Tufail Shah

Biogenically tailored anatase TiO ₂ nanoparticles (S3, 13–15 nm) were engineered via sequential mild thermal pre-treatment of an Eucalyptus globulus leaf extract-derived precursor, governing crystal nucleation-growth kinetics. This controlled thermal pre-treatment yielded a photocatalyst with enhanced crystallinity, suppressed aggregation, a shifted isoelectric point (IEP = 5.5–6.3), and a functionalised surface bearing residual biogenic carbonaceous species (5.33 wt% C). The S3 catalyst matched or outperformed commercial Degussa P25 in the degradation and mineralisation of three anionic azo dyes, Methyl Orange (MO), Acid Orange 7 (AO), and Orange G (OG), under both UV and natural solar irradiation, demonstrating its practical photocatalytic relevance. Dark adsorption assays ( AO > MO, governed by the higher structural charge of the divalent OG molecule and stabilisation of reactive hydrazone tautomers. Conversely, alkaline regimes induced electrostatic repulsion (Ti–O ⁻ ), shifting the degradation hierarchy to AO > OG > MO. Total organic carbon (TOC) analysis confirmed robust mineralisation with high carbon removal efficiency across all tested conditions. Complementary DFT calculations (M06-2X/6-31+G(d,p)) revealed that electrophilic ^• OH attack proceeds preferentially via exergonic C–N bond addition rather than N–N cleavage, with azo-hydrazone tautomerism serving as the key regioselectivity-governing factor.

Wastewater contaminated with hexavalent chromium (Cr(VI)) is a potential health and environmental hazard and hence the need for sustainable and cost-effective adsorbents. Cellulose nanocrystals (CNCs) were isolated from sugarcane bagasse by mild acid hydrolysis (10 % v/v H2SO4) and then used to prepare two different membranes, Membrane 1 (Chitosan-CNC, NaOH-crosslinked) and Membrane 2 (PVA-CNC, crosslinker-free) for comparative Cr(VI) removal from synthetic wastewater. DLS and XRD indicated the CNCs were colloidally stable (zeta potential: −25.7 mV) and were crystalline (cellulose Iβ) and had an average particle size of 90–126 nm. Successful composite formation and superior hydrophilicity of Membrane 2 (37.4°) compared to Membrane 1 (74.2°) was confirmed by FESEM, FTIR and contact angle measurements. The maximum adsorption capacities for Cr(VI) were 67.0 and 80.0 mg g ⁻¹ for the Membrane 1 and Membrane 2, respectively, which were obtained in batch adsorption studies at pH 4 and pH 3, respectively. The adsorption behavior of both membranes was well described by the Langmuir and Freundlich isotherm models, indicating monolayer adsorption on homogeneous sites alongside adsorption on heterogeneous surfaces. The pseudo-second-order kinetic model, together with positive values of Δ H ° and Δ S °, and negative for Δ G ° suggested that the adsorption process was predominantly chemisorption-driven, endothermic, and spontaneous. Moreover, after 5 regeneration cycles, both membranes still showed a good Cr(VI) removal percentage (Membrane 1: 86–70 %, Membrane 2: 94–72 %), proving their reusability. The results indicate that the agro-waste produced nanocellulose composites, with very little use of chemicals, can be useful, mechanically strong, and environmentally friendly heavy-metal adsorbents.

A pot experiment was conducted at the Nuclear Institute for Food and Agriculture (NIFA), Tarnab, Peshawar to increase the wheat (Triticum aestivum L.) growth and yield parameters by using different phosphatic fertilizers alone and in combination with organic source (FYM). Twelve treatments of inorganic and organic sources in sole or mixed ratios including control were applied in completely randomize design with three replications. Highly significant differences were noted for all the studied parameters except the harvest index. The soil used for the experiment was clay loam, alkaline in nature with lime content of 12.82% and low organic matter contents of 0.76%. The total nitrogen, extractable P and K were 0.13%, 2.89 mg kg-1, and 88 mg kg-1, respectively. Statistical analysis of the data showed that triple superphosphate (60 kg P) integrated with farm yard manure (5 t ha-1) significantly enhanced the plant height (61.76 cm), number of tillers pot-1 (13), spike length (6.81 cm), number of grains spike-1 (73), thousand grains weight (40.67 g), grain yield (33.60 g pot-1), and biological yield (69.50 g pot-1) of wheat plants. Chemical analysis of the wheat plants showed the significant effect of combined use of TSP and FYM (5 t ha-1) on plant P concentration in grains and straws, which was 0.50% and 0.17%, respectively. Whereas the maximum P uptake of 168.17 g pot-1 and 62.84 g pot-1 in grains and straws was recorded. It is suggested that the combined application of chemical fertilizers and organic manures could increase the growth and yield of crops under sustainable agriculture.

With increasing phosphate (P) entering the environment during agricultural application, the subsurface flow of particular P has been recently discussed as a vital P transport pathway. Iron (oxyhydr)oxide colloid-facilitated P transport is critical for iron and P biogeochemical processes in the subsurface. This study investigated the ferrihydrite colloid-facilitated P transport through adsorption and column experiments under different P concentrations and three pH conditions. Increased P loading on ferrihydrite colloids decreased the transport of ferrihydrite colloids (< 8.0%) under acid conditions through pore straining and irreversible attachment. Under neutral and alkaline conditions, ferrihydrite colloids exhibited more negative surfaces and smaller diameters with increasing P, which further enhanced ferrihydrite colloid transport (maximum to 95.6%). Ferrihydrite colloid-facilitated P transport was limited under acid conditions, and it was 10% - 57% enhancement under neutral and alkaline conditions with increasing P adsorption. Under neutral conditions, ferrihydrite colloid-facilitated P transport was strongest (maximum to 68.84%) because of its stronger ferrihydrite colloid transport than under acid conditions and larger P adsorption capacity than under alkaline conditions. Our findings indicate that the facilitated transport of ferrihydrite colloids in the presence of P may be appreciable in iron and phosphate-rich soil and subsurface systems, which is essential for evaluating the fate of iron and iron-facilitated P and potential environmental risks of P transport in the subsurface.