1373 articles published within 27 years between 1993 and 2020 were extracted from the Scopus database. In the beginning, less attention was given to the said topic, because after the oldest article was published in 1993, there was no record of other publications until after 5 years (1998). However, from 2002 there was a growing interest in research in that field, with a cumulative increase every year to date, except for a few years with fewer publications. Meanwhile, the number of publications has risen significantly from 2017 to 2020, with an increase of more than 70 publications every year; this is expected to increase rapidly in the coming years. Recently researchers are focusing on developing efficient photocatalysts for contaminants of emerging concern, like pharmaceutical and refinery wastewater, however, the usage of conducting polymers to produce nanocomposite which was found to be very effective is still lagged in wastewater treatment, as such it will be a good area of future research on effective photocatalysts for wastewater treatment. Supplementary Information: The online version contains supplementary material available at 10.1007/s40899-023-00868-5.

A simultaneous removal of ammonium and turbidity via an adsorptive coagulation for drinking water treatment process.

The utilization of natural zeolite (NZ) as an adsorbent for NH4+ removal was investigated. Three types of NZ (i.e., NZ01, NZ02, and NZ03) were characterized, and their NH4+ adsorption process in aqueous solution was evaluated. The effect of pH towards NH4+ adsorption showed that the NZ01 has the highest NH4+ adsorption capacity compared with other natural zeolites used. The application of NZ01 for a simultaneous removal of NH4+ and turbidity in synthetic NH4+-kaolin suspension by adsorptive coagulation process for treating drinking water was studied. The addition of NZ01 into the system increased the NH4+ removal efficiency (ηNH4+) from 11.64% without NZ01 to 41.86% with the addition of 0.2 g L-1 of NZ01. The turbidity removal (ηT), however, was insignificantly affected since the ηT was already higher than 98.0% over all studied parameter's ranges. The thermodynamic and kinetic data analyses suggested that the removal of NH4+ obeyed the Temkin isotherm model and pseudo-second-order kinetic model, respectively. Generally, the turbidity removal was due to the flocculation of destabilized solid particles by alum in the suspension system. The ηNH4+ in surface water was 29.31%, which is lower compared with the removal in the synthetic NH4+-kaolin suspension, but a high ηT (98.65%) was observed. It was found that the addition of the NZ01 could enhance the removal of NH4+ as well as other pollutants in the surface water.

An ionic liquid treatment and fractionation of cellulose, hemicellulose and lignin from oil palm empty fruit bunch.

This work reports on a complete isolation and characterization of lignocellulosic compounds from oil palm empty fruit bunch (OPEFB) by ionic liquid (IL) treatment and alkaline treatment processes. The fractionated lignocellulosic compounds were confirmed by FTIR and CP/MAS 13CNMR analyses. The yield of the cellulose, hemicellulose and lignin fractions was 52.72±1.50% wt., 27.17±1.68% wt. and 16.82±1.15% wt. with molecular weight of 1869g/mol, 1736g/mol and 2695g/mol, and degradation temperature of 325.65°C, 236.25°C, and 201.40°C, respectively. The SEM image illustrates the bundle-like fiber of cellulose fraction and smaller particle size of hemicellulose and lignin fractions with inconsistent shape. The XRD patterns depict the crystalline cellulose, amorphous lignin and partially amorphous hemicellulose fractions property. The IL could be recovered and reused with an overall recovery of 48% wt. after the fourth cycle.